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• Java: If vs. Switch

  - by _ande_turner_

  I have a piece of code with a) which I replaced with b) purely for legibility ... a) if ( WORD[ INDEX ] == 'A' ) branch = BRANCH.A; /* B through to Y */ if ( WORD[ INDEX ] == 'Z' ) branch = BRANCH.Z; b) switch ( WORD[ INDEX ] ) { case 'A' : branch = BRANCH.A; break; /* B through to Y */ case 'Z' : branch = BRANCH.Z; break; } ... will the switch version cascade through all the permutations or jump to a case ? EDIT: Some of the answers below regard alternative approaches to the approach above. I have included the following to provide context for its use. The reason I asked, the Question above, was because the speed of adding words empirically improved. This isn't production code by any means, and was hacked together quickly as a PoC. The following seems to be a confirmation of failure for a thought experiment. I may need a much bigger corpus of words than the one I am currently using though. The failure arises from the fact I did not account for the null references still requiring memory. ( doh ! ) public class Dictionary { private static Dictionary ROOT; private boolean terminus; private Dictionary A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z; private static Dictionary instantiate( final Dictionary DICTIONARY ) { return ( DICTIONARY == null ) ? new Dictionary() : DICTIONARY; } private Dictionary() { this.terminus = false; this.A = this.B = this.C = this.D = this.E = this.F = this.G = this.H = this.I = this.J = this.K = this.L = this.M = this.N = this.O = this.P = this.Q = this.R = this.S = this.T = this.U = this.V = this.W = this.X = this.Y = this.Z = null; } public static void add( final String...STRINGS ) { Dictionary.ROOT = Dictionary.instantiate( Dictionary.ROOT ); for ( final String STRING : STRINGS ) Dictionary.add( STRING.toUpperCase().toCharArray(), Dictionary.ROOT , 0, STRING.length() - 1 ); } private static void add( final char[] WORD, final Dictionary BRANCH, final int INDEX, final int INDEX_LIMIT ) { Dictionary branch = null; switch ( WORD[ INDEX ] ) { case 'A' : branch = BRANCH.A = Dictionary.instantiate( BRANCH.A ); break; case 'B' : branch = BRANCH.B = Dictionary.instantiate( BRANCH.B ); break; case 'C' : branch = BRANCH.C = Dictionary.instantiate( BRANCH.C ); break; case 'D' : branch = BRANCH.D = Dictionary.instantiate( BRANCH.D ); break; case 'E' : branch = BRANCH.E = Dictionary.instantiate( BRANCH.E ); break; case 'F' : branch = BRANCH.F = Dictionary.instantiate( BRANCH.F ); break; case 'G' : branch = BRANCH.G = Dictionary.instantiate( BRANCH.G ); break; case 'H' : branch = BRANCH.H = Dictionary.instantiate( BRANCH.H ); break; case 'I' : branch = BRANCH.I = Dictionary.instantiate( BRANCH.I ); break; case 'J' : branch = BRANCH.J = Dictionary.instantiate( BRANCH.J ); break; case 'K' : branch = BRANCH.K = Dictionary.instantiate( BRANCH.K ); break; case 'L' : branch = BRANCH.L = Dictionary.instantiate( BRANCH.L ); break; case 'M' : branch = BRANCH.M = Dictionary.instantiate( BRANCH.M ); break; case 'N' : branch = BRANCH.N = Dictionary.instantiate( BRANCH.N ); break; case 'O' : branch = BRANCH.O = Dictionary.instantiate( BRANCH.O ); break; case 'P' : branch = BRANCH.P = Dictionary.instantiate( BRANCH.P ); break; case 'Q' : branch = BRANCH.Q = Dictionary.instantiate( BRANCH.Q ); break; case 'R' : branch = BRANCH.R = Dictionary.instantiate( BRANCH.R ); break; case 'S' : branch = BRANCH.S = Dictionary.instantiate( BRANCH.S ); break; case 'T' : branch = BRANCH.T = Dictionary.instantiate( BRANCH.T ); break; case 'U' : branch = BRANCH.U = Dictionary.instantiate( BRANCH.U ); break; case 'V' : branch = BRANCH.V = Dictionary.instantiate( BRANCH.V ); break; case 'W' : branch = BRANCH.W = Dictionary.instantiate( BRANCH.W ); break; case 'X' : branch = BRANCH.X = Dictionary.instantiate( BRANCH.X ); break; case 'Y' : branch = BRANCH.Y = Dictionary.instantiate( BRANCH.Y ); break; case 'Z' : branch = BRANCH.Z = Dictionary.instantiate( BRANCH.Z ); break; } if ( INDEX == INDEX_LIMIT ) branch.terminus = true; else Dictionary.add( WORD, branch, INDEX + 1, INDEX_LIMIT ); } public static boolean is( final String STRING ) { Dictionary.ROOT = Dictionary.instantiate( Dictionary.ROOT ); return Dictionary.is( STRING.toUpperCase().toCharArray(), Dictionary.ROOT, 0, STRING.length() - 1 ); } private static boolean is( final char[] WORD, final Dictionary BRANCH, final int INDEX, final int INDEX_LIMIT ) { Dictionary branch = null; switch ( WORD[ INDEX ] ) { case 'A' : branch = BRANCH.A; break; case 'B' : branch = BRANCH.B; break; case 'C' : branch = BRANCH.C; break; case 'D' : branch = BRANCH.D; break; case 'E' : branch = BRANCH.E; break; case 'F' : branch = BRANCH.F; break; case 'G' : branch = BRANCH.G; break; case 'H' : branch = BRANCH.H; break; case 'I' : branch = BRANCH.I; break; case 'J' : branch = BRANCH.J; break; case 'K' : branch = BRANCH.K; break; case 'L' : branch = BRANCH.L; break; case 'M' : branch = BRANCH.M; break; case 'N' : branch = BRANCH.N; break; case 'O' : branch = BRANCH.O; break; case 'P' : branch = BRANCH.P; break; case 'Q' : branch = BRANCH.Q; break; case 'R' : branch = BRANCH.R; break; case 'S' : branch = BRANCH.S; break; case 'T' : branch = BRANCH.T; break; case 'U' : branch = BRANCH.U; break; case 'V' : branch = BRANCH.V; break; case 'W' : branch = BRANCH.W; break; case 'X' : branch = BRANCH.X; break; case 'Y' : branch = BRANCH.Y; break; case 'Z' : branch = BRANCH.Z; break; } if ( branch == null ) return false; if ( INDEX == INDEX_LIMIT ) return branch.terminus; else return Dictionary.is( WORD, branch, INDEX + 1, INDEX_LIMIT ); } }

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• How can I make a jQuery UI 'draggable()' div draggable for touchscreen?

  - by artlung

  I have a jQuery UI draggable() that works in Firefox and Chrome. The user interface concept is basically click to create a "post-it" type item. Basically, I click or tap on div#everything (100% high and wide) that listens for clicks, and an input textarea displays. You add text, and then when you're done it saves it. You can drag this element around. That is working on normal browsers, but on an iPad I can test with I can't drag the items around. If I touch to select (it then dims slightly), I can't then drag it. It won't drag left or right at all. I can drag up or down, but I'm not dragging the individual div, I'm dragging the whole webpage. So here's the code I use to capture clicks: $('#everything').bind('click', function(e){ var elem = document.createElement('DIV'); STATE.top = e.pageY; STATE.left = e.pageX; var e = $(elem).css({ top: STATE.top, left: STATE.left }).html('<textarea></textarea>') .addClass('instance') .bind('click', function(event){ return false; }); $(this).append(e); }); And here's the code I use to "save" the note and turn the input div into just a display div: $('textarea').live('mouseleave', function(){ var val = jQuery.trim($(this).val()); STATE.content = val; if (val == '') { $(this).parent().remove(); } else { var div = $(this).parent(); div.text(val).css({ height: '30px' }); STATE.height = 30; if ( div.width() !== div[0].clientWidth || div.height () !== div[0].clientHeight ) { while (div.width() !== div[0].clientWidth || div.height () !== div[0].clientHeight) { var h = div.height() + 10; STATE.height = h; div.css({ height: (h) + 'px' }); // element just got scrollbars } } STATE.guid = uniqueID() div.addClass('savedNote').attr('id', STATE.guid).draggable({ stop: function() { var offset = $(this).offset(); STATE.guid = $(this).attr('id'); STATE.top = offset.top; STATE.left = offset.left; STATE.content = $(this).text(); STATE.height = $(this).height(); STATE.save(); } }); STATE.save(); $(this).remove(); } }); And I have this code when I load the page for saved notes: $('.savedNote').draggable({ stop: function() { STATE.guid = $(this).attr('id'); var offset = $(this).offset(); STATE.top = offset.top; STATE.left = offset.left; STATE.content = $(this).text(); STATE.height = $(this).height(); STATE.save(); } }); My STATE object handles saving the notes. Onload, this is the whole html body: <body> <div id="everything"></div> <div class="instance savedNote" id="iddd1b0969-c634-8876-75a9-b274ff87186b" style="top:134px;left:715px;height:30px;">Whatever dude</div> <div class="instance savedNote" id="id8a129f06-7d0c-3cb3-9212-0f38a8445700" style="top:131px;left:347px;height:30px;">Appointment 11:45am</div> <div class="instance savedNote" id="ide92e3d13-afe8-79d7-bc03-818d4c7a471f" style="top:144px;left:65px;height:80px;">What do you think of a board where you can add writing as much as possible?</div> <div class="instance savedNote" id="idef7fe420-4c19-cfec-36b6-272f1e9b5df5" style="top:301px;left:534px;height:30px;">This was submitted</div> <div class="instance savedNote" id="id93b3b56f-5e23-1bd1-ddc1-9be41f1efb44" style="top:390px;left:217px;height:30px;">Hello world from iPad.</div> </body> So, my question is really: how can I make this work better on iPad? I'm not set on jQuery UI, I'm wondering if this is something I'm doing wrong with jQuery UI, or jQuery, or whether there may be better frameworks for doing cross-platform/backward compatible draggable() elements that will work for touchscreen UIs. More general comments about how to write UI components like this would be welcome as well. Thanks!

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• Python bindings for C++ code using OpenCV giving segmentation fault

  - by lightalchemist

  I'm trying to write a python wrapper for some C++ code that make use of OpenCV but I'm having difficulties returning the result, which is a OpenCV C++ Mat object, to the python interpreter. I've looked at OpenCV's source and found the file cv2.cpp which has conversions functions to perform conversions to and fro between PyObject* and OpenCV's Mat. I made use of those conversions functions but got a segmentation fault when I tried to use them. I basically need some suggestions/sample code/online references on how to interface python and C++ code that make use of OpenCV, specifically with the ability to return OpenCV's C++ Mat to the python interpreter or perhaps suggestions on how/where to start investigating the cause of the segmentation fault. Currently I'm using Boost Python to wrap the code. Thanks in advance to any replies. The relevant code: // This is the function that is giving the segmentation fault. PyObject* ABC::doSomething(PyObject* image) { Mat m; pyopencv_to(image, m); // This line gives segmentation fault. // Some code to create cppObj from CPP library that uses OpenCV cv::Mat processedImage = cppObj->align(m); return pyopencv_from(processedImage); } The conversion functions taken from OpenCV's source follows. The conversion code gives segmentation fault at the commented line with "if (!PyArray_Check(o)) ...". static int pyopencv_to(const PyObject* o, Mat& m, const char* name = "<unknown>", bool allowND=true) { if(!o || o == Py_None) { if( !m.data ) m.allocator = &g_numpyAllocator; return true; } if( !PyArray_Check(o) ) // Segmentation fault inside PyArray_Check(o) { failmsg("%s is not a numpy array", name); return false; } int typenum = PyArray_TYPE(o); int type = typenum == NPY_UBYTE ? CV_8U : typenum == NPY_BYTE ? CV_8S : typenum == NPY_USHORT ? CV_16U : typenum == NPY_SHORT ? CV_16S : typenum == NPY_INT || typenum == NPY_LONG ? CV_32S : typenum == NPY_FLOAT ? CV_32F : typenum == NPY_DOUBLE ? CV_64F : -1; if( type < 0 ) { failmsg("%s data type = %d is not supported", name, typenum); return false; } int ndims = PyArray_NDIM(o); if(ndims >= CV_MAX_DIM) { failmsg("%s dimensionality (=%d) is too high", name, ndims); return false; } int size[CV_MAX_DIM+1]; size_t step[CV_MAX_DIM+1], elemsize = CV_ELEM_SIZE1(type); const npy_intp* _sizes = PyArray_DIMS(o); const npy_intp* _strides = PyArray_STRIDES(o); bool transposed = false; for(int i = 0; i < ndims; i++) { size[i] = (int)_sizes[i]; step[i] = (size_t)_strides[i]; } if( ndims == 0 || step[ndims-1] > elemsize ) { size[ndims] = 1; step[ndims] = elemsize; ndims++; } if( ndims >= 2 && step[0] < step[1] ) { std::swap(size[0], size[1]); std::swap(step[0], step[1]); transposed = true; } if( ndims == 3 && size[2] <= CV_CN_MAX && step[1] == elemsize*size[2] ) { ndims--; type |= CV_MAKETYPE(0, size[2]); } if( ndims > 2 && !allowND ) { failmsg("%s has more than 2 dimensions", name); return false; } m = Mat(ndims, size, type, PyArray_DATA(o), step); if( m.data ) { m.refcount = refcountFromPyObject(o); m.addref(); // protect the original numpy array from deallocation // (since Mat destructor will decrement the reference counter) }; m.allocator = &g_numpyAllocator; if( transposed ) { Mat tmp; tmp.allocator = &g_numpyAllocator; transpose(m, tmp); m = tmp; } return true; } static PyObject* pyopencv_from(const Mat& m) { if( !m.data ) Py_RETURN_NONE; Mat temp, *p = (Mat*)&m; if(!p->refcount || p->allocator != &g_numpyAllocator) { temp.allocator = &g_numpyAllocator; m.copyTo(temp); p = &temp; } p->addref(); return pyObjectFromRefcount(p->refcount); } My python test program: import pysomemodule # My python wrapped library. import cv2 def main(): myobj = pysomemodule.ABC("faces.train") # Create python object. This works. image = cv2.imread('61.jpg') processedImage = myobj.doSomething(image) cv2.imshow("test", processedImage) cv2.waitKey() if __name__ == "__main__": main()

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• What is the right tool to detect VMT or heap corruption in Delphi ?

  - by Roland Bengtsson

  I'm a member in a team that use Delphi 2007 for a larger application and we suspect heap corruption because sometimes there are strange bugs that have no other explanation. I believe that the Rangechecking option for the compiler is only for arrays. I want a tool that give an exception or log when there is a write on a memory address that is not allocated by the application. Regards EDIT: The error is of type: Error: Access violation at address 00404E78 in module 'BoatLogisticsAMCAttracsServer.exe'. Read of address FFFFFFDD EDIT2: Thanks for all suggestions. Unfortunately I think that the solution is deeper than that. We use a patched version of Bold for Delphi as we own the source. Probably there are some errors introduced in the Bold framwork. Yes we have a log with callstacks that are handled by JCL and also trace messages. So a callstack with the exception can lock like this: 20091210 16:02:29 (2356) [EXCEPTION] Raised EBold: Failed to derive ServerSession.mayDropSession: Boolean OCL expression: not active and not idle and timeout and (ApplicationKernel.allinstances->first.CurrentSession <> self) Error: Access violation at address 00404E78 in module 'BoatLogisticsAMCAttracsServer.exe'. Read of address FFFFFFDD. At Location BoldSystem.TBoldMember.CalculateDerivedMemberWithExpression (BoldSystem.pas:4016) Inner Exception Raised EBold: Failed to derive ServerSession.mayDropSession: Boolean OCL expression: not active and not idle and timeout and (ApplicationKernel.allinstances->first.CurrentSession <> self) Error: Access violation at address 00404E78 in module 'BoatLogisticsAMCAttracsServer.exe'. Read of address FFFFFFDD. At Location BoldSystem.TBoldMember.CalculateDerivedMemberWithExpression (BoldSystem.pas:4016) Inner Exception Call Stack: [00] System.TObject.InheritsFrom (sys\system.pas:9237) Call Stack: [00] BoldSystem.TBoldMember.CalculateDerivedMemberWithExpression (BoldSystem.pas:4016) [01] BoldSystem.TBoldMember.DeriveMember (BoldSystem.pas:3846) [02] BoldSystem.TBoldMemberDeriver.DoDeriveAndSubscribe (BoldSystem.pas:7491) [03] BoldDeriver.TBoldAbstractDeriver.DeriveAndSubscribe (BoldDeriver.pas:180) [04] BoldDeriver.TBoldAbstractDeriver.SetDeriverState (BoldDeriver.pas:262) [05] BoldDeriver.TBoldAbstractDeriver.Derive (BoldDeriver.pas:117) [06] BoldDeriver.TBoldAbstractDeriver.EnsureCurrent (BoldDeriver.pas:196) [07] BoldSystem.TBoldMember.EnsureContentsCurrent (BoldSystem.pas:4245) [08] BoldSystem.TBoldAttribute.EnsureNotNull (BoldSystem.pas:4813) [09] BoldAttributes.TBABoolean.GetAsBoolean (BoldAttributes.pas:3069) [10] BusinessClasses.TLogonSession._GetMayDropSession (code\BusinessClasses.pas:31854) [11] DMAttracsTimers.TAttracsTimerDataModule.RemoveDanglingLogonSessions (code\DMAttracsTimers.pas:237) [12] DMAttracsTimers.TAttracsTimerDataModule.UpdateServerTimeOnTimerTrig (code\DMAttracsTimers.pas:482) [13] DMAttracsTimers.TAttracsTimerDataModule.TimerKernelWork (code\DMAttracsTimers.pas:551) [14] DMAttracsTimers.TAttracsTimerDataModule.AttracsTimerTimer (code\DMAttracsTimers.pas:600) [15] ExtCtrls.TTimer.Timer (ExtCtrls.pas:2281) [16] Classes.StdWndProc (common\Classes.pas:11583) The inner exception part is the callstack at the moment an exception is reraised. EDIT3: The theory right now is that the Virtual Memory Table (VMT) is somehow broken. When this happen there is no indication of it. Only when a method is called an exception is raised (ALWAYS on address FFFFFFDD, -35 decimal) but then it is too late. You don't know the real cause for the error. Any hint of how to catch a bug like this is really appreciated!!! We have tried with SafeMM, but the problem is that the memory consumption is too high even when the 3 GB flag is used. So now I try to give a bounty to the SO community :) EDIT4: One hint is that according the log there is often (or even always) another exception before this. It can be for example optimistic locking in the database. We have tried to raise exceptions by force but in test environment it just works fine. EDIT5: Story continues... I did a search on the logs for the last 30 days now. The result: "Read of address FFFFFFDB" 0 "Read of address FFFFFFDC" 24 "Read of address FFFFFFDD" 270 "Read of address FFFFFFDE" 22 "Read of address FFFFFFDF" 7 "Read of address FFFFFFE0" 20 "Read of address FFFFFFE1" 0 So the current theory is that an enum (there is a lots in Bold) overwrite a pointer. I got 5 hits with different address above. It could mean that the enum holds 5 values where the second one is most used. If there is an exception a rollback should occur for the database and Boldobjects should be destroyed. Maybe there is a chance that not everything is destroyed and a enum still can write to an address location. If this is true maybe it is possible to search the code by a regexpr for an enum with 5 values ? EDIT6: To summarize, no there is no solution to the problem yet. I realize that I may mislead you a bit with the callstack. Yes there are a timer in that but there are other callstacks without a timer. Sorry for that. But there are 2 common factors. An exception with Read of address FFFFFFxx. Top of callstack is System.TObject.InheritsFrom (sys\system.pas:9237) This convince me that VilleK best describe the problem. I'm also convinced that the problem is somewhere in the Bold framework. But the BIG question is, how can problems like this be solved ? It is not enough to have an Assert like VilleK suggest as the damage has already happened and the callstack is gone at that moment. So to describe my view of what may cause the error: Somewhere a pointer is assigned a bad value 1, but it can be also 0, 2, 3 etc. An object is assigned to that pointer. There is method call in the objects baseclass. This cause method TObject.InheritsForm to be called and an exception appear on address FFFFFFDD. Those 3 events can be together in the code but they may also be used much later. I think this is true for the last method call. EDIT7: We work closely with the the author of Bold Jan Norden and he recently found a bug in the OCL-evaluator in Bold framework. When this was fixed these kinds of exceptions decreased a lot but they still occasionally come. But it is a big relief that this is almost solved.

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• Design pattern for parsing data that will be grouped to two different ways and flipped

  - by lewisblackfan

  I'm looking for an easily maintainable and extendable design model for a script to parse an excel workbook into two separate workbooks after pulling data from other locations like the command line, and a database. The high level details are as follows. I need to parse an excel workbook containing a sheet that lists unique question names, the only reliable information that can be parsed from the question name is the book code that identifies the title and edition of the textbook the question is associated with, the rest of the question name is not standardized well enough to be reliably parsed by computer. The general form of the question name is best described by the following regular expression. '^(\w+)\s(\w{1,2})\.(\w{1,2})\.(\w{1,3})\.(\w{1,3}\.)*$' The first sub-pattern is the book code, the second sub-pattern is 90% of the time the chapter, and the rest of the sub-patterns could be section, problem type, problem number, or question type information. There is no simple logic, at least not one I can find. There will be a minimum of three other columns in this spreadsheet; one column will be the chapter the question is associated with, the second will be the section within the chapter the question is associated with, and the third will be some kind of asset indicated by a uniform resource locator. 1 | 1 | qname1 | url | description | url | description ... 1 | 1 | qname2 | url | description 1 | 1 | qname3 | url | description | url | description | url | The asset can be indicated by a full or partial uniform resource locator, the partial url will need to be completed before it can be fed into the application. There theoretically could be no limit to the number of asset columns, the assets will be grouped in columns by type. Some times additional data will have to be retrieved from a database or combined with the book code before the asset url is complete and can be understood by the application that will be using the asset. The type is an abstraction, there are eight types right now, each with their own logic in how the uniform resource locator is handled and or completed, and I have to add a new type and its logic every three or four months. For each asset url there is the possibility of a description column, a character string for display in the application, but not always. (I've already worked out validating the description text, and squashing MSs obscure code page down to something 7-bit ascii can handle.) Now that all the details are filled-in I can get to the actual problem of parsing the file. I need to split the information in this excel workbook into two separate workbooks. The first workbook will group all the questions by section in rows. With the first cell being the section doublet and the rest of the cells in the row are the question names. 1.1 | qname1 | qname2 | qname3 | qname4 | 1.2 | qname1 | qname2 | qname3 | 1.3 | qname1 | qname2 | qname3 | qname4 | qname5 There is no set number of questions for each section as you can see from the above example. The second workbook is more complicated, there is one row per asset, and question names that have more than one asset will be duplicated. There will be four or five columns on this sheet. The first is the question name for the asset, the second is a media type used to select the correct icon for the asset in the application, the third is string representing the asset type, the four is the full and complete uniform resource locator for the asset, and the fifth columns is the optional text description for the asset. q1 | mtype1 | atype1 | url | description q1 | mtype2 | atype2 | url | description q1 | mtype2 | atype3 | url | description q2 | mtype1 | atype1 | url | description q2 | mtype2 | atype3 | url | description For the original six types I did have a script that parsed the source excel workbook into the other two excel workbooks, and I was able to add two more types until I ran aground on the implementation of the ninth type and tenth types. What broke my script was the fact that the ninth type is actually a sub-type of one of the original six, but with entirely different logic, and my mostly procedural script could not accommodate without duplicating a lot of code. I also had a lot of bugs in the script and will be writing the test first on this time around. I'm stuck with the format for the resulting two workbooks, this script is glue code, development went ahead with the project without bothering to get a complete spec from the sponsor. I work for the same company as the developers but in the editorial department, editorial is co-sponsor of the project, and am expected to fix pesky details like this (I'm foaming at the mouth as I type this). I've tried factories, I've tried different object models, but each resulting workbook is so different when I find a design that works for generating one workbook the code is not really usable for generating the other. What I would really like are ideas about a maintainable and extensible design for parsing the source workbook into both workbooks with maximum code reuse, and or sympathy.

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• Alpha Beta Search

  - by Becky

  I'm making a version of Martian Chess in java with AI and so far I THINK my move searching is semi-working, it seems to work alright for some depths but if I use a depth of 3 it returns a move for the opposite side...now the game is a bit weird because when a piece crosses half of the board, it becomes property of the other player so I think this is part of the problem. I'd be really greatful if someone could look over my code and point out any errors you think are there! (pls note that my evaluation function isn't nearly complete lol) MoveSearch.java public class MoveSearch { private Evaluation evaluate = new Evaluation(); private int blackPlayerScore, whitePlayerScore; public MoveContent bestMove; public MoveSearch(int blackScore, int whiteScore) { blackPlayerScore = blackScore; whitePlayerScore = whiteScore; } private Vector<Position> EvaluateMoves(Board board) { Vector<Position> positions = new Vector<Position>(); for (int i = 0; i < 32; i++) { Piece piece = null; if (!board.chessBoard[i].square.isEmpty()) { // store the piece piece = board.chessBoard[i].square.firstElement(); } // skip empty squares if (piece == null) { continue; } // skip the other players pieces if (piece.pieceColour != board.whosMove) { continue; } // generate valid moves for the piece PieceValidMoves validMoves = new PieceValidMoves(board.chessBoard, i, board.whosMove); validMoves.generateMoves(); // for each valid move for (int j = 0; j < piece.validMoves.size(); j++) { // store it as a position Position move = new Position(); move.startPosition = i; move.endPosition = piece.validMoves.elementAt(j); Piece pieceAttacked = null; if (!board.chessBoard[move.endPosition].square.isEmpty()) { // if the end position is not empty, store the attacked piece pieceAttacked = board.chessBoard[move.endPosition].square.firstElement(); } // if a piece is attacked if (pieceAttacked != null) { // append its value to the move score move.score += pieceAttacked.pieceValue; // if the moving pieces value is less than the value of the attacked piece if (piece.pieceValue < pieceAttacked.pieceValue) { // score extra points move.score += pieceAttacked.pieceValue - piece.pieceValue; } } // add the move to the set of positions positions.add(move); } } return positions; } // EvaluateMoves() private int SideToMoveScore(int score, PieceColour colour) { if (colour == PieceColour.Black){ return -score; } else { return score; } } public int AlphaBeta(Board board, int depth, int alpha, int beta) { //int best = -9999; // if the depth is 0, return the score of the current board if (depth <= 0) { board.printBoard(); System.out.println("Score: " + evaluate.EvaluateBoardScore(board)); System.out.println(""); int boardScore = evaluate.EvaluateBoardScore(board); return SideToMoveScore(boardScore, board.whosMove); } // fill the positions with valid moves Vector<Position> positions = EvaluateMoves(board); // if there are no available positions if (positions.size() == 0) { // and its blacks move if (board.whosMove == PieceColour.Black) { if (blackPlayerScore > whitePlayerScore) { // and they are winning, return a high number return 9999; } else if (whitePlayerScore == blackPlayerScore) { // if its a draw, lower number return 500; } else { // if they are losing, return a very low number return -9999; } } if (board.whosMove == PieceColour.White) { if (whitePlayerScore > blackPlayerScore) { return 9999; } else if (blackPlayerScore == whitePlayerScore) { return 500; } else { return -9999; } } } // for each position for (int i = 0; i < positions.size(); i++) { // store the position Position move = positions.elementAt(i); // temporarily copy the board Board temp = board.copyBoard(board); // make the move temp.makeMove(move.startPosition, move.endPosition); for (int x = 0; x < 32; x++) { if (!temp.chessBoard[x].square.isEmpty()) { PieceValidMoves validMoves = new PieceValidMoves(temp.chessBoard, x, temp.whosMove); validMoves.generateMoves(); } } // repeat the process recursively, decrementing the depth int val = -AlphaBeta(temp, depth - 1, -beta, -alpha); // if the value returned is better than the current best score, replace it if (val >= beta) { // beta cut-off return beta; } if (val > alpha) { alpha = val; bestMove = new MoveContent(alpha, move.startPosition, move.endPosition); } } // return the best score return alpha; } // AlphaBeta() } This is the makeMove method public void makeMove(int startPosition, int endPosition) { // quick reference to selected piece and attacked piece Piece selectedPiece = null; if (!(chessBoard[startPosition].square.isEmpty())) { selectedPiece = chessBoard[startPosition].square.firstElement(); } Piece attackedPiece = null; if (!(chessBoard[endPosition].square.isEmpty())) { attackedPiece = chessBoard[endPosition].square.firstElement(); } // if a piece is taken, amend score if (!(chessBoard[endPosition].square.isEmpty()) && attackedPiece != null) { if (attackedPiece.pieceColour == PieceColour.White) { blackScore = blackScore + attackedPiece.pieceValue; } if (attackedPiece.pieceColour == PieceColour.Black) { whiteScore = whiteScore + attackedPiece.pieceValue; } } // actually move the piece chessBoard[endPosition].square.removeAllElements(); chessBoard[endPosition].addPieceToSquare(selectedPiece); chessBoard[startPosition].square.removeAllElements(); // changing piece colour based on position if (endPosition > 15) { selectedPiece.pieceColour = PieceColour.White; } if (endPosition <= 15) { selectedPiece.pieceColour = PieceColour.Black; } //change to other player if (whosMove == PieceColour.Black) whosMove = PieceColour.White; else if (whosMove == PieceColour.White) whosMove = PieceColour.Black; } // makeMove()

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• Why is android:FLAG_BLUR_BEHIND creating a gradient background in my new activity instead of bluring

  - by nderraugh

  Hi, I've got two activities. One is supposed to be a blur in front of the other. The background activity has several ImageViews which are set up as thin gradients extending across most of the screen and 10dip high. When I start the second activity it sets the background as a gradient occupying the entire window space, that is it appears to be fill_parent'd for both height and width. If I comment out the ImageViews then it blurs and looks as expected. Any thoughts? Here's the code doing the blur. import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.WindowManager; import android.view.View.OnClickListener; public class TransluscentBlurSummaryB extends Activity { @Override protected void onCreate(Bundle icicle) { super.onCreate(icicle); getWindow().setFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND, WindowManager.LayoutParams.FLAG_BLUR_BEHIND); getWindow().getAttributes().dimAmount = 0.5f; getWindow().setFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND, WindowManager.LayoutParams.FLAG_DIM_BEHIND); setContentView(R.layout.sheetbdetails); OnClickListener clickListener = new OnClickListener() { public void onClick(View v) { TransluscentBlurSummaryB.this.finish(); } }; findViewById(R.id.sheetbdetailstable).setOnClickListener(clickListener); } } And here's the layout with the ImageView gradients. <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/summarysparent" > <!-- view1 goes on top --> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/view2" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true"> <Button android:layout_height="wrap_content" android:id="@+id/ButtonBack" android:layout_width="wrap_content" android:text="Back" android:width="100dp"></Button> <Button android:layout_height="wrap_content" android:id="@+id/ButtonNext" android:layout_width="wrap_content" android:layout_alignParentRight="true" android:text="Start Over" android:width="100dp"></Button> </RelativeLayout> <TextView android:id="@+id/view1" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_width="wrap_content" android:layout_centerHorizontal="true" android:textSize="10pt" android:text="Summary"/> <ScrollView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:id="@+id/summaryscrollview" android:layout_below="@+id/view1" android:layout_above="@+id/view2"> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:id="@+id/summarydetails" > <!-- view2 goes on the bottom --> <TextView android:id="@+id/textview2" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_below="@+id/view1" android:layout_centerHorizontal="true" android:text="Recommended Child Support Order" android:layout_marginTop="10dip" /> <ImageView android:id="@+id/horizontalLine1" android:layout_width="fill_parent" android:layout_marginLeft="5dip" android:layout_marginRight="5dip" android:layout_height="10dip" android:src="@drawable/black_white_gradient" android:layout_below="@+id/textview2" android:layout_marginTop="10dip" /> <TextView android:id="@+id/textview3" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_below="@+id/horizontalLine1" android:layout_centerHorizontal="true" android:text="You" android:layout_marginTop="10dip" /> <TextView android:id="@+id/textview10" android:layout_height="wrap_content" android:layout_width="150dp" android:layout_below="@+id/textview3" android:layout_centerHorizontal="true" android:layout_marginTop="10dip" android:gravity="center_horizontal" /> <ImageView android:id="@+id/horizontalLine2" android:layout_width="fill_parent" android:layout_marginLeft="5dip" android:layout_marginRight="5dip" android:layout_height="10dip" android:src="@drawable/black_white_gradient" android:layout_below="@+id/textview10" android:layout_marginTop="10dip" /> <TextView android:id="@+id/textview4" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_below="@+id/horizontalLine2" android:layout_centerHorizontal="true" android:text="Other Parent" android:layout_marginTop="10dip" /> <TextView android:id="@+id/textview11" android:layout_height="wrap_content" android:layout_width="150dp" android:layout_below="@+id/textview4" android:layout_centerHorizontal="true" android:layout_marginTop="10dip" android:text="$536.18" android:gravity="center_horizontal" /> <ImageView android:id="@+id/horizontalLine3" android:layout_width="fill_parent" android:layout_marginLeft="5dip" android:layout_marginRight="5dip" android:layout_height="10dip" android:src="@drawable/black_white_gradient" android:layout_below="@+id/textview11" android:layout_marginTop="10dip" /> <TextView android:id="@+id/textview5" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_below="@+id/horizontalLine3" android:layout_centerHorizontal="true" android:text="Calculation Details" android:layout_marginTop="15dip" /> <ImageView android:id="@+id/infoButton" android:src="@drawable/ic_menu_info_details" android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_below="@+id/horizontalLine3" android:layout_toRightOf="@+id/textview5" android:clickable="true" /> <ImageView android:id="@+id/horizontalLine4" android:layout_width="fill_parent" android:layout_marginLeft="5dip" android:layout_marginRight="5dip" android:layout_height="10dip" android:src="@drawable/black_white_gradient" android:layout_below="@+id/textview5" android:layout_marginTop="18dip" /> </RelativeLayout> </ScrollView> </RelativeLayout> The gradient drawable is this. <?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"> <gradient android:startColor="#FFFFFF" android:centerColor="#000000" android:endColor="#FFFFFF" android:angle="270"/> <padding android:left="7dp" android:top="7dp" android:right="7dp" android:bottom="7dp" /> <corners android:radius="8dp" /> </shape> And here's the layout from the activity doing the blurring on top. <?xml version="1.0" encoding="utf-8"?> <ScrollView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/sheetbdetails" android:layout_width="fill_parent" android:layout_height="fill_parent" android:clickable="true" > <TableLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:scrollbars="vertical" android:shrinkColumns="0" android:id="@+id/sheetbdetailstable" > <TableRow> <TextView android:padding="3dip" /> <TextView android:text="You" android:padding="3dip" /> <TextView android:text="@string/otherparent" android:padding="3dip" /> <TextView android:text="Combined" android:padding="3dip" /> </TableRow> </TableLayout> </ScrollView> The transparent windows are themed from styles.xml in the apidemos using @style/Theme.Transparent.

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• Java image conversion to RGB565

  - by Vladimir

  I try to convert image to RGB565 format. I read this image: BufferedImage bufImg = ImageIO.read(imagePathFile); sendImg = new BufferedImage(CONTROLLER_LCD_WIDTH/*320*/, CONTROLLER_LCD_HEIGHT/*240*/, BufferedImage.TYPE_USHORT_565_RGB); sendImg .getGraphics().drawImage(bufImg, 0, 0, CONTROLLER_LCD_WIDTH/*320*/, CONTROLLER_LCD_HEIGHT/*240*/, null); Here is it: Then I convert it to RGB565: int numByte=0; byte[] OutputImageArray = new byte[CONTROLLER_LCD_WIDTH*CONTROLLER_LCD_HEIGHT*2]; int i=0; int j=0; int len = OutputImageArray.length; for (i=0;i<CONTROLLER_LCD_WIDTH;i++) { for (j=0;j<CONTROLLER_LCD_HEIGHT;j++) { Color c = new Color(sendImg.getRGB(i, j)); int aRGBpix = sendImg.getRGB(i, j); int alpha; int red = c.getRed(); int green = c.getGreen(); int blue = c.getBlue(); //RGB888 red = (aRGBpix >> 16) & 0x0FF; green = (aRGBpix >> 8) & 0x0FF; blue = (aRGBpix >> 0) & 0x0FF; alpha = (aRGBpix >> 24) & 0x0FF; //RGB565 red = red >> 3; green = green >> 2; blue = blue >> 3; //A pixel is represented by a 4-byte (32 bit) integer, like so: //00000000 00000000 00000000 11111111 //^ Alpha ^Red ^Green ^Blue //Converting to RGB565 short pixel_to_send = 0; int pixel_to_send_int = 0; pixel_to_send_int = (red << 11) | (green << 5) | (blue); pixel_to_send = (short) pixel_to_send_int; //dividing into bytes byte byteH=(byte)((pixel_to_send >> 8) & 0x0FF); byte byteL=(byte)(pixel_to_send & 0x0FF); //Writing it to array - High-byte is second OutputImageArray[numByte]=byteH; OutputImageArray[numByte+1]=byteL; numByte+=2; } } Then I try to restore this from resulting array OutputImageArray: i=0; j=0; numByte=0; BufferedImage NewImg = new BufferedImage(CONTROLLER_LCD_WIDTH, CONTROLLER_LCD_HEIGHT, BufferedImage.TYPE_USHORT_565_RGB); for (i=0;i<CONTROLLER_LCD_WIDTH;i++) { for (j=0;j<CONTROLLER_LCD_HEIGHT;j++) { int curPixel=0; int alpha=0x0FF; int red; int green; int blue; byte byteL=0; byte byteH=0; byteH = OutputImageArray[numByte]; byteL = OutputImageArray[numByte+1]; curPixel= (byteH << 8) | (byteL); //RGB565 red = (curPixel >> (6+5)) & 0x01F; green = (curPixel >> 5) & 0x03F; blue = (curPixel) & 0x01F; //RGB888 red = red << 3; green = green << 2; blue = blue << 3; //aRGB curPixel = 0; curPixel = (alpha << 24) | (red << 16) | (green << 8) | (blue); NewImg.setRGB(i, j, curPixel); numByte+=2; } } I output this restored image. But I see that it looks very poor. I expected the lost of pictures quality. But as I thought, this picture has to have almost the same quality as the previous picture. - Is it right? Is my code right?

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• AS3 XML Slideshow Woes

  - by Chris

  Hello All, I am hoping someone out there can possibly shed some light on a couple issues I am having with an image slideshow I have been working on a simple slideshow for a project and everything was going great/as expected up until I created a function to hide the previous images before displaying the next. On the first pass through everything seems to run fine; once the slideshow starts over, the images don't show up, yet when it goes to load the following image, it plays the tween from the hide previous function which shows the image briefly before fading out. So essentially the display is blank, then the timer calls in the next slide and its a brief flash of an image fading out, and then blank again. Another issue I am having is the text that I am loading in from the XML does not seem to want to tween in or out as they are supposed to. Here is the code: import fl.transitions.Tween; import fl.transitions.easing.*; import fl.transitions.TweenEvent; import flash.display.BitmapData; import flash.display.Bitmap; import flash.display.Sprite; import flash.utils.Timer; import flash.events.TimerEvent; var filePath:String = "photo1.xml"; var iArray:Array = new Array(); var titleArray:Array = new Array(); var dateArray:Array = new Array(); var catArray:Array = new Array(); var descArray:Array = new Array(); var rotationSpeed:Number; var totalImages:Number; var dataList:XMLList; var imagesLoaded:Number = 0; var currImage:Number = 0; var rotationTimer:Timer; var oldTween:Tween; var imageContainer:Sprite = new Sprite(); var imageHolder:Sprite = new Sprite(); var titleContainer:Sprite = new Sprite(); var dateContainer:Sprite = new Sprite(); var catContainer:Sprite = new Sprite(); var descContainer:Sprite = new Sprite(); var theMask:Sprite = new Sprite(); theMask.graphics.beginFill(0x000000); theMask.graphics.drawRect(114, 25, 323, 332); addChild(theMask); var loader:URLLoader = new URLLoader(); loader.addEventListener(Event.COMPLETE, onComplete); loader.load(new URLRequest(filePath)); function onComplete (evt:Event):void{ var pigData:XML = new XML(evt.target.data); pigData.ignoreWhitespace; dataList = pigData.pic; totalImages = dataList.length(); rotationSpeed = pigData.@speed * 1000; stage.scaleMode = StageScaleMode.NO_SCALE; loadImages(); rotationTimer = new Timer(rotationSpeed); rotationTimer.addEventListener(TimerEvent.TIMER, rotateImage); rotationTimer.start(); } function loadImages() { for (var i:Number = 0; i < totalImages; i++) { var imageURL:String = dataList[i].big; var imageLoader:Loader = new Loader(); imageLoader.load(new URLRequest(imageURL)); imageLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, imageLoaded); iArray.push(imageLoader); var titleField:TextField = new TextField(); var dateField:TextField = new TextField(); var catField:TextField = new TextField(); var descField:TextField = new TextField(); titleField.text = dataList[i].title; titleField.autoSize = TextFieldAutoSize.LEFT; titleArray.push(titleField); dateField.text = dataList[i].date; dateField.autoSize = TextFieldAutoSize.LEFT; dateArray.push(dateField); catField.text = dataList[i].category; catField.autoSize = TextFieldAutoSize.LEFT; catArray.push(catField); descField.text = dataList[i].description; descField.autoSize = TextFieldAutoSize.LEFT; descArray.push(descField); } } function imageLoaded(evt:Event):void { imagesLoaded++; if (imagesLoaded == totalImages) { showImage(); } } function showImage():void { addChild(imageContainer); imageContainer.addChild(imageHolder); imageContainer.addChild(titleContainer); imageContainer.addChild(dateContainer); imageContainer.addChild(catContainer); imageContainer.addChild(descContainer); changeImage(); } function changeImage():void { var currentImage:Loader = Loader(iArray[currImage]); imageHolder.addChild(currentImage); currentImage.x = (stage.stageWidth - currentImage.width)/2; currentImage.y = (imageHolder.height - currentImage.height)/2; imageHolder.mask = theMask; new Tween(imageHolder, "alpha", Regular.easeOut, 0, 1, 1, true); var titleField:TextField = TextField(titleArray[currImage]); titleContainer.addChild(titleField); titleField.x = 107; titleField.y = 365; var titleTween:Tween = new Tween(titleField, "alpha", Regular.easeOut, 0, 1, 1, true); var dateField:TextField = TextField(dateArray[currImage]); dateContainer.addChild(dateField); dateField.x = 107; dateField.y = 375; var dateTween:Tween = new Tween(dateField, "alpha", Regular.easeOut, 0, 1, 1, true); var catField:TextField = TextField(catArray[currImage]); catContainer.addChild(catField); catField.x = 107; catField.y = 385; var catTween:Tween = new Tween(catField, "alpha", Regular.easeOut, 0, 1, 1, true); var descField:TextField = TextField(descArray[currImage]); descContainer.addChild(descField); descField.x = 107; descField.y = 395; var descTween:Tween = new Tween(descField, "alpha", Regular.easeOut, 0, 1, 1, true); } function rotateImage(evt:TimerEvent) { hidePrev(); currImage++; if (currImage == totalImages) { currImage = 0; } changeImage(); } function hidePrev():void{ var oldImage:Loader = Loader(imageHolder.getChildAt(0)); oldTween = new Tween(oldImage,"alpha", Regular.easeOut, 1, 0, 1, true); oldTween.addEventListener(TweenEvent.MOTION_FINISH, onFadeOut) var oldTitle:TextField = TextField(titleContainer.getChildAt(0)); var oldTitleTween:Tween = new Tween(oldTitle,"alpha", Regular.easeOut, 1, 0, 1, true); var oldDate:TextField = TextField(dateContainer.getChildAt(0)); var oldDateTween:Tween = new Tween(oldDate,"alpha",Regular.easeOut,1,0,1,true); var oldCat:TextField = TextField(catContainer.getChildAt(0)); var oldCatTween:Tween = new Tween(oldCat,"alpha",Regular.easeOut,1,0,1,true); var oldDesc:TextField = TextField(descContainer.getChildAt(0)); var oldDescTween:Tween = new Tween(oldDesc,"alpha",Regular.easeOut,1,0,1,true); } function onFadeOut(evt:TweenEvent):void{ imageHolder.removeChildAt(0); titleContainer.removeChildAt(0); dateContainer.removeChildAt(0); catContainer.removeChildAt(0); descContainer.removeChildAt(0); } I'm no flash whiz, bet can generally figure most issues out by either analyzing the code, or digging around online; however, this has me stumped. Any help would really be appreciated, and I thank you all in advance.

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• Modelling boost::Lockable with semaphore rather than mutex (previously titled: Unlocking a mutex fr

  - by dan

  I'm using the C++ boost::thread library, which in my case means I'm using pthreads. Officially, a mutex must be unlocked from the same thread which locks it, and I want the effect of being able to lock in one thread and then unlock in another. There are many ways to accomplish this. One possibility would be to write a new mutex class which allows this behavior. For example: class inter_thread_mutex{ bool locked; boost::mutex mx; boost::condition_variable cv; public: void lock(){ boost::unique_lock<boost::mutex> lck(mx); while(locked) cv.wait(lck); locked=true; } void unlock(){ { boost::lock_guard<boost::mutex> lck(mx); if(!locked) error(); locked=false; } cv.notify_one(); } // bool try_lock(); void error(); etc. } I should point out that the above code doesn't guarantee FIFO access, since if one thread calls lock() while another calls unlock(), this first thread may acquire the lock ahead of other threads which are waiting. (Come to think of it, the boost::thread documentation doesn't appear to make any explicit scheduling guarantees for either mutexes or condition variables). But let's just ignore that (and any other bugs) for now. My question is, if I decide to go this route, would I be able to use such a mutex as a model for the boost Lockable concept. For example, would anything go wrong if I use a boost::unique_lock< inter_thread_mutex for RAII-style access, and then pass this lock to boost::condition_variable_any.wait(), etc. On one hand I don't see why not. On the other hand, "I don't see why not" is usually a very bad way of determining whether something will work. The reason I ask is that if it turns out that I have to write wrapper classes for RAII locks and condition variables and whatever else, then I'd rather just find some other way to achieve the same effect. EDIT: The kind of behavior I want is basically as follows. I have an object, and it needs to be locked whenever it is modified. I want to lock the object from one thread, and do some work on it. Then I want to keep the object locked while I tell another worker thread to complete the work. So the first thread can go on and do something else while the worker thread finishes up. When the worker thread gets done, it unlocks the mutex. And I want the transition to be seemless so nobody else can get the mutex lock in between when thread 1 starts the work and thread 2 completes it. Something like inter_thread_mutex seems like it would work, and it would also allow the program to interact with it as if it were an ordinary mutex. So it seems like a clean solution. If there's a better solution, I'd be happy to hear that also. EDIT AGAIN: The reason I need locks to begin with is that there are multiple master threads, and the locks are there to prevent them from accessing shared objects concurrently in invalid ways. So the code already uses loop-level lock-free sequencing of operations at the master thread level. Also, in the original implementation, there were no worker threads, and the mutexes were ordinary kosher mutexes. The inter_thread_thingy came up as an optimization, primarily to improve response time. In many cases, it was sufficient to guarantee that the "first part" of operation A, occurs before the "first part" of operation B. As a dumb example, say I punch object 1 and give it a black eye. Then I tell object 1 to change it's internal structure to reflect all the tissue damage. I don't want to wait around for the tissue damage before I move on to punch object 2. However, I do want the tissue damage to occur as part of the same operation; for example, in the interim, I don't want any other thread to reconfigure the object in such a way that would make tissue damage an invalid operation. (yes, this example is imperfect in many ways, and no I'm not working on a game) So we made the change to a model where ownership of an object can be passed to a worker thread to complete an operation, and it actually works quite nicely; each master thread is able to get a lot more operations done because it doesn't need to wait for them all to complete. And, since the event sequencing at the master thread level is still loop-based, it is easy to write high-level master-thread operations, as they can be based on the assumption that an operation is complete when the corresponding function call returns. Finally, I thought it would be nice to use inter_thread mutex/semaphore thingies using RAII with boost locks to encapsulate the necessary synchronization that is required to make the whole thing work.

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• scrolling lags in emacs 23.2 with GTK

  - by mefiX

  Hey there, I am using emacs 23.2 with the GTK toolkit. I built emacs from source using the following configure-params: ./configure --prefix=/usr --without-makeinfo --without-sound Which builds emacs with the following configuration: Where should the build process find the source code? /home/****/incoming/emacs-23.2 What operating system and machine description files should Emacs use? `s/gnu-linux.h' and `m/intel386.h' What compiler should emacs be built with? gcc -g -O2 -Wdeclaration-after-statement -Wno-pointer-sign Should Emacs use the GNU version of malloc? yes (Using Doug Lea's new malloc from the GNU C Library.) Should Emacs use a relocating allocator for buffers? yes Should Emacs use mmap(2) for buffer allocation? no What window system should Emacs use? x11 What toolkit should Emacs use? GTK Where do we find X Windows header files? Standard dirs Where do we find X Windows libraries? Standard dirs Does Emacs use -lXaw3d? no Does Emacs use -lXpm? yes Does Emacs use -ljpeg? yes Does Emacs use -ltiff? yes Does Emacs use a gif library? yes -lgif Does Emacs use -lpng? yes Does Emacs use -lrsvg-2? no Does Emacs use -lgpm? yes Does Emacs use -ldbus? yes Does Emacs use -lgconf? no Does Emacs use -lfreetype? yes Does Emacs use -lm17n-flt? no Does Emacs use -lotf? yes Does Emacs use -lxft? yes Does Emacs use toolkit scroll bars? yes When I'm scrolling within files of a common size (about 1000 lines) holding the up/down-keys, emacs almost hangs and produces about 50% CPU-load. I use the following plugins: ido linum tabbar auto-complete-config Starting emacs with -q fixes the problem, but then I don't have any plugins. I can't figure out, which part of my .emacs is responsible for this behaviour. Here's an excerpt of my .emacs-file: (require 'ido) (ido-mode 1) (require 'linum) (global-linum-mode 1) (require 'tabbar) (tabbar-mode 1) (tabbar-local-mode 0) (tabbar-mwheel-mode 0) (setq tabbar-buffer-groups-function (lambda () (list "All"))) (global-set-key [M-left] 'tabbar-backward) (global-set-key [M-right] 'tabbar-forward) ;; hide the toolbar (gtk etc.) (tool-bar-mode -1) ;; Mouse scrolling enhancements (setq mouse-wheel-progressive-speed nil) (setq mouse-wheel-scroll-amount '(5 ((shift) . 5) ((control) . nil))) ;; Smart-HOME (defun smart-beginning-of-line () "Forces the cursor to jump to the first none whitespace char of the current line when pressing HOME" (interactive) (let ((oldpos (point))) (back-to-indentation) (and (= oldpos (point)) (beginning-of-line)))) (put 'smart-beginning-of-line 'CUA 'move) (global-set-key [home] 'smart-beginning-of-line) (custom-set-variables ;; custom-set-variables was added by Custom. ;; If you edit it by hand, you could mess it up, so be careful. ;; Your init file should contain only one such instance. ;; If there is more than one, they won't work right. '(column-number-mode t) '(cua-mode t nil (cua-base)) '(custom-buffer-indent 4) '(delete-selection-mode nil) '(display-time-24hr-format t) '(display-time-day-and-date 1) '(display-time-mode t) '(global-font-lock-mode t nil (font-lock)) '(inhibit-startup-buffer-menu t) '(inhibit-startup-screen t) '(pc-select-meta-moves-sexps t) '(pc-select-selection-keys-only t) '(pc-selection-mode t nil (pc-select)) '(scroll-bar-mode (quote right)) '(show-paren-mode t) '(standard-indent 4) '(uniquify-buffer-name-style (quote forward) nil (uniquify))) (setq-default tab-width 4) (setq-default indent-tabs-mode t) (setq c-basic-offset 4) ;; Highlighting of the current line (global-hl-line-mode 1) (set-face-background 'hl-line "#E8F2FE") (defalias 'yes-or-no-p 'y-or-n-p) (display-time) (set-language-environment "Latin-1") ;; Change cursor color according to mode (setq djcb-read-only-color "gray") ;; valid values are t, nil, box, hollow, bar, (bar . WIDTH), hbar, ;; (hbar. HEIGHT); see the docs for set-cursor-type (setq djcb-read-only-cursor-type 'hbar) (setq djcb-overwrite-color "red") (setq djcb-overwrite-cursor-type 'box) (setq djcb-normal-color "black") (setq djcb-normal-cursor-type 'bar) (defun djcb-set-cursor-according-to-mode () "change cursor color and type according to some minor modes." (cond (buffer-read-only (set-cursor-color djcb-read-only-color) (setq cursor-type djcb-read-only-cursor-type)) (overwrite-mode (set-cursor-color djcb-overwrite-color) (setq cursor-type djcb-overwrite-cursor-type)) (t (set-cursor-color djcb-normal-color) (setq cursor-type djcb-normal-cursor-type)))) (add-hook 'post-command-hook 'djcb-set-cursor-according-to-mode) (define-key global-map '[C-right] 'forward-sexp) (define-key global-map '[C-left] 'backward-sexp) (define-key global-map '[s-left] 'windmove-left) (define-key global-map '[s-right] 'windmove-right) (define-key global-map '[s-up] 'windmove-up) (define-key global-map '[s-down] 'windmove-down) (define-key global-map '[S-down-mouse-1] 'mouse-stay-and-copy) (define-key global-map '[C-M-S-down-mouse-1] 'mouse-stay-and-swap) (define-key global-map '[S-mouse-2] 'mouse-yank-and-kill) (define-key global-map '[C-S-down-mouse-1] 'mouse-stay-and-kill) (define-key global-map "\C-a" 'mark-whole-buffer) (custom-set-faces ;; custom-set-faces was added by Custom. ;; If you edit it by hand, you could mess it up, so be careful. ;; Your init file should contain only one such instance. ;; If there is more than one, they won't work right. '(default ((t (:inherit nil :stipple nil :background "#f7f9fa" :foreground "#191919" :inverse-video nil :box nil :strike-through nil :overline nil :underline nil :slant normal :weight normal :height 98 :width normal :foundry "unknown" :family "DejaVu Sans Mono")))) '(font-lock-builtin-face ((((class color) (min-colors 88) (background light)) (:foreground "#642880" :weight bold)))) '(font-lock-comment-face ((((class color) (min-colors 88) (background light)) (:foreground "#3f7f5f")))) '(font-lock-constant-face ((((class color) (min-colors 88) (background light)) (:weight bold)))) '(font-lock-doc-face ((t (:inherit font-lock-string-face :foreground "#3f7f5f")))) '(font-lock-function-name-face ((((class color) (min-colors 88) (background light)) (:foreground "Black" :weight bold)))) '(font-lock-keyword-face ((((class color) (min-colors 88) (background light)) (:foreground "#7f0055" :weight bold)))) '(font-lock-preprocessor-face ((t (:inherit font-lock-builtin-face :foreground "#7f0055" :weight bold)))) '(font-lock-string-face ((((class color) (min-colors 88) (background light)) (:foreground "#0000c0")))) '(font-lock-type-face ((((class color) (min-colors 88) (background light)) (:foreground "#7f0055" :weight bold)))) '(font-lock-variable-name-face ((((class color) (min-colors 88) (background light)) (:foreground "Black")))) '(minibuffer-prompt ((t (:foreground "medium blue")))) '(mode-line ((t (:background "#222222" :foreground "White")))) '(tabbar-button ((t (:inherit tabbar-default :foreground "dark red")))) '(tabbar-button-highlight ((t (:inherit tabbar-default :background "white" :box (:line-width 2 :color "white"))))) '(tabbar-default ((t (:background "gray90" :foreground "gray50" :box (:line-width 3 :color "gray90") :height 100)))) '(tabbar-highlight ((t (:underline t)))) '(tabbar-selected ((t (:inherit tabbar-default :foreground "blue" :weight bold)))) '(tabbar-separator ((t nil))) '(tabbar-unselected ((t (:inherit tabbar-default))))) Any suggestions? Kind regards, mefiX

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• How to associate Wi-Fi beacon info with a virtual "location"?

  - by leander

  We have a piece of embedded hardware that will sense 802.11 beacons, and we're using this to make a map of currently visible bssid -> signalStrength. Given this map, we would like to make a determination: Is this likely to be a location I have been to before? If so, what is its ID? If not, I should remember this location: generate a new ID. Now what should I store (and how should I store it) to make future determinations easier? This is for an augmented-reality app/game. We will be using it to associate particular characters and events with "locations". The device does not have internet or cellular access, so using a geolocation service is out of consideration for the time being. (We don't really need to know where we are in reality, just be able to determine if we return there.) It isn't crucial that it be extremely accurate, but it would be nice if it was tolerant to signal strength changes or the occasional missing beacon. It should be usable in relatively low numbers of access points (e.g. rural house with one wireless router) or many (wandering around a dense metropolis). In the case of a city, it should change location every few minutes of walking (continuously-overlapping signals make this a bit more tricky in naive code). A reasonable number of false positives (match a location when we aren't actually there) is acceptable. The wrong character/event showing up just adds a bit of variety. False negatives (no location match) are a bit more troublesome: this will tend to add a better-matching new location to the saved locations, masking the old one. While we will have additional logic to ensure locations that the device hasn't seen in a while will "orphan" any associated characters or events (if e.g. you move to a different country), we'd prefer not to mask and eventually orphan locations you do visit regularly. Some technical complications: signalStrength is returned as 1-4; presumably it's related to dB, but we are not sure exactly how; in my experiments it tends to stick to either 1 or 4, but occasionally we see numbers in between. (Tech docs on the hardware are sparse.) The device completes a scan of one-quarter of the channel space every second; so it takes about 4-5 seconds to get a complete picture of what's around. The list isn't always complete. (We are making strides to fix this using some slight sampling period randomization, as recommended by the library docs. We're also investigating ways to increase the number of scans without killing our performance; the hardware/libs are poorly behaved when it comes to saturating the bus.) We have only kilobytes to store our history. We have a "working" impl now, but it is relatively naive, and flaky in the face of real-world Wi-Fi behavior. Rough pseudocode: // recordLocation() -- only store strength 4 locations m_savedLocations[g_nextId++] = filterForStrengthGE( m_currentAPs, 4 ); // determineLocation() bestPoints = -inf; foreach ( oldLoc in m_savedLocations ) { points = 0.0; foreach ( ap in m_currentAPs ) { if ( oldLoc.has( ap ) ) { switch ( ap.signalStrength ) { case 3: points += 1.0; break; case 4: points += 2.0; break; } } } points /= oldLoc.numAPs; if ( points > bestPoints ) { bestLoc = oldLoc; bestPoints = points; } } if ( bestLoc && bestPoints > 1.0 ) { if ( bestPoints >= (2.0 - epsilon) ) { // near-perfect match. // update location with any new high-strength APs that have appeared bestLoc.addAPs( filterForStrengthGE( m_currentAPs, 4 ) ); } return bestLoc; } else { return NO_MATCH; } We record a location currently only when we have NO_MATCH and the app determines it's time for a new event. (The "near-perfect match" code above would appear to make it harder to match in the future... It's mostly to keep new powerful APs from being associated with other locations, but you'd think we'd need something to counter this if e.g. an AP doesn't show up in the next 10 times I match a location.) I have a feeling that we're missing some things from set theory or graph theory that would assist in grouping/classification of this data, and perhaps providing a better "confidence level" on matches, and better robustness against missed beacons, signal strength changes, and the like. Also it would be useful to have a good method for mutating locations over time. Any useful resources out there for this sort of thing? Simple and/or robust approaches we're missing?

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• Save object states in .data or attr - Performance vs CSS?

  - by Neysor

  In response to my answer yesterday about rotating an Image, Jamund told me to use .data() instead of .attr() First I thought that he is right, but then I thought about a bigger context... Is it always better to use .data() instead of .attr()? I looked in some other posts like what-is-better-data-or-attr or jquery-data-vs-attrdata The answers were not satisfactory for me... So I moved on and edited the example by adding CSS. I thought it might be useful to make a different Style on each image if it rotates. My style was the following: .rp[data-rotate="0"] { border:10px solid #FF0000; } .rp[data-rotate="90"] { border:10px solid #00FF00; } .rp[data-rotate="180"] { border:10px solid #0000FF; } .rp[data-rotate="270"] { border:10px solid #00FF00; } Because design and coding are often separated, it could be a nice feature to handle this in CSS instead of adding this functionality into JavaScript. Also in my case the data-rotate is like a special state which the image currently has. So in my opinion it make sense to represent it within the DOM. I also thought this could be a case where it is much better to save with .attr() then with .data(). Never mentioned before in one of the posts I read. But then i thought about performance. Which function is faster? I built my own test following: <!DOCTYPE HTML> <html> <head> <title>test</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> <script type="text/javascript"> function runfirst(dobj,dname){ console.log("runfirst "+dname); console.time(dname+"-attr"); for(i=0;i<10000;i++){ dobj.attr("data-test","a"+i); } console.timeEnd(dname+"-attr"); console.time(dname+"-data"); for(i=0;i<10000;i++){ dobj.data("data-test","a"+i); } console.timeEnd(dname+"-data"); } function runlast(dobj,dname){ console.log("runlast "+dname); console.time(dname+"-data"); for(i=0;i<10000;i++){ dobj.data("data-test","a"+i); } console.timeEnd(dname+"-data"); console.time(dname+"-attr"); for(i=0;i<10000;i++){ dobj.attr("data-test","a"+i); } console.timeEnd(dname+"-attr"); } $().ready(function() { runfirst($("#rp4"),"#rp4"); runfirst($("#rp3"),"#rp3"); runlast($("#rp2"),"#rp2"); runlast($("#rp1"),"#rp1"); }); </script> </head> <body> <div id="rp1">Testdiv 1</div> <div id="rp2" data-test="1">Testdiv 2</div> <div id="rp3">Testdiv 3</div> <div id="rp4" data-test="1">Testdiv 4</div> </body> </html> It should also show if there is a difference with a predefined data-test or not. One result was this: runfirst #rp4 #rp4-attr: 515ms #rp4-data: 268ms runfirst #rp3 #rp3-attr: 505ms #rp3-data: 264ms runlast #rp2 #rp2-data: 260ms #rp2-attr: 521ms runlast #rp1 #rp1-data: 284ms #rp1-attr: 525ms So the .attr() function did always need more time than the .data() function. This is an argument for .data() I thought. Because performance is always an argument! Then I wanted to post my results here with some questions, and in the act of writing I compared with the questions Stack Overflow showed me (similar titles) And true enough, there was one interesting post about performance I read it and run their example. And now I am confused! This test showed that .data() is slower then .attr() !?!! Why is that so? First I thought it is because of a different jQuery library so I edited it and saved the new one. But the result wasn't changing... So now my questions to you: Why are there some differences in the performance in these two examples? Would you prefer to use data- HTML5 attributes instead of data, if it represents a state? Although it wouldn't be needed at the time of coding? Why - Why not? Now depending on the performance: Would performance be an argument for you using .attr() instead of data, if it shows that .attr() is better? Although data is meant to be used for .data()? UPDATE 1: I did see that without overhead .data() is much faster. Misinterpreted the data :) But I'm more interested in my second question. :) Would you prefer to use data- HTML5 attributes instead of data, if it represents a state? Although it wouldn't be needed at the time of coding? Why - Why not? Are there some other reasons you can think of, to use .attr() and not .data()? e.g. interoperability? because .data() is jquery style and HTML Attributes can be read by all... UPDATE 2: As we see from T.J Crowder's speed test in his answer attr is much faster then data! which is again confusing me :) But please! Performance is an argument, but not the highest! So give answers to my other questions please too!

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• Error using CreateFileMapping - C

  - by Jamie Keeling

  Hello, I am using the tutorial on this MSDN link to implement a way of transferring data from one process to another. Although I was advised in an earlier question to use the Pipe methods, due to certain constraints I have no choice but to use the CreateFileMapping method. Now, i've succesfully managed to make two seperate window form projects within the same solution and by editing some properties both of the forms load at the same time. Furthermore I have managed to implement the code given in the MSDN sample into the first (Producer) and second (Consumer) program without any compilation errors. The problem I am having now is when I run the first program and try to create the handle to the mapped file, I am given an error saying it was unsuccesful and I do not understand why this is happening. I have added both the Producer and Consumer code files to demonstrate what I am trying to do. Producer: #include <windows.h> #include <stdio.h> #include <conio.h> //File header definitions #define IDM_FILE_ROLLDICE 1 #define IDM_FILE_QUIT 2 #define BUF_SIZE 256 TCHAR szName[]=TEXT("Global\\MyFileMappingObject"); TCHAR szMsg[]=TEXT("Message from first process!"); void AddMenus(HWND); LRESULT CALLBACK WindowFunc(HWND, UINT, WPARAM, LPARAM); ////Standard windows stuff - omitted to save space. ////////////////////// // WINDOWS FUNCTION // ////////////////////// LRESULT CALLBACK WindowFunc(HWND hMainWindow, UINT message, WPARAM wParam, LPARAM lParam) { WCHAR buffer[256]; LPCTSTR pBuf; struct DiceData storage; HANDLE hMapFile; switch(message) { case WM_CREATE: { // Create Menus AddMenus(hMainWindow); } break; case WM_COMMAND: // Intercept menu choices switch(LOWORD(wParam)) { case IDM_FILE_ROLLDICE: { //Roll dice and store results in variable //storage = RollDice(); ////Copy results to buffer //swprintf(buffer,255,L"Dice 1: %d, Dice 2: %d",storage.dice1,storage.dice2); ////Show via message box //MessageBox(hMainWindow,buffer,L"Dice Result",MB_OK); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { MessageBox(hMainWindow,L"Could not create file mapping object",L"Error",NULL); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainWindow,L"Could not map view of file",L"Error",NULL); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, szMsg, (_tcslen(szMsg) * sizeof(TCHAR))); _getch(); UnmapViewOfFile(pBuf); CloseHandle(hMapFile); } break; case IDM_FILE_QUIT: SendMessage(hMainWindow, WM_CLOSE, 0, 0); break; } break; case WM_DESTROY: PostQuitMessage(0); break; } return DefWindowProc(hMainWindow, message, wParam, lParam); } // //Setup menus // Consumer: #include <windows.h> #include <stdio.h> #include <conio.h> //File header definitions #define IDM_FILE_QUIT 1 #define IDM_FILE_POLL 2 #define BUF_SIZE 256 TCHAR szName[]=TEXT("Global\\MyFileMappingObject"); //Prototypes void AddMenus(HWND); LRESULT CALLBACK WindowFunc(HWND, UINT, WPARAM, LPARAM); //More standard windows creation, again omitted. ////////////////////// // WINDOWS FUNCTION // ////////////////////// LRESULT CALLBACK WindowFunc(HWND hMainWindow, UINT message, WPARAM wParam, LPARAM lParam) { HANDLE hMapFile; LPCTSTR pBuf; switch(message) { case WM_CREATE: { // Create Menus AddMenus(hMainWindow); break; } case WM_COMMAND: { // Intercept menu choices switch(LOWORD(wParam)) { case IDM_FILE_POLL: { hMapFile = OpenFileMapping( FILE_MAP_ALL_ACCESS, // read/write access FALSE, // do not inherit the name szName); // name of mapping object if (hMapFile == NULL) { MessageBox(hMainWindow,L"Could not open file mapping object",L"Error",NULL); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainWindow,L"Could not map view of file",L"Error",NULL); CloseHandle(hMapFile); return 1; } MessageBox(NULL, pBuf, TEXT("Process2"), MB_OK); UnmapViewOfFile(pBuf); CloseHandle(hMapFile); break; } case IDM_FILE_QUIT: SendMessage(hMainWindow, WM_CLOSE, 0, 0); break; } break; } case WM_DESTROY: { PostQuitMessage(0); break; } } return DefWindowProc(hMainWindow, message, wParam, lParam); } // //Setup menus // It's by no means tidy and final but it's just a start, thanks for any help.

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• HDFS some datanodes of cluster are suddenly disconnected while reducers are running

  - by user1429825

  I have 8 slave computers and 1 master computer for running Hadoop (ver 0.21) some datanodes of cluster are suddenly disconnected while I was running MapReduce code on 10GB data After all mappers finished and around 80% of reducers was processed, randomly one or more datanode disconned from network. and then the other datanodes start to disappear from network even if I killed the MapReduce job when I found some datanode was disconnected. I've tried to change dfs.datanode.max.xcievers to 4096, turned off fire-walls of all computing node, disabled selinux and increased the number of file open limit to 20000 but they didn't work at all... anyone have a idea to solve this problem? followings are error log from mapreduce 12/06/01 12:31:29 INFO mapreduce.Job: Task Id : attempt_201206011227_0001_r_000006_0, Status : FAILED java.io.IOException: Bad connect ack with firstBadLink as ***.***.***.148:20010 at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:889) at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:820) at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:427) and followings are logs from datanode 2012-06-01 13:01:01,118 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Receiving block blk_-5549263231281364844_3453 src: /*.*.*.147:56205 dest: /*.*.*.142:20010 2012-06-01 13:01:01,136 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(*.*.*.142:20010, storageID=DS-1534489105-*.*.*.142-20010-1337757934836, infoPort=20075, ipcPort=20020) Starting thread to transfer block blk_-3849519151985279385_5906 to *.*.*.147:20010 2012-06-01 13:01:19,135 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(*.*.*.142:20010, storageID=DS-1534489105-*.*.*.142-20010-1337757934836, infoPort=20075, ipcPort=20020):Failed to transfer blk_-5797481564121417802_3453 to *.*.*.146:20010 got java.net.ConnectException: > Connection timed out at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:701) at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206) at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:373) at org.apache.hadoop.hdfs.server.datanode.DataNode$DataTransfer.run(DataNode.java:1257) at java.lang.Thread.run(Thread.java:722) 2012-06-01 13:06:20,342 INFO org.apache.hadoop.hdfs.server.datanode.DataBlockScanner: Verification succeeded for blk_6674438989226364081_3453 2012-06-01 13:09:01,781 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(*.*.*.142:20010, storageID=DS-1534489105-*.*.*.142-20010-1337757934836, infoPort=20075, ipcPort=20020):Failed to transfer blk_-3849519151985279385_5906 to *.*.*.147:20010 got java.net.SocketTimeoutException: 480000 millis timeout while waiting for channel to be ready for write. ch : java.nio.channels.SocketChannel[connected local=/*.*.*.142:60057 remote=/*.*.*.147:20010] at org.apache.hadoop.net.SocketIOWithTimeout.waitForIO(SocketIOWithTimeout.java:246) at org.apache.hadoop.net.SocketOutputStream.waitForWritable(SocketOutputStream.java:164) at org.apache.hadoop.net.SocketOutputStream.transferToFully(SocketOutputStream.java:203) at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendChunks(BlockSender.java:388) at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendBlock(BlockSender.java:476) at org.apache.hadoop.hdfs.server.datanode.DataNode$DataTransfer.run(DataNode.java:1284) at java.lang.Thread.run(Thread.java:722) hdfs-site.xml <configuration> <property> <name>dfs.name.dir</name> <value>/home/hadoop/data/name</value> </property> <property> <name>dfs.data.dir</name> <value>/home/hadoop/data/hdfs1,/home/hadoop/data/hdfs2,/home/hadoop/data/hdfs3,/home/hadoop/data/hdfs4,/home/hadoop/data/hdfs5</value> </property> <property> <name>dfs.replication</name> <value>3</value> </property> <property> <name>dfs.datanode.max.xcievers</name> <value>4096</value> </property> <property> <name>dfs.http.address</name> <value>0.0.0.0:20070</value> <description>50070 The address and the base port where the dfs namenode web ui will listen on. If the port is 0 then the server will start on a free port. </description> </property> <property> <name>dfs.datanode.http.address</name> <value>0.0.0.0:20075</value> <description>50075 The datanode http server address and port. If the port is 0 then the server will start on a free port. </description> </property> <property> <name>dfs.secondary.http.address</name> <value>0.0.0.0:20090</value> <description>50090 The secondary namenode http server address and port. If the port is 0 then the server will start on a free port. </description> </property> <property> <name>dfs.datanode.address</name> <value>0.0.0.0:20010</value> <description>50010 The address where the datanode server will listen to. If the port is 0 then the server will start on a free port. </description> <property> <name>dfs.datanode.ipc.address</name> <value>0.0.0.0:20020</value> <description>50020 The datanode ipc server address and port. If the port is 0 then the server will start on a free port. </description> </property> <property> <name>dfs.datanode.https.address</name> <value>0.0.0.0:20475</value> </property> <property> <name>dfs.https.address</name> <value>0.0.0.0:20470</value> </property> </configuration> mapred-site.xml <configuration> <property> <name>mapred.job.tracker</name> <value>masternode:29001</value> </property> <property> <name>mapred.system.dir</name> <value>/home/hadoop/data/mapreduce/system</value> </property> <property> <name>mapred.local.dir</name> <value>/home/hadoop/data/mapreduce/local</value> </property> <property> <name>mapred.map.tasks</name> <value>32</value> <description> default number of map tasks per job.</description> </property> <property> <name>mapred.tasktracker.map.tasks.maximum</name> <value>4</value> </property> <property> <name>mapred.reduce.tasks</name> <value>8</value> <description> default number of reduce tasks per job.</description> </property> <property> <name>mapred.map.child.java.opts</name> <value>-Xmx2048M</value> </property> <property> <name>io.sort.mb</name> <value>500</value> </property> <property> <name>mapred.task.timeout</name> <value>1800000</value> <!-- 30 minutes --> </property> <property> <name>mapred.job.tracker.http.address</name> <value>0.0.0.0:20030</value> <description> 50030 The job tracker http server address and port the server will listen on. If the port is 0 then the server will start on a free port. </description> </property> <property> <name>mapred.task.tracker.http.address</name> <value>0.0.0.0:20060</value> <description> 50060 </property> </configuration>

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• Why does C qicksort function implementation works much slower (tape comparations, tape swapping) than bobble sort function?

  - by Artur Mustafin

  I'm going to implement a toy tape "mainframe" for a students, showing the quickness of "quicksort" class functions (recursive or not, does not really matters, due to the slow hardware, and well known stack reversal techniques) comparatively to the "bubblesort" function class, so, while I'm clear about the hardware implementation ans controllers, i guessed that quicksort function is much faster that other ones in terms of sequence, order and comparation distance (it is much faster to rewind the tape from the middle than from the very end, because of different speed of rewind). Unfortunately, this is not the true, this simple "bubble" code shows great improvements comparatively to the "quicksort" functions in terms of comparison distances, direction and number of comparisons and writes. So I have 3 questions: Does I have mistaken in my implememtation of quicksort function? Does I have mistaken in my implememtation of bubblesoft function? If not, why the "bubblesort" function is works much faster in (comparison and write operations) than "quicksort" function? I already have a "quicksort" function: void quicksort(float *a, long l, long r, const compare_function& compare) { long i=l, j=r, temp, m=(l+r)/2; if (l == r) return; if (l == r-1) { if (compare(a, l, r)) { swap(a, l, r); } return; } if (l < r-1) { while (1) { i = l; j = r; while (i < m && !compare(a, i, m)) i++; while (m < j && !compare(a, m, j)) j--; if (i >= j) { break; } swap(a, i, j); } if (l < m) quicksort(a, l, m, compare); if (m < r) quicksort(a, m, r, compare); return; } } and the kind of my own implememtation of the "bubblesort" function: void bubblesort(float *a, long l, long r, const compare_function& compare) { long i, j, k; if (l == r) { return; } if (l == r-1) { if (compare(a, l, r)) { swap(a, l, r); } return; } if (l < r-1) { while(l < r) { i = l; j = l; while (i < r) { i++; if (!compare(a, j, i)) { continue; } j = i; } if (l < j) { swap(a, l, j); } l++; i = r; k = r; while(l < i) { i--; if (!compare(a, i, k)) { continue; } k = i; } if (k < r) { swap(a, k, r); } r--; } return; } } I have used this sort functions in a test sample code, like this: #include <stdio.h> #include <stdlib.h> #include <math.h> #include <conio.h> long swap_count; long compare_count; typedef long (*compare_function)(float *, long, long ); typedef void (*sort_function)(float *, long , long , const compare_function& ); void init(float *, long ); void print(float *, long ); void sort(float *, long, const sort_function& ); void swap(float *a, long l, long r); long less(float *a, long l, long r); long greater(float *a, long l, long r); void bubblesort(float *, long , long , const compare_function& ); void quicksort(float *, long , long , const compare_function& ); void main() { int n; printf("n="); scanf("%d",&n); printf("\r\n"); long i; float *a = (float *)malloc(n*n*sizeof(float)); sort(a, n, &bubblesort); print(a, n); sort(a, n, &quicksort); print(a, n); free(a); } long less(float *a, long l, long r) { compare_count++; return *(a+l) < *(a+r) ? 1 : 0; } long greater(float *a, long l, long r) { compare_count++; return *(a+l) > *(a+r) ? 1 : 0; } void swap(float *a, long l, long r) { swap_count++; float temp; temp = *(a+l); *(a+l) = *(a+r); *(a+r) = temp; } float tg(float x) { return tan(x); } float ctg(float x) { return 1.0/tan(x); } void init(float *m,long n) { long i,j; for (i = 0; i < n; i++) { for (j=0; j< n; j++) { m[i + j*n] = tg(0.2*(i+1)) + ctg(0.3*(j+1)); } } } void print(float *m, long n) { long i, j; for(i = 0; i < n; i++) { for(j = 0; j < n; j++) { printf(" %5.1f", m[i + j*n]); } printf("\r\n"); } printf("\r\n"); } void sort(float *a, long n, const sort_function& sort) { long i, sort_compare = 0, sort_swap = 0; init(a,n); for(i = 0; i < n*n; i+=n) { if (fmod (i / n, 2) == 0) { compare_count = 0; swap_count = 0; sort(a, i, i+n-1, &less); if (swap_count == 0) { compare_count = 0; sort(a, i, i+n-1, &greater); } sort_compare += compare_count; sort_swap += swap_count; } } printf("compare=%ld\r\n", sort_compare); printf("swap=%ld\r\n", sort_swap); printf("\r\n"); }

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• Segmentation fault in my C program

  - by user233542

  I don't understand why this would give me a seg fault. Any ideas? This is the function that returns the signal to stop the program (plus the other function that is called within this): double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } The values buff, l, N are defined using a #define statement. l = 401, buff = 50, N = 2000 Here is the full code: #include <stdio.h> #include <stdlib.h> #include <math.h> #define w 10 /*characteristic width of a soliton*/ #define dx 0.05 /*distance between lattice sites*/ #define s (2*w)/dx /*size of soliton shape*/ #define l (int)(s+1) /*array length for soliton*/ #define N (int)2000 /*length of field array--lattice sites*/ #define Pi (double)4*atan(1) #define buff (int)50 double shoot(double Sol[N],double A,double c); double bisect(double A0,double A1,double Sol[N],double tol,double c); void super_pos(double antiSol[N],double Sol[N],double phi[][N]); void vel_ver(double phi[][N],double v,double c,int tsteps,double dt); int main(int argc, char **argv) { double c,Sol[N],antiSol[N],A,A0,A1,tol,v,dt; int tsteps,i; FILE *fp1,*fp2,*fp3; fp1 = fopen("soliton.dat","w"); fp2 = fopen("final-phi.dat","w"); fp3 = fopen("energy.dat","w"); printf("Please input the number of time steps:"); scanf("%d",&tsteps); printf("Also, enter the time step size:"); scanf("%lf",&dt); do{ printf("Please input the parameter c in the interval [-1/3,1]:"); scanf("%lf",&c);} while(c < (-1./3.) || c > 1.); printf("Please input the inital speed of eiter soliton:"); scanf("%lf",&v); double phi[tsteps+1][N]; tol = 0.0000001; A0 = 0.; A1 = 2.*Pi; A = bisect(A0,A1,Sol,tol,c); shoot(Sol,A,c); for (i=0;i<N;i++) { fprintf(fp1,"%d\t",i); fprintf(fp1,"%lf\n",Sol[i]); } fclose(fp1); super_pos(antiSol,Sol,phi); /*vel_ver(phi,v,c,tsteps,dt); for (i=0;i<N;i++){ fprintf(fp2,"%d\t",i); fprintf(fp2,"%lf\n",phi[tsteps][i]); }*/ } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } void super_pos(double antiSol[N],double Sol[N],double phi[][N]) { int i; /*for (i=0;i<N;i++) { phi[i]=0; } for (i=buffer+s;i<1950-s;i++) { phi[i]=2*Pi; }*/ for (i=0;i<N;i++) { antiSol[i] = Sol[N-i]; } /*for (i=0;i<s+1;i++) { phi[buffer+j] = Sol[j]; phi[1549+j] = antiSol[j]; }*/ for (i=0;i<N;i++) { phi[0][i] = antiSol[i] + Sol[i] - 2.*Pi; } } /* This funciton will set the 2nd input array to the derivative at the time t, for all points x in the lattice */ void deriv2(double phi[][N],double DphiDx2[][N],int t) { //double SolDer2[s+1]; int x; for (x=0;x<N;x++) { DphiDx2[t][x] = (phi[buff+x+1][t] + phi[buff+x-1][t] - 2.*phi[x][t])/(dx*dx); } /*for (i=0;i<N;i++) { ptr[i] = &SolDer2[i]; }*/ //return DphiDx2[x]; } void vel_ver(double phi[][N],double v,double c,int tsteps,double dt) { int t,x; double d1,d2,dp,DphiDx1[tsteps+1][N],DphiDx2[tsteps+1][N],dpdt[tsteps+1][N],p[tsteps+1][N]; for (t=0;t<tsteps;t++){ if (t==0){ for (x=0;x<N;x++){//inital conditions deriv2(phi,DphiDx2,t); dpdt[t][x] = DphiDx2[t][x] - sin(phi[t][x]) - sin(3.*phi[t][x]); DphiDx1[t][x] = (phi[t][x+1] - phi[t][x])/dx; p[t][x] = -v*DphiDx1[t][x]; } } for (x=0;x<N;x++){//velocity-verlet phi[t+1][x] = phi[t][x] + dt*p[t][x] + (dt*dt/2)*dpdt[t][x]; p[t+1][x] = p[t][x] + (dt/2)*dpdt[t][x]; deriv2(phi,DphiDx2,t+1); dpdt[t][x] = DphiDx2[t][x] - sin(phi[t+1][x]) - sin(3.*phi[t+1][x]); p[t+1][x] += (dt/2)*dpdt[t+1][x]; } } } So, this really isn't due to my overwriting the end of the Sol array. I've commented out both functions that I suspected of causing the problem (bisect or shoot) and inserted a print function. Two things happen. When I have code like below: double A,Pi,B,c; c=0; Pi = 4.*atan(1.); A = Pi; B = 1./4.; printf("%lf",B); B = shoot(Sol,A,c); printf("%lf",B); I get a segfault from the function, shoot. However, if I take away the shoot function so that I have: double A,Pi,B,c; c=0; Pi = 4.*atan(1.); A = Pi; B = 1./4.; printf("%lf",B); it gives me a segfault at the printf... Why!?

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• New hire expectations... (Am I being unreasonable?)

  - by user295841

  I work for a very small custom software shop. We currently consist me and my boss. My boss is an old FoxPro DOS developer and OOP makes him uncomfortable. He is planning on taking a back seat in the next few years to hopefully enjoy a “partial retirement”. I will be taking over the day to day operations and we are now desperately looking for more help. We tried Monster.com, Dice.com, and others a few years ago when we started our search. We had no success. We have tried outsourcing overseas (total disaster), hiring kids right out of college (mostly a disaster but that’s where I came from), interns (good for them, not so good for us) and hiring laid off “experienced” developers (there was a reason they were laid off). I have heard hiring practices discussed on podcasts, blogs, etc... and have tried a few. The “Fizz Buzz” test was a good one. One kid looked physically ill before he finally gave up. I think my problem is that I have grown so much as a developer since I started here that I now have a high standard. I hear/read very intelligent people podcasts and blogs and I know that there are lots of people out there that can do the job. I don’t want to settle for less than a “good” developer. Perhaps my expectations are unreasonable. I expect any good developer (entry level or experienced) to be billable (at least paying their own wage) in under one month. I expect any good developer to be able to be productive (at least dangerous) in any language or technology with only a few days of research/training. I expect any good developer to be able to take a project from initial customer request to completion with little or no help from others. Am I being unreasonable? What constitutes a valuable developer? What should be expected of an entry level developer? What should be expected of an experienced developer? I realize that everyone is different but there has to be some sort of expectations standard, right? I have been giving the test project below to potential canidates to weed them out. Good idea? Too much? Too little? Please let me know what you think. Thanks. Project ID: T00001 Description: Order Entry System Deadline: 1 Week Scope The scope of this project is to develop a fully function order entry system. Screen/Form design must be user friendly and promote efficient data entry and modification. User experience (Navigation, Screen/Form layouts, Look and Feel…) is at the developer’s discretion. System may be developed using any technologies that conform to the technical and system requirements. Deliverables Complete source code Database setup instructions (Scripts or restorable backup) Application installation instructions (Installer or installation procedure) Any necessary documentation Technical Requirements Server Platform – Windows XP / Windows Server 2003 / SBS Client Platform – Windows XP Web Browser (If applicable) – IE 8 Database – At developer’s discretion (Must be a relational SQL database.) Language – At developer’s discretion All data must be normalized. (+) All data must maintain referential integrity. (++) All data must be indexed for optimal performance. System must handle concurrency. System Requirements Customer Maintenance Customer records must have unique ID. Customer data will include Name, Address, Phone, etc. User must be able to perform all CRUD (Create, Read, Update, and Delete) operations on the Customer table. User must be able to enter a specific Customer ID to edit. User must be able to pull up a sortable/queryable search grid/utility to find a customer to edit. Validation must be performed prior to database commit. Customer record cannot be deleted if the customer has an order in the system. (++) Inventory Maintenance Part records must have unique ID. Part data will include Description, Price, UOM (Unit of Measure), etc. User must be able to perform all CRUD operations on the part table. User must be able to enter a specific Part ID to edit. User must be able to pull up a sortable/queryable search grid/utility to find a part to edit. Validation must be performed prior to database commit. Part record cannot be deleted if the part has been used in an order. (++) Order Entry Order records must have a unique auto-incrementing key (Order Number). Order data must be split into a header/detail structure. (+) Order can contain an infinite number of detail records. Order header data will include Order Number, Customer ID (++), Order Date, Order Status (Open/Closed), etc. Order detail data will include Part Number (++), Quantity, Price, etc. User must be able to perform all CRUD operations on the order tables. User must be able to enter a specific Order Number to edit. User must be able to pull up a sortable/queryable search grid/utility to find an order to edit. User must be able to print an order form from within the order entry form. Validation must be performed prior to database commit. Reports Customer Listing – All Customers in the system. Inventory Listing – All parts in the system. Open Order Listing – All open orders in system. Customer Order Listing – All orders for specific customer. All reports must include sorts and filter functions where applicable. Ex. Customer Listing by range of Customer IDs. Open Order Listing by date range.

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• System.Timers.Timer leaking due to "direct delegate roots"

  - by alimbada

  Apologies for the rather verbose and long-winded post, but this problem's been perplexing me for a few weeks now so I'm posting as much information as I can in order to get this resolved quickly. We have a WPF UserControl which is being loaded by a 3rd party app. The 3rd party app is a presentation application which loads and unloads controls on a schedule defined by an XML file which is downloaded from a server. Our control, when it is loaded into the application makes a web request to a web service and uses the data from the response to display some information. We're using an MVVM architecture for the control. The entry point of the control is a method that is implementing an interface exposed by the main app and this is where the control's configuration is set up. This is also where I set the DataContext of our control to our MainViewModel. The MainViewModel has two other view models as properties and the main UserControl has two child controls. Depending on the data received from the web service, the main UserControl decides which child control to display, e.g. if there is a HTTP error or the data received is not valid, then display child control A, otherwise display child control B. As you'd expect, these two child controls bind two separate view models each of which is a property of MainViewModel. Now child control B (which is displayed when the data is valid) has a RefreshService property/field. RefreshService is an object that is responsible for updating the model in a number of ways and contains 4 System.Timers.Timers; a _modelRefreshTimer a _viewRefreshTimer a _pageSwitchTimer a _retryFeedRetrievalOnErrorTimer (this is only enabled when something goes wrong with retrieving data). I should mention at this point that there are two types of data; the first changes every minute, the second changes every few hours. The controls' configuration decides which type we are using/displaying. If data is of the first type then we update the model quite frequently (every 30 seconds) using the _modelRefreshTimer's events. If the data is of the second type then we update the model after a longer interval. However, the view still needs to be refreshed every 30 seconds as stale data needs to be removed from the view (hence the _viewRefreshTimer). The control also paginates the data so we can see more than we can fit on the display area. This works by breaking the data up into Lists and switching the CurrentPage (which is a List) property of the view model to the right List. This is done by handling the _pageSwitchTimer's Elapsed event. Now the problem My problem is that the control, when removed from the visual tree doesn't dispose of it's timers. This was first noticed when we started getting an unusually high number of requests on the web server end very soon after deploying this control and found that requests were being made at least once a second! We found that the timers were living on and not stopping hours after the control had been removed from view and that the more timers there were the more requests piled up at the web server. My first solution was to implement IDisposable for the RefreshService and do some clean up when the control's UnLoaded event was fired. Within the RefreshServices Dispose method I've set Enabled to false for all the timers, then used the Stop() method on all of them. I've then called Dispose() too and set them to null. None of this worked. After some reading around I found that event handlers may hold references to Timers and prevent them from being disposed and collected. After some more reading and researching I found that the best way around this was to use the Weak Event Pattern. Using this blog and this blog I've managed to work around the shortcomings in the Weak Event pattern. However, none of this solves the problem. Timers are still not being disabled or stopped (let alone disposed) and web requests are continuing to build up. Mem Profiler tells me that "This type has N instances that are directly rooted by a delegate. This can indicate the delegate has not been properly removed" (where N is the number of instances). As far as I can tell though, all listeners of the Elapsed event for the timers are being removed during the cleanup so I can't understand why the timers continue to run. Thanks for reading. Eagerly awaiting your suggestions/comments/solutions (if you got this far :-p)

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• Record audio via MediaRecorder

  - by Isuru Madusanka

  I am trying to record audio by MediaRecorder, and I get an error, I tried to change everything and nothing works. Last two hours I try to find the error, I used Log class too and I found out that error occurred when it call recorder.start() method. What could be the problem? public class AudioRecorderActivity extends Activity { MediaRecorder recorder; File audioFile = null; private static final String TAG = "AudioRecorderActivity"; private View startButton; private View stopButton; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); startButton = findViewById(R.id.start); stopButton = findViewById(R.id.stop); setContentView(R.layout.main); } public void startRecording(View view) throws IOException{ startButton.setEnabled(false); stopButton.setEnabled(true); File sampleDir = Environment.getExternalStorageDirectory(); try{ audioFile = File.createTempFile("sound", ".3gp", sampleDir); }catch(IOException e){ Toast.makeText(getApplicationContext(), "SD Card Access Error", Toast.LENGTH_LONG).show(); Log.e(TAG, "Sdcard access error"); return; } recorder = new MediaRecorder(); recorder.setAudioSource(MediaRecorder.AudioSource.MIC); recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB); recorder.setAudioEncodingBitRate(16); recorder.setAudioSamplingRate(44100); recorder.setOutputFile(audioFile.getAbsolutePath()); recorder.prepare(); recorder.start(); } public void stopRecording(View view){ startButton.setEnabled(true); stopButton.setEnabled(false); recorder.stop(); recorder.release(); addRecordingToMediaLibrary(); } protected void addRecordingToMediaLibrary(){ ContentValues values = new ContentValues(4); long current = System.currentTimeMillis(); values.put(MediaStore.Audio.Media.TITLE, "audio" + audioFile.getName()); values.put(MediaStore.Audio.Media.DATE_ADDED, (int)(current/1000)); values.put(MediaStore.Audio.Media.MIME_TYPE, "audio/3gpp"); values.put(MediaStore.Audio.Media.DATA, audioFile.getAbsolutePath()); ContentResolver contentResolver = getContentResolver(); Uri base = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; Uri newUri = contentResolver.insert(base, values); sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, newUri)); Toast.makeText(this, "Added File" + newUri, Toast.LENGTH_LONG).show(); } } And here is the xml layout. <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/RelativeLayout1" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <Button android:id="@+id/start" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:layout_marginTop="146dp" android:onClick="startRecording" android:text="Start Recording" /> <Button android:id="@+id/stop" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/start" android:layout_below="@+id/start" android:layout_marginTop="41dp" android:enabled="false" android:onClick="stopRecording" android:text="Stop Recording" /> </RelativeLayout> And I added permission to AndroidManifest file. <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="in.isuru.audiorecorder" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="8" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <activity android:name=".AudioRecorderActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.RECORD_AUDIO" /> </manifest> I need to record high quality audio. Thanks!

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• Image not loading onto JPanel?

  - by None None

  I have been trying to figure out how to add an image to a JPanel as a background, but still have complete control over the placing of JButtons, JLabels, and etc. This is one method I found, but it is crashing and not loading the image or buttons. Here is the code: import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JButton; import java.awt.BorderLayout; import java.awt.FlowLayout; import java.awt.GridLayout; public class PanelDemo extends JFrame { private static final long serialVersionUID = 1L; private JButton btn1 = new JButton("EASY"); private JButton btn2 = new JButton("MEDIUM"); private JButton btn3 = new JButton("HARD"); private JButton btn4 = new JButton("High Score"); public PanelDemo() { super("Image Panel Demo"); JPanel panel = new ImagePanel( new FlowLayout(FlowLayout.CENTER, 50, 180)); JPanel panelbtn = new JPanel(new GridLayout(4, 1)); btn1.setBackground(new java.awt.Color(0, 0, 0)); btn1.setFont(new java.awt.Font("Showcard Gothic", 1, 24)); btn1.setForeground(new java.awt.Color(0, 255, 102)); btn2.setBackground(new java.awt.Color(0, 0, 0)); btn2.setFont(new java.awt.Font("Showcard Gothic", 1, 24)); btn2.setForeground(new java.awt.Color(0, 255, 102)); btn3.setBackground(new java.awt.Color(0, 0, 0)); btn3.setFont(new java.awt.Font("Showcard Gothic", 1, 24)); btn3.setForeground(new java.awt.Color(0, 255, 102)); btn4.setBackground(new java.awt.Color(0, 0, 0)); btn4.setFont(new java.awt.Font("Showcard Gothic", 1, 24)); btn4.setForeground(new java.awt.Color(0, 255, 102)); panel.add(panelbtn); panelbtn.add(btn1); panelbtn.add(btn2); panelbtn.add(btn3); panelbtn.add(btn4); add(panel, BorderLayout.CENTER); setSize(640, 480); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } public static void main(String... args) { new PanelDemo().setVisible(true); } } ImagePanel.java import java.awt.Graphics; import java.awt.Image; import java.awt.LayoutManager; import javax.swing.ImageIcon; import javax.swing.JPanel; public class ImagePanel extends JPanel { private static final long serialVersionUID = 1L; String imageFile = "/rsc/img/background.jpg"; public ImagePanel() { super(); } public ImagePanel(String image) { super(); this.imageFile = image; } public ImagePanel(LayoutManager layout) { super(layout); } public void paintComponent(Graphics g) { ImageIcon imageicon = new ImageIcon(getClass().getResource(imageFile)); Image image = imageicon.getImage(); super.paintComponent(g); if (image != null) g.drawImage(image, 0, 0, getWidth(), getHeight(), this); } } Error: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at javax.swing.ImageIcon.<init>(Unknown Source) at ImagePanel.paintComponent(ImagePanel.java:27) at javax.swing.JComponent.paint(Unknown Source) at javax.swing.JComponent.paintChildren(Unknown Source) at javax.swing.JComponent.paint(Unknown Source) at javax.swing.JComponent.paintChildren(Unknown Source) at javax.swing.JComponent.paint(Unknown Source) at javax.swing.JLayeredPane.paint(Unknown Source) at javax.swing.JComponent.paintChildren(Unknown Source) at javax.swing.JComponent.paintToOffscreen(Unknown Source) at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source) at javax.swing.RepaintManager$PaintManager.paint(Unknown Source) at javax.swing.RepaintManager.paint(Unknown Source) at javax.swing.JComponent.paint(Unknown Source) at java.awt.GraphicsCallback$PaintCallback.run(Unknown Source) at sun.awt.SunGraphicsCallback.runOneComponent(Unknown Source) at sun.awt.SunGraphicsCallback.runComponents(Unknown Source) at java.awt.Container.paint(Unknown Source) at java.awt.Window.paint(Unknown Source) at javax.swing.RepaintManager$3.run(Unknown Source) at javax.swing.RepaintManager$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source) at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source) at javax.swing.RepaintManager.prePaintDirtyRegions(Unknown Source) at javax.swing.RepaintManager.access$1000(Unknown Source) at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source) at java.awt.event.InvocationEvent.dispatch(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$200(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source) Also, if anyone knows of a better way to put a background image on a JPanel, pease do tell. Thank you in advance.

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• TStringList and TThread that does not free all of its memory

  - by VanillaH

  Version used: Delphi 7. I'm working on a program that does a simple for loop on a Virtual ListView. The data is stored in the following record: type TList=record Item:Integer; SubItem1:String; SubItem2:String; end; Item is the index. SubItem1 the status of the operations (success or not). SubItem2 the path to the file. The for loop loads each file, does a few operations and then, save it. The operations take place in a TStringList. Files are about 2mb each. Now, if I do the operations on the main form, it works perfectly. Multi-threaded, there is a huge memory problem. Somehow, the TStringList doesn't seem to be freed completely. After 3-4k files, I get an EOutofMemory exception. Sometimes, the software is stuck to 500-600mb, sometimes not. In any case, the TStringList always return an EOutofMemory exception and no file can be loaded anymore. On computers with more memory, it takes longer to get the exception. The same thing happens with other components. For instance, if I use THTTPSend from Synapse, well, after a while, the software cannot create any new threads because the memory consumption is too high. It's around 500-600mb while it should be, max, 100mb. On the main form, everything works fine. I guess the mistake is on my side. Maybe I don't understand threads enough. I tried to free everything on the Destroy event. I tried FreeAndNil procedure. I tried with only one thread at a time. I tried freeing the thread manually (no FreeOnTerminate...) No luck. So here is the thread code. It's only the basic idea; not the full code with all the operations. If I remove the LoadFile prodecure, everything works good. A thread is created for each file, according to a thread pool. unit OperationsFiles; interface uses Classes, SysUtils, Windows; type TOperationFile = class(TThread) private Position : Integer; TPath, StatusMessage: String; FileStringList: TStringList; procedure UpdateStatus; procedure LoadFile; protected procedure Execute; override; public constructor Create(Path: String; LNumber: Integer); end; implementation uses Form1; procedure TOperationFile.LoadFile; begin try FileStringList.LoadFromFile(TPath); // Operations... StatusMessage := 'Success'; except on E : Exception do StatusMessage := E.ClassName; end; end; constructor TOperationFile.Create(Path : String; LNumber: Integer); begin inherited Create(False); TPath := Path; Position := LNumber; FreeOnTerminate := True; end; procedure TOperationFile.UpdateStatus; begin FileList[Position].SubItem1 := StatusMessage; Form1.ListView4.UpdateItems(Position,Position); end; procedure TOperationFile.Execute; begin FileStringList:= TStringList.Create; LoadFile; Synchronize(UpdateStatus); FileStringList.Free; end; end. What could be the problem? I thought at one point that, maybe, too many threads are created. If a user loads 1 million files, well, ultimately, 1 million threads is going to be created -- although, only 50 threads are created and running at the same time. Thanks for your input.

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• CSS content overflowing containing div

  - by kaese

  Hi, Currently have a problem with some DIVs overlapping their containing DIVs. See image below (the 3 products at the bottom): All the body content of the page is held within the #content DIV: div#content { width: 960px; float: left; background-image: url("../img/contentBg.png"); background-repeat: repeat; margin-top: 10px; line-height: 1.8em; border-top: 8px solid #5E88A2; padding: 10px 15px 10px 15px; } And here is the CSS for the product boxes within the #content div: .upper { text-transform: uppercase; } .center { text-align: center; } div#products { float: left; width: 100%; margin-bottom: 25px; } div.productContainer { float: left; width: 265px; font-size: 1em; margin-left: 50px; height: 200px; padding-top: 25px; text-align: right; } div.product { float: left; width: 200px; } div.product p { } div.product a { display: block; } div.product img { float: left; } div.product img:hover { opacity: 0.8; filter: alpha(opacity = 80); } div.transparent { opacity: 0.8; filter: alpha(opacity = 80); } And here is the HTML for the boxes: <div class="productContainer"> <div class="product"> <h2 class="upper center">A2 Print</h2> <a href='../edit/?productId=5&amp;align=v' class='upper'> <img src="../../wflow/tmp/133703b808c91b8ec7e7c7cdf19320b7A2-Print.png" alt="Representation of image printed at A2 Print through MyPersonalPoster." /></a> <p class="upper">16.5 inches x 23.4 inches<br /><strong>&pound;15.99</strong></p> <p class="upper smaller"><em><span><span class="yes">Yes</span> - your picture quality is high enough for this size</span> </em></p> <p><a href='../edit/?productId=5&amp;align=v' class='upper'><span>Select</span></a></p> </div> </div> <div class="productContainer"> <div class="product transparent"> <h2 class="upper center">A1 Print</h2> <a href='../edit/?productId=11&amp;align=v' class='upper'> <img src="../../wflow/tmp/133703b808c91b8ec7e7c7cdf19320b7A1-Print.png" alt="Representation of image printed at A1 Print through MyPersonalPoster." /></a> <p class="upper">23.4 inches x 33.1 inches<br /><strong>&pound;19.99</strong></p> <p class="upper smaller"><em><span><span class="no">Warning</span> - your picture quality may not be sufficient for this size</span> </em></p> <p><a href='../edit/?productId=11&amp;align=v' class='upper'><span>Select</span></a></p> </div> </div> <div class="productContainer"> <div class="product transparent"> <h2 class="upper center">Poster Print (60cm x 80cm)</h2> <a href='../edit/?productId=12&amp;align=v' class='upper'> <img src="../../wflow/tmp/133703b808c91b8ec7e7c7cdf19320b7Poster-Print-(60cm-x-80cm).png" alt="Representation of image printed at Poster Print (60cm x 80cm) through MyPersonalPoster." /></a> <p class="upper">23.6 inches x 31.5 inches<br /><strong>&pound;13.95</strong></p> <p class="upper smaller"><em><span><span class="no">Warning</span> - your picture quality may not be sufficient for this size</span> </em></p> <p><a href='../edit/?productId=12&amp;align=v' class='upper'><span>Select</span></a></p> </div> </div> Any idea what could be causing these DIVs to overlap? What I'd like is for all the boxes to fit within the #container div as expected. It's driving me crazy! Cheers

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• How to autostart this slide

  - by lchales

  Hello there: first of all i have no idea on coding or anything related, simple question: is there any simple way to tell this code to autostart the slide? at the current moment the images change on click. currently the index page only have one image, what i want is to add a few but without the need to click to see the next one here is the code from my index: <script type="text/javascript"> //<![CDATA[ /* the images preload plugin */ (function($) { $.fn.preload = function(options) { var opts = $.extend({}, $.fn.preload.defaults, options), o = $.meta ? $.extend({}, opts, this.data()) : opts; var c = this.length, l = 0; return this.each(function() { var $i = $(this); $('<img/>').load(function(i){ ++l; if(l == c) o.onComplete(); }).attr('src',$i.attr('src')); }); }; $.fn.preload.defaults = { onComplete : function(){return false;} }; })(jQuery); //]]> </script><script type="text/javascript"> //<![CDATA[ $(function() { var $tf_bg = $('#tf_bg'), $tf_bg_images = $tf_bg.find('img'), $tf_bg_img = $tf_bg_images.eq(0), $tf_thumbs = $('#tf_thumbs'), total = $tf_bg_images.length, current = 0, $tf_content_wrapper = $('#tf_content_wrapper'), $tf_next = $('#tf_next'), $tf_prev = $('#tf_prev'), $tf_loading = $('#tf_loading'); //preload the images $tf_bg_images.preload({ onComplete : function(){ $tf_loading.hide(); init(); } }); //shows the first image and initializes events function init(){ //get dimentions for the image, based on the windows size var dim = getImageDim($tf_bg_img); //set the returned values and show the image $tf_bg_img.css({ width : dim.width, height : dim.height, left : dim.left, top : dim.top }).fadeIn(); //resizing the window resizes the $tf_bg_img $(window).bind('resize',function(){ var dim = getImageDim($tf_bg_img); $tf_bg_img.css({ width : dim.width, height : dim.height, left : dim.left, top : dim.top }); }); //expand and fit the image to the screen $('#tf_zoom').live('click', function(){ if($tf_bg_img.is(':animated')) return false; var $this = $(this); if($this.hasClass('tf_zoom')){ resize($tf_bg_img); $this.addClass('tf_fullscreen') .removeClass('tf_zoom'); } else{ var dim = getImageDim($tf_bg_img); $tf_bg_img.animate({ width : dim.width, height : dim.height, top : dim.top, left : dim.left },350); $this.addClass('tf_zoom') .removeClass('tf_fullscreen'); } } ); //click the arrow down, scrolls down $tf_next.bind('click',function(){ if($tf_bg_img.is(':animated')) return false; scroll('tb'); }); //click the arrow up, scrolls up $tf_prev.bind('click',function(){ if($tf_bg_img.is(':animated')) return false; scroll('bt'); }); //mousewheel events - down / up button trigger the scroll down / up $(document).mousewheel(function(e, delta) { if($tf_bg_img.is(':animated')) return false; if(delta > 0) scroll('bt'); else scroll('tb'); return false; }); //key events - down / up button trigger the scroll down / up $(document).keydown(function(e){ if($tf_bg_img.is(':animated')) return false; switch(e.which){ case 38: scroll('bt'); break; case 40: scroll('tb'); break; } }); } //show next / prev image function scroll(dir){ //if dir is "tb" (top -> bottom) increment current, //else if "bt" decrement it current = (dir == 'tb')?current + 1:current - 1; //we want a circular slideshow, //so we need to check the limits of current if(current == total) current = 0; else if(current < 0) current = total - 1; //flip the thumb $tf_thumbs.flip({ direction : dir, speed : 400, onBefore : function(){ //the new thumb is set here var content = '<span id="tf_zoom" class="tf_zoom"><\/span>'; content +='<img src="' + $tf_bg_images.eq(current).attr('longdesc') + '" alt="Thumb' + (current+1) + '"/>'; $tf_thumbs.html(content); } }); //we get the next image var $tf_bg_img_next = $tf_bg_images.eq(current), //its dimentions dim = getImageDim($tf_bg_img_next), //the top should be one that makes the image out of the viewport //the image should be positioned up or down depending on the direction top = (dir == 'tb')?$(window).height() + 'px':-parseFloat(dim.height,10) + 'px'; //set the returned values and show the next image $tf_bg_img_next.css({ width : dim.width, height : dim.height, left : dim.left, top : top }).show(); //now slide it to the viewport $tf_bg_img_next.stop().animate({ top : dim.top },700); //we want the old image to slide in the same direction, out of the viewport var slideTo = (dir == 'tb')?-$tf_bg_img.height() + 'px':$(window).height() + 'px'; $tf_bg_img.stop().animate({ top : slideTo },700,function(){ //hide it $(this).hide(); //the $tf_bg_img is now the shown image $tf_bg_img = $tf_bg_img_next; //show the description for the new image $tf_content_wrapper.children() .eq(current) .show(); }); //hide the current description $tf_content_wrapper.children(':visible') .hide() } //animate the image to fit in the viewport function resize($img){ var w_w = $(window).width(), w_h = $(window).height(), i_w = $img.width(), i_h = $img.height(), r_i = i_h / i_w, new_w,new_h; if(i_w > i_h){ new_w = w_w; new_h = w_w * r_i; if(new_h > w_h){ new_h = w_h; new_w = w_h / r_i; } } else{ new_h = w_w * r_i; new_w = w_w; } $img.animate({ width : new_w + 'px', height : new_h + 'px', top : '0px', left : '0px' },350); } //get dimentions of the image, //in order to make it full size and centered function getImageDim($img){ var w_w = $(window).width(), w_h = $(window).height(), r_w = w_h / w_w, i_w = $img.width(), i_h = $img.height(), r_i = i_h / i_w, new_w,new_h, new_left,new_top; if(r_w > r_i){ new_h = w_h; new_w = w_h / r_i; } else{ new_h = w_w * r_i; new_w = w_w; } return { width : new_w + 'px', height : new_h + 'px', left : (w_w - new_w) / 2 + 'px', top : (w_h - new_h) / 2 + 'px' }; } }); //]]> </script>

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• How should I implement simple caches with concurrency on Redis?

  - by solublefish

  Background I have a 2-tier web service - just my app server and an RDBMS. I want to move to a pool of identical app servers behind a load balancer. I currently cache a bunch of objects in-process. I hope to move them to a shared Redis. I have a dozen or so caches of simple, small-sized business objects. For example, I have a set of Foos. Each Foo has a unique FooId and an OwnerId. One "owner" may own multiple Foos. In a traditional RDBMS this is just a table with an index on the PK FooId and one on OwnerId. I'm caching this in one process simply: Dictionary<int,Foo> _cacheFooById; Dictionary<int,HashSet<int>> _indexFooIdsByOwnerId; Reads come straight from here, and writes go here and to the RDBMS. I usually have this invariant: "For a given group [say by OwnerId], the whole group is in cache or none of it is." So when I cache miss on a Foo, I pull that Foo and all the owner's other Foos from the RDBMS. Updates make sure to keep the index up to date and respect the invariant. When an owner calls GetMyFoos I never have to worry that some are cached and some aren't. What I did already The first/simplest answer seems to be to use plain ol' SET and GET with a composite key and json value: SET( "ServiceCache:Foo:" + theFoo.Id, JsonSerialize(theFoo)); I later decided I liked: HSET( "ServiceCache:Foo", theFoo.FooId, JsonSerialize(theFoo)); That lets me get all the values in one cache as HVALS. It also felt right - I'm literally moving hashtables to Redis, so perhaps my top-level items should be hashes. This works to first order. If my high-level code is like: UpdateCache(myFoo); AddToIndex(myFoo); That translates into: HSET ("ServiceCache:Foo", theFoo.FooId, JsonSerialize(theFoo)); var myFoos = JsonDeserialize( HGET ("ServiceCache:FooIndex", theFoo.OwnerId) ); myFoos.Add(theFoo.OwnerId); HSET ("ServiceCache:FooIndex", theFoo.OwnerId, JsonSerialize(myFoos)); However, this is broken in two ways. Two concurrent operations can read/modify/write at the same time. The latter "wins" the final HSET and the former's index update is lost. Another operation could read the index in between the first and second lines. It would miss a Foo that it should find. So how do I index properly? I think I could use a Redis set instead of a json-encoded value for the index. That would solve part of the problem since the "add-to-index-if-not-already-present" would be atomic. I also read about using MULTI as a "transaction" but it doesn't seem like it does what I want. Am I right that I can't really MULTI; HGET; {update}; HSET; EXEC since it doesn't even do the HGET before I issue the EXEC? I also read about using WATCH and MULTI for optimistic concurrency, then retrying on failure. But WATCH only works on top-level keys. So it's back to SET/GET instead of HSET/HGET. And now I need a new index-like-thing to support getting all the values in a given cache. If I understand it right, I can combine all these things to do the job. Something like: while(!succeeded) { WATCH( "ServiceCache:Foo:" + theFoo.FooId ); WATCH( "ServiceCache:FooIndexByOwner:" + theFoo.OwnerId ); WATCH( "ServiceCache:FooIndexAll" ); MULTI(); SET ("ServiceCache:Foo:" + theFoo.FooId, JsonSerialize(theFoo)); SADD ("ServiceCache:FooIndexByOwner:" + theFoo.OwnerId, theFoo.FooId); SADD ("ServiceCache:FooIndexAll", theFoo.FooId); EXEC(); //TODO somehow set succeeded properly } Finally I'd have to translate this pseudocode into real code depending how my client library uses WATCH/MULTI/EXEC; it looks like they need some sort of context to hook them together. All in all this seems like a lot of complexity for what has to be a very common case; I can't help but think there's a better, smarter, Redis-ish way to do things that I'm just not seeing. How do I lock properly? Even if I had no indexes, there's still a (probably rare) race condition. A: HGET - cache miss B: HGET - cache miss A: SELECT B: SELECT A: HSET C: HGET - cache hit C: UPDATE C: HSET B: HSET ** this is stale data that's clobbering C's update. Note that C could just be a really-fast A. Again I think WATCH, MULTI, retry would work, but... ick. I know in some places people use special Redis keys as locks for other objects. Is that a reasonable approach here? Should those be top-level keys like ServiceCache:FooLocks:{Id} or ServiceCache:Locks:Foo:{Id}? Or make a separate hash for them - ServiceCache:Locks with subkeys Foo:{Id}, or ServiceCache:Locks:Foo with subkeys {Id} ? How would I work around abandoned locks, say if a transaction (or a whole server) crashes while "holding" the lock?

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