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  • How can I free all allocated memory at once?

    - by Tommy
    Here is what I am working with: char* qdat[][NUMTBLCOLS]; char** tdat[]; char* ptr_web_data; // Loop thru each table row of the query result set for(row_index = 0; row_index < number_rows; row_index++) { // Loop thru each column of the query result set and extract the data for(col_index = 0; col_index < number_cols; col_index++) { ptr_web_data = (char*) malloc((strlen(Data) + 1) * sizeof(char)); memcpy (ptr_web_data, column_text, strlen(column_text) + 1); qdat[row_index][web_data_index] = ptr_web_data; } } tdat[row_index] = qdat[col_index]; After the data is used, the memory allocated is released one at a time using free(). for(row_index = 0; row_index < number_rows; row_index++) { // Loop thru all columns used for(col_index = 0; col_index < SARWEBTBLCOLS; col_index++) { // Free memory block pointed to by results set array free(tdat[row_index][col_index]); } } Is there a way to release all the allocated memory at once, for this array? Thank You.

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  • The fastest way to iterate through a collection of objects

    - by Trev
    Hello all, First to give you some background: I have some research code which performs a Monte Carlo simulation, essential what happens is I iterate through a collection of objects, compute a number of vectors from their surface then for each vector I iterate through the collection of objects again to see if the vector hits another object (similar to ray tracing). The pseudo code would look something like this for each object { for a number of vectors { do some computations for each object { check if vector intersects } } } As the number of objects can be quite large and the amount of rays is even larger I thought it would be wise to optimise how I iterate through the collection of objects. I created some test code which tests arrays, lists and vectors and for my first test cases found that vectors iterators were around twice as fast as arrays however when I implemented a vector in my code in was somewhat slower than the array I was using before. So I went back to the test code and increased the complexity of the object function each loop was calling (a dummy function equivalent to 'check if vector intersects') and I found that when the complexity of the function increases the execution time gap between arrays and vectors reduces until eventually the array was quicker. Does anyone know why this occurs? It seems strange that execution time inside the loop should effect the outer loop run time.

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  • Same query has nested loops when used with INSERT, but Hash Match without.

    - by AaronLS
    I have two tables, one has about 1500 records and the other has about 300000 child records. About a 1:200 ratio. I stage the parent table to a staging table, SomeParentTable_Staging, and then I stage all of it's child records, but I only want the ones that are related to the records I staged in the parent table. So I use the below query to perform this staging by joining with the parent tables staged data. --Stage child records INSERT INTO [dbo].[SomeChildTable_Staging] ([SomeChildTableId] ,[SomeParentTableId] ,SomeData1 ,SomeData2 ,SomeData3 ,SomeData4 ) SELECT [SomeChildTableId] ,D.[SomeParentTableId] ,SomeData1 ,SomeData2 ,SomeData3 ,SomeData4 FROM [dbo].[SomeChildTable] D INNER JOIN dbo.SomeParentTable_Staging I ON D.SomeParentTableID = I.SomeParentTableID; The execution plan indicates that the tables are being joined with a Nested Loop. When I run just the select portion of the query without the insert, the join is performed with Hash Match. So the select statement is the same, but in the context of an insert it uses the slower nested loop. I have added non-clustered index on the D.SomeParentTableID so that there is an index on both sides of the join. I.SomeParentTableID is a primary key with clustered index. Why does it use a nested loop for inserts that use a join? Is there a way to improve the performance of the join for the insert?

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  • Working with Decimal fields in SSIS

    - by CoffeeAddict
    I'm using SQL Server 2008 w/SP2. I've got an incoming decimal(9,2) field incoming through my OLE DB transformation to my recordset destination transformation. It's like it's reading it as something other than a decimal? I don't know..I'm not an SSIS guru. So continuing on...the problem I have starts here with me trying to stuff the value into a variable for this decimal field. In a foreach loop, I have a variable to represent this decimal field so I can work with it. The first problem that I believe is pretty well known is SSIS variables do not have a decimal type. And from my own testing and what I've read out there, people are using type object for the variable to make SSIS "happy" with decimal values? It makes mine happy. But, then in my foreach loop, I have a for loop. And inside that I'm using an E*xecute SQL Task transformation*. In it, I need to create a parameter mapping to my variable so I can work with that decimal field in my T-SQL call in here. So now I see a type decimal for the parameter and use it and set that to point to my variable. When I run SSIS and it hits my SQL call, I get this in my output window.: The type is not supported.DBTYPE_DECIMAL So I am hitting a wall here. All I wanna do is work with a decimal!!!

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  • for cycle not works allright

    - by joseph
    Hello. I call addNotify() method in class that I posted here. The problem is, that when I call addNotify() as it is in the code, setKeys(objs) do nothing. Nothing appears in my explorer of running app. But when I call addNotify()without loop(for int....), and add only one item to ArrayList, it shows that one item correctly. Does anybody knows where can be problem? See the cede class ProjectsNode extends Children.Keys{ private ArrayList objs = new ArrayList(); public ProjectsNode() { } @Override protected Node[] createNodes(Object o) { MainProject obj = (MainProject) o; AbstractNode result = new AbstractNode (new DiagramsNode(), Lookups.singleton(obj)); result.setDisplayName (obj.getName()); return new Node[] { result }; } @Override protected void addNotify() { //this loop causes nothing appears in my explorer. //but when I replace this loop by single line "objs.add(new MainProject("project1000"));", it shows that one item in explorer for (int i=0;i==10;i++){ objs.add(new MainProject("project1000")); } setKeys (objs); } }

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  • Stack usage with MMX intrinsics and Microsoft C++

    - by arik-funke
    I have an inline assembler loop that cumulatively adds elements from an int32 data array with MMX instructions. In particular, it uses the fact that the MMX registers can accommodate 16 int32s to calculate 16 different cumulative sums in parallel. I would now like to convert this piece of code to MMX intrinsics but I am afraid that I will suffer a performance penalty because one cannot explicitly intruct the compiler to use the 8 MMX registers to accomulate 16 independent sums. Can anybody comment on this and maybe propose a solution on how to convert the piece of code below to use intrinsics? == inline assembler (only part within the loop) == paddd mm0, [esi+edx+8*0] ; add first & second pair of int32 elements paddd mm1, [esi+edx+8*1] ; add third & fourth pair of int32 elements ... paddd mm2, [esi+edx+8*2] paddd mm3, [esi+edx+8*3] paddd mm4, [esi+edx+8*4] paddd mm5, [esi+edx+8*5] paddd mm6, [esi+edx+8*6] paddd mm7, [esi+edx+8*7] ; add 15th & 16th pair of int32 elements esi points to the beginning of the data array edx provides the offset in the data array for the current loop iteration the data array is arranged such that the elements for the 16 independent sums are interleaved.

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  • Canceling a WSK I/O operation when driver is unloading

    - by eaducac
    I've been learning how to write drivers with the Windows DDK recently. After creating a few test drivers experimenting with system threads and synchronization, I decided to step it up a notch and write a driver that actually does something, albeit something useless. Currently, my driver connects to my other computer using Winsock Kernel and just loops and echoes back whatever I send to it until it gets the command "exit", which causes it to break out of the loop. In my loop, after I call WskReceive() to get some data from the other computer, I use KeWaitForMultipleObjects() to wait for either of two SynchronizationEvents. BlockEvent gets set by my IRP's CompletionRoutine() to let my thread know that it's received some data from the socket. EndEvent gets set by my DriverUnload() routine to tell the thread that it's being unloaded and it needs to terminate. When I send the "exit" command, the thread terminates with no problems, and I can safely unload the driver afterward. If I try to stop the driver while it's still waiting on data from the other computer, however, it blue screens with the error DRIVER_UNLOADED_WITHOUT_CANCELLING_PENDING_OPERATIONS. After I get the EndEvent but before I exit the loop, I've tried canceling the IRP with IoCancelIrp() and completing it with IoCompleteRequest(), but both of those give me DRIVER_IRQL_NOT_LESS_OR_EQUAL errors. I then tried calling WskDisconnect(), hoping that would cause the receive operation to complete, but that took me back to the CANCELLING_PENDING_OPERATIONS error. How do I cancel my pending I/O operation from my WSK socket at the IRQL I'm running at when the driver is unloaded?

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  • Python GUI does not update until entire process is finished

    - by ccwhite1
    I have a process that gets a files from a directory and puts them in a list. It then iterates that list in a loop. The last line of the loop being where it should update my gui display, then it begins the loop again with the next item in the list. My problem is that it does not actually update the gui until the entire process is complete, which depending on the size of the list could be 30 seconds to over a minute. This gives the feeling of the program being 'hung' What I wanted it to do was to process one line in the list, update the gui and then continue. Where did I go wrong? The line to update the list is # Populate listview with drive contents. The print statements are just for debug. def populateList(self): print "populateList" sSource = self.txSource.Value sDest = self.txDest.Value # re-intialize listview and validated list self.listView1.DeleteAllItems() self.validatedMove = None self.validatedMove = [] #Create list of files listOfFiles = getList(sSource) #prompt if no files detected if listOfFiles == []: self.lvActions.Append([datetime.datetime.now(),"Parse Source for .MP3 files","No .MP3 files in source directory"]) #Populate list after both Source and Dest are chosen if len(sDest) > 1 and len(sDest) > 1: print "-iterate listOfFiles" for file in listOfFiles: sFilename = os.path.basename(file) sTitle = getTitle(file) sArtist = getArtist(file) sAlbum = getAblum(file) # Make path = sDest + Artist + Album sDestDir = os.path.join (sDest, sArtist) sDestDir = os.path.join (sDestDir, sAlbum) #If file exists change destination to *.copyX.mp3 sDestDir = self.defineDestFilename(os.path.join(sDestDir,sFilename)) # Populate listview with drive contents self.listView1.Append([sFilename,sTitle,sArtist,sAlbum,sDestDir]) #populate list to later use in move command self.validatedMove.append([file,sDestDir]) print "-item added to SourceDest list" else: print "-list not iterated"

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  • How to make Web Storage persistent in Cordova using JS?

    - by ett
    I have a small quiz app, which is a cross-platform mobile app, that I plan for it to run on Android, iOS, and WP8. I want to store a local highscore, where it will keep track how many points the user had, and if he/she does better than the already stored highscore, update the current highscore. Though, I want the highscore to be persistent, what I mean is, every time the user opens the app I want the last highscore to be present and it to be compared with the new quiz score. Meaning, I don't want the highscore to be deleted after each time the app is closed. I also want for the first time when the app is ran, the highscore to be set to 0, so obviously the first time the user finishes the quiz gets a new highscore. I have those codes so far: scoredb.js // Wait for device API libraries to load document.addEventListener("deviceready", initScoreDB, false); // Device APIs are available function initScoreDB() { window.localStorage.setItem("score", 0); highscore = window.localStorage.getItem("score"); } main.js var correct = 0; var highscore; // In between I have some code that keeps incrementing // correct variable for each correct answer. if (correct > highscore) { window.localStorage.setItem("score", correct); highscore = correct; } It does seem to work okay once the app is started. I did the quiz three times, in the simulator, and it keeps the score as it should. Though, each time I open the app, highscore is reseted to 0. I guess it is due to the fact that I call initScoreDB when the device is ready, and I initialize the score to 0 there and give that value to highscore. Can someone help me to initialize the score to 0 only when the app is ran for the first time, and all the other times to keep the latest highscore as the current highscore and compare it each time with the score that is achieved when the quiz is finished. If someone can help me, I would be glad.

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  • how to update UI controls in cocoa application from background thread

    - by AmitSri
    following is .m code: #import "ThreadLabAppDelegate.h" @interface ThreadLabAppDelegate() - (void)processStart; - (void)processCompleted; @end @implementation ThreadLabAppDelegate @synthesize isProcessStarted; - (void)awakeFromNib { //Set levelindicator's maximum value [levelIndicator setMaxValue:1000]; } - (void)dealloc { //Never called while debugging ???? [super dealloc]; } - (IBAction)startProcess:(id)sender { //Set process flag to true self.isProcessStarted=YES; //Start Animation [spinIndicator startAnimation:nil]; //perform selector in background thread [self performSelectorInBackground:@selector(processStart) withObject:nil]; } - (IBAction)stopProcess:(id)sender { //Stop Animation [spinIndicator stopAnimation:nil]; //set process flag to false self.isProcessStarted=NO; } - (void)processStart { int counter = 0; while (counter != 1000) { NSLog(@"Counter : %d",counter); //Sleep background thread to reduce CPU usage [NSThread sleepForTimeInterval:0.01]; //set the level indicator value to showing progress [levelIndicator setIntValue:counter]; //increment counter counter++; } //Notify main thread for process completed [self performSelectorOnMainThread:@selector(processCompleted) withObject:nil waitUntilDone:NO]; } - (void)processCompleted { //Stop Animation [spinIndicator stopAnimation:nil]; //set process flag to false self.isProcessStarted=NO; } @end I need to clear following things as per the above code. How to interrupt/cancel processStart while loop from UI control? I also need to show the counter value in main UI, which i suppose to do with performSelectorOnMainThread and passing argument. Just want to know, is there anyother way to do that? When my app started it is showing 1 thread in Activity Monitor, but when i started the processStart() in background thread its creating two new thread,which makes the total 3 thread until or unless loop get finished.After completing the loop i can see 2 threads. So, my understanding is that, 2 thread created when i called performSelectorInBackground, but what about the thrid thread, from where it got created? What if thread counts get increases on every call of selector.How to control that or my implementation is bad for such kind of requirements? Thanks

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  • OpenMP - running things in parallel and some in sequence within them

    - by Sayan Ghosh
    Hi, I have a scenario like: for (i = 0; i < n; i++) { for (j = 0; j < m; j++) { for (k = 0; k < x; k++) { val = 2*i + j + 4*k if (val != 0) { for(t = 0; t < l; t++) { someFunction((i + t) + someFunction(j + t) + k*t) } } } } } Considering this is block A, Now I have two more similar blocks in my code. I want to put them in parallel, so I used OpenMP pragmas. However I am not able to parallelize it, because I am a tad confused that which variables would be shared and private in this case. If the function call in the inner loop was an operation like sum += x, then I could have added a reduction clause. In general, how would one approach parallelizing a code using OpenMP, when we there is a nested for loop, and then another inner for loop doing the main operation. I tried declaring a parallel region, and then simply putting pragma fors before the blocks, but definitely I am missing a point there! Thanks, Sayan

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  • small code redundancy within while-loops (doesn't feel clean)

    - by wallacoloo
    So, in Python (though I think it can be applied to many languages), I find myself with something like this quite often: the_input = raw_input("what to print?\n") while the_input != "quit": print the_input the_input = raw_input("what to print?\n") Maybe I'm being too picky, but I don't like how the line the_input = raw_input("what to print?\n") has to get repeated. It decreases maintainability and organization. But I don't see any workarounds for avoiding the duplicate code without further decreasing the problem. In some languages, I could write something like this: while ((the_input=raw_input("what to print?\n")) != "quit") { print the_input } This is definitely not Pythonic, and Python doesn't even allow for assignment within loop conditions AFAIK. This valid code fixes the redundancy, while 1: the_input = raw_input("what to print?\n") if the_input == "quit": break print the_input But doesn't feel quite right either. The while 1 implies that this loop will run forever; I'm using a loop, but giving it a fake condition and putting the real one inside it. Am I being too picky? Is there a better way to do this? Perhaps there's some language construct designed for this that I don't know of?

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  • Indentation control while developing a small python like language

    - by sap
    Hello, I'm developing a small python like language using flex, byacc (for lexical and parsing) and C++, but i have a few questions regarding scope control. just as python it uses white spaces (or tabs) for indentation, not only that but i want to implement index breaking like for instance if you type "break 2" inside a while loop that's inside another while loop it would not only break from the last one but from the first loop as well (hence the number 2 after break) and so on. example: while 1 while 1 break 2 'hello world'!! #will never reach this. "!!" outputs with a newline end 'hello world again'!! #also will never reach this. again "!!" used for cout end #after break 2 it would jump right here but since I don't have an "anti" tab character to check when a scope ends (like C for example i would just use the '}' char) i was wondering if this method would the the best: I would define a global variable, like "int tabIndex" on my yacc file that i would access in my lex file using extern. then every time i find a tab character on my lex file i would increment that variable by 1. when parsing on my yacc file if i find a "break" keyword i would decrement by the amount typed after it from the tabIndex variable, and when i reach and EOF after compiling and i get a tabIndex != 0 i would output compilation error. now the problem is, whats the best way to see if the indentation got reduced, should i read \b (backspace) chars from lex and then reduce the tabIndex variable (when the user doesn't use break)? another method to achieve this? also just another small question, i want every executable to have its starting point on the function called start() should i hardcode this onto my yacc file? sorry for the long question any help is greatly appreciated. also if someone can provide an yacc file for python would be nice as a guideline (tried looking on Google and had no luck). thanks in advance.

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  • MySql: Query multiple identical dynamic tables.

    - by JYelton
    I have a database with 500+ tables, each with identical structure, that contain historical data from sensors. I am trying to come up with a query that will locate, for example, all instances where sensor n exceeds x. The problem is that the tables are dynamic, the query must be able to dynamically obtain the list of tables. I can query information_schema.tables to get a list of the tables, like so: SELECT table_name FROM information_schema.tables WHERE table_schema = 'database_name'; I can use this to create a loop in the program and then query the database repeatedly, however it seems like there should be a way to have MySql do the multiple table search. I have not been able to make a stored procedure that works, but the examples I can find are generally for searching for a string in any column. I want to specifically find data in a specific column that exists in all tables. I admit I do not understand how to properly use stored procedures nor if they are the appropriate solution to this problem. An example query inside the loop would be: SELECT device_name, sensor_value FROM device_table WHERE sensor_value > 10; Trying the following does not work: SELECT device_name, sensor_value FROM ( SELECT table_name FROM information_schema.tables WHERE table_schema = 'database_name' ) WHERE sensor_value > 10; It results in an error: "Every derived table must have its own alias." The goal is to have a list of all devices that have had a given sensor value occur anywhere in their log (table). Ultimately, should I just loop in my program once I've obtained a list of tables, or is there a query structure that would be more efficient?

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  • IBM Worklight v6.1.0.1 : Error when using Ionic Framework with Worklight and run on IOS environment

    - by NickNguyen
    I have created demo app using Ionic with Worklight and it worked on Android but got error on IOS, when i used mobile browser simulator and debugged on IOS environment, i got the folowing error message: Uncaught InvalidCharacterError: Failed to execute 'add' on 'DOMTokenList': The token provided ('platform-ios - iphone') contains HTML space characters, which are not valid in tokens. I just add Ionic files in index.html: <!DOCTYPE HTML> <html> <head> <meta charset="UTF-8"> <title>index</title> <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=0"> <link rel="shortcut icon" href="images/favicon.png"> <link rel="apple-touch-icon" href="images/apple-touch-icon.png"> <link rel="stylesheet" href="css/main.css"> <link rel="stylesheet" href="ionic/css/ionic.css"> <script src="ionic/js/ionic.bundle.js"></script> </head> <body style="display: none;"> <!--application UI goes here--> <div class="bar bar-header bar-positive"> <h1 class="title">bar-positive</h1> </div> <script src="js/initOptions.js"></script> <script src="js/main.js"></script> <script src="js/messages.js"></script> </body> </html> I also tested on mobile device on both Android and IOS and only got error on IOS device. I don't know how to fix this. Can anyone help? Thanks.

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  • iPhone NSTimer OpenGL problem

    - by Toby Wilson
    I've got a problem that only seems to occur on the device, not in the simulator. My app's animation is started and stopped using these methods: NSTimer* animationTimer; -(void)startAnimation { if(animationTimer = nil) animationTimer = [NSTimer scheduledTimerWithTimeInterval:1.0f/60.0f target:self selector:@selector(drawView) userInfo:nil repeats:YES]; } -(void)stopAnimation { [animationTimer invalidate]; animationTimer = nil; } In the simulator this works fine and drawView starts being called at 60fps. On the device (testing on iPod Touch), the scheduleTimerWithTimeInterval method doesn't seem to work. Furthermore, [animationTimer invalidate] causes EXC_BAD_ACCESS. I've spotted an obvious but minor flaw; adding if(animationTimer != nil) to the stopAnimation method will prevent the crash, but doesn't solve the problem of the animation timer not being properly initialised. Edit: The above doesn't prevent a crash. animationTimer != nil yet calling invalidate causes EXC_BAD_ACCESS. Should also add, this problem doesn't occur all the time on the device. Maybe 40% of the time.

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  • Screen information while Windows system is locked (.NET)

    - by Matt
    We have a nightly process that updates applications on a user's pc, and that requires bringing the application down and back up again (not looking to get into changing that process). The problem is that we are building a Windows AppBar on launch which requires a valid screen, and when the system is locked there isn't one in the Screen class. So none of the visual effects are enabled and it shows up real ugly. The only way we currently have around this is to detect a locked screen and just spin and wait until the user unlocks the desktop, then continue launching. Leaving it down isn't an option, as this is a key part of our user's workflow, and they expect it to be up and running if they left it that way the night before. Any ideas?? I can't seem to find the display information anywhere, but it has to be stored off someplace, since the user is still logged in. The contents of the Screen.AllScreens array: ** When Locked: Device Name : DISPLAY Primary : True Bits Per Pixel : 0 Bounds : {X=-1280,Y=0,Width=2560,Height=1024} Working Area : {X=0,Y=0,Width=1280,Height=1024} ** When Unlocked: Device Name : \\.\DISPLAY1 Primary : True Bits Per Pixel : 32 Bounds : {X=0,Y=0,Width=1280,Height=1024} Working Area : {X=0,Y=0,Width=1280,Height=994} Device Name : \\.\DISPLAY2 Primary : False Bits Per Pixel : 32 Bounds : {X=-1280,Y=0,Width=1280,Height=1024} Working Area : {X=-1280,Y=0,Width=1280,Height=964}

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  • What can I read from the iPad Camera Connection Kit?

    - by HELVETICADE
    I'm building a small controller device that I'd like to partner with a computer. I've settled on using OSC out from my custom built hardware and am pretty satisfied with what I can get from WOscLib. Two goals I'd like to achieve are portability and a very ratio between battery:computing power, and this has lured me towards using iPhoneOS to accomplish my goals. I think the iPad would suit my needs perfectly, except that using wifi to broadcast OSC out from my device requires a third device and would destroy the goal of portability, whilst also introducing potential latency and stability headaches. My question is pretty simple: Can I push my OSC-out FROM my controller TO an iPad via USB and the Camera Connection Kit? If I could accomplish this, the two major goals of my project would be fulfilled very nicely. This seems like it should be a simple little question, but researching this obsessively over the past few weeks has left me more almost more uncertain than if I had done no research at all. I'd really like some more confidence before I go down this route, and it seems like it should be possible. Any insight would be very, very appreciated.

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  • Common Lisp condition system for transfer of control

    - by Ken
    I'll admit right up front that the following is a pretty terrible description of what I want to do. Apologies in advance. Please ask questions to help me explain. :-) I've written ETLs in other languages that consist of individual operations that look something like: // in class CountOperation IEnumerable<Row> Execute(IEnumerable<Row> rows) { var count = 0; foreach (var row in rows) { row["record number"] = count++; yield return row; } } Then you string a number of these operations together, and call The Dispatcher, which is responsible for calling Operations and pushing data between them. I'm trying to do something similar in Common Lisp, and I want to use the same basic structure, i.e., each operation is defined like a normal function that inputs a list and outputs a list, but lazily. I can define-condition a condition (have-value) to use for yield-like behavior, and I can run it in a single loop, and it works great. I'm defining the operations the same way, looping through the inputs: (defun count-records (rows) (loop for count from 0 for row in rows do (signal 'have-value :value `(:count ,count @,row)))) The trouble is if I want to string together several operations, and run them. My first attempt at writing a dispatcher for these looks something like: (let ((next-op ...)) ;; pick an op from the set of all ops (loop (handler-bind ((have-value (...))) ;; records output from operation (setq next-op ...) ;; pick a new next-op (call next-op))) But restarts have only dynamic extent: each operation will have the same restart names. The restart isn't a Lisp object I can store, to store the state of a function: it's something you call by name (symbol) inside the handler block, not a continuation you can store for later use. Is it possible to do something like I want here? Or am I better off just making each operation function explicitly look at its input queue, and explicitly place values on the output queue?

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  • Linux network stack : adding protocols with an LKM and dev_add_pack

    - by agent0range
    Hello, I have recently been trying to familiarize myself with the Linux Networking stack and device drivers (have both similarly named O'Reilly books) with the eventual goal of offloading UDP. I have already implemented UDP on the NIC but now the hard part... Rather than ask for assistance on this larger goal I was hoping someone could clarify for me a particular snippet I found that is part of a LKM which registeres a new protocol (OTP) that acts as a filter between the device driver and network stack. http://www.phrack.org/archives/55/p55_0x0c_Building%20Into%20The%20Linux%20Network%20Layer_by_lifeline%20&%20kossak.txt (Note: this Phrack article contains three different modules, code for the OTP is at the bottom of the page) In the init function of his example he has: otp_proto.type = htons(ETH_P_ALL); otp_proto.func = otp_func; dev_add_pack(&otp_proto); which (if I understand correctly) should register otp_proto as a packet sniffer and put it into the ptype_all data structure. My question is about the dev_add_pack. Is it the case that the protocol being registered as a filter will always be placed at this layer between L2 and the device driver? Or, for instance could I make such a filtering occur between the application and transport layers (analyze socket parameters) using the same process? I apologize if this is confusing - I am having some trouble wrapping my head around the bigger picture when it comes to modules altering kernel stack functionality. Thanks

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  • Help me to refactor this F# code to tail recursion

    - by Kev
    I write some code to learning F#. Here is a example: let nextPrime list= let rec loop n= match n with | _ when (list |> List.filter (fun x -> x <= ( n |> double |> sqrt |> int)) |> List.forall (fun x -> n % x <> 0)) -> n | _ -> loop (n+1) loop (List.max list + 1) let rec findPrimes num= match num with | 1 -> [2] | n -> let temp = findPrimes <| n-1 (nextPrime temp ) :: temp //find 10 primes findPrimes 10 |> printfn "%A" I'm very happy that it just works! I'm totally beginner to recursion Recursion is a wonderful thing. I think findPrimes is not efficient. Someone help me to refactor findPrimes to tail recursion if possible? BTW, is there some more efficient way to find first n primes?

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  • Bluetooth in Java Mobile: Handling connections that go out of range

    - by Albus Dumbledore
    I am trying to implement a server-client connection over the spp. After initializing the server, I start a thread that first listens for clients and then receives data from them. It looks like that: public final void run() { while (alive) { try { /* * Await client connection */ System.out.println("Awaiting client connection..."); client = server.acceptAndOpen(); /* * Start receiving data */ int read; byte[] buffer = new byte[128]; DataInputStream receive = client.openDataInputStream(); try { while ((read = receive.read(buffer)) > 0) { System.out.println("[Recieved]: " + new String(buffer, 0, read)); if (!alive) { return; } } } finally { System.out.println("Closing connection..."); receive.close(); } } catch (IOException e){ e.printStackTrace(); } } } It's working fine for I am able to receive messages. What's troubling me is how would the thread eventually die when a device goes out of range? Firstly, the call to receive.read(buffer) blocks so that the thread waits until it receives any data. If the device goes out of range, it would never proceed onward to check if meanwhile it has been interrupted. Secondly, it would never close the connection, i.e. the server would not accept the device once it goes back in range. Thanks! Any ideas would be highly appreciated! Merry Christmas!

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  • Placing PHP array values into a javascript array?

    - by Michael Harringon
    Is these a way i can loop through a PHP array and have the data outputted into a JavaScript array? For example, the JS script below will not work var mon_Loop = <?php echo $rowCount_Mon ?>; var mon_Events = new Array(); for(i = 0; i < mon_Loop; i++) { mon_Events[i] = <?php $divMon[i] ?> } I Know its because the "i" is not a php variable so therefore invalid inside the php section, but its just an way to show what i would like to achieve. The $rowCount variable count the number of rows and is then used to for the loop. Lets say, for example that I want to place the contents of the PHP array "$divMon[0]" into the javascript array mon_Events[0]. I know that i can do it manually, like below mon_Events[0] = <?php echo $divMon[0] ?> But i have lots of these and therefore need the loop, Is there some JS or PHP that could do this? Cheers.

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  • Java iteration reading & parsing

    - by Patrick Lorio
    I have a log file that I am reading to a string public static String Read (String path) throws IOException { StringBuilder sb = new StringBuilder(); InputStream in = new BufferedInputStream(new FileInputStream(path)); int r; while ((r = in.read()) != -1) { sb.append(r); } return sb.toString(); } Then I have a parser that iterates over the entire string once void Parse () { String con = Read("log.txt"); for (int i = 0; i < con.length; i++) { /* parsing action */ } } This is hugely a waste of cpu cycles. I loop over all the content in Read. Then I loop over all the content in Parse. I could just place the /* parsing action */ under the while loop in the Read method, which would be find but I don't want to copy the same code all over the place. How can I parse the file in one iteration over the contents and still have separate methods for parsing and reading? In C# I understand there is some sort of yield return thing, but I'm locked with Java. What are my options in Java?

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  • Scala newbie vproducer/consumer attempt running out of memory

    - by Nick
    I am trying to create a producer/consumer type Scala app. The LoopControl just sends a message to the MessageReceiver continually. The MessageReceiver then delegates work to the MessageCreatorActor (whose work is to check a map for an object, and if not found create one and start it up). Each MessageActor created by this MessageCreatorActor is associated with an Id. Eventually this is where I want to do business logic. But I run out of memory after 15 minutes. Its finding the cached actors,but quickly runs out of memory. Any help is appreciated. Or any one has any good code on producers consumers doing real stuff (not just adding numbers), please post. import scala.actors.Actor import java.util.HashMap import scala.actors.Actor._ case object LoopControl case object MessageReceiver case object MessageActor case object MessageActorCreator class MessageReceiver(msg: String) extends Actor { var messageActorMap = new HashMap[String, MessageActor] val messageCreatorActor = new MessageActorCreator(null, null) def act() { messageCreatorActor.start loop { react { case MessageActor(messageId) => if (msg.length() > 0) { var messageActor = messageActorMap.get(messageId); if(messageActor == null) { messageCreatorActor ! MessageActorCreator(messageId, messageActorMap) }else { messageActor ! MessageActor } } } } } } case class MessageActorCreator(msg:String, messageActorMap: HashMap[String, MessageActor]) extends Actor { def act() { loop { react { case MessageActorCreator(messageId, messageActorMap) => if(messageId != null ) { var messageActor = new MessageActor(messageId); messageActorMap.put(messageId, messageActor) println(messageActorMap) messageActor.start messageActor ! MessageActor } } } } } class LoopControl(messageReceiver:MessageReceiver) extends Actor { var count : Int = 0; def act() { while (true) { messageReceiver ! MessageActor ("00-122-0X95-FEC0" + count) //Thread.sleep(100) count = count +1; if(count > 5) { count = 0; } } } } case class MessageActor(msg: String) extends Actor { def act() { loop { react { case MessageActor => println() println("MessageActor: Got something-> " + msg) } } } } object messages extends Application { val messageReceiver = new MessageReceiver("bootstrap") val loopControl = new LoopControl(messageReceiver) messageReceiver.start loopControl.start }

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