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• VB.net/Excel- "Backwards" tab index For Each iteration with textboxes.

  - by MSD

  Hi there, I have a form with 3 textboxes and 1 button. textbox1 has tab index 0, and it's text = 1 textbox2 has tab index 1, and it's text = 2 textbox3 has tab index 2, and it's text = 3 I want to iterate thru the textboxes and place their values into cells so that... range("A1").value = txtbox1.text (ie: A1 = "1") range("A2").value = txtbox2.text (ie: A2 = "2") range("A3").value = txtbox3.text (ie: A3 = "3") but what I am getting is... range("A1").value = txtbox1.text (ie: A1 = "3") range("A2").value = txtbox2.text (ie: A2 = "2") range("A3").value = txtbox3.text (ie: A3 = "1") I have tried reversing the tab index for the text boxes, but it doesn't change the "backwards iteration". Is there something I can do to change this so that the loop runs from lowest tab index to highest? Thanks! Public Class Form1 Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim objExcel As New Microsoft.Office.Interop.Excel.Application 'Declaring the object. objExcel.Visible = True 'Setting Excel to visible. Dim cntrl As Control With objExcel .Workbooks.Add() 'Adding a workbook. .Range("A1").Select() 'Selecting cell A1. End With 'Form contains 3 text boxes, with one number in each (1,2,3), and one button to fire the code in this sub. For Each cntrl In Me.Controls 'For every control on the form... If TypeOf (cntrl) Is TextBox Then 'If the control is a textbox, then... With objExcel .ActiveCell.Value = cntrl.Text 'place the control's text in the active cell and... .ActiveCell.Offset(1, 0).Activate() 'offset down one row. End With End If 'If the control is not a textbox (if it's the button), do nothing. Next 'Go to the next control. objExcel = Nothing 'Release the object. GC.Collect() 'Clean up. End Sub End Class

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• How to "pin" C++/CLI pointers

  - by Kumar

  I am wrapping up a class which reading a custom binary data file and makes the data available to a .net/c# class However a couple of lines down the code, i start getting the memory access violation error which i believe is due to the GC moving memory around, the class is managed Here's the code if ( ! reader.OpenFile(...) ) return ; foreach(string fieldName in fields) { int colIndex = reader.GetColIndex( fieldName ); int colType = reader.GetColType( colIndex ); // error is raised here on 2nd iteration } for ( int r = 0 ; r < reader.NumFields(); r++ ) { foreach(string fieldName in fields) { int colIndex = reader.GetColIndex( fieldName ); int colType = reader.GetColType( colIndex ); // error is raised here on 2nd iteration switch ( colType ) { case 0 : // INT processField( r, fieldName, reader.GetInt(r,colIndex) ); break ; .... } } } .... i've looked at interior_ptr, pin_ptr but they give an error c3160 cannot be in a managed class Any workaround ? BTW, this is my 1st C++ program in a very long time !

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• How to optimalize my game calendar in C#?

  - by MartyIX

  Hi, I've implemented a simple calendar (message system) for my game which consists from: 1) List<Event> calendar; 2) public class Event { /// <summary> /// When to process the event /// </summary> public Int64 when; /// <summary> /// Which object should process the event /// </summary> public GameObject who; /// <summary> /// Type of event /// </summary> public EventType what; public int posX; public int posY; public int EventID; } 3) calendar.Add(new Event(...)) The problem with this code is that even thought the number of messages is not excessise per second. It allocates still new memory and GC will once need to take care of that. The garbage collection may lead to a slight lag in my game and therefore I'd like to optimalize my code. My considerations: To change Event class in a structure - but the structure is not entirely small and it takes some time to copy it wherever I need it. Reuse Event object somehow (add queue with used events and when new event is needed I'll just take from this queue). Does anybody has other idea how to solve the problem? Thanks for suggestions!

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• How do I handle freeing unmanaged structures on application close?

  - by LostKaleb

  I have a C# project in which i use several unmanaged C++ functions. More so, I also have static IntPtr that I use as parameters for those functions. I know that whenever I use them, I should implement IDisposable in that class and use a destructor to invoke the Dispose method, where I free the used IntPtr, as is said in the MSDN page. public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private void Dispose(bool disposing) { // Check to see if Dispose has already been called. if (!this.disposed) { if (disposing) { component.Dispose(); } CloseHandle(m_InstanceHandle); m_InstanceHandle = IntPtr.Zero; disposed = true; } } [System.Runtime.InteropServices.DllImport("Kernel32")] private extern static Boolean CloseHandle(IntPtr handle); However, when I terminate the application, I'm still left with a hanging process in TaskManager. I believe that it must be related to the used of the MarshalAs instruction in my structures: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; } When I create such a structure should I also be careful to free the space it allocs using a destructor? [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; ~SipxAudioCodec() { Marshal.FreeGlobal(something...); } }

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• Chrome.tabs.getSelected() doesn't work. What am I doing wrong ?

  - by warv3n

  Hi there ! I'm building my first GC extension, and I am having a problem using this function. I would like to get the url of the current tab, and to do so (after some google research, of course), I use the chrome.tabs.getSelected() function. Here it is in my code : ... socket.onopen = function(msg){ log("Welcome - status " + this.readyState); chrome.tabs.getSelected(null, function(tab){ sendUrl(tab.url); }); }; function sendUrl(tabUrl) { socket.send("#URL#"+ tabUrl); } The socket.open is a listener for the Websocket API I use in my extension. The log function print the status of the socket (1, which means it's OPEN or connected and ready to communicate, according to the Websocket API), but the chrome.tabs.getSelected() function do not seems to work, as the server do not receive anything (the socket is not the problem here, I tried to send a test message with socket.send() instead of chrome.tabs.getSelected() and the server received it). I put the permissions: ["tabs"] into the manifest.json so I can use this function. So I don't know what I am doing wrong here ? I also tried to put chrome.tab.getSelected() elsewhere in the code, but it is still not working. Any help is welcome :)

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• Peculiar JRE behaviour running RMI server under load, should I worry?

  - by darri

  I've been developing a minimalistic Java rich client CRUD application framework for the past few years, mostly as a hobby but also actively using it to write applications for my current employer. The framework provides database access to clients either via a local JDBC based connection or a lightweight RMI server. Last night I started a load testing application, which ran 100 headless clients, bombarding the server with requests, each client waiting only 1 - 2 seconds between running simple use cases, consisting of selecting records along with associated detail records from a simple e-store database (Chinook). This morning when I looked at the telemetry results from the server profiling session I noticed something which to me seemed strange (and made me keep the setup running for the remainder of the day), I don't really know what conclusions to draw from it. Here are the results: Memory GC activity Threads CPU load Interesting, right? So the question is, is this normal or erratic? Is this simply the JRE (1.6.0_03 on Windows XP) doing it's thing (perhaps related to the JRE configuration) or is my framework design somehow causing this? Running the server against MySQL as opposed to an embedded H2 database does not affect the pattern. I am leaving out the details of my server design, but I'll be happy to elaborate if this behaviour is deemed erratic.

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• Method returns an IDisposable - Should I dispose of the result, even if it's not assigned to anythin

  - by mjd79

  This seems like a fairly straightforward question, but I couldn't find this particular use-case after some searching around. Suppose I have a simple method that, say, determines if a file is opened by some process. I can do this (not 100% correctly, but fairly well) with this: public bool IsOpen(string fileName) { try { File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None); } catch { // if an exception is thrown, the file must be opened by some other process return true; } } (obviously this isn't the best or even correct way to determine this - File.Open throws a number of different exceptions, all with different meanings, but it works for this example) Now the File.Open call returns a FileStream, and FileStream implements IDisposable. Normally we'd want to wrap the usage of any FileStream instantiations in a using block to make sure they're disposed of properly. But what happens in the case where we don't actually assign the return value to anything? Is it still necessary to dispose of the FileStream, like so: try { using (File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None)); { /* nop */ } } catch { return true; } Should I create a FileStream instance and dispose of that? try { using (FileStream fs = File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None)); } ... Or are these totally unnecessary? Can we simply call File.Open and not assign it to anything (first code example), and let the GC dispose of it right away?

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• How do I handle freeing unmanaged structures in C# on application close?

  - by LostKaleb

  I have a C# project in which i use several unmanaged C++ functions. More so, I also have static IntPtr that I use as parameters for those functions. I know that whenever I use them, I should implement IDisposable in that class and use a destructor to invoke the Dispose method, where I free the used IntPtr, as is said in the MSDN page. public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private void Dispose(bool disposing) { // Check to see if Dispose has already been called. if (!this.disposed) { if (disposing) { component.Dispose(); } CloseHandle(m_InstanceHandle); m_InstanceHandle = IntPtr.Zero; disposed = true; } } [System.Runtime.InteropServices.DllImport("Kernel32")] private extern static Boolean CloseHandle(IntPtr handle); However, when I terminate the application, I'm still left with a hanging process in TaskManager. I believe that it must be related to the used of the MarshalAs instruction in my structures: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; } When I create such a structure should I also be careful to free the space it allocs using a destructor? [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; ~SipxAudioCodec() { Marshal.FreeGlobal(something...); } } Thanks in advance!

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• Which of the following Java coding fragments is better?

  - by Simon

  This isn't meant to be subjective, I am looking for reasons based on resource utilisation, compiler performance, GC performance etc. rather than elegance. Oh, and the position of brackets doesn't count, so no stylistic comments please. Take the following loop; Integer total = new Integer(0); Integer i; for (String str : string_list) { i = Integer.parse(str); total += i; } versus... Integer total = 0; for (String str : string_list) { Integer i = Integer.parse(str); total += i; } In the first one i is function scoped whereas in the second it is scoped in the loop. I have always thought (believed) that the first one would be more efficient because it just references an existing variable already allocated on the stack, whereas the second one would be pushing and popping i each iteration of the loop. There are quite a lot of other cases where I tend to scope variables more broadly than perhaps necessary so I thought I would ask here to clear up a gap in my knowledge. Also notice that assignment of the variable on initialisation either involving the new operator or not. Do any of these sorts of semi-stylistic semi-optimisations make any difference at all?

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• Dispose, when is it called?

  - by Snake

  Consider the following code: namespace DisposeTest { using System; class Program { static void Main(string[] args) { Console.WriteLine("Calling Test"); Test(); Console.WriteLine("Call to Test done"); } static void Test() { DisposeImplementation di = new DisposeImplementation(); } } internal class DisposeImplementation : IDisposable { ~DisposeImplementation() { Console.WriteLine("~ in DisposeImplementation instance called"); } public void Dispose() { Console.WriteLine("Dispose in DisposeImplementation instance called"); } } } The Dispose just never get's called, even if I put a wait loop after the Test(); invocation. So that quite sucks. I want to write a class that is straightforward and very easy to use, to make sure that every possible resource is cleaned up. I don't want to put that responsibilty to the user of my class. Possible solution: use using, or call Dispose myself(basicly the same). Can I force the user to use a using? Or can I force the dispose to be called? Calling GC.Collect(); after Test(); doesn't work either. Putting di to null doesn't invoke Dispose either. The Deconstructor DOES work, so the object get's deconstructed when it exits Test()

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• Need help managing MySql connections

  - by David Jenings

  I'm having trouble finding a clear explanation of connection pooling. I'm building an app using the .NET connector I downloaded from mysql.com. The app only needs one db connection but will be running simultaneously on about 6 machines on my network. Normally, I'd create the connection at startup and just leave it. But I'm seeing lots of posts from people who say that's bad practice. Also I'm concerned about timeouts. My app will run 24/7 and there may be extended periods without database activity. I'm leaning toward the following: using (MySqlConnection conn = new MySqlConnection(connStr)) { conn.Open(); // use connection } But I'm not sure I understand what's going on in the background. Is this actually closing the connection and allowing gc to kill the object, or is there a built in pooling behavior that preserves the object and redelivers it the next time I try to create one? I certainly don't want the app reauthenticating across the network every time I hit the database. Can anyone offer me some advise?

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• How to optimize my game calendar in C#?

  - by MartyIX

  Hi, I've implemented a simple calendar (message system) for my game which consists from: 1) List<Event> calendar; 2) public class Event { /// <summary> /// When to process the event /// </summary> public Int64 when; /// <summary> /// Which object should process the event /// </summary> public GameObject who; /// <summary> /// Type of event /// </summary> public EventType what; public int posX; public int posY; public int EventID; } 3) calendar.Add(new Event(...)) The problem with this code is that even thought the number of messages is not excessise per second. It allocates still new memory and GC will once need to take care of that. The garbage collection may lead to a slight lag in my game and therefore I'd like to optimalize my code. My considerations: To change Event class in a structure - but the structure is not entirely small and it takes some time to copy it wherever I need it. Reuse Event object somehow (add queue with used events and when new event is needed I'll just take from this queue). Does anybody has other idea how to solve the problem? Thanks for suggestions!

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• How to implement the disposable pattern in a class that inherits from another disposable class?

  - by TheRHCP

  Hi, I often used the disposable pattern in simple classes that referenced small amount of resources, but I never had to implement this pattern on a class that inherits from another disposable class and I am starting to be a bit confused in how to free the whole resources. I start with a little sample code: public class Tracer : IDisposable { bool disposed; FileStream fileStream; public Tracer() { //Some fileStream initialization } public void Dispose() { this.Dispose(true); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { if (!disposed) { if (disposing) { if (fileStream != null) { fileStream.Dispose(); } } disposed = true; } } } public class ServiceWrapper : Tracer { bool disposed; ServiceHost serviceHost; //Some properties public ServiceWrapper () { //Some serviceHost initialization } //protected override void Dispose(bool disposing) //{ // if (!disposed) // { // if (disposing) // { // if (serviceHost != null) // { // serviceHost.Close(); // } // } // disposed = true; // } //} } My real question is: how to implement the disposable pattern inside my ServiceWrapper class to be sure that when I will dispose an instance of it, it will dispose resources in both inherited and base class? Thanks.

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• How can I avoid garbage collection delays in Java games? (Best Practices)

  - by Brian

  I'm performance tuning interactive games in Java for the Android platform. Once in a while there is a hiccup in drawing and interaction for garbage collection. Usually it's less than one tenth of a second, but sometimes it can be as large as 200ms on very slow devices. I am using the ddms profiler (part of the Android SDK) to search out where my memory allocations come from and excise them from my inner drawing and logic loops. The worst offender had been short loops done like, for(GameObject gob : interactiveObjects) gob.onDraw(canvas); where every single time the loop was executed there was an iterator allocated. I'm using arrays (ArrayList) for my objects now. If I ever want trees or hashes in an inner loop I know that I need to be careful or even reimplement them instead of using the Java Collections framework since I can't afford the extra garbage collection. That may come up when I'm looking at priority queues. I also have trouble where I want to display scores and progress using Canvas.drawText. This is bad, canvas.drawText("Your score is: " + Score.points, x, y, paint); because Strings, char arrays and StringBuffers will be allocated all over to make it work. If you have a few text display items and run the frame 60 times a second that begins to add up and will increase your garbage collection hiccups. I think the best choice here is to keep char[] arrays and decode your int or double manually into it and concatenate strings onto the beginning and end. I'd like to hear if there's something cleaner. I know there must be others out there dealing with this. How do you handle it and what are the pitfalls and best practices you've discovered to run interactively on Java or Android? These gc issues are enough to make me miss manual memory management, but not very much.

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• A generic Re-usable C# Property Parser utility

  - by Shyam K Pananghat

  This is about a utility i have happened to write which can parse through the properties of a data contracts at runtime using reflection. The input required is a look like XPath string. since this is using reflection, you dont have to add the reference to any of your data contracts thus making pure generic and re- usable.. you can read about this and get the full c# sourcecode here. Property-Parser-A-C-utility-to-retrieve-values-from-any-Net-Data-contracts-at-runtime Now about the doubts which i have about this utility. i am using this utility enormously i many places of my code I am using Regex repetedly inside a recursion method. does this affect the memmory usage or GC collection badly ?do i have to dispose this manually. if yes how ?. The statements like obj.GetType().GetProperty() and obj.GetType().GetField() returns .net "object" which makes difficult or imposible to introduce generics here. Does this cause to have any overheads like boxing ? on an overall, please suggest to make this utility performance efficient and more light weight on memmory

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• Unable to build my c++ code with g++ 4.6.3

  - by Mriganka

  I am facing multiple issues with building my c++ code on Ubuntu 12.04. This code was building and running fine on RH Enterprise. I am using g++ 4.6.3. Here's the output of g++ -v. g++ -v Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/usr/lib/gcc/i686-linux-gnu/4.6/lto-wrapper Target: i686-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --enable-targets=all --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=i686-linux-gnu --host=i686-linux-gnu --target=i686-linux-gnu Thread model: posix gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) Here's a sample of my code: #include "Word.h" #include < string> using namespace std; pthread_mutex_t Word::_lock = PTHREAD_MUTEX_INITIALIZER; Word::Word(): _occurrences(1) { memset(_buf, 0, 25); } Word::Word(char *str): _occurrences(1) { memset(_buf, 0, 25); if (str != NULL) { strncpy(_buf, str, strlen(str)); } } g++ -c -ansi or g++ -c -std=c++98 or g++ -c -std=c++03, none of these options are able to build the code correctly. I get the following compilation errors: mriganka@ubuntu:~/WordCount$ make g++ -c -g -ansi Word.cpp -o Word.o Word.cpp: In constructor ‘Word::Word()’: Word.cpp:10:21: error: ‘memset’ was not declared in this scope Word.cpp: In constructor ‘Word::Word(char*)’: Word.cpp:16:21: error: ‘memset’ was not declared in this scope Word.cpp:19:34: error: ‘strlen’ was not declared in this scope Word.cpp:19:35: error: ‘strncpy’ was not declared in this scope Word.cpp: In member function ‘void Word::operator=(const Word&)’: Word.cpp:37:42: error: ‘strlen’ was not declared in this scope Word.cpp:37:43: error: ‘strncpy’ was not declared in this scope Word.cpp: In copy constructor ‘Word::Word(const Word&)’: Word.cpp:44:21: error: ‘memset’ was not declared in this scope Word.cpp:45:52: error: ‘strlen’ was not declared in this scope Word.cpp:45:53: error: ‘strncpy’ was not declared in this scope So basically g++ 4.6.3 on Ubuntu 12.04 is not able to recognize the standard c++ headers. And I am not finding a way out of this situation. Second problem: In order to make progress, I included < string.h instead of < string. But now I am facing linking errors with my message queue and pthread library functions. Here's the error that I am getting: mriganka@ubuntu:~/WordCount$ make g++ -c -g -ansi Word.cpp -o Word.o g++ -lrt -I/usr/lib/i386-linux-gnu Word.o HashMap.o main.o -o word_count main.o: In function `main': /home/mriganka/WordCount/main.cpp:75: undefined reference to `pthread_create' /home/mriganka/WordCount/main.cpp:90: undefined reference to `mq_open' /home/mriganka/WordCount/main.cpp:93: undefined reference to `mq_getattr' /home/mriganka/WordCount/main.cpp:113: undefined reference to `mq_send' /home/mriganka/WordCount/main.cpp:123: undefined reference to `pthread_join' /home/mriganka/WordCount/main.cpp:129: undefined reference to `mq_close' /home/mriganka/WordCount/main.cpp:130: undefined reference to `mq_unlink' main.o: In function `count_words(void*)': /home/mriganka/WordCount/main.cpp:151: undefined reference to `mq_open' /home/mriganka/WordCount/main.cpp:154: undefined reference to `mq_getattr' /home/mriganka/WordCount/main.cpp:162: undefined reference to `mq_timedreceive' collect2: ld returned 1 exit status Here's my makefile: CC=g++ CFLAGS=-c -g -ansi LDFLAGS=-lrt INC=-I/usr/lib/i386-linux-gnu SOURCES=Word.cpp HashMap.cpp main.cpp OBJECTS=$(SOURCES:.cpp=.o) EXECUTABLE=word_count all: $(SOURCES) $(EXECUTABLE) $(EXECUTABLE): $(OBJECTS) $(CC) $(LDFLAGS) $(INC) -pthread $(OBJECTS) -o $@ .cpp.o: $(CC) $(CFLAGS) $< -o $@ clean: rm -f *.o word_count Please help me to resolve both the issues. I searched online relentlessly for any solution of these problems, but no one seems to have encountered these issues.

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• Getting Wrong Answer in range maximum query [on hold]

  - by user3186829

  I've just learnt range minimum and maximum queries using segment trees.But when I implemented it on my own I'm getting wrong answer.Logically I don't find any mistake in my code but if any one can point it out then I would be really thankful. Code in C++: #include<bits/stdc++.h> using namespace std; #define LL long long #define mp make_pair #define pb push_back #define gc getchar_unlocked #define pc putchar_unlocked #define LD long double #define MAXN 19999999 #define max(a,b) ((a)>(b)?(a):(b)) LL P[MAXN+15]; LL ST[2*MAXN+25]; long N,M,i,A,B,K; void build(long id,long L,long R) { long M=(L+R)>>1L; long LCT=id<<1L; long RCT=LCT+1L; if(L==R) { ST[id]=P[L]; return; } build(LCT,L,M); build(RCT,M+1,R); } //Range Update of segment tree void updateST(long id,long L,long R,long Q1,long Q2,long val) { long M=(L+R)>>1L; long LCT=id<<1L; long RCT=LCT+1L; if(L>Q2||R<Q1) { return; } if(L==Q1&&R==Q2) { ST[id]+=val; return; } if(Q2<=M) { updateST(LCT,L,M,Q1,Q2,val); } else if(Q1>M) { updateST(RCT,M+1,R,Q1,Q2,val); } else { updateST(LCT,L,M,Q1,M,val); updateST(RCT,M+1,R,M+1,Q2,val); } } //Query for finding maximum element in a given range[Q1,Q2] and 1<=Q1,Q2<=N LL query2(long id,long L,long R,long Q1,long Q2) { long M=(L+R)>>1; long LCT=id<<1; long RCT=LCT+1; if(L>Q2||R<Q1) { return 0; } if(L==Q1&&R==Q2) { return ST[id]; } if(Q2<=M) { return query2(LCT,L,M,Q1,Q2); } else if(Q1>M) { return query2(RCT,M+1,R,Q1,Q2); } else { LL G=query2(LCT,L,M,Q1,M); LL H=query2(RCT,M+1,R,M+1,Q2); LL RES=max(G,H); return RES; } } int main() { scanf("%ld %ld",&N,&M); build(1,1,N); for(i=0;i<M;i++) { scanf("%ld %ld %ld",&A,&B,&K); updateST(1,1,N,A,B,K); } //Finding maximum element in range[1,N]] cout<<query2(1,1,N,1,N); return 0; }

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• Profiling Startup Of VS2012 &ndash; JustTrace Profiler

  - by Alois Kraus

  JustTrace is made by Telerik which is mainly known for its collection of UI controls. The current version (2012.3.1127.0) does include a performance and memory profiler which does cost 614€ and is currently with a special offer for 306€ on sale. It does include one year of free upgrades. The uneven € numbers are calculated from the 799€ and 50% dicsount price. The UI is already in Metro style and simple to use. Multi process, attach, method recording filter are not supported. It looks like JustTrace is like Ants a Just My Code profiler. For stuff where you do not have the pdbs or you want to dig deeper into the BCL code you will not get far. After getting the profile data you get in the All Methods grid a plain list with hit count and own time. The method list for all methods is also suspiciously short which is a clear sign that you will not get far during the analysis of foreign code. But at least there is also a memory profiler included. For this I have to choose in the first window for Profiling Type “Memory Profiler” to check the memory consumption of VS.  There are some interesting number to see but I do really miss from YourKit the thread stack window. How am I supposed to get a clue when much memory is allocated and the CPU consumption is high in which places I should look? The Snapshot summary gives a rough overview which is ok for a first impression. Next is Assemblies? This gives you a list of all loaded assemblies. Not terribly useful.   The By Type view gives you exactly what it is supposed to do. You have to keep in mind that this list is filtered by the types you did check in the Assemblies list. The By Type instance list does only show types from assemblies which do not originate from Microsoft. By default mscorlib and System are not checked. That is the reason why for the first time my By Type window looked like The idea behind this feature is to show only your instances because you are ultimately responsible for the overall memory consumption. I am not sure if I do like this feature because by default it does hide too much. I do want to see at least how many strings and arrays are allocated. A simple namespace filter would also do it in my opinion. Now you can examine all string instances and look who in the object graph does keep a reference on them. That is nice but YourKit has the big plus that you can also look into the string contents.  I am also not sure how in the graph cycles are visualized and what will happen if you have thousands of objects referencing you. That's pretty much it about JustTrace. It can help the average developer to pinpoint performance and memory issues by just looking at his own code and instances. Showing them more will not help them because the sheer amount of information will overwhelm them. And you need to have a pretty good understanding how the GC and the CLR does work. When you have a performance issue at a customer machine it is sometimes very helpful to be able a bring a profiler onto the machine (no pdbs, …) and to get a full snapshot of all processes which are in the problematic use case involved. For these more advanced use cased JustTrace is certainly the wrong tool. Next: SpeedTrace

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• Application using JOGL stays in Limbo when closing

  - by Roy T.

  I'm writing a game using Java and OpenGL using the JOGL bindings. I noticed that my game doesn't terminate properly when closing the window even though I've set the closing operation of the JFrame to EXIT_ON_CLOSE. I couldn't track down where the problem was so I've made a small reproduction case. Note that on some computers the program terminates normally when closing the window but on other computers (notably my own) something in the JVM keeps lingering, this causes the JFrame to never be disposed and the application to never exit. I haven't found something in common between the computers that had difficulty terminating. All computers had Windows 7, Java 7 and the same version of JOGL and some terminated normally while others had this problem. The test case is as follows: public class App extends JFrame implements GLEventListener { private GLCanvas canvas; @Override public void display(GLAutoDrawable drawable) { GL3 gl = drawable.getGL().getGL3(); gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); gl.glClear(GL3.GL_COLOR_BUFFER_BIT); gl.glFlush(); } // The overrides for dispose (the OpenGL one), init and reshape are empty public App(String title, boolean full_screen, int width, int height) { //snipped setting the width and height of the JFRAME GLProfile profile = GLProfile.get(GLProfile.GL3); GLCapabilities capabilities = new GLCapabilities(profile); canvas = new GLCanvas(capabilities); canvas.addGLEventListener(this); canvas.setSize(getWidth(), getHeight()); add(canvas); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //!!! setVisible(true); } @Override public void dispose() { System.out.println("HELP"); // } public static void main( String[] args ) { new App("gltut 01", false, 1280, 720); } } As you can see this doesn't do much more than adding a GLCanvas to the frame and registering the main class as the GLEventListener. So what keeps lingering? I'm not sure. I've made some screenshots. The application running normally. The application after the JFrame is closed, note that the JVM still hasn't exited or printed a return code. The application after it was force closed. Note the return code -1, so it wasnt just the JVM standing by or something the application really hadn't exited yet. So what is keeping the application in Limbo? Might it be the circular reference between the GLCanvas and the JFrame? I thought the GC could figure that out. If so how should I deal with that when I want to exit? Is there any other clean-up required when using JOGL? I've tried searching but it doesn't seem to be necessary. Edit, to clarify: there are 2 dispose functions dispose(GLAutoDrawable arg) which is a member of GLEventListener and dispose() which is a member of JFrame. The first one is called correctly (but I wouldn't know what to there, destroying the GLAutoDrawable or the GLCanvas gives an infinite exception loop) the second one is never called.

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• Oracle????????(2013?7?)

  - by Steve He(???)

  ???? ?? ?? ???? ?? ????? ???????,??25??????5???Q&A??,????????????,???????,???????????,????????????????????? 7?11?14:00 ?? ?My Oracle Support????????? "?My Oracle Support??????"??????????????????Oracle??????????????????My Oracle Support??????????????????????????? ??????????My Oracle Support?????????,?????????????????????,????My Oracle Support???????,???????????????????:30??? 7?25?14:00 ?? WebLogic Server ????????????? ????WebLogic Server??????????,?????????1???????????????????WebLogic Server ????????????????????????????????? 7?17?14:00 ?? Exadata????: Diagnostic Assistant   ??Exadata???????Diagnostic Assistent (DA). ??????????????,????????????????,??ADR,RDA,OCM,Explorer? ?????????????: ????????,??Diagnostic Assistant?Exadata??????? ?????????????,????????????,????????????? 7?18?14:00 ?? E-Business Suite ?????? ????????????E-Business ???????????,??????????????? ?60???????????E-Business Suite???????????,????????????????DBA? 7?16?14:00 ?? ?????? My Oracle Support ??????????????????????,??? world clock.??????? Oracle ?????????????,??? note 603505.1 ????????????,??????????????(Mandarin)?????? Internet Explorer ??? My Oracle Support ????????????????? ?? ?? ?? ?? Oracle Support Best Practices(Oracle??????)(?) ???? ?? ?? GetProactive: Resolve Fast(??????)(?) ???? ?? ?? WebLogic GC & OutOfMemory Diagnostic(?) ????? ?? ?? Creating Customer Value ???? ?? ?? Oracle Support Basics ???? ?? ?? An Introduction to My Oracle Support ???? ?? ?? Service Request Management ???? ?? ?? Customer User Administration ???? ?? ?? Managing Favorite ???? ?? ?? Quick Search ???? ?? ?? Hot Topic Email ???? ?? ?? Patch and Update ???? ?? ?? Site Alert ???? ?? ?? Search and Browse Features in My Oracle Support ???? ?? ?? Why Use Configuration Manager In The My Oracle Support ???? ?? ?? Enterprise Manager 11g and My Oracle Support ???? ?? ?? Oracle Collaborative Support ???? ?? ?? How to Escalate a Service Request within Oracle Support ???? ?? ?? ????????,?? Support Training Community ??????????

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• New Exchange 2010 CAS cannot find domain controllers

  - by NorbyTheGeek

  I am experiencing problems migrating from Exchange 2003 to Exchange 2010. I am on the first step: installing a new 2010 Client Access Server role. The Active Directory domain functional level is 2003. All domain controllers are 2003 R2. The only existing Exchange 2003 server happens to be housed on one of the domain controllers. It is running Exchange 2003 Standard w/ SP2. IPv6 is enabled and working on all domain controllers, servers, and routers, including this new Exchange server. After installing the CAS role on a new 2008 R2 server (Hyper-V VM) I am receiving 2114 Events: Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=1600). Topology discovery failed, error 0x80040a02 (DSC_E_NO_SUITABLE_CDC). Look up the Lightweight Directory Access Protocol (LDAP) error code specified in the event description. To do this, use Microsoft Knowledge Base article 218185, "Microsoft LDAP Error Codes." Use the information in that article to learn more about the cause and resolution to this error. Use the Ping or PathPing command-line tools to test network connectivity to local domain controllers. Prior to each, I receive the following 2080 Event: Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=1600). Exchange Active Directory Provider has discovered the following servers with the following characteristics: (Server name | Roles | Enabled | Reachability | Synchronized | GC capable | PDC | SACL right | Critical Data | Netlogon | OS Version) In-site: b.company.intranet CDG 1 0 0 1 0 0 0 0 0 s.company.intranet CDG 1 0 0 1 0 0 0 0 0 Out-of-site: a.company.intranet CD- 1 0 0 0 0 0 0 0 0 o.company.intranet CD- 1 0 0 0 0 0 0 0 0 g.company.intranet CD- 1 0 0 0 0 0 0 0 0 Connectivity between the new Exchange server and all domain controllers via IPv4 and IPv6 are all working. I have verified that the new Exchange server is a member of the following groups: Exchange Servers Exchange Domain Servers Exchange Install Domain Servers Exchange Trusted Subsystem Heck, I even put the new Exchange server into Domain Admins just to see if it would help. It didn't. I can't find any evidence of Active Directory replication problems, all pre-setup Setup tasks (/PrepareLegacyExchangePermissions, /PrepareSchema, /PrepareAD, /PrepareDomain) completed successfully. The only problem so far that I haven't been able to resolve with my Active Directory is I am unable to get my IPv6 subnets into Sites and Services Where should I proceed from here?

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• StackOverFlowError while creating Mac object on AS400/Java

  - by Prasanna K Rao

  Hello all, I am a newbie to AS400-Java programming. I am trying to create my first program to test the implementation of Message Authentication Code (MAC). I am trying to use the HMACSHA1 hash function. My (Java 1.4) program runs fine on a dev box (V5R4).But fails terribly on the QA box (V5R3). My program is as below: ===================================================== import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import java.security.Security; import java.security.Provider; import javax.crypto.Mac; import javax.crypto.spec.SecretKeySpec; import javax.crypto.SecretKey; public class Test01 { private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1"; public static void main (String [] arguments) { byte[] key = { 1,2,3,4,5,6,7,8}; SecretKeySpec SHA1key = new SecretKeySpec(key, "HmacSHA1"); Mac hmac; String strFinalRslt = ""; try { hmac = Mac.getInstance("HmacSHA1"); hmac.init(SHA1key); byte[] result = hmac.doFinal(); strFinalRslt = toHexString(result); }catch (NoSuchAlgorithmException e) { // TODO Auto-generated catch block e.printStackTrace(); }catch (InvalidKeyException e) { // TODO Auto-generated catch block e.printStackTrace(); }catch(StackOverflowError e){ e.printStackTrace(); } System.out.println(strFinalRslt); System.out.println("All done!!!"); } public static byte[] fromHexString ( String s ) { int stringLength = s.length(); if ( (stringLength & 0x1) != 0 ) { throw new IllegalArgumentException ( "fromHexString requires an even number of hex characters" ); } byte[] b = new byte[stringLength / 2]; for ( int i=0,j=0; i 4] ); //look up low nibble char sb.append( hexChar [b[i] & 0x0f] ); } return sb.toString(); } static char[] hexChar = { '0' , '1' , '2' , '3' , '4' , '5' , '6' , '7' , '8' , '9' , 'a' , 'b' , 'c' , 'd' , 'e' , 'f'}; } This program compiles fine and gets the correct response on my win-xp client and also my dev box. But, fails with the following error on the QA box: java.lang.StackOverflowError at java.lang.Throwable.(Throwable.java:180) at java.lang.Error.(Error.java:37) at java.lang.StackOverflowError.(StackOverflowError.java:24) at java.io.Os400FileSystem.list(Native method) at java.io.File.list(File.java:922) at javax.crypto.b.e(Unknown source) at javax.crypto.b.a(Unknown source) at javax.crypto.b.c(Unknown source) at javax.crypto.b£0.run(Unknown source) at javax.crypto.b.(Unknown source) at javax.crypto.Mac.getInstance(Unknown source) I have verified the java.security file and entry corresponding to the jce files are all ok. The DMPJVM command gives me the following response: Thu Jun 03 12:25:34 E Java Virtual Machine Information 016822/QPGMR/11111 ........................................................................ . Classpath . ........................................................................ java.version=1.4 sun.boot.class.path=/QIBM/ProdData/OS400/Java400/jdk/lib/jdkptf14.zip:/QIBM /ProdData/OS400/Java400/ext/ibmjssefw.jar:/QIBM/ProdData/CAP/ibmjsseprovide r.jar:/QIBM/ProdData/OS400/Java400/ext/ibmjsseprovider2.jar:/QIBM/ProdData/ OS400/Java400/ext/ibmpkcs11impl.jar:/QIBM/ProdData/CAP/ibmjssefips.jar:/QIB M/ProdData/OS400/Java400/jdk/lib/IBMiSeriesJSSE.jar:/QIBM/ProdData/OS400/Ja va400/jdk/lib/jce.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/jaas.jar:/QIBM/P rodData/OS400/Java400/jdk/lib/ibmcertpathfw.jar:/QIBM/ProdData/OS400/Java40 0/jdk/lib/ibmcertpathprovider.jar:/QIBM/ProdData/OS400/Java400/ext/ibmpkcs. jar:/QIBM/ProdData/OS400/Java400/jdk/lib/ibmjgssfw.jar:/QIBM/ProdData/OS400 /Java400/jdk/lib/ibmjgssprovider.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/s ecurity.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/charsets.jar:/QIBM/ProdDat a/OS400/Java400/jdk/lib/resources.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/ rt.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/sunrsasign.jar:/QIBM/ProdData/O S400/Java400/ext/IBMmisc.jar:/QIBM/ProdData/Java400/ java.class.path=/myhome/lib/commons-codec-1.3.jar:/myhome/lib/commons-httpc lient-3.1.jar:/myhome/lib/commons-logging-1.1.jar:/myhome/lib/log4j-1.2.15.jar:/myhome/lib/log4j-core.jar ; java.ext.dirs=/QIBM/ProdData/OS400/Java400/jdk/lib/ext:/QIBM/UserData/Java4 00/ext:/QIBM/ProdData/Java400/jdk14/lib/ext java.library.path=/QSYS.LIB/ROBOTLIB.LIB:/QSYS.LIB/QTEMP.LIB:/QSYS.LIB/ODIP GM.LIB:/QSYS.LIB/QGPL.LIB ........................................................................ . Garbage Collection . ........................................................................ Garbage collector parameters Initial size: 16384 K Max size: 240000000 K Current values Heap size: 437952 K Garbage collections: 58 Additional values JIT heap size: 53824 K JVM heap size: 55752 K Last GC cycle time: 1333 ms ........................................................................ . Thread information . ........................................................................ Information for 4 thread(s) of 4 thread(s) processed Thread: 00000004 Thread-0 TDE: B00380000BAA0000 Thread priority: 5 Thread status: Running Thread group: main Runnable: java/lang/Thread Stack: java/io/Os400FileSystem.list(Ljava/io/File;)[Ljava/lang/String;+0 (Os400FileSystem.java:0) java/io/File.list()[Ljava/lang/String;+19 (File.java:922) javax/crypto/b.e()[B+127 (:0) javax/crypto/b.a(Ljava/security/cert/X509Certificate;)V+7 (:0) javax/crypto/b.access$500(Ljava/security/cert/X509Certificate;)V+1 (:0) javax/crypto/b$0.run()Ljava/lang/Object;+98 (:0) javax/crypto/b.()V+507 (:0) javax/crypto/Mac.getInstance(Ljava/lang/String;)Ljavax/crypto/Mac;+10 (:0) Locks: None Thread: 00000007 jitcompilethread TDE: B00380000BD58000 Thread priority: 5 Thread status: Java wait Thread group: system Runnable: java/lang/Thread Stack: None Locks: None Thread: 00000005 Reference Handler TDE: B00380000BAAC000 Thread priority: 10 Thread status: Waiting Wait object: java/lang/ref/Reference$Lock Thread group: system Runnable: java/lang/ref/Reference$ReferenceHandler Stack: java/lang/Object.wait()V+1 (Object.java:452) java/lang/ref/Reference$ReferenceHandler.run()V+47 (Reference.java:169) Locks: None Thread: 00000006 Finalizer TDE: B00380000BAB3000 Thread priority: 8 Thread status: Waiting Wait object: java/lang/ref/ReferenceQueue$Lock Thread group: system Runnable: java/lang/ref/Finalizer$FinalizerThread Stack: java/lang/ref/ReferenceQueue.remove(J)Ljava/lang/ref/Reference;+43 (ReferenceQueue.java:111) java/lang/ref/ReferenceQueue.remove()Ljava/lang/ref/Reference;+1 (ReferenceQueue.java:127) java/lang/ref/Finalizer$FinalizerThread.run()V+3 (Finalizer.java:171) Locks: None ........................................................................ . Class loader information . ........................................................................ 0 Default class loader 1 sun/reflect/DelegatingClassLoader 2 sun/misc/Launcher$ExtClassLoader ........................................................................ . GC heap information . ........................................................................ Loader Objects Class name ------ ------- ---------- 0 1493 [C 0 2122181 java/lang/String 0 47 [Ljava/util/Hashtable$Entry; 0 68 [Ljava/lang/Object; 0 1016 java/lang/Class 0 31 java/util/HashMap 0 37 java/util/Hashtable 0 2 java/lang/ThreadGroup 0 2 java/lang/RuntimePermission 0 2 java/lang/ref/ReferenceQueue$Null 0 5 java/lang/ref/ReferenceQueue 0 50 java/util/Vector 0 4 java/util/Stack 0 3 sun/misc/SoftCache 0 1 [Ljava/lang/ThreadGroup; 0 5 [Ljava/io/ObjectStreamField; 0 1 sun/reflect/ReflectionFactory 0 7 java/lang/ref/ReferenceQueue$Lock 0 10 java/lang/Object 0 1 java/lang/String$CaseInsensitiveComparator 0 1 java/util/Hashtable$EmptyEnumerator 0 1 java/util/Hashtable$EmptyIterator 0 33 [Ljava/util/HashMap$Entry; 0 19210 [J 0 1 sun/nio/cs/StandardCharsets 0 5 java/util/TreeMap 0 1075 java/util/TreeMap$Entry 0 469 [Ljava/lang/String; 0 1 java/lang/StringBuffer 0 2 java/io/FileInputStream 0 2 java/io/FileOutputStream 0 2 java/io/BufferedOutputStream 0 1 java/lang/reflect/ReflectPermission 0 1 [[Ljava/lang/ref/SoftReference; 0 2 [Ljava/lang/ref/SoftReference; 0 2 sun/nio/cs/Surrogate$Parser 0 3 sun/misc/Signal 0 1 [Ljava/io/File; 0 6 java/io/File 0 1 java/util/BitSet 0 17 sun/reflect/NativeConstructorAccessorImpl 0 2 java/net/URLClassLoader$ClassFinder 0 12 java/util/ArrayList 0 32 java/io/RandomAccessFile 0 16 java/lang/Thread 0 1 java/lang/ref/Reference$ReferenceHandler 0 1 java/lang/ref/Finalizer$FinalizerThread 0 266 [B 0 2 java/util/Properties 0 71 java/lang/ref/Finalizer 0 2 com/ibm/nio/cs/DirectEncoder 0 38 java/lang/reflect/Constructor 0 33 java/util/jar/JarFile 0 19200 java/lang/StackOverflowError 0 5 java/security/AccessControlContext 0 2 [Ljava/lang/Thread; 0 4 java/lang/OutOfMemoryError 0 1065 java/util/Hashtable$Entry 0 1 java/io/BufferedInputStream 0 2 java/io/PrintStream 0 2 java/io/OutputStreamWriter 0 428 [I 0 3 java/lang/ClassLoader$NativeLibrary 0 25 java/util/Locale 0 3 sun/misc/URLClassPath 0 30 java/util/zip/Inflater 0 612 java/util/HashMap$Entry 0 2 java/io/FilePermission 0 10 java/io/ObjectStreamField 0 1 java/security/BasicPermissionCollection 0 2 java/security/ProtectionDomain 0 1 java/lang/Integer$1 0 1 java/lang/ref/Reference$Lock 0 1 java/lang/Shutdown$Lock 0 1 java/lang/Runtime 0 36 java/io/FileDescriptor 0 1 java/lang/Long$1 0 202 java/lang/Long 0 3 java/lang/ThreadLocal 0 3 java/nio/charset/CodingErrorAction 0 2 java/nio/charset/CoderResult 0 1 java/nio/charset/CoderResult$1 0 1 java/nio/charset/CoderResult$2 0 1 sun/misc/Unsafe 0 2 java/nio/ByteOrder 0 1 java/io/Os400FileSystem 0 3 java/lang/Boolean 0 1 java/lang/Terminator$1 0 23 java/lang/Integer 0 2 sun/misc/NativeSignalHandler 0 1 sun/misc/Launcher$Factory 0 1 sun/misc/Launcher 0 53 [Ljava/lang/Class; 0 1 java/lang/reflect/ReflectAccess 0 18 sun/reflect/DelegatingConstructorAccessorImpl 0 1 sun/net/www/protocol/file/Handler 0 3 java/util/HashSet 0 3 sun/net/www/protocol/jar/Handler 0 1 java/util/jar/JavaUtilJarAccessImpl 0 1 java/net/UnknownContentHandler 0 2 [Ljava/security/Principal; 0 10 [Ljava/security/cert/Certificate; 0 2 sun/misc/AtomicLongCSImpl 0 3 sun/reflect/DelegatingMethodAccessorImpl 0 1 sun/security/util/ByteArrayLexOrder 0 1 sun/security/util/ByteArrayTagOrder 0 7 sun/security/x509/CertificateVersion 0 7 sun/security/x509/CertificateSerialNumber 0 7 sun/security/x509/SerialNumber 0 7 sun/security/x509/CertificateAlgorithmId 0 7 sun/security/x509/CertificateIssuerName 0 60 sun/security/x509/RDN 0 60 [Lsun/security/x509/AVA; 0 67 sun/security/util/DerInputStream 0 3 [Ljava/math/BigInteger; 0 2 com/ibm/nio/cs/Converter 0 2 sun/nio/cs/StreamEncoder$CharsetSE 0 35 java/lang/ref/SoftReference 0 2 java/nio/HeapByteBuffer 0 2 java/io/BufferedWriter 0 33 sun/misc/URLClassPath$JarLoader 0 4 java/lang/ThreadLocal$ThreadLocalMap$Entry 0 76 java/net/URL 0 1 sun/misc/Launcher$ExtClassLoader 0 1 sun/misc/Launcher$AppClassLoader 0 4 java/lang/Throwable 0 7 java/lang/reflect/Method 0 2 sun/misc/URLClassPath$FileLoader 0 2 java/security/CodeSource 0 2 java/security/Permissions 0 2 java/io/FilePermissionCollection 0 1 java/lang/ThreadLocal$ThreadLocalMap 0 1 javax/crypto/spec/SecretKeySpec 0 17 java/util/jar/Attributes$Name 0 1 [Ljava/lang/ThreadLocal$ThreadLocalMap$Entry; 0 1 java/security/SecureRandom 0 2 sun/security/provider/Sun 0 1 java/util/jar/JarFile$JarFileEntry 0 1 java/util/jar/JarVerifier 0 3 sun/reflect/NativeMethodAccessorImpl 0 116 sun/security/util/ObjectIdentifier 0 1 java/lang/Package 0 2 [S 0 104 java/math/BigInteger 0 20 sun/security/x509/AlgorithmId 0 14 sun/security/x509/X500Name 0 14 [Lsun/security/x509/RDN; 0 60 sun/security/x509/AVA 0 67 sun/security/util/DerValue 0 67 sun/security/util/DerInputBuffer 0 21 sun/security/x509/AVAKeyword 0 6 sun/security/x509/X509CertImpl 0 7 sun/security/x509/X509CertInfo 0 1 [Lsun/security/util/ObjectIdentifier; 0 1 [[Ljava/lang/Byte; 0 3 [[B 0 7 sun/security/provider/DSAPublicKey 0 7 sun/security/x509/AuthorityKeyIdentifierExtension 0 12 [Ljava/lang/Byte; 0 14 java/lang/Byte 0 7 sun/security/x509/CertificateSubjectName 0 7 sun/security/x509/CertificateX509Key 0 14 sun/security/x509/KeyIdentifier 0 4 [Z 0 5 sun/text/Normalizer$Mode 0 7 sun/security/x509/CertificateValidity 0 14 java/util/Date 0 7 sun/security/provider/DSAParameters 0 7 sun/security/util/BitArray 0 7 sun/security/x509/CertificateExtensions 0 7 java/security/AlgorithmParameters 0 7 sun/security/x509/SubjectKeyIdentifierExtension 0 5 sun/security/x509/BasicConstraintsExtension 0 2 sun/security/x509/KeyUsageExtension 0 1 sun/text/CompactCharArray 0 1 sun/text/CompactByteArray 0 1 sun/net/www/protocol/jar/JarFileFactory 0 1 java/util/Collections$EmptySet 0 1 java/util/Collections$EmptyList 0 1 java/util/Collections$ReverseComparator 0 1 com/ibm/security/jgss/i18n/PropertyResource 0 1 javax/crypto/b$0 0 1 sun/security/provider/X509Factory 0 1 sun/reflect/BootstrapConstructorAccessorImpl 1 1 sun/reflect/GeneratedConstructorAccessor3202134454 2 1 com/ibm/crypto/provider/IBMJCE 0 6 java/util/ResourceBundle$LoaderReference 0 1 [Lsun/security/x509/NetscapeCertTypeExtension$MapEntry; 0 1 com/sun/rsajca/Provider 0 1 com/ibm/security/cert/IBMCertPath 0 1 com/ibm/as400/ibmonly/net/ssl/Provider 0 1 com/ibm/jsse/IBMJSSEProvider 0 1 com/ibm/security/jgss/IBMJGSSProvider 0 5 org/ietf/jgss/Oid 0 1 java/util/PropertyResourceBundle 0 7 java/util/ResourceBundle$ResourceCacheKey 0 2 sun/net/www/protocol/jar/URLJarFile 0 6 sun/misc/SoftCache$ValueCell 0 1 java/util/Random 0 1 java/util/Collections$EmptyMap 0 112 com/ibm/security/util/ObjectIdentifier 0 5 java/security/Security$ProviderProperty 0 1 java/security/cert/CertificateFactory 0 1 sun/security/provider/SecureRandom 0 2 java/security/MessageDigest$Delegate 0 2 sun/security/provider/SHA 0 1 sun/util/calendar/ZoneInfo 0 4 com/ibm/security/x509/X500Name 0 2 [Ljava/security/cert/X509Certificate; 0 1 sun/reflect/DelegatingClassLoader 0 1 sun/security/x509/NetscapeCertTypeExtension 0 7 sun/security/x509/NetscapeCertTypeExtension$MapEntry 0 3 [[Ljava/lang/String; 0 3 java/util/Arrays$ArrayList 0 7 com/ibm/security/x509/NetscapeCertTypeExtension$MapEntry 0 1 com/ibm/security/validator/EndEntityChecker 0 1 java/util/AbstractList$Itr 0 1 com/ibm/security/util/ByteArrayLexOrder 0 1 com/ibm/security/util/ByteArrayTagOrder 0 18 [Lcom/ibm/security/x509/AVA; 0 18 com/ibm/security/util/DerInputStream 0 5 com/ibm/security/util/text/Normalizer$Mode 0 1 com/ibm/security/validator/SimpleValidator 0 1 [Lcom/ibm/security/x509/NetscapeCertTypeExtension$MapEntry; 0 4 [Lcom/ibm/security/x509/RDN; 0 1 java/util/Hashtable$Enumerator 0 4 java/util/LinkedHashMap$Entry 0 1 sun/text/resources/LocaleElements 0 1 sun/text/resources/LocaleElements_en 0 22 com/ibm/security/x509/AVAKeyword 0 4 javax/security/auth/x500/X500Principal 0 18 com/ibm/security/x509/RDN 0 18 com/ibm/security/x509/AVA 0 18 com/ibm/security/util/DerInputBuffer 0 18 com/ibm/security/util/DerValue 0 1 com/ibm/security/util/text/CompactCharArray 0 1 com/ibm/security/util/text/CompactByteArray 0 2 java/util/LinkedHashMap 0 1 java/net/InetAddress$1 0 2 [Ljava/net/InetAddress; 0 2 java/net/InetAddress$Cache 0 1 java/net/Inet4AddressImpl 0 3 java/net/Inet4Address 0 2 java/net/InetAddress$CacheEntry ........................................................................ . Global registry information . ........................................................................ Loader Objects Class name ------ ------- ---------- 0 23 [C 0 1017 java/lang/Class 0 1 java/lang/ref/Reference$ReferenceHandler 0 1 java/lang/ref/Finalizer$FinalizerThread 0 1 sun/misc/Launcher$AppClassLoader 0 32 java/io/RandomAccessFile 0 32 [B Can someone please advise me? Thanks a lot, Prasanna

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• Control layout using graphviz twopi

  - by vy32

  I am trying to draw a graph showing search prefixes using twopi. I have a simple input file and am getting this output: (full image) Here is the input file: digraph search { // ordering=out; // color=blue; // rank=same; // overlap=scale; rankdir=LR; root=root; ranksep=1.25; overlap=true; "root"; a [color=none,fontsize=12]; b [color=none,fontsize=12]; c [color=none,fontsize=12]; d [color=none,fontsize=12]; e [color=none,fontsize=12]; f [color=none,fontsize=12]; #g [color=none,fontsize=12]; h [color=none,fontsize=12]; i [color=none,fontsize=12]; j [color=none,fontsize=12]; k [color=none,fontsize=12]; l [color=none,fontsize=12]; m [color=none,fontsize=12]; n [color=none,fontsize=12]; o [color=none,fontsize=12]; p [color=none,fontsize=12]; q [color=none,fontsize=12]; r [color=none,fontsize=12]; s [color=none,fontsize=12]; t [color=none,fontsize=12]; u [color=none,fontsize=12]; v [color=none,fontsize=12]; w [color=none,fontsize=12]; x [color=none,fontsize=12]; y [color=none,fontsize=12]; #ga [color=none,fontsize=12]; gb [color=none,fontsize=12]; gc [color=none,fontsize=12]; gd [color=none,fontsize=12]; ge [color=none,fontsize=12]; gf [color=none,fontsize=12]; gg [color=none,fontsize=12]; gh [color=none,fontsize=12]; gi [color=none,fontsize=12]; gj [color=none,fontsize=12]; gk [color=none,fontsize=12]; gl [color=none,fontsize=12]; gm [color=none,fontsize=12]; gn [color=none,fontsize=12]; go [color=none,fontsize=12]; gp [color=none,fontsize=12]; gq [color=none,fontsize=12]; gr [color=none,fontsize=12]; gs [color=none,fontsize=12]; gt [color=none,fontsize=12]; gu [color=none,fontsize=12]; gv [color=none,fontsize=12]; gw [color=none,fontsize=12]; gx [color=none,fontsize=12]; gy [color=none,fontsize=12]; gaa [color=none,fontsize=12]; gab [color=none,fontsize=12]; gac [color=none,fontsize=12]; gad [color=none,fontsize=12]; gae [color=none,fontsize=12]; gaf [color=none,fontsize=12]; gag [color=none,fontsize=12]; gah [color=none,fontsize=12]; gai [color=none,fontsize=12]; gaj [color=none,fontsize=12]; gak [color=none,fontsize=12]; gal [color=none,fontsize=12]; gam [color=none,fontsize=12]; gan [color=none,fontsize=12]; gao [color=none,fontsize=12]; gap [color=none,fontsize=12]; gaq [color=none,fontsize=12]; #gaz [color=none,fontsize=12]; gas [color=none,fontsize=12]; gat [color=none,fontsize=12]; gau [color=none,fontsize=12]; gav [color=none,fontsize=12]; gaw [color=none,fontsize=12]; gax [color=none,fontsize=12]; gay [color=none,fontsize=12]; gaza [color=none,fontsize=12]; gazb [color=none,fontsize=12]; gazc [color=none,fontsize=12]; gazd [color=none,fontsize=12]; gaze [color=none,fontsize=12]; #gazf [color=none,fontsize=12]; gazg [color=none,fontsize=12]; gazh [color=none,fontsize=12]; gazi [color=none,fontsize=12]; gazj [color=none,fontsize=12]; gazk [color=none,fontsize=12]; gazl [color=none,fontsize=12]; gazm [color=none,fontsize=12]; gazn [color=none,fontsize=12]; gazo [color=none,fontsize=12]; gazp [color=none,fontsize=12]; gazq [color=none,fontsize=12]; gazr [color=none,fontsize=12]; gazs [color=none,fontsize=12]; gazt [color=none,fontsize=12]; gazu [color=none,fontsize=12]; gazv [color=none,fontsize=12]; gazw [color=none,fontsize=12]; gazx [color=none,fontsize=12]; gazy [color=none,fontsize=12]; root -> a [minlen=2]; root -> b [minlen=2]; root -> c [minlen=2]; root -> d [minlen=2]; root -> e [minlen=2]; root -> f [minlen=2]; root -> g [minlen=2]; root -> h [minlen=2]; root -> i [minlen=2]; root -> j [minlen=2]; root -> k [minlen=2]; root -> l [minlen=2]; root -> m [minlen=2]; root -> n [minlen=2]; root -> o [minlen=2]; root -> p [minlen=2]; root -> q [minlen=2]; root -> r [minlen=2]; root -> s [minlen=20]; root -> t [minlen=2]; root -> u [minlen=2]; root -> v [minlen=2]; root -> w [minlen=2]; root -> x [minlen=2]; root -> y [minlen=2]; root -> 0 [minlen=2]; root -> 1 [minlen=2]; root -> 2 [minlen=2]; root -> 3 [minlen=2]; root -> 4 [minlen=2]; root -> 5 [minlen=2]; root -> 6 [minlen=2]; root -> 7 [minlen=2]; root -> 8 [minlen=2]; root -> 9 [minlen=2]; root -> "." [minlen=2]; g -> ga ; g -> gb ; g -> gc ; g -> gd ; g -> ge ; g -> gf ; g -> gg ; g -> gh ; g -> gi ; g -> gj ; g -> gk ; g -> gl ; g -> gm ; g -> gn ; g -> go ; g -> gp ; g -> gq ; g -> gr ; g -> gs ; g -> gt ; g -> gu ; g -> gv ; g -> gw ; g -> gx ; g -> gy ; ga -> gaa ; ga -> gab ; ga -> gac ; ga -> gad ; ga -> gae ; ga -> gaf ; ga -> gag ; ga -> gah ; ga -> gai ; ga -> gaj ; ga -> gak ; ga -> gal ; ga -> gam ; ga -> gan ; ga -> gao ; ga -> gap ; ga -> gaq ; ga -> gaz ; ga -> gas ; ga -> gat ; ga -> gau ; ga -> gav ; ga -> gaw ; ga -> gax ; ga -> gay ; gaz -> gaza ; gaz -> gazb ; gaz -> gazc ; gaz -> gazd ; gaz -> gaze ; gaz -> gazf ; gaz -> gazg ; gaz -> gazh ; gaz -> gazi ; gaz -> gazj ; gaz -> gazk ; gaz -> gazl ; gaz -> gazm ; gaz -> gazn ; gaz -> gazo ; gaz -> gazp ; gaz -> gazq ; gaz -> gazr ; gaz -> gazs ; gaz -> gazt ; gaz -> gazu ; gaz -> gazv ; gaz -> gazw ; gaz -> gazx ; gaz -> gazy ; gazo -> "Blue Tuesday" ; "Blue Tuesday" [ fontsize=10]; // Layout engines: circo dot fdp neato nop nop1 nop2 osage patchwork sfdp twopi } This output is generated with: twopi -os1.png -Tpng s1.dot I'm posting here because the printout is pretty dreadful. All of the nodes hung of "gaz" are overlapping; I've tried specifying nodesep and it is simply ignored. I would like to see the lines from root to the single letters further apart, but again, I can't control that. This seems to be a bug in twopi. The documentation says it should clearly follow these directives, but it doesn't seem to. My questions: Is there any way to make twopi behave? Failing that, is there a better layout engine to use? Thanks.

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• trouble running smooth animation in thread only when using key listener

  - by heysuse renard

  first time using a forum for coding help so sorry if i post this all wrong. i have more than a few classes i don't think screenManger or core holds the problem but i included them just incase. i got most of this code working through a set of tutorials. but a certain point started trying to do more on my own. i want to play the animation only when i'm moving my sprite. in my KeyTest class i am using threads to run the animation it used to work (poorly) but now not at all pluss it really gunks up my computer. i think it's because of the thread. im new to threads so i'm not to sure if i should even be using one in this situation or if its dangerous for my computer. the animation worked smoothly when i had the sprite bouce around the screen forever. the animation loop played with out stopping. i think the main problem is between the animationThread, Sprite, and keyTest classes, but itcould be more indepth. if someone could point me in the right direction for making the animation run smoothly when i push down a key and stop runing when i let off it would be greatly apriciated. i already looked at this Java a moving animation (sprite) obviously we were doing the same tutorial. but i feel my problem is slightly different. p.s. sorry for the typos. import java.awt.*; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import java.util.ArrayList; import javax.swing.ImageIcon; import javax.swing.JFrame; public class KeyTest extends Core implements KeyListener { public static void main(String[] args) { new KeyTest().run(); } Sprite player1; Image hobo; Image background; animation hoboRun; animationThread t1; //init also calls init form superclass public void init() { super.init(); loadImages(); Window w = s.getFullScreenWindow(); w.setFocusTraversalKeysEnabled(false); w.addKeyListener(this); } //load method will go here. //load all pics need for animation and sprite public void loadImages() { background = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\yellow square.jpg").getImage(); Image face1 = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\circle.png").getImage(); Image face2 = new ImageIcon("\\\\STUART-PC\\Users\\Stuart\\workspace\\Gaming\\one eye.png").getImage(); hoboRun = new animation(); hoboRun.addScene(face1, 250); hoboRun.addScene(face2, 250); player1 = new Sprite(hoboRun); this.t1 = new animationThread(); this.t1.setAnimation(player1); } //key pressed public void keyPressed(KeyEvent e) { int keyCode = e.getKeyCode(); if (keyCode == KeyEvent.VK_ESCAPE) { stop(); } if (keyCode == KeyEvent.VK_RIGHT) { player1.setVelocityX(0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_LEFT) { player1.setVelocityX(-0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_DOWN) { player1.setVelocityY(0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1); th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } if (keyCode == KeyEvent.VK_UP) { player1.setVelocityY(-0.3f); try { this.t1.setRunning(true); Thread th1 = new Thread(this.t1);; th1.start(); } catch (Exception ex) { System.out.println("noooo"); } } else { e.consume(); } } //keyReleased @SuppressWarnings("static-access") public void keyReleased(KeyEvent e) { int keyCode = e.getKeyCode(); if (keyCode == KeyEvent.VK_RIGHT || keyCode == KeyEvent.VK_LEFT) { player1.setVelocityX(0); try { this.t1.setRunning(false); } catch (Exception ex) { } } if (keyCode == KeyEvent.VK_UP || keyCode == KeyEvent.VK_DOWN) { player1.setVelocityY(0); try { this.t1.setRunning(false); } catch (Exception ex) { } } else { e.consume(); } } //last method from interface public void keyTyped(KeyEvent e) { e.consume(); } //draw public void draw(Graphics2D g) { Window w = s.getFullScreenWindow(); g.setColor(w.getBackground()); g.fillRect(0, 0, s.getWidth(), s.getHieght()); g.setColor(w.getForeground()); g.drawImage(player1.getImage(), Math.round(player1.getX()), Math.round(player1.getY()), null); } public void update(long timePassed) { player1.update(timePassed); } } abstract class Core { private static DisplayMode modes[] = { new DisplayMode(1600, 900, 64, 0), new DisplayMode(800, 600, 32, 0), new DisplayMode(800, 600, 24, 0), new DisplayMode(800, 600, 16, 0), new DisplayMode(800, 480, 32, 0), new DisplayMode(800, 480, 24, 0), new DisplayMode(800, 480, 16, 0),}; private boolean running; protected ScreenManager s; //stop method public void stop() { running = false; } public void run() { try { init(); gameLoop(); } finally { s.restoreScreen(); } } //set to full screen //set current background here public void init() { s = new ScreenManager(); DisplayMode dm = s.findFirstCompatibleMode(modes); s.setFullScreen(dm); Window w = s.getFullScreenWindow(); w.setFont(new Font("Arial", Font.PLAIN, 20)); w.setBackground(Color.GREEN); w.setForeground(Color.WHITE); running = true; } //main gameLoop public void gameLoop() { long startTime = System.currentTimeMillis(); long cumTime = startTime; while (running) { long timePassed = System.currentTimeMillis() - cumTime; cumTime += timePassed; update(timePassed); Graphics2D g = s.getGraphics(); draw(g); g.dispose(); s.update(); try { Thread.sleep(20); } catch (Exception ex) { } } } //update animation public void update(long timePassed) { } //draws to screen abstract void draw(Graphics2D g); } class animationThread implements Runnable { String name; boolean playing; Sprite a; //constructor takes input from keyboard public animationThread() { } //The run method for animation public void run() { long startTime = System.currentTimeMillis(); long cumTime = startTime; boolean test = getRunning(); while (test) { long timePassed = System.currentTimeMillis() - cumTime; cumTime += timePassed; test = getRunning(); } } public String getName() { return name; } public void setAnimation(Sprite a) { this.a = a; } public void setName(String name) { this.name = name; } public void setRunning(boolean running) { this.playing = running; } public boolean getRunning() { return playing; } } class animation { private ArrayList scenes; private int sceneIndex; private long movieTime; private long totalTime; //constructor public animation() { scenes = new ArrayList(); totalTime = 0; start(); } //add scene to ArrayLisy and set time for each scene public synchronized void addScene(Image i, long t) { totalTime += t; scenes.add(new OneScene(i, totalTime)); } public synchronized void start() { movieTime = 0; sceneIndex = 0; } //change scenes public synchronized void update(long timePassed) { if (scenes.size() > 1) { movieTime += timePassed; if (movieTime >= totalTime) { movieTime = 0; sceneIndex = 0; } while (movieTime > getScene(sceneIndex).endTime) { sceneIndex++; } } } //get animations current scene(aka image) public synchronized Image getImage() { if (scenes.size() == 0) { return null; } else { return getScene(sceneIndex).pic; } } //get scene private OneScene getScene(int x) { return (OneScene) scenes.get(x); } //Private Inner CLASS////////////// private class OneScene { Image pic; long endTime; public OneScene(Image pic, long endTime) { this.pic = pic; this.endTime = endTime; } } } class Sprite { private animation a; private float x; private float y; private float vx; private float vy; //Constructor public Sprite(animation a) { this.a = a; } //change position public void update(long timePassed) { x += vx * timePassed; y += vy * timePassed; } public void startAnimation(long timePassed) { a.update(timePassed); } //get x position public float getX() { return x; } //get y position public float getY() { return y; } //set x public void setX(float x) { this.x = x; } //set y public void setY(float y) { this.y = y; } //get sprite width public int getWidth() { return a.getImage().getWidth(null); } //get sprite height public int getHeight() { return a.getImage().getHeight(null); } //get horizontal velocity public float getVelocityX() { return vx; } //get vertical velocity public float getVelocityY() { return vx; } //set horizontal velocity public void setVelocityX(float vx) { this.vx = vx; } //set vertical velocity public void setVelocityY(float vy) { this.vy = vy; } //get sprite / image public Image getImage() { return a.getImage(); } } class ScreenManager { private GraphicsDevice vc; public ScreenManager() { GraphicsEnvironment e = GraphicsEnvironment.getLocalGraphicsEnvironment(); vc = e.getDefaultScreenDevice(); } //get all compatible DM public DisplayMode[] getCompatibleDisplayModes() { return vc.getDisplayModes(); } //compares DM passed into vc DM and see if they match public DisplayMode findFirstCompatibleMode(DisplayMode modes[]) { DisplayMode goodModes[] = vc.getDisplayModes(); for (int x = 0; x < modes.length; x++) { for (int y = 0; y < goodModes.length; y++) { if (displayModesMatch(modes[x], goodModes[y])) { return modes[x]; } } } return null; } //get current DM public DisplayMode getCurrentDisplayMode() { return vc.getDisplayMode(); } //checks if two modes match each other public boolean displayModesMatch(DisplayMode m1, DisplayMode m2) { if (m1.getWidth() != m2.getWidth() || m1.getHeight() != m2.getHeight()) { return false; } if (m1.getBitDepth() != DisplayMode.BIT_DEPTH_MULTI && m2.getBitDepth() != DisplayMode.BIT_DEPTH_MULTI && m1.getBitDepth() != m2.getBitDepth()) { return false; } if (m1.getRefreshRate() != DisplayMode.REFRESH_RATE_UNKNOWN && m2.getRefreshRate() != DisplayMode.REFRESH_RATE_UNKNOWN && m1.getRefreshRate() != m2.getRefreshRate()) { return false; } return true; } //make frame full screen public void setFullScreen(DisplayMode dm) { JFrame f = new JFrame(); f.setUndecorated(true); f.setIgnoreRepaint(true); f.setResizable(false); vc.setFullScreenWindow(f); if (dm != null && vc.isDisplayChangeSupported()) { try { vc.setDisplayMode(dm); } catch (Exception ex) { } } f.createBufferStrategy(2); } //sets graphics object = this return public Graphics2D getGraphics() { Window w = vc.getFullScreenWindow(); if (w != null) { BufferStrategy s = w.getBufferStrategy(); return (Graphics2D) s.getDrawGraphics(); } else { return null; } } //updates display public void update() { Window w = vc.getFullScreenWindow(); if (w != null) { BufferStrategy s = w.getBufferStrategy(); if (!s.contentsLost()) { s.show(); } } } //returns full screen window public Window getFullScreenWindow() { return vc.getFullScreenWindow(); } //get width of window public int getWidth() { Window w = vc.getFullScreenWindow(); if (w != null) { return w.getWidth(); } else { return 0; } } //get height of window public int getHieght() { Window w = vc.getFullScreenWindow(); if (w != null) { return w.getHeight(); } else { return 0; } } //get out of full screen public void restoreScreen() { Window w = vc.getFullScreenWindow(); if (w != null) { w.dispose(); } vc.setFullScreenWindow(null); } //create image compatible with monitor public BufferedImage createCopatibleImage(int w, int h, int t) { Window win = vc.getFullScreenWindow(); if (win != null) { GraphicsConfiguration gc = win.getGraphicsConfiguration(); return gc.createCompatibleImage(w, h, t); } return null; } }

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• Why lock-free data structures just aren't lock-free enough

  - by Alex.Davies

  Today's post will explore why the current ways to communicate between threads don't scale, and show you a possible way to build scalable parallel programming on top of shared memory. The problem with shared memory Soon, we will have dozens, hundreds and then millions of cores in our computers. It's inevitable, because individual cores just can't get much faster. At some point, that's going to mean that we have to rethink our architecture entirely, as millions of cores can't all access a shared memory space efficiently. But millions of cores are still a long way off, and in the meantime we'll see machines with dozens of cores, struggling with shared memory. Alex's tip: The best way for an application to make use of that increasing parallel power is to use a concurrency model like actors, that deals with synchronisation issues for you. Then, the maintainer of the actors framework can find the most efficient way to coordinate access to shared memory to allow your actors to pass messages to each other efficiently. At the moment, NAct uses the .NET thread pool and a few locks to marshal messages. It works well on dual and quad core machines, but it won't scale to more cores. Every time we use a lock, our core performs an atomic memory operation (eg. CAS) on a cell of memory representing the lock, so it's sure that no other core can possibly have that lock. This is very fast when the lock isn't contended, but we need to notify all the other cores, in case they held the cell of memory in a cache. As the number of cores increases, the total cost of a lock increases linearly. A lot of work has been done on "lock-free" data structures, which avoid locks by using atomic memory operations directly. These give fairly dramatic performance improvements, particularly on systems with a few (2 to 4) cores. The .NET 4 concurrent collections in System.Collections.Concurrent are mostly lock-free. However, lock-free data structures still don't scale indefinitely, because any use of an atomic memory operation still involves every core in the system. A sync-free data structure Some concurrent data structures are possible to write in a completely synchronization-free way, without using any atomic memory operations. One useful example is a single producer, single consumer (SPSC) queue. It's easy to write a sync-free fixed size SPSC queue using a circular buffer*. Slightly trickier is a queue that grows as needed. You can use a linked list to represent the queue, but if you leave the nodes to be garbage collected once you're done with them, the GC will need to involve all the cores in collecting the finished nodes. Instead, I've implemented a proof of concept inspired by this intel article which reuses the nodes by putting them in a second queue to send back to the producer. * In all these cases, you need to use memory barriers correctly, but these are local to a core, so don't have the same scalability problems as atomic memory operations. Performance tests I tried benchmarking my SPSC queue against the .NET ConcurrentQueue, and against a standard Queue protected by locks. In some ways, this isn't a fair comparison, because both of these support multiple producers and multiple consumers, but I'll come to that later. I started on my dual-core laptop, running a simple test that had one thread producing 64 bit integers, and another consuming them, to measure the pure overhead of the queue. So, nothing very interesting here. Both concurrent collections perform better than the lock-based one as expected, but there's not a lot to choose between the ConcurrentQueue and my SPSC queue. I was a little disappointed, but then, the .NET Framework team spent a lot longer optimising it than I did. So I dug out a more powerful machine that Red Gate's DBA tools team had been using for testing. It is a 6 core Intel i7 machine with hyperthreading, adding up to 12 logical cores. Now the results get more interesting. As I increased the number of producer-consumer pairs to 6 (to saturate all 12 logical cores), the locking approach was slow, and got even slower, as you'd expect. What I didn't expect to be so clear was the drop-off in performance of the lock-free ConcurrentQueue. I could see the machine only using about 20% of available CPU cycles when it should have been saturated. My interpretation is that as all the cores used atomic memory operations to safely access the queue, they ended up spending most of the time notifying each other about cache lines that need invalidating. The sync-free approach scaled perfectly, despite still working via shared memory, which after all, should still be a bottleneck. I can't quite believe that the results are so clear, so if you can think of any other effects that might cause them, please comment! Obviously, this benchmark isn't realistic because we're only measuring the overhead of the queue. Any real workload, even on a machine with 12 cores, would dwarf the overhead, and there'd be no point worrying about this effect. But would that be true on a machine with 100 cores? Still to be solved. The trouble is, you can't build many concurrent algorithms using only an SPSC queue to communicate. In particular, I can't see a way to build something as general purpose as actors on top of just SPSC queues. Fundamentally, an actor needs to be able to receive messages from multiple other actors, which seems to need an MPSC queue. I've been thinking about ways to build a sync-free MPSC queue out of multiple SPSC queues and some kind of sign-up mechanism. Hopefully I'll have something to tell you about soon, but leave a comment if you have any ideas.

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