Search Results

Search found 16731 results on 670 pages for 'memory limit'.

Page 597/670 | < Previous Page | 593 594 595 596 597 598 599 600 601 602 603 604 | Next Page >

Online file storage similar to Amazon S3

- by Joel G

I am looking to code a file storage application in perl similar to amazon s3. I already have a amazon s3 clone that I found online called parkplace but its in ruby and is old also isn't built for high loads. I am not really sure what modules and programs I should use so id like some help picking them out. My requirements are listed below (yes I know there are lots but I could start simple then add more once I get it going): Easy API implementation for client side apps. (maybe RESTful but extras like mkdir and cp (?) Centralized database server for the USERDB (maybe PostgreSQL (?). Logging of all connections, bandwidth used, well pretty much everything to a centralized server (maybe PostgreSQL again (?). Easy server side configuration (config file(s) stored on the servers). Web based control panel for admin(s) and user(s) to show logs. (could work just running queries from the databases) Fast High Uptime Low memory usage Some sort of load distribution/load balancer (maybe a dns based or pound or perlbal or something else (?). Maybe a cache of some sort (memcached or parlbal or something else (?). Thanks in advance

Read the article
Generated HTML word document not displaying image correctly

- by spiderdijon

I'm trying to add an image to a generated html word document that is embedded in a classic ASP page. The code looks something like this: <% Response.ContentType = "application/msword" %> <html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word"> ... <v:shape id="_x0000_s1030" type="#_x0000_t75" style='position:absolute; left:0;text-align:left;margin-left:0;margin-top:17.95pt;width:7in;height:116.85pt; z-index:2;mso-position-horizontal:center;mso-position-horizontal-relative:page; mso-position-vertical-relative:page'> <v:imagedata src="http://xxx/image001.gif" o:title="image001"/> <w:wrap anchorx="page" anchory="page"/> <w:anchorlock/> </v:shape><![endif]--><![if !vml]><span style='mso-ignore:vglayout;position: absolute;z-index:0;left:0px;margin-left:0px;margin-top:24px;width:672px; height:156px'><img width=672 height=156 src="http://xxx/image001.gif" v:shapes="_x0000_s1030"></span><![endif]> The image URL is correct and can be viewed through a browser, however when the word document opens, the image has a red x, with the error message: The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may be corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. If i copy the html code and try to open the word document on my local machine, it displays the image correctly. It just doesn't work when retrieving the document from the server. This happens for any images I try to add. Is there another way to add images to html-generated word documents that can be output from an asp page? Thanks.

Read the article
Avoiding a fork()/SIGCHLD race condition

- by larry

Please consider the following fork()/SIGCHLD pseudo-code. // main program excerpt for (;;) { if ( is_time_to_make_babies ) { pid = fork(); if (pid == -1) { /* fail */ } else if (pid == 0) { /* child stuff */ print "child started" exit } else { /* parent stuff */ print "parent forked new child ", pid children.add(pid); } } } // SIGCHLD handler sigchld_handler(signo) { while ( (pid = wait(status, WNOHANG)) > 0 ) { print "parent caught SIGCHLD from ", pid children.remove(pid); } } In the above example there's a race-condition. It's possible for "/* child stuff */" to finish before "/* parent stuff */" starts which can result in a child's pid being added to the list of children after it's exited, and never being removed. When the time comes for the app to close down, the parent will wait endlessly for the already-finished child to finish. One solution I can think of to counter this is to have two lists: started_children and finished_children. I'd add to started_children in the same place I'm adding to children now. But in the signal handler, instead of removing from children I'd add to finished_children. When the app closes down, the parent can simply wait until the difference between started_children and finished_children is zero. Another possible solution I can think of is using shared-memory, e.g. share the parent's list of children and let the children .add and .remove themselves? But I don't know too much about this. EDIT: Another possible solution, which was the first thing that came to mind, is to simply add a sleep(1) at the start of /* child stuff */ but that smells funny to me, which is why I left it out. I'm also not even sure it's a 100% fix. So, how would you correct this race-condition? And if there's a well-established recommended pattern for this, please let me know! Thanks.

Read the article
Displaying Flex Object References

- by Pie21

I have a bit of a memory leak issue in my Flex application, and the short version of my question is: is there any way (in AcitonScript 3) to find all live references to a given object? What I have is a number of views with presentation models behind each of them (using Swiz). The views of interest are children of a TabNavigator, so when I close the tab, the view is removed from the stage. When the view is removed from the stage, Swiz sets the model reference in the view to null, as it should. I also removeAllChildren() from the view. However when profiling the application, when I do this and run a GC, neither the view nor the presentation model are freed (though both set their references to each other to null). One model object used by the view (not a presenter, though) IS freed, so it's not completely broken. I've only just started profiling today (firmly believing in not optimising too early), so I imagine there's some kind of reference floating around somewhere, but I can't see where, and what would be super helpful would be the ability to debug and see a list of objects that reference the target object. Is this at all possible, and if not natively, is there some light-weight way to code this into future apps for debugging purposes? Cheers.

Read the article
CRONTAB doesn't finish svndump

- by Andrew

I just discovered that the automated dumps I've been creating of my SVN repository have been getting cut off early and basically only half the dump is there. It's not an emergency, but I hate being in this situation. It defeats the purpose of making automated backups in the first place. The command I'm using is below. If I execute it manually in the terminal, it completes fine; the output.txt file is 16 megs in size with all 335 revisions. But if I leave it to crontab, it bails at the halfway mark, at around 8.1 megs and only the first 169 revisions. # m h dom mon dow command 18 00 * * * svnadmin dump /var/svn/repos/myproject > /home/andrew/output.txt I actually save to a dated gzipped file, and there's no shortage of space on the server, so this is not a disk space issue. It seems to bail after two seconds, so this could be a time issue, but the file size is the same every single time for the past month, so I don't think it's that either. Does crontab execute within a limited memory space?

Read the article
char[] and char* compatibility?

- by Aerovistae

In essence, will this code work? And before you say "Run it and see!", I just realized my cygwin didn't come with gcc and it's currently 40 minutes away from completing reinstallation. That being said: char* words[1000]; for(int i = 0; i<1000; i++) words[i] = NULL; char buffer[ 1024 ]; //omit code that places "ADD splash\0" into the buffer if(strncmp (buffer, "ADD ", 4){ char* temp = buffer + 4; printf("Adding: %s", temp); int i = 0; while(words[i] != NULL) i++; words[i] = temp; } I'm mostly uncertain about the line char* temp = buffer + 4, and also whether I can assign words[i] in the manner that I am. Am I going to get type errors when I eventually try to compile this in 40 minutes? Also-- if this works, why don't I need to use malloc() on each element of words[]? Why can I say words[i] = temp, instead of needing to allocate memory for words[i] the length of temp?

Read the article
array of structures, or structure of arrays?

- by Jason S

Hmmm. I have a table which is an array of structures I need to store in Java. The naive don't-worry-about-memory approach says do this: public class Record { final private int field1; final private int field2; final private long field3; /* constructor & accessors here */ } List<Record> records = new ArrayList<Record>(); If I end up using a large number ( 106 ) of records, where individual records are accessed occasionally, one at a time, how would I figure out how the preceding approach (an ArrayList) would compare with an optimized approach for storage costs: public class OptimizedRecordStore { final private int[] field1; final private int[] field2; final private long[] field3; Record getRecord(int i) { return new Record(field1[i],field2[i],field3[i]); } /* constructor and other accessors & methods */ } edit: assume the # of records is something that is changed infrequently or never I'm probably not going to use the OptimizedRecordStore approach, but I want to understand the storage cost issue so I can make that decision with confidence. obviously if I add/change the # of records in the OptimizedRecordStore approach above, I either have to replace the whole object with a new one, or remove the "final" keyword. kd304 brings up a good point that was in the back of my mind. In other situations similar to this, I need column access on the records, e.g. if field1 and field2 are "time" and "position", and it's important for me to get those values as an array for use with MATLAB, so I can graph/analyze them efficiently.

Read the article
How the dispose() method works in C#.net?

- by Shailesh Jaiswal

I am developing smart device application in C#. It is a window application. In that application I have created the 4 to 5 window form. I am navigating in these forms from one form to another form by using linklabel control in C#. In linklabel_Click() method which I am using to navigate I am using the code form1.show() according to need. I read that form1.show() method automatically calls the form1.dispose() method on the from1. I also read that once we dispose the form it is removed from memory & we can not call it again. But in my application no one form gets disposed. I can see all the form even after calling the form1.show() method. when I use the link to go once again to from1 it does not get disposed. Is anything wrong in my concept? I am new in C#. Please tell me how the dispose method work in above context? What is the use of dispose method. It will be better if you describe me above issue with example.

Read the article
object / class methods serialized as well?

- by Mat90

I know that data members are saved to disk but I was wondering whether object's/class' methods are saved in binary format as well? Because I found some contradictionary info, for example: Ivor Horton: "Class objects contain function members as well as data members, and all the members, both data and functions, have access specifiers; therefore, to record objects in an external file, the information written to the file must contain complete specifications of all the class structures involved." and: Are methods also serialized along with the data members in .NET? Thus: are method's assembly instructions (opcodes and operands) stored to disk as well? Just like a precompiled LIB or DLL? During the DOS ages I used assembly so now and then. As far as I remember from Delphi and the following site (answer by dan04): Are methods also serialized along with the data members in .NET? sizeof(<OBJECT or CLASS>) will give the size of all data members together (no methods/procedures). Also a nice C example is given there with data and members declared in one class/struct but at runtime these methods are separate procedures acting on a struct of data. However, I think that later class/object implementations like Pascal's VMT may be different in memory.

Read the article
Hashing the state of a complex object in .NET

- by Jan

Some background information: I am working on a C#/WPF application, which basically is about creating, editing, saving and loading some data model. The data model contains of a hierarchy of various objects. There is a "root" object of class A, which has a list of objects of class B, which each has a list of objects of class C, etc. Around 30 classes involved in total. Now my problem is that I want to prompt the user with the usual "you have unsaved changes, save?" dialog, if he tries to exit the program. But how do I know if the data in current loaded model is actually changed? There is of course ways to solve this, like e.g. reloading the model from file and compare against the one in memory value by value or make every UI control set a flag indicating the model has been changed. Now instead, I want to create a hash value based on the model state on load and generate a new value when the user tries to exit, and compare those two. Now the question: So inspired of that, I was wondering if there exist some way to generate a hash value from the (value)state of some arbitrary complex object? Preferably in a generic way, e.g. no need to apply attributes to each involved class/field. One idea could be to use some of .NET's serialization functionality (assuming it will work out-of-the-box in this case) and apply a hash function to the content of the resulting file. However, I guess there exist some more suitable approach. Thanks in advance.

Read the article
jboss cache as hibernate 2nd level - cluster node doesn't persist replicated data

- by Sergey Grashchenko

I'm trying to build an architecture basically described in user guide http://www.jboss.org/file-access/default/members/jbosscache/freezone/docs/3.2.1.GA/userguide_en/html/cache_loaders.html#d0e3090 (Replicated caches with each cache having its own store.) but having jboss cache configured as hibernate second level cache. I've read manual for several days and played with the settings but could not achieve the result - the data in memory (jboss cache) gets replicated across the hosts, but it's not persisted in the datasource/database of the target (not original) cluster host. I had a hope that a node might become persistent at eviction, so I've got a cache listener and attached it to @NoveEvicted event. I found that though I could adjust eviction policy to fully control it, no any persistence takes place. Then I had a though that I could try to modify CacheLoader to set "passivate" to true, but I found that in my case (hibernate 2nd level cache) I don't have a way to access a loader. I wonder if replicated data persistence is possible at all by configuration tuning ? If not, will it work for me to create some manual peristence in CacheListener (I could check whether the eviction event is local, and if not - persist it to hibernate datasource somehow) ? I've used mvcc-entity configuration with the modification of cacheMode - set to REPL_ASYNC. I've also played with the eviction policy configuration. Last thing to mention is that I've tested entty persistence and replication in project that has been generated with Seam. I guess it's not important though.

Read the article
Using JRE 1.5, still maven says annotation not supported in -source 1.3

- by Abhijeet

Hi, I am using JRE 1.5. Still when I try to compile my code it fails by saying to use JRE 1.5 instead of 1.3 C:\temp\SpringExamplemvn -e clean install + Error stacktraces are turned on. [INFO] Scanning for projects... [INFO] ------------------------------------------------------------------------ [INFO] Building SpringExample [INFO] task-segment: [clean, install] [INFO] ------------------------------------------------------------------------ [INFO] [clean:clean {execution: default-clean}] [INFO] Deleting directory C:\temp\SpringExample\target [INFO] [resources:resources {execution: default-resources}] [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 6 resources [INFO] [compiler:compile {execution: default-compile}] [INFO] Compiling 6 source files to C:\temp\SpringExample\target\classes [INFO] ------------------------------------------------------------------------ [ERROR] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override [INFO] ------------------------------------------------------------------------ [INFO] Trace org.apache.maven.BuildFailureException: Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:715) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:556) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:535) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328) at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138) at org.apache.maven.cli.MavenCli.main(MavenCli.java:362) at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315) at org.codehaus.classworlds.Launcher.launch(Launcher.java:255) at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430) at org.codehaus.classworlds.Launcher.main(Launcher.java:375) Caused by: org.apache.maven.plugin.CompilationFailureException: Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:516) at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:114) at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694) ... 17 more [INFO] ------------------------------------------------------------------------ [INFO] Total time: 2 seconds [INFO] Finished at: Wed Dec 22 10:04:53 IST 2010 [INFO] Final Memory: 9M/16M [INFO] ------------------------------------------------------------------------ C:\temp\SpringExamplejavac -version javac 1.5.0_08 javac: no source files

Read the article
Better use a tuple or numpy array for storing coordinates

- by Ivan

Hi, I'm porting an C++ scientific application to python, and as I'm new to python, some problems come to my mind: 1) I'm defining a class that will contain the coordinates (x,y). These values will be accessed several times, but they only will be read after the class instantiation. Is it better to use an tuple or an numpy array, both in memory and access time wise? 2) In some cases, these coordinates will be used to build a complex number, evaluated on a complex function, and the real part of this function will be used. Assuming that there is no way to separate real and complex parts of this function, and the real part will have to be used on the end, maybe is better to use directly complex numbers to store (x,y)? How bad is the overhead with the transformation from complex to real in python? The code in c++ does a lot of these transformations, and this is a big slowdown in that code. 3) Also some coordinates transformations will have to be performed, and for the coordinates the x and y values will be accessed in separate, the transformation be done, and the result returned. The coordinate transformations are defined in the complex plane, so is still faster to use the components x and y directly than relying on the complex variables? Thank you

Read the article
Web Audio API and mobile browsers

- by Michael

I've run into a problem while implementing sound and music into an HTML game that I'm building. I'm using the Web Audio API, loading all the sound files with XMLHttpRequests and decoding them into an AudioBufferSourceNode with AudioContext.prototype.decodeAudioData(). It looks something like this: var request = new XMLHttpRequest(); request.open("GET", "soundfile.ogg", true); request.responseType = "arraybuffer"; request.onload = function() { context.decodeAudioData(request.response) } request.send(); Everything plays fine, but on mobile the decodeAudioData takes an absurdly long time for the background music. I then tried using AudioContext.prototype.createMediaElementSource() to load the music from an HTML Audio object, since they support streaming and don't have to load the whole file into memory at once. It looked something like this: var audio = new Audio('soundfile.ogg'); var source = context.createMediaElementSource(audio); var mainVolume = context.createGain(); source.connect(mainVolume); mainVolume.connect(context.destination); This loads much faster, but the audio volume isn't affected by the gain node. Works fine on desktop, so I'm assuming this is a bug/limitation of mobile Chrome (testing on Android). Is there actually no good, well-performing way to handle sound on mobile browsers or am just I doing something stupid?

Read the article
Create swipe controlled simple flipbook style animation in ObjC

- by eco_bach

Hi I am a beginner in Obj C development, though quite experienced (over 10 years) with other ECMAscript based languages and OOP development. I want to build a simple flipbook style animation, controlled through swiping motion. I'm sure extremely simple for any advanced ObjC coders. Can anyone with extensive ObjC-CocoaTouch experience give me some higher level recommendations? ie, 1 -general application design, should I start with a simple view based application, or navigation based or? 2 -should I use 3rd party animation frameworks such as Cocos2D, or stick with built in classes and methods? 3 -if using built in methods, classes, what is the recommended way of achieving a animation, that will be controlled via swipe and touch gestures? 4 -I want to eventually have multiple 'flipbooks' that I can 'instantly' swap with one another, ie to give the net effect of an object changing color, etc, but not sure how to approach this from a memory management point of view, related to #1 above Except for point 3 above, I'm not expecting any actual code examples. Just general guidelines to follow and perhaps, what are some next steps I should take in my goal as an ObjC code samurai.

Read the article
Want to display a 3D model on the iPhone: how to get started?

- by JeremyReimer

I want to display and rotate a single 3D model, preferably textured, on the iPhone. Doesn't have to zoom in and out, or have a background, or anything. I have the following: an iPhone a MacBook the iPhone SDK Blender My knowledge base: I can make 3D models in various 3D programs (I'm most comfortable with 3D Studio Max, which I once took a course on, but I've used others) General knowledge of procedural programming from years ago (QuickBasic - I'm old!) Beginner's knowledge of object-oriented programming from going through simple Java and C# tutorials (Head Start C# book and my wife's intro to OOP course that used Java) I have managed to display a 3D textured model and spin it using a tutorial in C# I got off the net (I didn't just copy and paste, I understand basically how it works) and the XNA game development library, using Visual Studio on Windows. What I do not know: Much about Objective C Anything about OpenGL or OpenGL ES, which the iPhone apparently uses Anything about XCode My main problem is that I don't know where to start! All the iPhone books I found seem to be about creating GUI applications, not OpenGL apps. I found an OpenGL book but I don't know how much, if any, applies to iPhone development. And I find the Objective C syntax somewhat confusing, with the weird nested method naming, things like "id" that don't make sense, and the scary thought that I have to do manual memory management. Where is the best place to start? I couldn't find any tutorials for this sort of thing, but maybe my Google-Fu is weak. Or maybe I should start with learning Objective C? I know of books like Aaron Hillgrass', but I've also read that they are outdated and much of the sample code doesn't work on the iPhone SDK, plus it seems geared towards the Model-View-Controller paradigm which doesn't seem that suited for 3D apps. Basically I'm confused about what my first steps should be.

Read the article
OpenCL Matrix Multiplication - Getting wrong answer

- by Yash

here's a simple OpenCL Matrix Multiplication kernel which is driving me crazy: __kernel void matrixMul( __global int* C, __global int* A, __global int* B, int wA, int wB){ int row = get_global_id(1); //2D Threas ID x int col = get_global_id(0); //2D Threas ID y //Perform dot-product accumulated into value int value; for ( int k = 0; k < wA; k++ ){ value += A[row*wA + k] * B[k*wB+col]; } C[row*wA+col] = value; //Write to the device memory } Where (inputs) A = [72 45 75 61] B = [26 53 46 76] Output I am getting: C = [3942 7236 3312 5472] But the output should be: C = [3943 7236 4756 8611] The problem I am facing here is that for any dimension array the elements of the first row of the resulting matrix is correct. The elements of all the other rows of the resulting matrix is wrong. By the way I am using pyopencl. I don't know what I mistake I am doing here. I have spent the entire day with no luck. Please help me with this

Read the article
Pump Messages During Long Operations + C# (it is urgent)

- by Newbie

Hi I have a web service that is doing huge computation and is taking more than a minute. I have generated the proxy file of the web service and then from my client end I am using the dll(of course I generated the proxy dll). My client side code is TimeSeries3D t = new TimeSeries3D(); int portfolioId = 4387919; string[] str = new string[2]; str[0] = "MKT_CAP"; DateRange dr = new DateRange(); dr.mStartDate = DateTime.Today; dr.mEndDate = DateTime.Today; Service1 sc = new Service1(); t = sc.GetAttributesForPortfolio(portfolioId, true, str, dr); But since it is taking to much time for the server to compute, after 1 minute I am receiving an error message The CLR has been unable to transition from COM context 0x33caf30 to COM context 0x33cb0a0 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. Kindly guide me what to do? It is very urgent. Thanks

Read the article
Does unboxing just return a pointer to the value within the boxed object on the heap?

- by Charles

I this MSDN Magazine article, the author states (emphasis mine): Note that boxing always creates a new object and copies the unboxed value's bits to the object. On the other hand, unboxing simply returns a pointer to the data within a boxed object: no memory copy occurs. However, it is commonly the case that your code will cause the data pointed to by the unboxed reference to be copied anyway. I'm confused by the sentence I've bolded and the sentence that follows it. From everything else I've read, including this MSDN page, I've never before heard that unboxing just returns a pointer to the value on the heap. I was under the impression that unboxing would result in you having a variable containing a copy of the value on the stack, just as you began with. After all, if my variable contains "a pointer to the value on the heap", then I haven't got a value type, I've got a pointer. Can someone explain what this means? Was the author on crack? (There is at least one other glaring error in the article). And if this is true, what are the cases where "your code will cause the data pointed to by the unboxed reference to be copied anyway"? I just noticed that the article is nearly 10 years old, so maybe this is something that changed very early on in the life of .Net.

Read the article
Java: autofiltering list?

- by Jason S

I have a series of items arriving which are used in one of my data structures, and I need a way to keep track of those items that are retained. interface Item {} class Foo implements Item { ... } class Baz implements Item { ... } class StateManager { List<Foo> fooList; Map<Integer, Baz> bazMap; public List<Item> getItems(); } What I want is that if I do the following: for (int i = 0; i < SOME_LARGE_NUMBER; ++i) { /* randomly do one of the following: * 1) put a new Foo somewhere in the fooList * 2) delete one or more members from the fooList * 3) put a new Baz somewhere in the bazMap * 4) delete one or more members from the bazMap */ } then if I make a call to StateManager.getItems(), I want to return a list of those Foo and Baz items, which are found in the fooList and the bazMap, in the order they were added. Items that were deleted or displaced from fooList and bazMap should not be in the returned list. How could I implement this? SOME_LARGE_NUMBER is large enough that I don't have the memory available to retain all the Foo and Baz items, and then filter them.

Read the article
Disposing ActiveX resources owned by another thread

- by Stefan Teitge

I've got a problem problem with threading and disposing resources. I've got a C# Windows Forms application which runs expensive operation in a thread. This thread instantiates an ActiveX control (AxControl). This control must be disposed as it uses a high amount of memory. So I implemented a Dispose() method and even a destructor. After the thread ends the destructor is called. This is sadly called by the UI thread. So invoking activexControl.Dispose(); fails with the message "COM object that has been separated from its underlying RCW", as the object belongs to another thread. How to do this correctly or is it just a bad design I use? (I stripped the code down to the minimum including removing any safety concerns.) class Program { [STAThread] static void Main() { // do stuff here, e.g. open a form new Thread(new ThreadStart(RunStuff); // do more stuff } private void RunStuff() { DoStuff stuff = new DoStuff(); stuff.PerformStuff(); } } class DoStuff : IDisposable { private AxControl activexControl; DoStuff() { activexControl = new AxControl(); activexControl.CreateControl(); // force instance } ~DoStuff() { Dispose(); } public void Dispose() { activexControl.Dispose(); } public void PerformStuff() { // invent perpetuum mobile here, takes time } }

Read the article
invasive vs non-invasive ref-counted pointers in C++

- by anon

For the past few years, I've generally accepted that if I am going to use ref-counted smart pointers invasive smart pointers is the way to go -- However, I'm starting to like non-invasive smart pointers due to the following: I only use smart pointers (so no Foo* lying around, only Ptr) I'm starting to build custom allocators for each class. (So Foo would overload operator new). Now, if Foo has a list of all Ptr (as it easily can with non-invasive smart pointers). Then, I can avoid memory fragmentation issues since class Foo move the objects around (and just update the corresponding Ptr). The only reason why this Foo moving objects around in non-invasive smart pointers being easier than invasive smart pointers is: In non-invasive smart pointers, there is only one pointer that points to each Foo. In invasive smart pointers, I have no idea how many objects point to each Foo. Now, the only cost of non-invasive smart pointers ... is the double indirection. [Perhaps this screws up the caches]. Does anyone have a good study of expensive this extra layer of indirection is?

Read the article
Is it possible to have asynchronous processing

- by prashant2361

Hi, I have a requirement where I need to send continuous updates to my clients. Client is browser in this case. We have some data which updates every sec, so once client connects to our server, we maintain a persistent connection and keep pushing data to the client. I am looking for suggestions of this implementation at the server end. Basically what I need is this: 1. client connects to server. I maintain the socket and metadata about the socket. metadata contains what updates need to be send to this client 2. server process now waits for new client connections 3. One other process will have the list of all the sockets opened and will go through each of them and send the updates if required. Can we do something like this in Apache module: 1. Apache process gets the new connection. It maintains the state for the connection. It keeps the state in some global memory and returns back to root process to signify that it is done so that it can accept the new connection 2. the Apache process though has returned the status to root process but it is also executing in parallel where it going through its global store and sending updates to the client, if any. So can a Apache process do these things: 1. Have more than one connection associated with it 2. Asynchronously waiting for new connection and at the same time processing the previous connections? Regards Prashant

Read the article
Request size limitation when using MultipartHttpServletRequest of Spring 3.0

- by Spiderman

I'd like to know what is the size limitation if I upload list of files in one client's form submition using HTTP multipart content type. On the server side I am using Spring's MultipartHttpServletRequest to handle the request. mM questions: Is there should be different file size limitation and total request size limitation or file size is the only limitation and the request is capable of uploading 100s of files as lonng as they are not too large. Doest the Spring request wrapper read the complete request and store it in the JAVA heap memory or it store temporaray files of it to be able to use big quota. Is the use of reading the httpservlet request in streaming would change the size limitation than using complete http request read at-once by the application server. What is the bottleneck of this process - Java heap size, the quota of the filesystem on which my web-server runs, the maximum allowed BLOB size that the DataBase in which I am gonna save the file alows? or Spring internal limitations? Related threads that still don't have exact answer to this: does-spring-framework-support-streaming-mode-in-mutlipart-requests is-there-a-way-to-get-raw-http-request-stream-from-java-servlet-handler how-to- drop-body-of-a-request-after-checking-headers-in-servlet apache-commons-fileupload-throws-malformedstreamexception

Read the article
Returning c_str from a function

- by user199421

This is from a small library that I found online: const char* GetHandStateBrief(const PostFlopState* state) { static std::ostringstream out; ... rest of the function ... return out.str().c_str() Now in my code I am doing this: const char *d = GetHandStateBrief(&post); std::cout<< d << std::endl; Now, at first d contained garbage. I then realized that the c string I am getting from the function is destroyed when the function returns because std::ostringstream is allocated on the stack. So I added: return strdup( out.str().c_str()); And now I can get the text I need from the function. I have two questions: 1) Am I understanding this correctly? 2) I later noticed that the ostringstream was was allocated with static storage. Doesn't that mean that the object is supposed to stay in memory until the program terminates? and if so , then why can't I access the string?

Read the article

< Previous Page | 593 594 595 596 597 598 599 600 601 602 603 604 | Next Page >