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• EAGLContext, EAGLSharegroups, RenderBuffers, FrameBuffers, oh my!

  - by quixoto

  Hi all, I'm trying to wrap my head around the OpenGL object model on iPhone OS. I'm currently rendering into a few different UIViews (build on CAEAGLayers) on the screen. I currently have each of these as using separate EAGLContext, each of which has a color renderbuffer and a framebuffer. I'm rendering similar things in them, and I'd like to share textures between these instances to save memory overhead. My current understanding is that I could use the same setup (some number of contexts, each with a FBO/RBO) but if I spawn the later ones using the EAGLShareGroup of the first one, then I can simply use the texture names (GLuints) from the first one in the later ones. Is this accurate? If this is the case, I guess the followup question is: what's the benefit to having it be a "sharegroup"? Could I just reuse the same context, and attach multiple FBOs/RBOs to that context? I think I'm struggling with the abstraction layer of a sharegroup, which seems to share "objects" (textures and other named things) but not "state" (matrices, enabled/disabled states) which are owned by the context. What's the best way to think of this? Thanks for any enlightenment!

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• Ruby - encrypted_strings

  - by Tom Andersen

  A bit of a Ruby newbie here - should be an easy question: I want to use the encrypted_strings gem to create a password encrypted string: (from http://rdoc.info/projects/pluginaweek/encrypted_strings) Question is: Everything works fine, but how come I don't need the password to decrypt the string? Say I want to store the string somewhere for a while,like the session. Is the password also stored with it? (which would seem very strange?). And no, I'm not planning on using 'secret-key' or any similar hack as a password. I am planning on dynamically generating a class variable @@password using a uuid, which I don't store other than in memory, and can change from one running of the program to the next. Symmetric: >> password = 'shhhh' => "shhhh" >> crypted_password = password.encrypt(:symmetric, :password => 'secret_key') => "qSg8vOo6QfU=\n" >> crypted_password.class => String >> crypted_password == 'shhhh' => true >> password = crypted_password.decrypt => "shhhh"

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• PInvokeStackImbalance -- C# with offreg.dll ( windows ddk7 )

  - by user301185

  I am trying to create an offline registry in memory using the offreg.dll provided in the windows ddk 7 package. You can find out more information on the offreg.dll here: MSDN Currently, while attempted to create the hive using ORCreateHive, I receive the following error: "Managed Debugging Assistant 'PInvokeStackImbalance' has detected a problem. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature." Here is the offreg.h file containing ORCreateHive: typedef PVOID ORHKEY; typedef ORHKEY *PORHKEY; VOID ORAPI ORGetVersion( __out PDWORD pdwMajorVersion, __out PDWORD pdwMinorVersion ); DWORD ORAPI OROpenHive ( __in PCWSTR lpHivePath, __out PORHKEY phkResult ); DWORD ORAPI ORCreateHive ( __out PORHKEY phkResult ); DWORD ORAPI ORCloseHive ( __in ORHKEY Handle ); The following is my C# code attempting to call the .dll and create the pointer for future use. using System.Runtime.InteropServices; namespace WindowsFormsApplication6 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } [DllImport("offreg.dll", CharSet = CharSet.Auto, EntryPoint = "ORCreateHive", SetLastError=true, CallingConvention = CallingConvention.StdCall)] public static extern IntPtr ORCreateHive2(); private void button1_Click(object sender, EventArgs e) { try { IntPtr myHandle = ORCreateHive2(); } catch (Exception r) { MessageBox.Show(r.ToString()); } } } } I have been able to create pointers in the past with no issue utilizing user32.dll, icmp.dll, etc. However, I am having no such luck with offreg.dll. Thank you.

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• High performance text file parsing in .net

  - by diamandiev

  Here is the situation: I am making a small prog to parse server log files. I tested it with a log file with several thousand requests (between 10000 - 20000 don't know exactly) What i have to do is to load the log text files into memory so that i can query them. This is taking the most resources. The methods that take the most cpu time are those (worst culprits first): string.split - splits the line values into a array of values string.contains - checking if the user agent contains a specific agent string. (determine browser ID) string.tolower - various purposes streamreader.readline - to read the log file line by line. string.startswith - determine if line is a column definition line or a line with values there were some others that i was able to replace. For example the dictionary getter was taking lots of resources too. Which i had not expected since its a dictionary and should have its keys indexed. I replaced it with a multidimensional array and saved some cpu time. Now i am running on a fast dual core and the total time it takes to load the file i mentioned is about 1 sec. Now this is really bad. Imagine a site that has tens of thousands of visits a day. It's going to take minutes to load the log file. So what are my alternatives? If any, cause i think this is just a .net limitation and i can't do much about it.

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• Writing fortran robust and "modern" code

  - by Blklight

  In some scientific environments, you often cannot go without FORTRAN as most of the developers only know that idiom, and there is lot of legacy code and related experience. And frankly, there are not many other cross-platform options for high performance programming ( C++ would do the task, but the syntax, zero-starting arrays, and pointers are too much for most engineers ;-) ). I'm a C++ guy but I'm stuck with some F90 projects. So, let's assume a new project must use FORTRAN (F90), but I want to build the most modern software architecture out of it. while being compatible with most "recent" compilers (intel ifort, but also including sun/HP/IBM own compilers) So I'm thinking of imposing: global variable forbidden, no gotos, no jump labels, "implicit none", etc. "object-oriented programming" (modules with datatypes + related subroutines) modular/reusable functions, well documented, reusable libraries assertions/preconditions/invariants (implemented using preprocessor statements) unit tests for all (most) subroutines and "objects" an intense "debug mode" (#ifdef DEBUG) with more checks and all possible Intel compiler checks possible (array bounds, subroutine interfaces, etc.) uniform and enforced legible coding style, using code processing tools C stubs/wrappers for libpthread, libDL (and eventually GPU kernels, etc.) C/C++ implementation of utility functions (strings, file operations, sockets, memory alloc/dealloc reference counting for debug mode, etc.) ( This may all seem "evident" modern programming assumptions, but in a legacy fortran world, most of these are big changes in the typical programmer workflow ) The goal with all that is to have trustworthy, maintainable and modular code. Whereas, in typical fortran, modularity is often not a primary goal, and code is trustworthy only if the original developer was very clever, and the code was not changed since then ! (i'm a bit joking here, but not much) I searched around for references about object-oriented fortran, programming-by-contract (assertions/preconditions/etc.), and found only ugly and outdated documents, syntaxes and papers done by people with no large-scale project involvement, and dead projects. Any good URL, advice, reference paper/books on the subject?

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• silverlight security with WCF service, Forms Authentication and Custom Form Ticket

  - by user74825

  I have a silverlight application with login on the silverlight page. It uses Forms Authentication with WCF authentication service and customer Membership Provider. Something like : http://blogs.msdn.com/phaniraj/archive/2009/09/10/using-the-ado-net-data-services-silverlight-client-library-in-x-domain-and-out-of-browser-scenarios-ii-forms-authentication.aspx So, SL page login page calls the WCF service authentication service, it validates using DB - brings back username and password. Now, in each subsequent calls (in Global.asax in Authenticate_Request, I get HttpContext.User.IsAuthenticated and HttpContext.User.UserName). I have all this working properly. But, I just don't want the username, but more information surrounding the user, like UserId, UserAddress, UserAssociateCustomer etc. I tried couple of different approaches. 1) Use HttpContext.Cache as a dictionary to save the item and get it off based on httpcontext.user.name, problem is cache can be erased if there memory is being used heavily. 2) Tried CustomFormsAuth Ticket, when forms authentication writes a ticket, I intercept CreatingCookie method and write additional info in formauthentication ticket, so that I can read it in subsequent requests, I am having problems with this approach, I don't find the ticket in subsequent requests. I read about how we should use REsponse.Redirect, but where do I redirect user from WCF call. How do you guys implement the above scenario? Any best practices.? Any issues you see with going on HTTPS? All examples (or most of them) just explains simple forms authentication with "I am logged in message".. Any suggestions ?

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• Load Balancing of PHP/MYSQL script without big code changes

  - by DR.GEWA

  Sorry for my Dummy Question, but... I am making a script on php/mysql (codeigniter) and I am extremally interested in knowing if there is a way without big architectural changes of the script make a load balancing. I mean, that for example now I will rent a medium dedicated server with 2GB ram, 200GB memory and good processor, and this will be enough lets say half year for the users which will come. But when they will become more and more, and as its a social net and at nights the server is waiting to have 500-1500 or 5000-8000 users online, I wander if there is a way for lets say just add second server with some config which will bear next pressure. After again one and so on... ???? <? if($answer=YES) { how(??); } esle{ whatToDo(??); } ?> If there is no way, than maybe you could point to a easiest way of load balancing solution.... I will be extremally thanksfull if you can tell me for such purposes , should I move lets say to PostgreSQl or FireBird? Which of them will be more easy in the future to handle ? I am getting on the mysite.com/users/show/$userId page something like 60queries for all data... maybe too much, but anyway....after some optimization it can be 20-30....

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• How can a program be detected as running?

  - by ryeguy

  I have written a program that is sort of an unofficial, standalone plugin for an application. It allows customers to get a service that is a lower priced alternative then the vendor-owned one. My program is not illegal, against any kind of TOS, and is certainly not a virus, adware, or anything like that. That being said, the vendor of course is not happy about me taking his competition, and is trying to block my application from running. He has already tried some tactics to stop people from running my app alongside his. He makes it so if it is detected, his app throws a fake error. First, he checked to see if my program was running by looking for an open window with the right title. I countered this by randomizing the program title at startup. Next, he looked for the running process name. I countered this by making the app copy itself when it is started as [random string].exe and then running that. Anyways, my question is this: what else can he do to detect if my program running? I know that you can read window text (ie status bar, labels). I'm prepared to counter this by replacing the labels with images (ugh, any other way?). But what else is there? Can you detect what .dlls a program has loaded? If so, could this be solved by randomizing the dll names before loading them? I know that it's possible to get a program's signature in memory and track it that way (like a virus scanner), but the chances of him doing that probably aren't good because that sounds pretty advanced. Even though this is kinda crappy of him to be doing, its kind of fun. It's like a nerdy fist fight. EDIT: When I said it's a plugin, that is just the (incorrect) term I used. It's a standalone EXE. The "API" between my program and the other is mine is simply entering data into the controls (like textboxes, etc).

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• Help Needed With AJAX Script

  - by Brian

  Hello All I am working on an AJAX script but am having difficulties. First, here is the script: var xmlHttp; function GetXmlHttpObject(){ var objXMLHttp=null if (window.XMLHttpRequest){ objXMLHttp=new XMLHttpRequest() } else if (window.ActiveXObject){ objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP") } return objXMLHttp } function retrieveData(){ var jBossServer = new Array(); jBossServer[0] = "d01"; jBossServer[1] = "d02"; jBossServer[2] = "p01"; jBossServer[3] = "p02"; for(var i=0; i<jBossServer.length; i++){ xmlHttp = GetXmlHttpObject(); if (xmlHttp == null){ alert ("Something weird happened ..."); return; } var url="./retrieveData.php"; url = url + "?jBossID=" + jBossServer[i]; url = url + "&sid=" + Math.random(); xmlHttp.open("GET",url,true); xmlHttp.onreadystatechange = updateMemory; xmlHttp.send(null); } } function updateMemory(){ if (xmlHttp.readyState == 4 || xmlHttp.readyState == "complete"){ aggregateArray = new Array(); aggregateArray = xmlHttp.responseText.split(','); for(var i=0; i<aggregateArray.length; i++){ alert(aggregateArray[i]); } return; } } The "retrieveData.php" page will return data that looks like this: d01,1 MB,2 MB,3 MB They relate to my 4 servers d01, d02, p01, and p02 (dev and prod). What I am doing is scraping the memory information from http://127.0.0.1:8080/web-console/ServerInfo.jsp I want to save code so I attempted to put the AJAX xmlHttp call into a loop, but I don't think it is working. All I ever get back is the information for "p02" four times. Am I able to do what I want or do I need four different functions for each server (i.e., xmlHttpServer01, xmlHttpServer02, xmlHttpServer03, xmlHttpServer04)? Thank you all for reading, have a good day. :)

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• Why did this work with Visual C++, but not with gcc?

  - by Carlos Nunez

  I've been working on a senior project for the last several months now, and a major sticking point in our team's development process has been dealing wtih rifts between Visual-C++ and gcc. (Yes, I know we all should have had the same development environment.) Things are about finished up at this point, but I ran into a moderate bug just today that had me wondering whether Visual-C++ is easier on newbies (like me) by design. In one of my headers, there is a function that relies on strtok to chop up a string, do some comparisons and return a string with a similar format. It works a little something like the following: int main() { string a, b, c; //Do stuff with a and b. c = get_string(a,b); } string get_string(string a, string b) { const char * a_ch, b_ch; a_ch = strtok(a.c_str(),","); b_ch = strtok(b.c_str(),","); } strtok is infamous for being great at tokenizing, but equally great at destroying the original string to be tokenized. Thus, when I compiled this with gcc and tried to do anything with a or b, I got unexpected behavior, since the separator used was completely removed in the string. Here's an example in case I'm unclear; if I set a = "Jim,Bob,Mary" and b="Grace,Soo,Hyun", they would be defined as a="JimBobMary" and b="GraceSooHyun" instead of staying the same like I wanted. However, when I compiled this under Visual C++, I got back the original strings and the program executed fine. I tried dynamically allocating memory to the strings and copying them the "standard" way, but the only way that worked was using malloc() and free(), which I hear is discouraged in C++. While I'm curious about that, the real question I have is this: Why did the program work when compiled in VC++, but not with gcc? (This is one of many conflicts that I experienced while trying to make the code cross-platform.) Thanks in advance! -Carlos Nunez

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• Django sphinx works only after app restart.

  - by Lhiash

  Hi, I've set up django-sphinx in my project, which works perfectly only for some time. Later it always returns empty result set. Surprisingly restarting django app fixes it. And search works again but again only for short time (or very limiter number of queries). Heres my sphinx.conf: source src_questions { # data source type = mysql sql_host = xxxxxx sql_user = xxxxxx #replace with your db username sql_pass = xxxxxx #replace with your db password sql_db = xxxxxx #replace with your db name # these two are optional sql_port = xxxxxx #sql_sock = /var/lib/mysql/mysql.sock # pre-query, executed before the main fetch query sql_query_pre = SET NAMES utf8 # main document fetch query sql_query = SELECT q.id AS id, q.title AS title, q.tagnames AS tags, q.html AS text, q.level AS level \ FROM question AS q \ WHERE q.deleted=0 \ # optional - used by command-line search utility to display document information sql_query_info = SELECT title, id, level FROM question WHERE id=$id sql_attr_uint = level } index questions { # which document source to index source = src_questions # this is path and index file name without extension # you may need to change this path or create this folder path = /home/rafal/core_index/index_questions # docinfo (ie. per-document attribute values) storage strategy docinfo = extern # morphology morphology = stem_en # stopwords file #stopwords = /var/data/sphinx/stopwords.txt # minimum word length min_word_len = 3 # uncomment next 2 lines to allow wildcard (*) searches min_infix_len = 1 enable_star = 1 # charset encoding type charset_type = utf-8 } # indexer settings indexer { # memory limit (default is 32M) mem_limit = 64M } # searchd settings searchd { # IP address on which search daemon will bind and accept # optional, default is to listen on all addresses, # ie. address = 0.0.0.0 address = 127.0.0.1 # port on which search daemon will listen port = 3312 # searchd run info is logged here - create or change the folder log = ../log/sphinx.log # all the search queries are logged here query_log = ../log/query.log # client read timeout, seconds read_timeout = 5 # maximum amount of children to fork max_children = 30 # a file which will contain searchd process ID pid_file = searchd.pid # maximum amount of matches this daemon would ever retrieve # from each index and serve to client max_matches = 1000 } and heres my search part from views.py: content = Question.search.query(keywords) if level: content = content.filter(level=level)#level is array of integers There are no errors in any logs, it just isnt returning any results. All help would be most appreciated.

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• A error about "Address 0x0 is not stack'd, malloc'd or (recently) free'd" in c program under linux

  - by MaiTiano

  There is a piece of my program: height = atoi(argv[3]); width = atoi(argv[2]); sprintf(seqName,"%s", argv[1]); // strcpy(seqName, argv[1]); After compiling it, a exe file test is generated, then I use Valgrind to check it. Then I got the following message, however I cannot understand what it tends to tell me. Can anyone provide some kind help, Thanks. 1 contexts (suppressed: 13 from 8) 1 contexts (suppressed: 13 from 8) jl@ubuntu:~/work/dsr_analysis$ valgrind --tool=memcheck --leak-check=yes ./test ==28940== Memcheck, a memory error detector ==28940== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al. ==28940== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info ==28940== Command: ./test ==28940== ==28940== Invalid read of size 1 ==28940== at 0x40260CA: strcpy (mc_replace_strmem.c:311) ==28940== by 0x804A5C6: main (me_search.c:1428) ==28940== Address 0x0 is not stack'd, malloc'd or (recently) free'd ==28940== ==28940== ==28940== Process terminating with default action of signal 11 (SIGSEGV) ==28940== Access not within mapped region at address 0x0 ==28940== at 0x40260CA: strcpy (mc_replace_strmem.c:311) ==28940== by 0x804A5C6: main (me_search.c:1428) ==28940== If you believe this happened as a result of a stack ==28940== overflow in your program's main thread (unlikely but ==28940== possible), you can try to increase the size of the ==28940== main thread stack using the --main-stacksize= flag. ==28940== The main thread stack size used in this run was 8388608. ==28940== ==28940== HEAP SUMMARY: ==28940== in use at exit: 0 bytes in 0 blocks ==28940== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==28940== ==28940== All heap blocks were freed -- no leaks are possible ==28940== ==28940== For counts of detected and suppressed errors, rerun with: -v ==28940== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 13 from 8)1 contexts (suppressed: 13 from 8) 1 contexts (suppressed: 13 from 8)

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• Nested factory methods in Objective-C

  - by StephenT

  What's the best way to handle memory management with nested factory methods, such as in the following example? @implementation MyClass + (MyClass *) SpecialCase1 { return [MyClass myClassWithArg:1]; } + (MyClass *) SpecialCase2 { return [MyClass myClassWithArg:2]; } + (MyClass *) myClassWithArg:(int)arg { MyClass *instance = [[[MyClass alloc] initWithArg:arg] autorelease]; return instance; } - (id) initWithArg:(int)arg { self = [super init]; if (nil != self) { self.arg = arg; } return self; } @end The problem here (I think) is that the autorelease pool is flushed before the SpecialCaseN methods return to their callers. Hence, the ultimate caller of SpecialCaseN can't rely on the result having been retained. (I get "[MyClass copyWithZone:]: unrecognized selector sent to instance 0x100110250" on trying to assign the result of [MyClass SpecialCase1] to a property on another object.) The reason for wanting the SpecialCaseN factory methods is that in my actual project, there are multiple parameters required to initialize the instance and I have a pre-defined list of "model" instances that I'd like to be able to create easily. I'm sure there's a better approach than this.

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• I don't know How to release NSString.

  - by Beomseok

  NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [path objectAtIndex:0]; NSString *databasePath = [documentsDirectory stringByAppendingPathComponent:@"DB"]; NSString *fileName = [newWordbookName stringByAppendingString:@".csv"]; NSString *fullPath = [databasePath stringByAppendingPathComponent:fileName]; [[NSFileManager defaultManager] createFileAtPath:fullPath contents:nil attributes:nil]; [databasePath release]; //[fileName release]; Error! //[fullPath release]; Error! //NSLog(@"#1 :databasePath: %d",[databasePath retainCount]); //NSLog(@"#1 :fileName: %d",[fileName retainCount]); //NSLog(@"#1 :fullPath: %d",[fullPath retainCount]); Hi guys, I'm using this code and want to release NSString* .. so, I declare fileName, fullPath, and databasePath of NSString. But database is released, fileName, fullpath doen't release. I don't know why it happen. I know that NSArray is Autoreleased. But Is documentsDirectory autoreleased? (newWordbookName is nsstring type) I hope that I look through a document about iPhone memory management. Please advice for me.

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• Discover periodic patterns in a large data-set

  - by Miner

  I have a large sequence of tuples on disk in the form (t1, k1) (t2, k2) ... (tn, kn) ti is a monotonically increasing timestamp and ki is a key (assume a fixed length string if needed). Neither ti nor ki are guaranteed to be unique. However, the number of unique tis and kis is huge (millions). n itself is very large (100 Million+) and the size of k (approx 500 bytes) makes it impossible to store everything in memory. I would like to find out periodic occurrences of keys in this sequence. For example, if I have the sequence (1, a) (2, b) (3, c) (4, b) (5, a) (6, b) (7, d) (8, b) (9, a) (10, b) The algorithm should emit (a, 4) and (b, 2). That is a occurs with a period of 4 and b occurs with a period of 2. If I build a hash of all keys and store the average of the difference between consecutive timestamps of each key and a std deviation of the same, I might be able to make a pass, and report only the ones that have an acceptable std deviation(ideally, 0). However, it requires one bucket per unique key, whereas in practice, I might have very few really periodic patterns. Any better ways?

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• Embedded non-relational (nosql) data store

  - by Igor Brejc

  I'm thinking about using/implementing some kind of an embedded key-value (or document) store for my Windows desktop application. I want to be able to store various types of data (GPS tracks would be one example) and of course be able to query this data. The amount of data would be such that it couldn't all be loaded into memory at the same time. I'm thinking about using sqlite as a storage engine for a key-value store, something like y-serial, but written in .NET. I've also read about FriendFeed's usage of MySQL to store schema-less data, which is a good pointer on how to use RDBMS for non-relational data. sqlite seems to be a good option because of its simplicity, portability and library size. My question is whether there are any other options for an embedded non-relational store? It doesn't need to be distributable and it doesn't have to support transactions, but it does have to be accessible from .NET and it should have a small download size. UPDATE: I've found an article titled SQLite as a Key-Value Database which compares sqlite with Berkeley DB, which is an embedded key-value store library.

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• Unexpected performance curve from CPython merge sort

  - by vkazanov

  I have implemented a naive merge sorting algorithm in Python. Algorithm and test code is below: import time import random import matplotlib.pyplot as plt import math from collections import deque def sort(unsorted): if len(unsorted) <= 1: return unsorted to_merge = deque(deque([elem]) for elem in unsorted) while len(to_merge) > 1: left = to_merge.popleft() right = to_merge.popleft() to_merge.append(merge(left, right)) return to_merge.pop() def merge(left, right): result = deque() while left or right: if left and right: elem = left.popleft() if left[0] > right[0] else right.popleft() elif not left and right: elem = right.popleft() elif not right and left: elem = left.popleft() result.append(elem) return result LOOP_COUNT = 100 START_N = 1 END_N = 1000 def test(fun, test_data): start = time.clock() for _ in xrange(LOOP_COUNT): fun(test_data) return time.clock() - start def run_test(): timings, elem_nums = [], [] test_data = random.sample(xrange(100000), END_N) for i in xrange(START_N, END_N): loop_test_data = test_data[:i] elapsed = test(sort, loop_test_data) timings.append(elapsed) elem_nums.append(len(loop_test_data)) print "%f s --- %d elems" % (elapsed, len(loop_test_data)) plt.plot(elem_nums, timings) plt.show() run_test() As much as I can see everything is OK and I should get a nice N*logN curve as a result. But the picture differs a bit: Things I've tried to investigate the issue: PyPy. The curve is ok. Disabled the GC using the gc module. Wrong guess. Debug output showed that it doesn't even run until the end of the test. Memory profiling using meliae - nothing special or suspicious. ` I had another implementation (a recursive one using the same merge function), it acts the similar way. The more full test cycles I create - the more "jumps" there are in the curve. So how can this behaviour be explained and - hopefully - fixed? UPD: changed lists to collections.deque UPD2: added the full test code UPD3: I use Python 2.7.1 on a Ubuntu 11.04 OS, using a quad-core 2Hz notebook. I tried to turn of most of all other processes: the number of spikes went down but at least one of them was still there.

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• Any HTTP proxies with explicit, configurable support for request/response buffering and delayed conn

  - by Carlos Carrasco

  When dealing with mobile clients it is very common to have multisecond delays during the transmission of HTTP requests. If you are serving pages or services out of a prefork Apache the child processes will be tied up for seconds serving a single mobile client, even if your app server logic is done in 5ms. I am looking for a HTTP server, balancer or proxy server that supports the following: A request arrives to the proxy. The proxy starts buffering in RAM or in disk the request, including headers and POST/PUT bodies. The proxy DOES NOT open a connection to the backend server. This is probably the most important part. The proxy server stops buffering the request when: A size limit has been reached (say, 4KB), or The request has been received completely, headers and body Only now, with (part of) the request in memory, a connection is opened to the backend and the request is relayed. The backend sends back the response. Again the proxy server starts buffering it immediately (up to a more generous size, say 64KB.) Since the proxy has a big enough buffer the backend response is stored completely in the proxy server in a matter of miliseconds, and the backend process/thread is free to process more requests. The backend connection is immediately closed. The proxy sends back the response to the mobile client, as fast or as slow as it is capable of, without having a connection to the backend tying up resources. I am fairly sure you can do 4-6 with Squid, and nginx appears to support 1-3 (and looks like fairly unique in this respect). My question is: is there any proxy server that empathizes these buffering and not-opening-connections-until-ready capabilities? Maybe there is just a bit of Apache config-fu that makes this buffering behaviour trivial? Any of them that it is not a dinosaur like Squid and that supports a lean single-process, asynchronous, event-based execution model? (Siderant: I would be using nginx but it doesn't support chunked POST bodies, making it useless for serving stuff to mobile clients. Yes cheap 50$ handsets love chunked POSTs... sigh)

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• What is the header of an array in .NET

  - by Thomas

  Hi all, I have a little bit seen the representation of an array in memory with Windbg and SOS plugin. Here it is the c# : class myobj{ public int[] arr; } class Program{ static void Main(string[] args){ myobj o = new myobj(); o.arr = new int[7]; o.arr[0] = 0xFFFFFF; o.arr[1] = 0xFFFFFF; o.arr[2] = 0xFFFFFF; o.arr[3] = 0xFFFFFF; o.arr[4] = 0xFFFFFF; } } I break at final of Main, and I observ : 0:000> !clrstack -l OS Thread Id: 0xc3c (0) ESP EIP 0015f0cc 0043d1cf test.Program.Main(System.String[]) LOCALS: 0x0015f0d8 = 0x018a2f58 0:000 !do 0x018a2f58 Name: test.myobj MethodTable: 0026309c EEClass: 00261380 Size: 12(0xc) bytes (C:\Users\admin\Documents\Visual Studio 2008\Projects\test\test\bin\Debug\test.exe) Fields: MT Field Offset Type VT Attr Value Name 01324530 4000001 4 System.Int32[] 0 instance 018a2f64 tab 0:000 dd 018a2f64 018a2f64 01324530 00000007 00ffffff 00ffffff 018a2f74 00ffffff 00ffffff 00ffffff 00000000 018a2f84 00000000 00000000 00000000 00000000 018a2f94 00000000 00000000 00000000 00000000 018a2fa4 00000000 00000000 00000000 00000000 018a2fb4 00000000 00000000 00000000 00000000 018a2fc4 00000000 00000000 00000000 00000000 018a2fd4 00000000 00000000 00000000 00000000 I can see that the header contains the size of the array (00000007) but my question is : what is the value 01324530 ? Thanks !

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• Objective-C autorelease pool not releasing object

  - by Chris

  Hi I am very new to Objective-C and was reading through memory management. I was trying to play around a bit with the NSAutoreleasePool but somehow it wont release my object. I have a class with a setter and getter which basically sets a NSString *name. After releasing the pool I tried to NSLog the object and it still works but I guess it should not? @interface TestClass : NSObject { NSString *name; } - (void) setName: (NSString *) string; - (NSString *) name; @end @implementation TestClass - (void) setName: (NSString *) string { name = string; } - (NSString *) name { return name; } @end int main (int argc, const char * argv[]) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; TestClass *var = [[TestClass alloc] init]; [var setName:@"Chris"]; [var autorelease]; [pool release]; // This should not be possible? NSLog(@"%@",[var name]); return 0; }

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• rewrite not a member of LiftRules

  - by José Leal

  Hi guys, I was following http://www.assembla.com/wiki/show/liftweb/URL_Rewriting tutorial for url rewritting in liftweb.. but I get this error: error: value rewrite is not a member of object net.liftweb.http.LiftRules .. it is really odd.. and the documentation says that it exists. I'm using idea IDE, and I've done everything from scratch, using the lift maven blank archifact. Some more info: [INFO] ------------------------------------------------------------------------ [INFO] Building Joseph3 [INFO] task-segment: [tomcat:run] [INFO] ------------------------------------------------------------------------ [INFO] Preparing tomcat:run [INFO] [resources:resources {execution: default-resources}] [WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 0 resource [INFO] [yuicompressor:compress {execution: default}] [INFO] nb warnings: 0, nb errors: 0 [INFO] artifact org.mortbay.jetty:jetty: checking for updates from scala-tools.org [INFO] artifact org.mortbay.jetty:jetty: checking for updates from central [INFO] [compiler:compile {execution: default-compile}] [INFO] Nothing to compile - all classes are up to date [INFO] [scala:compile {execution: default}] [INFO] Checking for multiple versions of scala [INFO] /home/dpz/Scala/Doit/Joseph3/src/main/scala:-1: info: compiling [INFO] Compiling 2 source files to /home/dpz/Scala/Doit/Joseph3/target/classes at 1274922123910 [ERROR] /home/dpz/Scala/Doit/Joseph3/src/main/scala/bootstrap/liftweb/Boot.scala:16: error: value rewrite is not a member of object net.liftweb.http.LiftRules [INFO] LiftRules.rewrite.prepend(NamedPF("ProductExampleRewrite") { [INFO] ^ [ERROR] one error found [INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] wrap: org.apache.commons.exec.ExecuteException: Process exited with an error: 1(Exit value: 1) [INFO] ------------------------------------------------------------------------ [INFO] For more information, run Maven with the -e switch [INFO] ------------------------------------------------------------------------ [INFO] Total time: 19 seconds [INFO] Finished at: Thu May 27 03:02:07 CEST 2010 [INFO] Final Memory: 20M/175M [INFO] ------------------------------------------------------------------------ Process finished with exit code 1 enter code here

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• XMLStreamReader and a real stream

  - by Yuri Ushakov

  Update There is no ready XML parser in Java community which can do NIO and XML parsing. This is the closest I found, and it's incomplete: http://wiki.fasterxml.com/AaltoHome I have the following code: InputStream input = ...; XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance(); XMLStreamReader streamReader = xmlInputFactory.createXMLStreamReader(input, "UTF-8"); Question is, why does the method #createXMLStreamReader() expects to have an entire XML document in the input stream? Why is it called a "stream reader", if it can't seem to process a portion of XML data? For example, if I feed: <root> <child> to it, it would tell me I'm missing the closing tags. Even before I begin iterating the stream reader itself. I suspect that I just don't know how to use a XMLStreamReader properly. I should be able to supply it with data by pieces, right? I need it because I'm processing a XML stream coming in from network socket, and don't want to load the whole source text into memory. Thank you for help, Yuri.

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• Default template parameters with forward declaration

  - by Seth Johnson

  Is it possible to forward declare a class that uses default arguments without specifying or knowing those arguments? For example, I would like to declare a boost::ptr_list< TYPE > in a Traits class without dragging the entire Boost library into every file that includes the traits. I would like to declare namespace boost { template<class T> class ptr_list< T >; }, but that doesn't work because it doesn't exactly match the true class declaration: template < class T, class CloneAllocator = heap_clone_allocator, class Allocator = std::allocator<void*> > class ptr_list { ... }; Are my options only to live with it or to specify boost::ptr_list< TYPE, boost::heap_clone_allocator, std::allocator<void*> in my traits class? (If I use the latter, I'll also have to forward declare boost::heap_clone_allocator and include <memory>, I suppose.) I've looked through Stroustrup's book, SO, and the rest of the internet and haven't found a solution. Usually people are concerned about not including STL, and the solution is "just include the STL headers." However, Boost is a much more massive and compiler-intensive library, so I'd prefer to leave it out unless I absolutely have to.

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• Suitable ESXi Spec

  - by Canacourse

  Finally I have some money to buy a new server and replace the one I have been using for 10 years. Im thinking of running ESXi on the new server. And intend to use it as follows; One W2008 R2 Guest running Exchange, File store, SVN and an accounting application for day to day running of the company. Multiple Guest VMs W2K, XP, Vista & WIN7 that were setup for testing in-house & real customer images also for testing. Probably Two Server Guest Os's W2003 & W2008 running at the same time again for testing. One Guest VM for builds & Continuous integration. Possibly one Guest running W220R2 for a customer website (Portal) This server will have to last another 10 years so I want to get the spec right. Althought I am clear on the memory and disk requirments I am not so clear on the processor(s). Im thinking of 2 Quadcore processors but welcome advice on this. Proposed Spec 10GB Ram 2TB Sata Drives (Hardware Raid 1) 2 Processors (TBC) Normally 3 Server VM's will running concurrently and the other VMs will be started as required. Max expected VMs running about 7. Max users = 4. TIA..

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• Why does setting this member in C fail?

  - by Lee Crabtree

  I'm writing a Python wrapper for a C++ library, and I'm getting a really weird when trying to set a struct's field in C. If I have a struct like this: struct Thing { PyOBJECT_HEAD unsigned int val; }; And have two functions like this: static PyObject* Thing_GetBit(Thing* self, PyObject* args) { unsigned int mask; if(!PyArg_ParseTuple(args, "I", &mask) Py_RETURN_FALSE; if((self->val & mask) != 0) Py_RETURN_TRUE; Py_RETURN_FALSE; } static PyObject* Thing_SetBit(Thing* self, PyObject* args) { unsigned int mask; bool on; if(!PyArg_ParseTuple(args, "Ii", &mask, &on)) Py_RETURN_FALSE; if(on) thing->val |= mask; else thing->val &= ~mask; Py_RETURN_TRUE; } Python code that calls the first method works just fine, giving back the value of the struct member. Calls to the SetBit method give an error about an object at address foo accessing memory at address bar, which couldn't be "written". I've poked around the code, and it's like I can look at the value all I want, both from C and Python, but the instant I try to set it, it blows up in my face. Am I missing something fundamental here?

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