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• Fastest reliable way for Clojure (Java) and Ruby apps to communicate

  - by jkndrkn

  Hi There, We have cloud-hosted (RackSpace cloud) Ruby and Java apps that will interact as follows: Ruby app sends a request to Java app. Request consists of map structure containing strings, integers, other maps, and lists (analogous to JSON). Java app analyzes data and sends reply to Ruby App. We are interested in evaluating both messaging formats (JSON, Buffer Protocols, Thrift, etc.) as well as message transmission channels/techniques (sockets, message queues, RPC, REST, SOAP, etc.) Our criteria: Short round-trip time. Low round-trip-time standard deviation. (We understand that garbage collection pauses and network usage spikes can affect this value). High availability. Scalability (we may want to have multiple instances of Ruby and Java app exchanging point-to-point messages in the future). Ease of debugging and profiling. Good documentation and community support. Bonus points for Clojure support. What combination of message format and transmission method would you recommend? Why? I've gathered here some materials we have already collected for review: Comparison of various java serialization options Comparison of Thrift and Protocol Buffers (old) Comparison of various data interchange formats Comparison of Thrift and Protocol Buffers Fallacies of Protocol Buffers RPC features Discussion of RPC in the context of AMQP (Message-Queueing) Comparison of RPC and message-passing in distributed systems (pdf) Criticism of RPC from perspective of message-passing fan Overview of Avro from Ruby programmer perspective

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• Caching vector addition over changing collections

  - by DRMacIver

  I have the following setup: I have a largish number of uuids (currently about 10k but expected to grow unboundedly - they're user IDs) and a function f : id - sparse vector with 32-bit integer values (no need to worry about precision). The function is reasonably expensive (not outrageously so, but probably on the order of a few 100ms for a given id). The dimension of the sparse vectors should be assumed to be infinite, as new dimensions can appear over time, but in practice is unlikely to ever exceed about 20k (and individual results of f are unlikely to have more than a few hundred non-zero values). I want to support the following operations efficiently: add a new ID to the collection invalidate an existing ID retrieve sum f(id) in O(changes since last retrieval) i.e. I want to cache the sum of the vectors in a way that's reasonable to do incrementally. One option would be to support a remove ID operation and treat invalidation as a remove followed by an add. The problem with this is that it requires us to keep track of all the old values of f, which is expensive in space. I potentially need to use many instances of this sort of cached structure, so I would like to avoid that. The likely usage pattern is that new IDs are added at a fairly continuous rate and are frequently invalidated at first. Ids which have been invalidated recently are much more likely to be invalidated again than ones which have remained valid for a long time, but in principle an old Id can still be invalidated. Ideally I don't want to do this in memory (or at least I want a way that lets me save the result to disk efficiently), so an idea which lets me piggyback off an existing DB implementation of some sort would be especially appreciated.

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• Design for fastest page download

  - by mexxican

  I have a file with millions of URLs/IPs and have to write a program to download the pages really fast. The connection rate should be at least 6000/s and file download speed at least 2000 with avg. 15kb file size. The network bandwidth is 1 Gbps. My approach so far has been: Creating 600 socket threads with each having 60 sockets and using WSAEventSelect to wait for data to read. As soon as a file download is complete, add that memory address(of the downloaded file) to a pipeline( a simple vector ) and fire another request. When the total download is more than 50Mb among all socket threads, write all the files downloaded to the disk and free the memory. So far, this approach has been not very successful with the rate at which I could hit not shooting beyond 2900 connections/s and downloaded data rate even less. Can somebody suggest an alternative approach which could give me better stats. Also I am working windows server 2008 machine with 8 Gig of memory. Also, do we need to hack the kernel so as we could use more threads and memory. Currently I can create a max. of 1500 threads and memory usage not going beyond 2 gigs [ which technically should be much more as this is a 64-bit machine ]. And IOCP is out of question as I have no experience in that so far and have to fix this application today. Thanks Guys!

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• How can I specify dependencies in the manifest file and then to include it into my .jar file?

  - by Roman

  I generated .class files by the following command: javac -cp \directoryName\external.jar myPackageDirectory\First.java myPackageDirectory\Second.java I needed to use -cp during compilation and name of .jar file of an "external" library (external.jar) to be able to use this library from my code. Using my .class files I have generated my .jar file in the following way: jar cfm app.jar manifest.txt myPackageDirectory\*.class manifest.txt contains just one line: Main-Class: myPackageName.First My problem is that I am not sure that I will be able to run my .jar file on other computers. I think so because during the compilation I specified the location of the .jar file of the external library. So, my .class files (included into the .jar file will try to find the .jar file of the external library in a specific directory and there is no guaranty that that the .jar file of the external library will be in the same directory as on the my computer. I heard that the above problem can be solved by a usage of a MANIFEST file that I include in my own jar, and which will list dependency locations but I do not understand how it works. I do need to specify location of the "external.jar" at the compilation stage (otherwise the compiler complains).

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• HIbernate 3.5.1 - can I just drop in EHCache 2.0.1?

  - by caerphilly

  I'm using Hibernate 3.5.1, which comes with EHCache 1.5 bundled. If I want to use the latest EHCache release (2.0.1), is it just a matter of removing the ehcache-1.5.jar from my project, and replacing with ehcache-core-2.0.1.jar? Any issues to be aware of? Also - is a cache "region" in the Hibernate mapping file that same as a cache "name" in the ehcache configuration xml? What I want to do is define 2 named cache regions - one for read-only reference entities that won't change (lookup lists etc), and one for all other entities. So in ehcache I want to define two elements; <cache name="readonly"> ... </cache> <cache name="mutable"> ... </cache> And then in my Hibernate mapping files, I will specify the cache to be used for each entity: <hibernate-mapping> <class name="lookuplist"> <cache region="readonly" usage="read-only"/> <property> ... </property> </class> </hibernate-mapping> Will that work? Some of the documentation seems to imply that a separate region/cache gets created for each mapped class... Thanks.

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• Strange compiler complaint when using similar code

  - by Jason

  For a project, I have to ask the user for a file name, and I'm reading it in character by character using getchar. From the main, I call the function char *coursename= introPrint(); //start off to print the usage directions and get the first bit of input. That function is defined as char *introPrint(){ int size= 20; int c; int length=0; char buffer[size]; //instructions printout, cut for brevity //get coursename from user and return it while ( (c=getchar()) != EOF && (c != '\n') ){ buffer[length++]= c; if (length==size-1) break; } buffer[length]=0; return buffer; } This is basically identical code I wrote to ask the user for input, replace the character echo with asterisks, then print out the results. Here, though, I'm getting a function returns address of local variable warning for the return statement. So why am I getting no warnings from the other program, but trigger one for this code?

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• Emulating a computer running MS-DOS

  - by Richard

  Writing emulators has always fascinated me. Now I want to write an emulator for an IBM PC and run MS-DOS on it (I've got the floppy image files). I have good experience in C++ and C and basic knowledge of assembler and the architecture of a CPU. I also know that there are thousands of emulators out there doing exactly what I want to do, but I'd be doing this for pure joy only. How much work do I have to expect? (If my goal is to boot DOS and create a text file with it, all emulated) What CPU should I emulate ? Where can I find documentation on how the machine code is organized and which opcodes mean what, so I can unpack and execute them correctly with my emulator? Does MS-DOS still run on the newest generations of processors? Would it theoretically be able to natively run on a 64-bit AMD Phenom 2 processor w/ a modern mainboard, HDD, RAM, etc.? What else, besides emulating the CPU, could be an important factor (in terms of difficulty)? I would only aim for outputting / inputting text to the system via the host system's console, no sound or other more advanced IO etc. Have you written an emulator yet? What was your first one for? How hard was it? Do you have any special tips for me? Thanks in advance

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• How to make a plot from summaryRprof?

  - by ThorDivDev

  This is a question for an university assignment. I was given three algorithms to calculate the GCD that I already did. My problem is getting the Rprof results to a plot so I can compare them side by side. From what little understanding I have about Rprof, summaryRprof and plot is that Rprof is used like this: Rprof() #To start #functions here Rprof(NULL) #TO end summaryRprof() # to print results I understand that plot has many different types of inputs, x and y values and something called a data frame which I assume is a fancy word for table. and to draw different lines and things I need to use this: http://www.harding.edu/fmccown/r/ what I cant figure out is how to get the summaryRprof results to the plot() function. > Rprof(filename="RProfOut2.out", interval=0.0001) > gcdBruteForce(10000, 33) [1] 1 > gcdEuclid(10000, 33) [1] 1 > gcdPrimeFact(10000, 33) [1] 1 > Rprof(NULL) > summaryRprof() ?????plot???? I have been reading on stack overflow that and other sites that I can also try to use profr and proftools although I am not very clear on the usage. The only graph I have been able to make is one using plot(system.time(gcdFunction(10,100))) As always any help is appreciated.

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• PHP, MySQL, Memcache / Ajax Scaling Problem

  - by Jeff Andersen

  I'm building a ajax tic tac toe game in PHP/MySQL. The premise of the game is to be able to share a url like mygame.com/123 with your friends and you play multiple simultaneous games. The way I have it set up is that a file (reload.php) is being called every 3 seconds while the user is viewing their game board space. This reload.php builds their game boards and the output (html) replaces their current game board (thus showing games in which it is their turn) Initially I built it entirely with PHP/MySQL and had zero caching. A friend gave me a suggestion to try doing all of the temporary/quick read information through memcache (storing moves, and ID matchups) and then building the game boards from this information. My issue is that, both solutions encounter a wall when there is roughly 30-40 active users with roughly 40-50 games running. It is running on a VPS from VPS.net with 2 nodes. (Dedicated CPU: 1.2GHz, RAM: 752MB) Each call to reload.php peforms 3 selects and 2 insert queries. The size of the data being pulled is negligible. The same actions happen on index.php to build the boards for the initial visit. Now that the backstory is done, my question is: Would there be a bottleneck in that each user is polling the same file every 3 seconds to rebuild their gameboards, and that all users are sitting on index.php from which the AJAX calls are made within the HTML. If so, is it possible to spread the users' calls out over a set of files designated to building the game boards (eg. reload1.php 2, 3 etc) and direct users to the appropriate file. Would this relieve the pressure? A long winded explanation; however, I didn't have anywhere else to ask. Thanks very much for any insight.

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• Segmentation Fault

  - by Biranchi

  Hi All, I have the following piece of code for getting the hostname and IP address, #include <stdlib.h> #include <stdio.h> #include <netdb.h> /* This is the header file needed for gethostbyname() */ #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> int main(int argc, char *argv[]) { struct hostent *he; if (argc!=2){ printf("Usage: %s <hostname>\n",argv[0]); exit(-1); } if ((he=gethostbyname(argv[1]))==NULL){ printf("gethostbyname() error\n"); exit(-1); } printf("Hostname : %s\n",he->h_name); /* prints the hostname */ printf("IP Address: %s\n",inet_ntoa(*((struct in_addr *)he->h_addr))); /* prints IP address */ } but i am getting a warning and segmentation fault as host.c: In function ‘main’: host.c:24: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘int’ What is the error in the code ?? Thanks

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• My method is too specific. How can I make it more generic?

  - by EricBoersma

  I have a class, the outline of which is basically listed below. import org.apache.commons.math.stat.Frequency; public class WebUsageLog { private Collection<LogLine> logLines; private Collection<Date> dates; WebUsageLog() { this.logLines = new ArrayList<LogLine>(); this.dates = new ArrayList<Date>(); } SortedMap<Double, String> getFrequencyOfVisitedSites() { SortedMap<Double, String> frequencyMap = new TreeMap<Double, String>(Collections.reverseOrder()); //we reverse order to sort from the highest percentage to the lowest. Collection<String> domains = new HashSet<String>(); Frequency freq = new Frequency(); for (LogLine line : this.logLines) { freq.addValue(line.getVisitedDomain()); domains.add(line.getVisitedDomain()); } for (String domain : domains) { frequencyMap.put(freq.getPct(domain), domain); } return frequencyMap; } } The intention of this application is to allow our Human Resources folks to be able to view Web Usage Logs we send to them. However, I'm sure that over time, I'd like to be able to offer the option to view not only the frequency of visited sites, but also other members of LogLine (things like the frequency of assigned categories, accessed types [text/html, img/jpeg, etc...] filter verdicts, and so on). Ideally, I'd like to avoid writing individual methods for compilation of data for each of those types, and they could each end up looking nearly identical to the getFrequencyOfVisitedSites() method. So, my question is twofold: first, can you see anywhere where this method should be improved, from a mechanical standpoint? And secondly, how would you make this method more generic, so that it might be able to handle an arbitrary set of data?

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• Flash browser game - HTTP + PHP vs Socket + Something else

  - by Maurycy Zarzycki

  I am developing a non-real time browser RPG game (think Kingdom of Loathing) which would be played from within a Flash app. At first I just wanted to make the communication with server using simply URLLoader to tell PHP what I am doing, and using $_SESSION to store data needed in-between request. I wonder if it wouldn't be better to base it on a socket connection, an app residing on a server written in Java or Python. The problem is I have never ever written such an app so I have no idea how much I'd have to "shift" my thoughts from simple responding do request (like PHP) to continuously working application. I won't hide I am also concerned about the memory and CPU usage of such Server app, when for example there would be hundreds of users connected. I've done some research. I have tried to do some research, but thanks to my nil knowledge on the sockets subject I haven't found anything helpful. So, considering the fact I don't need real time data exchange, will it be wise to develop the server side part as socket server, not in plain ol' PHP?

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• Best approach to cache Counts from SQL tables ?

  - by pixel3cs

  I would like to develop a Forum from scratch, with special needs and customization. I would like to prepare my forum for intensive usage and wondering how to cache things like User posts count and User replies count. Having only three tables, tblForum, tblForumTopics, tblForumReplies, what is the best approach of cache the User topics and replies counts ? Think at a simple scenario: user press a link and open the Replies.aspx?id=x&page=y page, and start reading replies. On the HTTP Request, the server will run an SQL command wich will fetch all replies for that page, also "inner joining with tblForumReplies to find out the number of User replies for each user that replied." select tblForumReplies.*, tblFR.TotalReplies from tblForumReplies inner join ( select IdRepliedBy, count(*) as TotalReplies from tblForumReplies group by IdRepliedBy ) as tblFR on tblFR.IdRepliedBy = tblForumReplies.IdRepliedBy Unfortunately this approach is very cpu intensive, and I would like to see your ideas of how to cache things like table Counts. If counting replies for each user on insert/delete, and store it in a separate field, how to syncronize with manual data changing. Suppose I will manually delete Replies from SQL.

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• How do I retrieve twitter xml for Flash site via php properly

  - by daidai

  Am I using TwitterScript to retrieve Twitter data for inside a Flash site. Due to Twitter's crossdomain policy, I need to setup a php proxy... Firstly I made a simple one <?php $url = $_GET['url']; readfile($url); ?> but I then get this error URL file-access is disabled in the server configuration which is only resolved by getting my host to turn fopen() on, which I don't want to do. Then I found this <?php function get_content($url) { $ch = curl_init(); curl_setopt ($ch, CURLOPT_URL, $url); curl_setopt ($ch, CURLOPT_HEADER, 0); ob_start(); curl_exec ($ch); curl_close ($ch); $string = ob_get_contents(); ob_end_clean(); return $string; } #usage: $url = $_GET['url']; $content = get_content ($url); var_dump ($content); ?> which solves that problem but the data now is the correct XML but looks like: string(39950) "<?xml version="1.0" encoding="UTF-8"?> <statuses type="array"> <status> ... </statuses>" How do I get the XML data out of that string?

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• C++ RPC library suggestions

  - by Oxsnarder

  I'm looking for suggestions regarding RPC libraries implemented in C++, for C++ developers. Some requirements constraints: Should work on both linux/unix and win32 systems Be able to execute free function and class methods Hopefully written in modern C++ not 90's/java-esque C++ Be able to function over networks and hetrogenous architectures Not too slow or inefficient Hopefully provide interfaces for TR1 style std::function's et al. My example usage is to invoke the free function foo on a remote machine. ---snip--- // foo translation unit int foo(int i, int j) { return i + j; } ---snip--- ---snip--- // client side main int main() { //register foo on client and server //setup necassary connections and states int result; if (RPCmechanism.invoke("foo",4,9,result)) std::cout << "foo(4,9) = " result << std::endl; else std::cout << "failed to invoke foo(4,9)!" << std::endl; return 0; } ---snip--- Something that can achieve the above or similar would be great.

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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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• OpenGL Pixel Format Attributes (NSOpenGLPixelFormatAttibutes) explanation?

  - by nacho4d

  Hi, I am not new to OpenGL, but not an expert. Many tutorials teach how to draw, 3D, 2D, projections, orthogonal, etc, but How about setting a the view? (NSOpenGLView in Cocoa, Macs). For example I have this: - (id) initWithFrame: (NSRect) frame { GLuint attribs[] = { //PF: PixelAttibutes NSOpenGLPFANoRecovery, NSOpenGLPFAWindow, NSOpenGLPFAAccelerated, NSOpenGLPFADoubleBuffer, NSOpenGLPFAColorSize, 24, NSOpenGLPFAAlphaSize, 8, NSOpenGLPFADepthSize, 24, NSOpenGLPFAStencilSize, 8, NSOpenGLPFAAccumSize, 0, 0 }; NSOpenGLPixelFormat* fmt = [[NSOpenGLPixelFormat alloc] initWithAttributes: (NSOpenGLPixelFormatAttribute*) attribs]; return self = [super initWithFrame:frame pixelFormat: [fmt autorelease]]; } And I don't understand very well their usage, specially when combining them. For example: If I want my view to be capable of full screen should I write NSOpenGLPFAFullScreen only ? or both? (by capable I mean not always in full screen) Regarding Double Buffer, what is this exactly? (Below: Apple's definition) If present, this attribute indicates that only double-buffered pixel formats are considered. Otherwise, only single-buffered pixel formats are considered Regarding Color: if NSOpenGLPFAColorSize is 24 and NSOpenGLPFAColorSize is 8 then it means that alpha and RGB components are treated differently? what happen if I set the former to 32 and the later to 0? Etc, etc,In general how do I learn to set my view from scratch? Thanks in advance. Ignacio.

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• finding long repeated substrings in a massive string

  - by Will

  I naively imagined that I could build a suffix trie where I keep a visit-count for each node, and then the deepest nodes with counts greater than one are the result set I'm looking for. I have a really really long string (hundreds of megabytes). I have about 1 GB of RAM. This is why building a suffix trie with counting data is too inefficient space-wise to work for me. To quote Wikipedia's Suffix tree: storing a string's suffix tree typically requires significantly more space than storing the string itself. The large amount of information in each edge and node makes the suffix tree very expensive, consuming about ten to twenty times the memory size of the source text in good implementations. The suffix array reduces this requirement to a factor of four, and researchers have continued to find smaller indexing structures. And that was wikipedia's comments on the tree, not trie. How can I find long repeated sequences in such a large amount of data, and in a reasonable amount of time (e.g. less than an hour on a modern desktop machine)? (Some wikipedia links to avoid people posting them as the 'answer': Algorithms on strings and especially Longest repeated substring problem ;-) )

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• How can flash call jquery function in its event

  - by user2955639

  I want jquery to do something during some of the events when an audio is playing. So I'm coding a function like this <script> $.fn.playMedia = function(options){ var opts = $.extend({}, { swfSrc: '' timeUpdated: function(currentTime){}, startPlay: function(){}, endPlay: function(){} }, options); return $(this).each(function(){ // call flash to play the media whose src is opts.swfSrc // Is it possible that flash can call the js functions(opts.timeUpdate, opts.startPlay and opts.endPlay) at each time of the event is triggered? }); }}; </script> // Usage <div id="player"></div> <script> $('#player').playMedia({ swfSrc: '/path/song.mp3', timeUpdated: function(currentTime){ comsole.log(currentTime); } }); </script> I'm a totally layman of flash, I just guess this works. Hope someone could tell me how to make up a swf file for this jquery function. Or is there any existing jquery plugin which does this thing but can re-design apperance flexibly. Thank you very much!

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• Whether to put method code in a VB.Net data storage class, or put it in a separate class?

  - by Alan K

  TLDR summary: (a) Should I include (lengthy) method code in classes which may spawn multiple objects at runtime, (b) does doing so cause memory usage bloat, (c) if so should I "outsource" the code to a class that is loaded only once and have the class methods call that, or alternatively (d) does the code get loaded only once with the object definition anyway and I'm worrying about nothing? ........ I don't know whether there's a good answer to this but if there is I haven't found it yet by searching in the usual places. In my VB.Net (2010 if it matters) WinForms project I have about a dozen or so class objects in an object model. Some of these are pretty simple and do little more than act as data storage repositories. The ones further up the object model, however, have an increasing number of methods. There can be a significant number of higher level objects in use though the exact number will be runtime dependent so I can't be more precise than that. As I was writing the method code for one of the top level ones I noticed that it was starting to get quite lengthy. Memory optimisation is something of a lost art given how much memory the average PC has these days but I don't want to make my application a resource hog. So my questions for anyone who knows .Net way better than I do (of which there will be many) are: Is the code loaded into memory with each instance of the class that's created? Alternatively is it loaded only once with the definition of the class, and all derived objects just refer to that definition? (I'm not really sure how that could be possible given that, for example, event handlers can be assigned dynamically, but no harm asking.) If the answer to the first one is yes, would it be more efficient to write the code in a "utility" object which is loaded only once and called from the real class' methods? Any thoughts appreciated.

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• lua metatable __lt __le __eq forced boolean conversion of return value

  - by chris g.

  Overloading __eq, __lt, and __le in a metatable always converts the returning value to a boolean. Is there a way to access the actual return value? This would be used in the following little lua script to create an expression tree for an argument usage: print(_.a + _.b - _.c * _.d + _.a) -> prints "(((a+b)-(c*d))+a)" which is perfectly what I would like to have but it doesn't work for print(_.a == _.b) since the return value gets converted to a boolean ps: print should be replaced later with a function processing the expression tree -- snip from lua script -- function binop(op1,op2, event) if op1[event] then return op1[event](op1, op2) end if op2[event] then return op2[event](op1, op2) end return nil end function eq(op1, op2)return binop(op1,op2, "eq") end ... function div(op1, op2)return binop(op1,op2, "div") end function exprObj(tostr) expr = { eq = binExpr("=="), lt = binExpr("<"), le = binExpr("<="), add = binExpr("+"), sub=binExpr("-"), mul = binExpr("*"), div= binExpr("/") } setmetatable(expr, { __eq = eq, __lt = lt, __le = le, __add = add, __sub = sub, __mul = mul, __div = div, __tostring = tostr }) return expr end function binExpr(exprType) function binExprBind(lhs, rhs) return exprObj(function(op) return "(" .. tostring(lhs) .. exprType .. tostring(rhs) .. ")" end) end return binExprBind end function varExpr(obj, name) return exprObj(function() return name end) end _ = {} setmetatable(_, { __index = varExpr }) -- snap -- Modifing the lua vm IS an option, however it would be nice if I could use an official release

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• log activity. intrusion detection. user event notification ( interraction ). messaging

  - by Julian Davchev

  Have three questions that I somehow find related so I put them in same place. Currently building relatively large LAMP system - making use of messaging(activeMQ) , memcache and other goodies. I wonder if there are best practices or nice tips and tricks on howto implement those. System is user aware - meaning all actions done can be bind to particular logged user. 1. How to log all actions/activities of users? So that stats/graphics might be extracted later for analysing. At best that will include all url calls, post data etc etc. Meaning tons of inserts. I am thinking sending messages to activeMQ and later cron dumping in DB and cron analysing might be good idea here. Since using Zend Framework I guess I may use some request plugin so I don't have to make the log() call all over the code. 2.How to log stuff so may be used for intrusion detection? I know most things might be done on http level using apache mods for example but there are also specific cases like (5 failed login attempts in a row (leads to captcha) etc etc..) This also would include tons of inserts. Here I guess direct usage of memcache might be best approach as data don't seem vital to be permanantly persisted. Not sure if cannot use data from point 1. 3.System will notify users of some events. Like need approval , something broke..whatever.Some events will need feedback(action) from user, others are just informational. Wonder if there is common solutions for needs like this. Example: Based on occuring event(s) user will be notifed (user inbox for example) what happend. There will be link or something to lead him to details of thingy that happend and take action accordingly. Those seem trivial at first look but problem I see if coding it directly is becoming really fast hard to maintain.

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• What is the correct install process to setup Node.js with Windows Azure Emulator

  - by PazoozaTest Pazman

  This question is related to this question: Node.js running under IIS Express Keeps Crashing to which I need help with reinstalling and getting node.js up and running in windows emulator working. Hello I am reinstalling my machine: Toshiha Laptop 2 GB Ram 32 bit processor What is the correct procedure from start to finish to get node.js development working, so far nothing has worked and the emulator (IIS Express) worker processor keeps crashing. No matter how many instances they all end up crashing. Up until two weeks ago my node development was working fine, but I had to do a reinstall, and since then I haven't been doing any node.js development on windows emulator because the latest June 2012 Azure SDK for Node.js is buggy. These are the steps I have taken: 1) Reformat HD 2) Insert Windows 7 N SP1 CD 3) Reboot machine into CD installation 4) Follow and wait until Windows 7 installed 5) Run Add/Remove programs + enable IIS + IIS management tools 6) Run Windows Update (installed about 53 updates) 7) Go here http://www.windowsazure.com/en-us/develop/nodejs/ 8) Click Windows Installer June 2012 and install Windows Azure SDK for Node.js - June 2012 9) Run Azure Powershell 10) Navigate to c:\node\testSite\webrole1 11) launch site: start-azureemulator -launch 12) Play around on website (then crash!) Problem signature: Problem Event Name: APPCRASH Application Name: iisexpress.exe Application Version: 8.0.8298.0 Application Timestamp: 4f620349 Fault Module Name: iiscore.dll Fault Module Version: 8.0.8298.0 Fault Module Timestamp: 4f63b65c Exception Code: c0000005 Exception Offset: 00021767 OS Version: 6.1.7601.2.1.0.256.28 Locale ID: 1033 Additional Information 1: f66d Additional Information 2: f66d807b515d6b2dc6f28f66db769a01 Additional Information 3: 7b2f Additional Information 4: 7b2f6797d07ebc2c23f2b227e779722e Am I missing a step in my resintall process? Do I have all the required files to do node.js windows azure emulator development? Why is IIS Express crashing all the time? Can I still do node.js windows azure emulator development without using IIS Express and use my local Windows 7 N (SP1) IIS 7.x that comes shipped?

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• How to check volume is mounted or not using python with a dynamic volume name

  - by SR query

  import subprocess def volumeCheck(volume_name): """This function will check volume name is mounted or not. """ volume_name = raw_input('Enter volume name:') volumeCheck(volume_name) print 'volume_name=',volume_name p = subprocess.Popen(['df', '-h'], stdout=subprocess.PIPE, stderr=subprocess.PIPE) p1, err = p.communicate() pattern = p1 if pattern.find(volume_name): print 'volume found' else: print 'volume not found' While running i always got wrong result "volume found". root@sr-query:/# df -h Filesystem Size Used Avail Use% Mounted on rootfs 938M 473M 418M 54% / /dev/md0 938M 473M 418M 54% / none 250M 4.9M 245M 2% /dev /dev/md2 9.7M 1.2M 8.0M 13% /usr/config /dev/md7 961M 18M 895M 2% /downloads tmpfs 250M 7.9M 242M 4% /var/volatile tmpfs 250M 0 250M 0% /dev/shm tmpfs 250M 0 250M 0% /media/ram **/dev/mapper/vg9-lv9 1016M 65M 901M 7% /VolumeData/sp /dev/mapper/vg10-lv10 1016M 65M 901M 7% /VolumeData/cp** root@sr-query:/# root@sr-query:/# root@sr-query:/# python volume_check.py Enter volume name:raid_10volume volume_name= raid_10volume **volume found** root@sr-query:/# I enterd raid_10volume its not listed here please check the df -h command out put(only 2 volume there sp and cp) , then how it reached else part. what is wrong in my code? Thanks in advance. is there any other way to do this work ! ?

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• Minimizing server load in case of many XMLHttpRequest calls

  - by user1888975

  I am making a website where users are to like some articles. Whenever the like button is clicked I am sending a XMLHttpRequest to the server to run a file called like_clicked.php along with the get data of article id and user id. This file takes article id and user id and updates the sql database and also adds a node in an xml file related to the user. This is the first time I am doing something for mass usage. I am worried about the server load when too many users call the like_clicked.php file. Please help me, if this method is ok. I am also thinking of an alternative in case the above method fails. I am thinking of making many like_clicked files (namely like_clicked1.php, like_clicked2.php ... ) to minimize load on a single i-node. Is there a method to detect that it is better to call the next like_clicked file. Here we would need to detect how many calls per unit time are coming for the particular file. How do we handle this? Thanks in advance.

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