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  • How should a multi-threaded C application handle a failed malloc()?

    - by user294463
    A part of an application I'm working on is a simple pthread-based server that communicates over a TCP/IP socket. I am writing it in C because it's going to be running in a memory constrained environment. My question is: what should the program do if one of the threads encounters a malloc() that returns NULL? Possibilities I've come up with so far: No special handling. Let malloc() return NULL and let it be dereferenced so that the whole thing segfaults. Exit immediately on a failed malloc(), by calling abort() or exit(-1). Assume that the environment will clean everything up. Jump out of the main event loop and attempt to pthread_join() all the threads, then shut down. The first option is obviously the easiest, but seems very wrong. The second one also seems wrong since I don't know exactly what will happen. The third option seems tempting except for two issues: first, all of the threads need not be joined back to the main thread under normal circumstances and second, in order to complete the thread execution, most of the remaining threads will have to call malloc() again anyway. What shall I do?

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  • Creating 3rd party library in Android. Need suggestions!!

    - by Lalith
    Hello all, I am planning to create a 3rd party library for android application developers. Also the main concern is I do not want the users to make many changes to their code base. The following are the main things I want to clarify before diving into the project. 1) I want to attach my own event handlers dynamically to the application. As per above limitations I mentioned, I cannot make users put the relevant code in their handlers as I need to support existing applications as well. I found out that we cannot attach more than one event handler per one listener. For example Button.setOnclickListener(somelistener) .. will set one listener. In traditional desktop applications we can add more than one handlers but here if I do one more Button.setOnclickListener(someOtherListener) this one overwrites the previous listener. Is there any way I can attach my own listener along with application's existing listeners dynamically? Also is it really not supported on android yet? 2) Is there any 3rd party alternative that exists already that monitors user's interactions in androidi? 3) If this is not supported now are there any future plans to support this feature? Please let me know about this as I did not get much feedback on Stackoverflow. Any suggestions and workarounds would really help me continue with this project. Regards, Lalith

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  • Error with `Thread.Sleep` during automatic testing on TeamCity 5

    - by yeyeyerman
    Hello, I'm having some problems executing the tests of the application I'm developing. All the tests execute normally with ReSharper and in NCover. However, the execution of one of these tests in TeamCity is generating an error. This test initializes two objects, the object under test and a simulator of a real object. Both objects will communicate throug a serial link in a representation of the real scenario. ObjectSimulator r_simulator = new ObjectSimulator(...); ObjectDriver r_driver = new ObjectDriver(...); Assert.IsTrue(r_driver.Connect() == ErrorCode.Success); The simulator just do the following in the constructor public class ObjectSimulator { ... public ObjectSimulator() { // serial port configuration m_port = new SerialPort(); m_port.DataReceived += DataReceivedEvent; } ... } The main object has two threads. The main thread of the application and a timer to refresh a watchdog timer in the real object. public ErrorCode Connect() { ... StartSynchroTimer(); Thread.Sleep(4); // to check if the timer is working properly ... } The problem seems to be comming from the Thread.Sleep() call, as when I remove it everything works. The ObjectSimulator somehow doesn't execute the DataReceived event callback. How can I resolve this issue?

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  • Best way to get distinct values from large table

    - by derivation
    I have a db table with about 10 or so columns, two of which are month and year. The table has about 250k rows now, and we expect it to grow by about 100-150k records a month. A lot of queries involve the month and year column (ex, all records from march 2010), and so we frequently need to get the available month and year combinations (ie do we have records for april 2010?). A coworker thinks that we should have a separate table from our main one that only contains the months and years we have data for. We only add records to our main table once a month, so it would just be a small update on the end of our scripts to add the new entry to this second table. This second table would be queried whenever we need to find the available month/year entries on the first table. This solution feels kludgy to me and a violation of DRY. What do you think is the correct way of solving this problem? Is there a better way than having two tables?

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  • Firebird 2.1 + EXISTS = query bug?

    - by Atlas
    Using Delphi 2009 + Firebird 2.1.3. Database is ODS 11.1, default char set is UTF8. My prepared query is as follows: SELECT a.po_id, a.po_no FROM purchase_order a WHERE EXISTS (SELECT 1 FROM sales_order_item z1 JOIN purchase_order_item z2 ON z2.so_item_id = z1.so_item_id AND z2.po_id = a.po_id WHERE z1.so_id = :soid) ORDER BY a.po_no Now when I loop this say 1000 times because I have 1000 x so_id, the CPU usage get at 100% for FBSERVER.EXE Anyone encountered this problem?

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  • javascript: use getElementsByName for 'this'?

    - by stelmate
    I need to get some children elements and loop over them using inline javascript for a onmouseover event. When I try to use this.getElementsByName I'm getting an error that the object does not support this property. I was under the impression that getElementsByName work for element objects which I thought 'this' would be considered. Anyone have any other ideas on how I can achieve this?

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  • Get last/newly added element in std::set

    - by Dave17
    can you get the last or newly added element in std::set? for example say if the loop runs to collect the elements to fill in the std::set. if on the first run the set was, [0] "A" [1] "B" [2] "D" and, on second run, the set becomes [0] "A" [1] "B" [2] "C" [3] "D" How would you check if 'C' is the new element that was added?

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  • Using Predicate of a class to Search Generic list - Faster than looping?

    - by Srikanth
    Lets say we have a generic list of Class1, typically having ~100 objects for a given session. I would like to see if the list has a particular object. ASP.NET 2.0 allows me to do this: Dim objResult as Class1 = objList.Find(objSearch) How does this approach rate when compared to a traditional For loop, looking at a performance perspective? How would this vary with increase or decrease in length of the list?

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  • Static variable definition order in c++

    - by rafeeq
    Hi i have a class tools which has static variable std::vector m_tools. Can i insert the values into the static variable from Global scope of other classes defined in other files. Example: tools.h File class Tools { public: static std::vector<std::vector> m_tools; void print() { for(int i=0 i< m_tools.size() ; i++) std::cout<<"Tools initialized :"<< m_tools[i]; } } tools.cpp File std::vector<std::vector> Tools::m_tools; //Definition Using register class constructor for inserting the new string into static variable. class Register { public: Register(std::string str) { Tools::m_tools.pushback(str); } }; Different class which inserts the string to static variable in static variable first_tool.cpp //Global scope declare global register variable Register a("first_tool"); //////// second_tool.cpp //Global scope declare global register variable Register a("second_tool"); Main.cpp void main() { Tools abc; abc.print(); } Will this work? In the above example on only one string is getting inserted in to the static list. Problem look like "in Global scope it tries to insert the element before the definition is done" Please let me know is there any way to set the static definiton priority? Or is there any alternative way of doing the same.

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  • Multi threading question..

    - by dotnet-practitioner
    I would like to invoke heavy duty method dowork on a separate thread and kill it if its taking longer than 3 seconds. Is there any problem with the following code? class Class1 { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main(string[] args) { Console.WriteLine("starting new thread"); Thread t = new Thread(new ThreadStart(dowork)); t.Start(); DateTime start = DateTime.Now; TimeSpan span = DateTime.Now.Subtract(start); bool wait = true; while (wait == true) { if (span.Seconds > 3) { t.Abort(); wait = false; } span = DateTime.Now.Subtract(start); } Console.WriteLine("ending new thread after seconds = {0}", span.Seconds); Console.WriteLine("all done"); Console.ReadLine(); } static void dowork() { Console.WriteLine("doing heavy work inside hello"); Thread.Sleep(7000); Console.WriteLine("*** finished**** doing heavy work inside hello"); } }

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  • Function pointers uasage

    - by chaitanyavarma
    Hi All, Why these two codes give the same output, Case - 1: #include <stdio.h> typedef void (*mycall) (int a ,int b); void addme(int a,int b); void mulme(int a,int b); void subme(int a,int b); main() { mycall x[10]; x[0] = &addme; x[1] = &subme; x[2] = &mulme; (x[0])(5,2); (x[1])(5,2); (x[2])(5,2); } void addme(int a, int b) { printf("the value is %d\n",(a+b)); } void mulme(int a, int b) { printf("the value is %d\n",(a*b)); } void subme(int a, int b) { printf("the value is %d\n",(a-b)); } Output: the value is 7 the value is 3 the value is 10 Case -2 : #include <stdio.h> typedef void (*mycall) (int a ,int b); void addme(int a,int b); void mulme(int a,int b); void subme(int a,int b); main() { mycall x[10]; x[0] = &addme; x[1] = &subme; x[2] = &mulme; (*x[0])(5,2); (*x[1])(5,2); (*x[2])(5,2); } void addme(int a, int b) { printf("the value is %d\n",(a+b)); } void mulme(int a, int b) { printf("the value is %d\n",(a*b)); } void subme(int a, int b) { printf("the value is %d\n",(a-b)); } Output: the value is 7 the value is 3 the value is 10

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  • how to number the datas from mysql

    - by udaya
    Hi This is a doubt on mysql select query let me axplain my doubt with a simple example consider this is my query SELECT dbCountry from tableCountry tableCountry has fields dbCuntryId dbCountry and dbState I have the result as dbCountry india america england kenya pakisthan I need the result as 1 india 2 america 3 england 4 kenya 5 pakisthan the numbers 12345 must be generated with the increase in data and itis not a autoincrement id How can i get it is it something like loop

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  • selected option not clearing from memory android

    - by user2980560
    I have a small random number spinner that when you click gives a random number. I am having two problems. The first is when the main activity loads it displays a random number on the screen without the random number spinner being clicked. I am unsure what to set to false to keep it from opening with the main activity. The second problem is that when you select an option from the spinner it does not clear. Meaning that If you click on option D6 or D20 then you can not click on the same option again until selecting the other option first. Essentially the selection does not clear out of memory after the random number is selected. Here is the random number code public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) { Random rand = new Random(); int roll; // An item was selected. if (spinner1.getSelectedItemPosition()==0) { roll = rand.nextInt(6)+1; } else { roll = rand.nextInt(20)+1; } // Put the result into a string. String text = "You rolled a " + roll; // Build a dialog box and with the result string and a single button AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setMessage(text).setCancelable(false) .setPositiveButton("OK", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { // do things when the user clicks ok. } }); AlertDialog alert = builder.create(); // Show the dialog box. alert.show(); }

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  • vs2002: c# multi threading question..

    - by dotnet-practitioner
    I would like to invoke heavy duty method dowork on a separate thread and kill it if its taking longer than 3 seconds. Is there any problem with the following code? class Class1 { /// <summary> /// The main entry point for the application. /// </summary> /// [STAThread] static void Main(string[] args) { Console.WriteLine("starting new thread"); Thread t = new Thread(new ThreadStart(dowork)); t.Start(); DateTime start = DateTime.Now; TimeSpan span = DateTime.Now.Subtract(start); bool wait = true; while (wait == true) { if (span.Seconds>3) { t.Abort(); wait = false; } span = DateTime.Now.Subtract(start); } Console.WriteLine("ending new thread after seconds = {0}", span.Seconds); Console.WriteLine("all done"); Console.ReadLine(); } static void dowork() { Console.WriteLine("doing heavy work inside hello"); Thread.Sleep(7000); Console.WriteLine("*** finished**** doing heavy work inside hello"); } }

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  • How to get four following text inputs after each checkbox?

    - by Richard Knop
    I am traversing checkboxes like this: $('.day').each(function() { // here I need to get the following 4 text inputs in the HTML // and set some attributes on them }); After every checkbox there are four text input fields (there are also some div, span tags for CSS around them). So inside the loop above I need to get four text input fields that follow the checkbox in the HTML source so I can set some attributes on them. How would I go about that?

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  • Optimizing grep (or using AWK) in a shell script

    - by Ode
    Hi - In my shell script, I am trying to search using terms found in a $sourcefile against the same $targetfile over and over. My $sourcefile is formatted as such: pattern1 pattern2 etc... The inefficient loop I have to search with is: for line in $(< $sourcefile);do fgrep $line $targetfile | fgrep "RID" >> $outputfile done I understand it would be possible to improve this by either loading the whole $targetfile into memory, or perhaps by using AWK? Thanks

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  • JQuery: Get SRC for each image that has specific atrtibute

    - by adbox
    Hey Guys, I am wokring on a dialog, where in execution I want to round up all items that have a specific attribute and place an attribute value of their's into a comma delited list. This is as far as I have gotten, which isnt far. buttons: { 'Hook': function(){ $('.grid_pic:has(border=3)').(loop through id's, grab src, build variable with srcs comma delimeited) } Any ideas?

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  • Template specialization to use default type if class member typedef does not exist

    - by Frank
    Hi Everyone, I'm trying to write code that uses a member typedef of a template argument, but want to supply a default type if the template argument does not have that typedef. A simplified example I've tried is this: struct DefaultType { DefaultType() { printf("Default "); } }; struct NonDefaultType { NonDefaultType() { printf("NonDefault "); } }; struct A {}; struct B { typedef NonDefaultType Type; }; template<typename T, typename Enable = void> struct Get_Type { typedef DefaultType Type; }; template<typename T> struct Get_Type< T, typename T::Type > { typedef typename T::Type Type; }; int main() { Get_Type::Type test1; Get_Type::Type test2; } I would expect this to print "Default NonDefault", but instead it prints "Default Default". My expectation is that the second line in main() should match the specialized version of Get_Type, because B::Type exists. However, this does not happen. Can anyone explain what's going on here and how to fix it, or another way to accomplish the same goal? Thank you.

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  • Log4j Logging to the Wrong Directory

    - by John
    I have a relatively complex log4j.xml configuration file with many appenders. Some machines the application runs on need a separate log directory, which is actually a mapped network drive. To get around this, we embed a system property as part of the filename in order to specify the directory. Here is an example: The "${user.dir}" part is set as a system property on each system, and is normally set to the root directory of the application. On some systems, this location is not the root of the application. The problem is that there is always one appender where this is not set, and the file appears not to write to the mapped drive. The rest of the appenders do write to the correct location per the system property. As a unit test, I set up our QA lab to hard-code the values for the appender above, and it worked: however, a different appender will then append to the wrong file. The mis-logged file is always the same for a given configuration: it is not a random file each time. My best educated guess is that there is a HashMap somewhere containing these appenders, and for some reason, the first one retrieved from the map does not have the property set. Our application does have custom system properties loading: the main() method loads a properties file and calls into System.setProperties(). My first instinct was to check the static initialization order, and to ensure the controller class with the main method does not call into log4j (directly or indirectly) before setting the properties just in case this was interfering with log4j's own initialization. Even removing all vestiges of log4j from the initialization logic, this error condition still occurs.

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  • How should I solve this MySql problem (PHP) ? (Beginner)

    - by Camran
    I have several tables in a MySql database. I have a classifieds website, and at the bottom I display the users last visited classifieds. I do this by storing the ID:s of the ads to an array in the cookie. Now, my db is made up like this kindof: Main Table: // Stores global information, ie these fields have to be filled out in every record, never be blank ID Price category Seller Item Table: // Stores descriptive info about whats for sale ID AD_ID (FK) //This is the same as ID in the MAIN TABLE Color Size Mileage etc My problem is that I need to know what category the ad is in, in order to query mysql for the right information I think. So I need two variables, but the cookie only has one (ID) stored. Offcourse I could make two queries, first one just matching the ID to the main_table and fetch the category from the Main_table. Then make the second query and fetch all other info from the right table. Here is an example if the category was Vehicles: SELECT * FROM main_table, vehicles_table, WHERE main_table.id=$id_from_cookie AND main_table.ad_id=vehicles_table.ad_id As you can see above, I need the category to write in what table to check, right? But I think there must be a smarter way, like fetching them in one single query using only one variable (id from cookie)? How should I do this? Understand? Let me know if you need more input... Thanks

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