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  • Wake up thread blocked on accept() call

    - by selbie
    Sockets on Linux question I have a worker thread that is blocked on an accept() call. It simply waits for an incoming network connection, handles it, and then returns to listening for the next connection. When it is time for the program to exit, how do I signal this network worker thread (from the main thread) to return from the accept() call while still being able to gracefully exit its loop and handle it's cleanup code. Some things I tried: 1. pthread_kill to send a signal. Feels kludgy to do this, plus it doesn't reliably allow the thread to do it's shutdown logic. Also makes the program terminate as well. I'd like to avoid signals if at all possible. pthread_cancel. Same as above. It's a harsh kill on the thread. That, and the thread may be doing something else. Closing the listen socket from the main thread in order to make accept() abort. This doesn't reliably work. Some constraints: If the solution involves making the listen socket non-blocking, that is fine. But I don't want to accept a solution that involves the thread waking up via a select call every few seconds to check the exit condition. The thread condition to exit may not be tied to the process exiting. Essentially, the logic I am going for looks like this. void* WorkerThread(void* args) { DoSomeImportantInitialization(); // initialize listen socket and some thread specific stuff while (HasExitConditionBeenSet()==false) { listensize = sizeof(listenaddr); int sock = accept(listensocket, &listenaddr, &listensize); // check if exit condition has been set using thread safe semantics if (HasExitConditionBeenSet()) { break; } if (sock < 0) { printf("accept returned %d (errno==%d)\n", sock, errno); } else { HandleNewNetworkCondition(sock, &listenaddr); } } DoSomeImportantCleanup(); // close listen socket, close connections, cleanup etc.. return NULL; } void SignalHandler(int sig) { printf("Caught CTRL-C\n"); } void NotifyWorkerThreadToExit(pthread_t thread_handle) { // signal thread to exit } int main() { void* ptr_ret= NULL; pthread_t workerthread_handle = 0; pthread_create(&workerthread, NULL, WorkerThread, NULL); signal(SIGINT, SignalHandler); sleep((unsigned int)-1); // sleep until the user hits ctrl-c printf("Returned from sleep call...\n"); SetThreadExitCondition(); // sets global variable with barrier that worker thread checks on // this is the function I'm stalled on writing NotifyWorkerThreadToExit(workerthread_handle); // wait for thread to exit cleanly pthread_join(workerthread_handle, &ptr_ret); DoProcessCleanupStuff(); }

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  • Help Me Make My Pascal Program Display Multiple Names Which Were Entered Plz.

    - by Sketchie
    Hey,Guys I'm having trouble displaying names using arrays in my Pascal program. But first heres the question I'm writing the program to answer : Develop pseudocode that accepts as input the name of an unspecified number of masqueraders who each have paid the full cost of their costume and the amount each has paid. A masquerader may have paid for a costume in any of the five sections in the band. The algorithm should determine the section in which the masquerader plays, based on the amount he/she has paid for the costume. The algorithm should also determine the number of masqueraders who have paid for costumes in each section. The names of persons and the section for which they have paid should be printed. A listing of the sections and the total number of persons registered to play in each section should also be printed, along with the total amount paid in each section. And here's what I've done so far(It's a bit messy): program Maqueprgrm; uses wincrt; type names=array [1..30]of string; var name:string; s1_nms:names; s2_nms:names; s3_nms:names; s4_nms:names; s5_nms:names; amt_paid:integer; stop,x,full,ins,ttl1,ttl2,ttl3,ttl4,ttl5,sec_1,sec_2,sec_3,sec_4,sec_5,sec:integer; begin stop := 0; writeln ('To Begin Data Collecting Section Press 1, To End Press 0'); readln(stop); while stop <0 do begin for x:= 1 to 30 do x:= x+1; writeln ('Please Enter The Name of Masquerader.'); readln (name); writeln ('Please Enter The Amount Paid For Costume.'); readln (amt_paid); IF amt_paid = 144 THEN Begin full:=full+1; {people who paid in full + 1} sec_1:=sec_1+1; {people in this section + 1} ttl1:= ttl1+amt_paid; {total money earned in this section + amount person paid} s1_nms[x]:= name; {People's names in this section plus current entry's name} End else IF amt_paid = 184 then Begin ins:=ins+1; sec_1:=sec_1+1; ttl1:=ttl1+amt_paid; s1_nms[x]:= name; end else IF amt_paid = 198 then Begin full:=full+1; sec_2:=sec_2+1; ttl2:=ttl2+amt_paid; s2_nms[x]:= 'name'; end else IF amt_paid = 153 then Begin ins:=ins+1; sec_2:=sec_2+1; ttl2:=ttl2+amt_paid; s2_nms[x]:= 'name'; end else IF amt_paid = 264 then Begin full:=full+1; sec_3:=sec_3+1; ttl3:=ttl3+amt_paid; s3_nms[x]:= 'name'; end else IF amt_paid = 322 then Begin ins:=ins+1; sec_3:=sec_3+1; ttl3:=ttl3+amt_paid; s3_nms[x]:= 'name'; end else IF amt_paid = 315 then Begin full:=full+1; sec_4:=sec_4+1; ttl4:=ttl4+amt_paid; s4_nms[x]:= 'name'; end else IF amt_paid = 402 then Begin ins:=ins+1; sec_4:=sec_4+1; ttl4:=ttl4+amt_paid; s4_nms[x]:= 'name'; end else IF amt_paid = 382. then Begin ins:=ins+1; sec_4:=sec_4+1; ttl4:=ttl4+amt_paid; s4_nms[x]:= 'name'; end else IF amt_paid = 488 then Begin ins:=ins+1; sec_5:=sec_5+1; ttl5:=ttl5+amt_paid; s5_nms[x]:= 'name'; end else begin Writeln ('Invalid Entry'); For x:= 1 to 30 do end; writeln (' To Enter More Data Press 1, To Print Data and Calculations Press 0'); Readln (stop); End; writeln ('For Information on Sections Press 1, 2, 3, 4, or 5 Respectively'); Readln (sec); IF Sec= 1 THEN Begin for x:= 1 to 30 do; begin writeln ('The Number of Revelers in This Section is ',Sec_1,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Full Is ', Full,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Installments is ', Ins ,'.'); Writeln ('The Names of Revelers in This Section is ', S1_Nms[x], '.'); Writeln ('The Total Amount Collected By This Section Is ', Ttl1, '.'); End; end else IF Sec= 2 THEN Begin For x:= 1 to 30 do begin Writeln ('The Number of Revelers in This Section is ', Sec_2,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Full Is ', Full,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Installments is ', Ins ,'.'); Writeln ('The Names of Revelers in This Section is ', S2_Nms[x] ,'.'); Writeln ('The Total Amount Collected By This Section Is ', Ttl2, '.'); End; End else IF Sec= 3 THEN Begin For x:= 1 to 30 do begin writeln ('The Number of Revelers in This Section is ', Sec_3,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Full Is ', Full,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Installments is ', Ins ,'.'); Writeln ('The Names of Revelers in This Section is ', S3_Nms[x] ,'.'); Writeln ('The Total Amount Collected By This Section Is ', Ttl3, '.'); End; End else IF Sec= 4 THEN Begin For x:= 1 to 30 do begin writeln ('The Number of Revelers in This Section is ', Sec_4,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Full Is ', Full,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Installments is ', Ins, '.'); Writeln ('The Names of Revelers in This Section is ', S4_Nms [x],'.'); Writeln ('The Total Amount Collected By This Section Is ', Ttl4 ,'.'); End; End else IF Sec= 5 THEN Begin For x:= 1 to 30 do begin writeln ('The Number of Revelers in This Section is ', Sec_5,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Full Is ', Full,'.'); Writeln ('The Number of Revelers in the Band Who Paid in Installments is ', Ins, '.'); Writeln ('The Names of Revelers in This Section is ', S5_Nms[x], '.'); Writeln ('The Total Amount Collected By This Section Is ', Ttl5 ,'.'); End; End else BEGIN Writeln ('Invalid Entry. For Information on Sections Press 1, 2, 3, 4, or 5 Respectively. '); End; end. The result I keep getting is that for the names in the section it is only the name of the last person entered that is displayed. For example it would display: The number of revelers in this section is 2 The number of revelers in the band who paid in full is 2 {Band is the whole thing divided into 5 section} The number of revelers in the band who paid in installments is 0 The names of revelers in this section is Amy Total amount collected by this section is 288 So yea, the program only displays "Amy" even though I entered more than 1 name. Do you guys know how to fix it also if it's not asking too much could you help me to make a while loop for the last portion of the program so that after the user sees the info for a section he can see another section. It sucks that I've been working on it for a while but if it doesn't run properly tomorrow I'll fail. Help would be greatly appreciated and responses are welcome anytime cause i'll be up anyway. P.S. Sorry for the long post.

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  • Haskell: How to compose `not` with a function of arbitrary arity?

    - by Hynek -Pichi- Vychodil
    When I have some function of type like f :: (Ord a) => a -> a -> Bool f a b = a > b I should like make function which wrap this function with not. e.g. make function like this g :: (Ord a) => a -> a -> Bool g a b = not $ f a b I can make combinator like n f = (\a -> \b -> not $ f a b) But I don't know how. *Main> let n f = (\a -> \b -> not $ f a b) n :: (t -> t1 -> Bool) -> t -> t1 -> Bool Main> :t n f n f :: (Ord t) => t -> t -> Bool *Main> let g = n f g :: () -> () -> Bool What am I doing wrong? And bonus question how I can do this for function with more and lest parameters e.g. t -> Bool t -> t1 -> Bool t -> t1 -> t2 -> Bool t -> t1 -> t2 -> t3 -> Bool

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  • How can I programmatically get the connection status of OSX network services?

    - by BigBrainz
    In the OS X System Preferences, when I click on 'Network' I see a green dot by 'Ethernet', and red dots by 'AirPort' and 'FireWire'. This is because I turned off AirPort and FireWire, as I access networks and the Internet via Ethernet. I need to programmatically determine which of these network services displayed in System Preferences have green dots and which have red dots. For Ethernet and FireWire the displayed status is 'Connected' or 'Not Connected', and for AirPort the displayed status is 'On' or 'Off'. Perhaps other network services have other status labels. I have picked through all the plist files in '/Library/Preferences/SystemConfiguration', particularly 'preferences.plist' and 'NetworkInterfaces.plist'. I can get all sorts of information there, such as the Location set, network service order, proxy information (which is also important to my task), but I cannot find how to determine whether a given network service is on or off--the equivalent of having the green dot displayed. I have also tried using System Configuration framework, specifically the SCNetworkConnectionGetStatus function, but all I get are invalid connection statuses. Does anyone know how to actually retrieve this connection status information? Thanks.

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  • Getting started with MIT Proto

    - by Charles
    MIT Proto lacks a basic getting started guide. How do I find a shell that accepts commands like (def foo...) and proto -n 1000 -l -m ...? http://groups.csail.mit.edu/stpg/proto.html I can run in my bash shell: ./proto -n 1000 -s 0.1 -T -l "(red (gradient (= (mid) 0)))" I can't figure out how to run e.g. channel.proto: (def channel (src dst width) (let* ((d (distance src dst)) (trail (<= (+ (gradient src) (gradient dst)) (+ d 0.01))) ;; float error ;; (trail (= (+ (gradient src) (gradient dst)) d)) ) (dilate trail width))) ;; To see a channel calculated from geometric primitives, run: ;; proto -n 1000 -l -m -s 0.5 "(blue (channel (sense 1) (sense 2) 10))" ;; click on a device and hit 't' to set up the source, then click on ;; another device and hit 'y' to designate the destination. At first ;; every device will be blue, but then it should clear and you should ;; see a thick blue path connecting the two devices you selected. Thanks! P.S. Somebody please tag this mit-proto. I can't.

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  • Python: Calling method A from class A within class B?

    - by Tommo
    There are a number of questions that are similar to this, but none of the answers hits the spot - so please bear with me. I am trying my hardest to learn OOP using Python, but i keep running into errors (like this one) which just make me think this is all pointless and it would be easier to just use methods. Here is my code: class TheGUI(wx.Frame): def __init__(self, title, size): wx.Frame.__init__(self, None, 1, title, size=size) # The GUI is made ... textbox.TextCtrl(panel1, 1, pos=(67,7), size=(150, 20)) button1.Bind(wx.EVT_BUTTON, self.button1Click) self.Show(True) def button1Click(self, event): #It needs to do the LoadThread function! class WebParser: def LoadThread(self, thread_id): #It needs to get the contents of textbox! TheGUI = TheGUI("Text RPG", (500,500)) TheParser = WebParser TheApp.MainLoop() So the problem i am having is that the GUI class needs to use a function that is in the WebParser class, and the WebParser class needs to get text from a textbox that exists in the GUI class. I know i could do this by passing the objects around as parameters, but that seems utterly pointless, there must be a more logical way to do this that doesn't using classes seem so pointless? Thanks in advance!

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  • Abstract over X

    - by Bruno Bieth
    Sorry for this english related question but I only came across that expression in the context of IT. What does abstracting over something mean ? For example abstracting over objects or abstracting over classes. Thanks

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  • Properly handling NSURLConnection errors

    - by Cal S
    Hi, I have a simple form interface set up that send username and password information to a server: (working) NSString *postData = [NSString stringWithFormat:@"user=%@&pass=%@",[self urlEncodeValue:sysUsername],[self urlEncodeValue:password]]; NSLog(@"Post data -> %@", postData); /// NSData* postVariables = [postData dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES]; NSMutableURLRequest* request = [[[NSMutableURLRequest alloc] init] autorelease]; NSString* postLength = [NSString stringWithFormat:@"%d", [postVariables length]]; NSURL* postUrl = [NSURL URLWithString:@"http://localhost/~csmith/cocoa/test.php"]; [request setURL:postUrl]; [request setHTTPMethod:@"POST"]; [request setValue:postLength forHTTPHeaderField:@"Content-Length"]; [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"]; [request setHTTPBody: postVariables]; NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:NULL error:NULL]; NSLog(@"Post data SENT & returned -> %@", returnData); How do I handle connection errors such as no internet connection, firewall, etc. Also, does this method use the system-wide proxy settings? Many of my users are behind a proxy. Thanks a lot!

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  • Capture IP packets on Dialup connection - Windows 7

    - by Assaf Levy
    Our product utilizes (the wonderful) Winpcap to capture ip packets from all devices with an IP address and analyze them in real time. Unfortunately, we discovered that it does NOT capture any packets on dialup (e.g. PPP) connections on Windows 7, and that there are no near-term plans for enabling this (1). So we need something else. Microsoft Network Monitor and Windows Packet Filter are two options that surfaced during a bit of googling, but before delving into research I wanted to ask the experienced: what are out options, given the following requirements: Capture all in/outbound IP packets on the machine. Complete background processing - no UI should be involved. Support Windows Vista / 7. Performance (user should not feel the difference). Thanks in advance.

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  • how to access child instances in a vector in c++

    - by tsubasa
    I have a parent class and child class (inherited from parent). In the child class, I have a member function named function_blah(); I used vector<parent*> A to store 5 parent instances, 3 child instances. So the total number of elements in the vector is 8. I can easily access to member functions of element A[0] to A[4], which are parent instances. But whenever I try to have access to member functions of element A[5] to A[7], the compiler complains that class parent has no member named 'function_blah' The way I access to elements is using index. e.x A[i] with i = 0..7. Is it correct? if not, how?

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  • WCF or Sockets for Communication in a real-time environment?

    - by PieterG
    I have a scenario where I need to send a series of data across 2 clients. The data includes Serialized XML that will contain commands that the other client will need to react to. I will also need to send images across the wire as I need to provide a chat facility in the form of video/audio chat. I would like a single communication medium for both, as the number of messages/commands might be a few. WCF or Sockets?

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  • How do I have my apps dialog box pop up and take focus from the current running app?

    - by simba
    I know this type of thing is looked negatively upon but I write software for people with disabilities and sometimes good gui practices don't make sense. In this case, the user interacts with a assistive interface and under certain conditions, my control app needs to prompt the user with a question. My background process creates a dialog (I'm using wxwidgets wxDialog class) and calls Show(). The dialog box appears but it does not have focus (the application that the user was previously using keeps it). Since my users can't use mice, they can't simply click on the window. I've tried calling show and then followed by SetFocus(HWND) but that doesn't do it. What's the problem? Is this even possible? Window7. I'm thinking that it might have something to do with it being a dialog and not a full window (wxFrame). Any help is greatly appreciated.

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  • CSS Brace Styles

    - by Nimbuz
    I'm unable to figure how the standard (or just popular) brace style names apply to CSS. Here're all the brace styles: /* one - pico? */ selector { property: value; property: value; } /* two */ selector { property: value; /* declaration starts on newline */ property: value; } /* three */ selector { property: value; property: value; } /* four - Allman or GNU?*/ selector { property: value; /* declaration starts on newline */ property: value; }? /* five */ selector { property: value; property: value; } /* six - horstmann? */ selector { property: value; /* declaration starts on newline */ property: value; } /* seven - banner?*/ selector { property: value; property: value; } /* eight */ selector { property: value; /* declaration starts on newline */ property: value; } Can someone please name each brace style for me? Many thanks!

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  • When machine code is generated from a program how does it translates to hardware level operations ??

    - by user553492
    Like if say the instruction is something like 100010101 1010101 01010101 011101010101. Now how is this translating to an actual job of deleting something from memory? Memory consists of actual physical transistors the HOLD data. What causes them to lose that data is some external signal? I want to know how that signal is generated. Like how some binary numbers change the state of a physical transistor. Is there a level beyond machine code that isn't explicitly visible to a programmer? I have heard of microcode that handle code at hardware level, even below assembly language. But still I pretty much don't understand. Thanks!

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  • Why does Ordered[A] use a compare method instead of reusing compareTo?

    - by soc
    trait Ordered[A] extends java.lang.Comparable[A] { def compare(that: A): Int def < (that: A): Boolean = (this compare that) < 0 def > (that: A): Boolean = (this compare that) > 0 def <= (that: A): Boolean = (this compare that) <= 0 def >= (that: A): Boolean = (this compare that) >= 0 def compareTo(that: A): Int = compare(that) } Isn't it a bit useless to have both compare and compareTo? What is the huge benefit I'm missing here? If they had just used compareTo I could just had replaced Comparable with Ordered in my code and be done.

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  • SQL finding overlapping of times pass midnight (across 2 days)

    - by janechii
    Hi everyone, I know there are lots of these types of questions, but i didn't see one that was similar enough to my criteria. So i'd like to ask for your help please. The fields i have are just start and end which are of time types. I cannot involve any specific dates in this. If the time ranges don't go pass midnight across day, i'd just compare two tuples as such: end1 > start2 AND start1 < end2 (end points touching are not considered overlapped here.) But when I involve time range that pass (or at) midnight, this obviously doesn't work. For example, given: start | end --------+-------- 06:00PM | 01:00AM 03:00PM | 09:00PM Without involving dates, how can i achieve this, please. My assumption is, if end is less than start, then we're involving 2 days. I'm trying to do this in plain standard SQL, so just a simple and concise logic in the WHERE clause. Thank you everyone!

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