Re: WaitForSingleObject

"Larry" <>
Thu, 28 Jan 2010 15:28:15 +0100
"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp> ha scritto nel messaggio

No, use CRITICAL_SECTION. It has less overhead.

After initializing it (InitializeCriticalSection(&cs)), surround all
accesses to data shared between threads like this:

...access or change shared data

The first statement suspends the calling thread if another thread is
"inside" a similar code block. When the other thread does the Leave..,.
call the first thread is allowed to proceed.

Ok! I am going to need a little help from you's a typical
scenario of my app:

// Buffer structs "circular"

struct buffer
    unsigned char data[1024]; // binary data container
    int bytesRecorded; // bytes actually written (to read)
    int flag; // Empty/filled (enum)
    buffer(...); // constructor()

struct circular
    circular_buffer<buffer> cb; // Cicular buffer based on "buffer"

// Global maps

map<int, circular> users;
map<int, circular>::iterator uit;
map<int, HANDLE> eventi;

int main()
 // TODO: launch Producer thread.

 // TODO: Set up server and accept incoming
 // requests. Each time a client connects
 // spawn a new Consumer thread

 return 0; // never for the moment!

// Thread Consumer is launched
// anytime a client conencts.

thread Consumer
 int threadid = (int)GetCurrentThreadId();

     // Create event & push it in the "eventi" map
     HANDLE hevent = CreateEvent(NULL,0,0,NULL);
     eventi.insert(make_pair(threadid, hevent));

 // Prepare & add circular buffer to the "users" map
     circular c;
 users.insert(make_pair(threadid, c));

 // Loop...
  // Callback event
  WaitForSingleObject(eventi[threadid], INFINITE);

  // TODO: read buffer from "users" map
  // and send it to the client. If the
  // client disconnect break the while loop

  // Close & remove event from event map

 // Remove buffer from the map

 return 0;

// Thread Producer is launched
// once. Its main goal is to write
// the same data to all the Consumer
// threads.

thread Producer
  // TODO: write on every
  // element of map "users"
  for(uit=users.begin(); uit!=users.end(); ++uit)

   // Signal event in the Cosumer
   // thread (buffer written).
 return 0;


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