pthread_cond_wait isn't doing what I'm expecting

Question

I am trying to use pthread_cond_wait in the way I think it should be used. I use it in a method, that is waiting for something to change, and when it does it will call another method to get the data. it looks like below:

void waitForSomething(const std::string& _str) {

    //lock my mutex here

     while (!ifStringInSomeCollection(_str)) {
             std::cout << "waiting.." << std::endl;
             pthread_cond_wait(&_condMutex, &_myMutex);
     }
     //unlock my mutex here

     //this method also acquires my mutex lock
     std::cout << getData(_str) << std::endl;
}

Now in my other method that will break the condition and broadcast/signal the waiting condition, I first unlock the mutex before broadcasting/signalling - so that should not be an issue.

But even without that, what currently happens is, it constantly checks for condition in the while loop instead of pthread_cond_wait - actually waiting. I've been stuck with this for a while, any ideas would be much appreciated. Thanks!

==================

Following discussion, I wrote the following to test, to get the condition to wait in a test situation. I still get repeated "locked" message. I must be doing something wrong? http://ideone.com/eVuKEC

#include<pthread.h>
#include <iostream>

pthread_mutex_t mutex;
pthread_cond_t cond;
bool something;

void test() {
   pthread_mutex_lock(&mutex);
   while(!something) {
      std::cout <<"locked" << std::endl;
      pthread_cond_wait(&cond,&mutex);
   }
   pthread_mutex_unlock(&mutex);
}

int main(){
   pthread_mutex_init(&mutex, NULL);
   pthread_cond_init(&cond, NULL);  
   something=false;  
   test();
   return 0;
}

Answer 1

Compile with the -pthread option to g++