sc/condition/README.md

# Condition

#### Overview

- Condition wrapper.
- Provides passing data between signal and wait threads.
- Normally, if no thread waits on a condition, signal is missed. This  
  implementation differs as it will keep a result variable when 'signal' is  
  called. Signal will mark the condition 'done', so when another thread calls  
  wait(), it won't be blocked, it will return immediately with the user  
  provided data.
- Conditions can be problematic if you are looking for performance. E.g :
  - Thread A calls wait()
  - Thread B locks the mutex and calls signal() and just before it calls   
    mutex unlock(), Thread A wakes up and sees mutex is still locked so it goes  
    back to sleep.
  - So, this implementation provides 'async wait()' semantics, 'wait  
    thread2 can call wait() later, even after signal thread completes its job.
    


##### Usage

```c
#include "sc_cond.h"

#include <stdio.h>

int main()
{
    struct sc_cond cond;

    sc_cond_init(&cond);
    sc_cond_signal(&cond, "test"); // Call this on thread-1
    char* p = sc_cond_wait(&cond); // Call this on another thread.

    printf("%s \n", p);

    return 0;
}
```