p99_rwl Struct Reference

A simple rwlock implementation. More...

#include <p99_rwl.h>

Related Functions
(Note that these are not member functions.)
bool	p99_rwl_haswaiters (p99_rwl volatile *p00_r)
	Tell if has waiters. More...
bool	p99_rwl_islocked (p99_rwl volatile *p00_r)
	Tell if is locked. More...
int	p99_rwl_rdlock (p99_rwl volatile *p00_r)
	establish a shared lock for rwlock p00_c. More...
int	p99_rwl_unlock (p99_rwl volatile *p00_r)
	release a lock on rwlock p00_r. More...
int	p99_rwl_wrlock (p99_rwl volatile *p00_r)
	establish an exclusive lock for rwlock p00_r. More...

Detailed Description

A simple rwlock implementation.

This is implemented more or less efficiently according to the features that the platform provides:

• one that uses atomic operations and futexes for signaling
• one that mutexes all access and uses a condition variable for signaling.

It has the following properties:

• A lock that is obtained is not bound to a specific thread, any thread may unlock it.
• If there is a rdlock that is hold, any thread may call p99_rwl_rdlock, again, on the same object. It is the responsibility of the application to ensure that p99_rwl_unlock is called as many times as it has been locked.
• If a wrlock is hold, nobody, the holding thread including, will be blocked when calling p99_rwl_rdlock or p99_rwl_wrlock.

As a consequence, this form of lock can be easily cleaned up if a thread has left it locked and then walked away:

p99_rwl rwl = P99_RWL_INITIALIZER;
 
while (p99_rwl_islocked(&rwl))
      p99_rwl_unlock(&rwl);

This takes care of all situations where no other thread actively is trying to achieve the lock.

Definition at line 66 of file p99_rwl.h.

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The documentation for this struct was generated from the following file:

• p99_rwl.h