[EINVAL] different mutexes for concurrent waits.
[EINVAL] mutex is not owned by calling thread.
Mutex is always unlocked (before wait) and relocked (after wait)
inside pthread_cond_timedwait, even if the wait fails, times out, or
is canceled.
pthread_cond_wait
int pthread_cond_wait ( pthread_cond_t pthread_mutex_t
*cond, *mutex);
Wait on condition variable cond, until awakened by a signal or broadcast.
References: 3.3, 5.2.2 Headers: <pthread.h>
Errors: [EINVAL] cond or mutex is invalid.
[EINVAL] different mutexes for concurrent waits. [EINVAL] mutex is not owned by calling thread.
Hint: Mutex is always unlocked (before wait) and relocked (after wait) in-
side pthread_cond_wait, even if the wait fails or is canceled.
9.3.6 Cancellation
Cancellation provides a way to request that a thread terminate 'gracefully' when you no longer need it to complete its normal execution. Each thread can control how and whether cancellation affects it, and can repair the shared state as it terminates due to cancellation.
pthread_cancel
int pthread_cancel (
pthread_t thread);
Requests that thread be canceled.
References: 5.3 Headers: <pthread.h>
Errors: [ESRCH] no thread found corresponding to thread.
Hint: Cancellation is asynchronous. Use pthread_join to wait for termi-
nation of thread if necessary.
pthread_cleanup_pop
void pthread_cleanup_pop (int execute);
Pop the most recently pushed cleanup handler. Invoke the cleanup handler if execute is nonzero.
References: 5.3 Headers: <pthread.h>
Hint: Specify execute as nonzero to avoid duplication of common cleanup
code.
pthread_cleanup_push
void pthread_cleanup_push (
void (*routine)(void *),
void *arg);
Push a new cleanup handler onto the thread's stack of cleanup handlers. Invoke the cleanup handler if execute is nonzero. Each cleanup handler pushed onto the stack is popped and invoked with the argument arg when the thread exits by calling pthread_exit, when the thread acts on a cancellation request, or when the thread calls pthread_cleanup_pop with a nonzero execute argument.
References: 5.3 Headers: <pthread.h>
Hint: pthread_cleanup_push and pthread_cleanup_pop must be paired
in the same lexical scope.
pthread_setcancelstate
int pthread_setcancelstate (
int state,
int *oldstate);
Atomically set the calling thread's cancelability state to state and return the previous cancelability state at the location referenced by oldstate.
state, oldstate
PTHREAD_CANCEL_ENABLE
Cancellation is enabled.
PTHREAD_CANCEL_DISABLE
Cancellatlon is disabled.
References: 5.3
Headers: <pthread.h>
Errors: [EINVAL]stateisinvalid.
Hint: Use to disable cancellation around 'atomic' code that includes can-
cellation points.
pthread_setcanceltype
int pthread_setcanceltype (
int type,
int *oldtype);
Atomically set the calling thread's cancelability type to type and return the previous cancelability type at the location referenced by oldtype.
type, oldtype
PTHREAD_CANCEL_DEFERRED
Only deferred cancellation is allowed.
PTHREAD_CANCEL_ASYNCHRONOUS Asynchronous cancellation is
allowed.
References: 5.3
Headers: <pthread.h>
Errors: [EINVAL] type is invalid.
Hint: Use with caution — most code is not safe for use with asynchronous
cancelability type.
pthread_testcancel
void pthread_testcancel (void);
Creates a deferred cancellation point in the calling thread. The call has no effect if the current cancelability state is PTHREAD_CANCEL_DISABLE.
References: 5.3 Headers: <pthread.h>
Hint: Cancellation is asynchronous. Use pthread_join to wait for termi-
nation of thread if necessary.
9.3.7 Thread-specific data
Thread-specific data provides a way to declare variables that have a common 'name' in all threads, but a unique value in each thread. You should consider using thread-speciflc data in a threaded program in many cases where a non-threaded program would use 'static' data. When the static data maintains context across a series of calls to some function, for example, the context should generally be thread-specific. (If not, the static data must be protected by a mutex.)
pthread_getspecific
void *pthread_getspecific (
pthread_key_t key);
