Struct
GLibMutex
Description [src]
union GMutex {
/* No available fields */
}
The GMutex struct is an opaque data structure to represent a mutex
(mutual exclusion). It can be used to protect data against shared access.
Take for example the following function:
int
give_me_next_number (void)
{
static int current_number = 0;
// now do a very complicated calculation to calculate the new
// number, this might for example be a random number generator
current_number = calc_next_number (current_number);
return current_number;
}
It is easy to see that this won’t work in a multi-threaded
application. There current_number must be protected against shared
access. A GMutex can be used as a solution to this problem:
int
give_me_next_number (void)
{
static GMutex mutex;
static int current_number = 0;
int ret_val;
g_mutex_lock (&mutex);
ret_val = current_number = calc_next_number (current_number);
g_mutex_unlock (&mutex);
return ret_val;
}
Notice that the GMutex is not initialised to any particular value.
Its placement in static storage ensures that it will be initialised
to all-zeros, which is appropriate.
If a GMutex is placed in other contexts (eg: embedded in a struct)
then it must be explicitly initialised using g_mutex_init().
A GMutex should only be accessed via g_mutex_ functions.
Instance methods
g_mutex_lock
Locks mutex. If mutex is already locked by another thread, the
current thread will block until mutex is unlocked by the other thread.
g_mutex_trylock
Tries to lock mutex. If mutex is already locked by another thread,
it immediately returns FALSE. Otherwise it locks mutex and returns
TRUE.
g_mutex_unlock
Unlocks mutex. If another thread is blocked in a g_mutex_lock()
call for mutex, it will become unblocked and can lock mutex itself.