[Freeswitch-dev] What is the purpose of BLOCK in switch_event.c
zhangkai.fswitch at gmail.com
Sun Jul 22 05:37:55 MSD 2012
Recently I read the codes in switch_event.c, and I am confused about the
purpose of BLOCK.
There are 2 locks defined in switch_event.c:
static switch_mutex_t *BLOCK = NULL;
static switch_thread_rwlock_t *RWLOCK = NULL;
My understanding is the RWLOCK is wrlocked when binding or unbinding an
event callback function, and rdlocked when executing the callback. So
the RWLOCK is enough to protect multi-threads from modifying the event
binding list at the same time, why we need another mutex BLOCK?
And in the codes, when never the mutex BLOCK is requested to be locked,
the RWLOCK must already be locked for write. like this:
So if BLOCK is mean to protect something, the RWLOCK is already
guaranteed the exclusiveness.
Please tell me if I am wrong.
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