mirror of
https://github.com/libevent/libevent.git
synced 2025-01-31 09:12:55 +08:00
76cd2b70bb
Previously, our default lock model kind of assumed that every lock was potentially a read-write lock. This was a poor choice, since read-write locks are far more expensive than regular locks, and so the lock API should only use them when we can actually take advantage of them. Neither our pthreads or win32 lock implementation provided rw locks. Now that we have a way (not currently used!) to indicate that we really want a read-write lock, we shouldn't actually say "lock this for reading" or "lock this for writing" unless we mean it.
154 lines
5.6 KiB
C
154 lines
5.6 KiB
C
/*
|
|
* Copyright (c) 2008-2009 Niels Provos, Nick Mathewson
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. The name of the author may not be used to endorse or promote products
|
|
* derived from this software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
#ifndef _EVTHREAD_INTERNAL_H_
|
|
#define _EVTHREAD_INTERNAL_H_
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
#include "event-config.h"
|
|
#include "util-internal.h"
|
|
|
|
struct event_base;
|
|
|
|
#ifndef _EVENT_DISABLE_THREAD_SUPPORT
|
|
/* Global function pointers to lock-related functions. NULL if locking isn't
|
|
enabled. */
|
|
extern struct evthread_lock_callbacks _evthread_lock_fns;
|
|
extern unsigned long (*_evthread_id_fn)(void);
|
|
|
|
/** True iff the given event_base is set up to use locking */
|
|
#define EVBASE_USING_LOCKS(base) \
|
|
(base != NULL && (base)->th_base_lock != NULL)
|
|
|
|
/** Return the ID of the current thread, or 1 if threading isn't enabled. */
|
|
#define EVTHREAD_GET_ID() \
|
|
(_evthread_id_fn ? _evthread_id_fn() : 1)
|
|
|
|
/** Return true iff we're in the thread that is currently running a given
|
|
* event_base's loop. */
|
|
#define EVBASE_IN_THREAD(base) \
|
|
(_evthread_id_fn == NULL || \
|
|
(base)->th_owner_id == _evthread_id_fn())
|
|
|
|
/** Allocate a new lock, and store it in lockvar, a void*. Sets lockvar to
|
|
NULL if locking is not enabled. */
|
|
#define EVTHREAD_ALLOC_LOCK(lockvar, locktype) \
|
|
((lockvar) = _evthread_lock_fns.alloc ? \
|
|
_evthread_lock_fns.alloc(locktype) : NULL)
|
|
|
|
/** Free a given lock, if it is present and locking is enabled. */
|
|
#define EVTHREAD_FREE_LOCK(lockvar, locktype) \
|
|
do { \
|
|
void *_lock_tmp_ = (lockvar); \
|
|
if (_lock_tmp_ && _evthread_lock_fns.free) \
|
|
_evthread_lock_fns.free(_lock_tmp_, (locktype)); \
|
|
} while (0)
|
|
|
|
/** Acquire a lock. */
|
|
#define EVLOCK_LOCK(lockvar,mode) \
|
|
do { \
|
|
if (lockvar) \
|
|
_evthread_lock_fns.lock(mode, lockvar); \
|
|
} while (0)
|
|
|
|
/** Release a lock */
|
|
#define EVLOCK_UNLOCK(lockvar,mode) \
|
|
do { \
|
|
if (lockvar) \
|
|
_evthread_lock_fns.unlock(mode, lockvar); \
|
|
} while (0)
|
|
|
|
/** Helper: put lockvar1 and lockvar2 into pointerwise ascending order. */
|
|
#define _EVLOCK_SORTLOCKS(lockvar1, lockvar2) \
|
|
do { \
|
|
if (lockvar1 && lockvar2 && lockvar1 > lockvar2) { \
|
|
void *tmp = lockvar1; \
|
|
lockvar1 = lockvar2; \
|
|
lockvar2 = tmp; \
|
|
} \
|
|
} while (0)
|
|
|
|
/** Acquire both lock1 and lock2. Always allocates locks in the same order,
|
|
* so that two threads locking two locks with LOCK2 will not deadlock. */
|
|
#define EVLOCK_LOCK2(lock1,lock2,mode1,mode2) \
|
|
do { \
|
|
void *_lock1_tmplock = (lock1); \
|
|
void *_lock2_tmplock = (lock2); \
|
|
_EVLOCK_SORTLOCKS(_lock1_tmplock,_lock2_tmplock); \
|
|
EVLOCK_LOCK(_lock1_tmplock,mode1); \
|
|
if (_lock2_tmplock != _lock1_tmplock) \
|
|
EVLOCK_LOCK(_lock2_tmplock,mode2); \
|
|
} while (0)
|
|
|
|
/** Release both lock1 and lock2. */
|
|
#define EVLOCK_UNLOCK2(lock1,lock2,mode1,mode2) \
|
|
do { \
|
|
void *_lock1_tmplock = (lock1); \
|
|
void *_lock2_tmplock = (lock2); \
|
|
_EVLOCK_SORTLOCKS(_lock1_tmplock,_lock2_tmplock); \
|
|
if (_lock2_tmplock != _lock1_tmplock) \
|
|
EVLOCK_UNLOCK(_lock2_tmplock,mode2); \
|
|
EVLOCK_UNLOCK(_lock1_tmplock,mode1); \
|
|
} while (0)
|
|
|
|
|
|
/** Lock an event_base, if it is set up for locking. Acquires the lock
|
|
in the base structure whose field is named 'lockvar'. */
|
|
#define EVBASE_ACQUIRE_LOCK(base, lockvar) do { \
|
|
if (EVBASE_USING_LOCKS(base)) \
|
|
_evthread_lock_fns.lock(0, (base)->lockvar); \
|
|
} while (0)
|
|
|
|
/** Unlock an event_base, if it is set up for locking. */
|
|
#define EVBASE_RELEASE_LOCK(base, lockvar) do { \
|
|
if (EVBASE_USING_LOCKS(base)) \
|
|
_evthread_lock_fns.unlock(0, (base)->lockvar); \
|
|
} while (0)
|
|
#else /* _EVENT_DISABLE_THREAD_SUPPORT */
|
|
|
|
#define EVTHREAD_GET_ID() 1
|
|
#define EVTHREAD_ALLOC_LOCK(lockvar, locktype) _EVUTIL_NIL_STMT
|
|
#define EVTHREAD_FREE_LOCK(lockvar, locktype) _EVUTIL_NIL_STMT
|
|
|
|
#define EVLOCK_LOCK(lockvar, mode) _EVUTIL_NIL_STMT
|
|
#define EVLOCK_UNLOCK(lockvar, mode) _EVUTIL_NIL_STMT
|
|
#define EVLOCK_LOCK2(lock1,lock2,mode1,mode2) _EVUTIL_NIL_STMT
|
|
#define EVLOCK_UNLOCK2(lock1,lock2,mode1,mode2) _EVUTIL_NIL_STMT
|
|
|
|
#define EVBASE_IN_THREAD(base) 1
|
|
#define EVBASE_ACQUIRE_LOCK(base, lock) _EVUTIL_NIL_STMT
|
|
#define EVBASE_RELEASE_LOCK(base, lock) _EVUTIL_NIL_STMT
|
|
|
|
#endif
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* _EVTHREAD_INTERNAL_H_ */
|