text: /*
   * Copyright (c) 2008-2010 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 <event2/thread.h>
  #include "event2/event-config.h"
  #include "util-internal.h"
  
  struct event_base;
  
  #ifndef WIN32
  /* On Windows, the way we currently make DLLs, it's not allowed for us to
   * have shared global structures.  Thus, we only do the direct-call-to-function
   * code path if we know that the local shared library system supports it.
   */
  #define EVTHREAD_EXPOSE_STRUCTS
  #endif
  
  #if ! defined(_EVENT_DISABLE_THREAD_SUPPORT) && defined(EVTHREAD_EXPOSE_STRUCTS)
  /* Global function pointers to lock-related functions. NULL if locking isn't
     enabled. */
  extern struct evthread_lock_callbacks _evthread_lock_fns;
  extern struct evthread_condition_callbacks _evthread_cond_fns;
  extern unsigned long (*_evthread_id_fn)(void);
  extern int _evthread_lock_debugging_enabled;
  
  /** 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 (or most recently)
   * running a given event_base's loop. Requires lock. */
  #define EVBASE_IN_THREAD(base)				 \
  	(_evthread_id_fn == NULL ||			 \
  	(base)->th_owner_id == _evthread_id_fn())
  
  /** Return true iff we need to notify the base's main thread about changes to
   * its state, because it's currently running the main loop in another
   * thread. Requires lock. */
  #define EVBASE_NEED_NOTIFY(base)			 \
  	(_evthread_id_fn != NULL &&			 \
  	    (base)->running_loop &&			 \
  	    (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)
  
  /** 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 {				\
  		EVLOCK_LOCK((base)->lockvar, 0);			\
  	} while (0)
  
  /** Unlock an event_base, if it is set up for locking. */
  #define EVBASE_RELEASE_LOCK(base, lockvar) do {				\
  		EVLOCK_UNLOCK((base)->lockvar, 0);			\
  	} while (0)
  
  /** If lock debugging is enabled, and lock is non-null, assert that 'lock' is
   * locked and held by us. */
  #define EVLOCK_ASSERT_LOCKED(lock)					\
  	do {								\
  		if ((lock) && _evthread_lock_debugging_enabled) {	\
  			EVUTIL_ASSERT(_evthread_is_debug_lock_held(lock)); \
  		}							\
  	} while (0)
  
  /** Try to grab the lock for 'lockvar' without blocking, and return 1 if we
   * manage to get it. */
  static inline int EVLOCK_TRY_LOCK(void *lock);
  static inline int
  EVLOCK_TRY_LOCK(void *lock)
  {
  	if (lock && _evthread_lock_fns.lock) {
  		int r = _evthread_lock_fns.lock(EVTHREAD_TRY, lock);
  		return !r;
  	} else {
  		/* Locking is disabled either globally or for this thing;
  		 * of course we count as having the lock. */
  		return 1;
  	}
  }
  
  /** Allocate a new condition variable and store it in the void *, condvar */
  #define EVTHREAD_ALLOC_COND(condvar)					\
  	do {								\
  		(condvar) = _evthread_cond_fns.alloc_condition ?	\
  		    _evthread_cond_fns.alloc_condition(0) : NULL;	\
  	} while (0)
  /** Deallocate and free a condition variable in condvar */
  #define EVTHREAD_FREE_COND(cond)					\
  	do {								\
  		if (cond)						\
  			_evthread_cond_fns.free_condition((cond));	\
  	} while (0)
  /** Signal one thread waiting on cond */
  #define EVTHREAD_COND_SIGNAL(cond)					\
  	( (cond) ? _evthread_cond_fns.signal_condition((cond), 0) : 0 )
  /** Signal all threads waiting on cond */
  #define EVTHREAD_COND_BROADCAST(cond)					\
  	( (cond) ? _evthread_cond_fns.signal_condition((cond), 1) : 0 )
  /** Wait until the condition 'cond' is signalled.  Must be called while
   * holding 'lock'.  The lock will be released until the condition is
   * signalled, at which point it will be acquired again.  Returns 0 for
   * success, -1 for failure. */
  #define EVTHREAD_COND_WAIT(cond, lock)					\
  	( (cond) ? _evthread_cond_fns.wait_condition((cond), (lock), NULL) : 0 )
  /** As EVTHREAD_COND_WAIT, but gives up after 'tv' has elapsed.  Returns 1
   * on timeout. */
  #define EVTHREAD_COND_WAIT_TIMED(cond, lock, tv)			\
  	( (cond) ? _evthread_cond_fns.wait_condition((cond), (lock), (tv)) : 0 )
  
  #elif ! defined(_EVENT_DISABLE_THREAD_SUPPORT)
  
  unsigned long _evthreadimpl_get_id(void);
  int _evthreadimpl_is_lock_debugging_enabled(void);
  void *_evthreadimpl_lock_alloc(unsigned locktype);
  void _evthreadimpl_lock_free(void *lock, unsigned locktype);
  int _evthreadimpl_lock_lock(unsigned mode, void *lock);
  int _evthreadimpl_lock_unlock(unsigned mode, void *lock);
  void *_evthreadimpl_cond_alloc(unsigned condtype);
  void _evthreadimpl_cond_free(void *cond);
  int _evthreadimpl_cond_signal(void *cond, int broadcast);
  int _evthreadimpl_cond_wait(void *cond, void *lock, const struct timeval *tv);
  
  #define EVTHREAD_GET_ID() _evthreadimpl_get_id()
  #define EVBASE_IN_THREAD(base)				\
  	((base)->th_owner_id == _evthreadimpl_get_id())
  #define EVBASE_NEED_NOTIFY(base)			 \
  	((base)->running_loop &&			 \
  	    ((base)->th_owner_id != _evthreadimpl_get_id()))
  
  #define EVTHREAD_ALLOC_LOCK(lockvar, locktype)		\
  	((lockvar) = _evthreadimpl_lock_alloc(locktype))
  
  #define EVTHREAD_FREE_LOCK(lockvar, locktype)				\
  	do {								\
  		void *_lock_tmp_ = (lockvar);				\
  		if (_lock_tmp_)						\
  			_evthreadimpl_lock_free(_lock_tmp_, (locktype)); \
  	} while (0)
  
  /** Acquire a lock. */
  #define EVLOCK_LOCK(lockvar,mode)					\
  	do {								\
  		if (lockvar)						\
  			_evthreadimpl_lock_lock(mode, lockvar);		\
  	} while (0)
  
  /** Release a lock */
  #define EVLOCK_UNLOCK(lockvar,mode)					\
  	do {								\
  		if (lockvar)						\
  			_evthreadimpl_lock_unlock(mode, lockvar);	\
  	} 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 {				\
  		EVLOCK_LOCK((base)->lockvar, 0);			\
  	} while (0)
  
  /** Unlock an event_base, if it is set up for locking. */
  #define EVBASE_RELEASE_LOCK(base, lockvar) do {				\
  		EVLOCK_UNLOCK((base)->lockvar, 0);			\
  	} while (0)
  
  /** If lock debugging is enabled, and lock is non-null, assert that 'lock' is
   * locked and held by us. */
  #define EVLOCK_ASSERT_LOCKED(lock)					\
  	do {								\
  		if ((lock) && _evthreadimpl_is_lock_debugging_enabled()) { \
  			EVUTIL_ASSERT(_evthread_is_debug_lock_held(lock)); \
  		}							\
  	} while (0)
  
  /** Try to grab the lock for 'lockvar' without blocking, and return 1 if we
   * manage to get it. */
  static inline int EVLOCK_TRY_LOCK(void *lock);
  static inline int
  EVLOCK_TRY_LOCK(void *lock)
  {
  	if (lock) {
  		int r = _evthreadimpl_lock_lock(EVTHREAD_TRY, lock);
  		return !r;
  	} else {
  		/* Locking is disabled either globally or for this thing;
  		 * of course we count as having the lock. */
  		return 1;
  	}
  }
  
  /** Allocate a new condition variable and store it in the void *, condvar */
  #define EVTHREAD_ALLOC_COND(condvar)					\
  	do {								\
  		(condvar) = _evthreadimpl_cond_alloc(0);		\
  	} while (0)
  /** Deallocate and free a condition variable in condvar */
  #define EVTHREAD_FREE_COND(cond)					\
  	do {								\
  		if (cond)						\
  			_evthreadimpl_cond_free((cond));		\
  	} while (0)
  /** Signal one thread waiting on cond */
  #define EVTHREAD_COND_SIGNAL(cond)					\
  	( (cond) ? _evthreadimpl_cond_signal((cond), 0) : 0 )
  /** Signal all threads waiting on cond */
  #define EVTHREAD_COND_BROADCAST(cond)					\
  	( (cond) ? _evthreadimpl_cond_signal((cond), 1) : 0 )
  /** Wait until the condition 'cond' is signalled.  Must be called while
   * holding 'lock'.  The lock will be released until the condition is
   * signalled, at which point it will be acquired again.  Returns 0 for
   * success, -1 for failure. */
  #define EVTHREAD_COND_WAIT(cond, lock)					\
  	( (cond) ? _evthreadimpl_cond_wait((cond), (lock), NULL) : 0 )
  /** As EVTHREAD_COND_WAIT, but gives up after 'tv' has elapsed.  Returns 1
   * on timeout. */
  #define EVTHREAD_COND_WAIT_TIMED(cond, lock, tv)			\
  	( (cond) ? _evthreadimpl_cond_wait((cond), (lock), (tv)) : 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_NEED_NOTIFY(base) 0
  #define EVBASE_ACQUIRE_LOCK(base, lock) _EVUTIL_NIL_STMT
  #define EVBASE_RELEASE_LOCK(base, lock) _EVUTIL_NIL_STMT
  #define EVLOCK_ASSERT_LOCKED(lock) _EVUTIL_NIL_STMT
  
  #define EVLOCK_TRY_LOCK(lock) 1
  
  #define EVTHREAD_ALLOC_COND(condvar) _EVUTIL_NIL_STMT
  #define EVTHREAD_FREE_COND(cond) _EVUTIL_NIL_STMT
  #define EVTHREAD_COND_SIGNAL(cond) _EVUTIL_NIL_STMT
  #define EVTHREAD_COND_BROADCAST(cond) _EVUTIL_NIL_STMT
  #define EVTHREAD_COND_WAIT(cond, lock) _EVUTIL_NIL_STMT
  #define EVTHREAD_COND_WAIT_TIMED(cond, lock, howlong) _EVUTIL_NIL_STMT
  
  #endif
  
  /* This code is shared between both lock impls */
  #if ! defined(_EVENT_DISABLE_THREAD_SUPPORT)
  /** 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)
  
  int _evthread_is_debug_lock_held(void *lock);
  void *_evthread_debug_get_real_lock(void *lock);
  #endif
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* _EVTHREAD_INTERNAL_H_ */
  