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32c6f1bacd
Previously we were using InitializeCriticalSection, which creates a lock that blocks immediately on contention and waits to be rescheduled. This is inefficient; it's better to wait for a little while before telling the US to reschedule us, in case the lock becomes available again really soon (since most locks mostly do). Good pthreads implementations do this automatically. On Windows, though, we need to call this magic function, and we need to pick the spin count ourselves.
107 lines
2.9 KiB
C
107 lines
2.9 KiB
C
/*
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* Copyright 2009 Niels Provos and Nick Mathewson
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "event-config.h"
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#ifdef WIN32
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#include <winsock2.h>
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#define WIN32_LEAN_AND_MEAN
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#include <windows.h>
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#undef WIN32_LEAN_AND_MEAN
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#include <sys/locking.h>
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#endif
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struct event_base;
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#include <event2/thread.h>
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#include "mm-internal.h"
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#define SPIN_COUNT 2000
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static void *
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evthread_win32_lock_create(unsigned locktype)
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{
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CRITICAL_SECTION *lock = mm_malloc(sizeof(CRITICAL_SECTION));
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if (!lock)
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return NULL;
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if (InitializeCriticalSectionAndSpinCount(lock, SPIN_COUNT) == 0) {
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mm_free(lock);
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return NULL;
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}
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return lock;
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}
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static void
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evthread_win32_lock_free(void *_lock, unsigned locktype)
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{
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CRITICAL_SECTION *lock = _lock;
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DeleteCriticalSection(lock);
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mm_free(lock);
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}
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static int
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evthread_win32_lock(unsigned mode, void *_lock)
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{
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CRITICAL_SECTION *lock = _lock;
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if ((mode & EVTHREAD_TRY)) {
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return TryEnterCriticalSection(lock) != 0;
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} else {
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EnterCriticalSection(lock);
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return 0;
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}
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}
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static int
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evthread_win32_unlock(unsigned mode, void *_lock)
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{
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CRITICAL_SECTION *lock = _lock;
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LeaveCriticalSection(lock);
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return 0;
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}
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static unsigned long
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evthread_win32_get_id(void)
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{
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return (unsigned long) GetCurrentThreadId();
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}
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int
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evthread_use_windows_threads(void)
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{
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struct evthread_lock_callbacks cbs = {
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EVTHREAD_LOCK_API_VERSION,
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EVTHREAD_LOCKTYPE_RECURSIVE,
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evthread_win32_lock_create,
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evthread_win32_lock_free,
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evthread_win32_lock,
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evthread_win32_unlock
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};
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evthread_set_lock_callbacks(&cbs);
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evthread_set_id_callback(evthread_win32_get_id);
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return 0;
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}
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