/***************************************************************************** Copyright (c) 1995, 2009, Innobase Oy. All Rights Reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA *****************************************************************************/ /**************************************************//** @file os/os0sync.c The interface to the operating system synchronization primitives. Created 9/6/1995 Heikki Tuuri *******************************************************/ #include "os0sync.h" #ifdef UNIV_NONINL #include "os0sync.ic" #endif #ifdef __WIN__ #include #endif #include "ut0mem.h" #include "srv0start.h" #include "srv0srv.h" /* Type definition for an operating system mutex struct */ struct os_mutex_struct{ os_event_t event; /*!< Used by sync0arr.c for queing threads */ void* handle; /*!< OS handle to mutex */ ulint count; /*!< we use this counter to check that the same thread does not recursively lock the mutex: we do not assume that the OS mutex supports recursive locking, though NT seems to do that */ UT_LIST_NODE_T(os_mutex_str_t) os_mutex_list; /* list of all 'slow' OS mutexes created */ }; /** Mutex protecting counts and the lists of OS mutexes and events */ UNIV_INTERN os_mutex_t os_sync_mutex; /** TRUE if os_sync_mutex has been initialized */ static ibool os_sync_mutex_inited = FALSE; /** TRUE when os_sync_free() is being executed */ static ibool os_sync_free_called = FALSE; /** This is incremented by 1 in os_thread_create and decremented by 1 in os_thread_exit */ UNIV_INTERN ulint os_thread_count = 0; /** The list of all events created */ static UT_LIST_BASE_NODE_T(os_event_struct_t) os_event_list; /** The list of all OS 'slow' mutexes */ static UT_LIST_BASE_NODE_T(os_mutex_str_t) os_mutex_list; UNIV_INTERN ulint os_event_count = 0; UNIV_INTERN ulint os_mutex_count = 0; UNIV_INTERN ulint os_fast_mutex_count = 0; /* The number of microsecnds in a second. */ static const ulint MICROSECS_IN_A_SECOND = 1000000; /* Because a mutex is embedded inside an event and there is an event embedded inside a mutex, on free, this generates a recursive call. This version of the free event function doesn't acquire the global lock */ static void os_event_free_internal(os_event_t event); /* On Windows (Vista and later), load function pointers for condition variable handling. Those functions are not available in prior versions, so we have to use them via runtime loading, as long as we support XP. */ static void os_cond_module_init(void); #ifdef __WIN__ /* Prototypes and function pointers for condition variable functions */ typedef VOID (WINAPI* InitializeConditionVariableProc) (PCONDITION_VARIABLE ConditionVariable); static InitializeConditionVariableProc initialize_condition_variable; typedef BOOL (WINAPI* SleepConditionVariableCSProc) (PCONDITION_VARIABLE ConditionVariable, PCRITICAL_SECTION CriticalSection, DWORD dwMilliseconds); static SleepConditionVariableCSProc sleep_condition_variable; typedef VOID (WINAPI* WakeAllConditionVariableProc) (PCONDITION_VARIABLE ConditionVariable); static WakeAllConditionVariableProc wake_all_condition_variable; typedef VOID (WINAPI* WakeConditionVariableProc) (PCONDITION_VARIABLE ConditionVariable); static WakeConditionVariableProc wake_condition_variable; #endif /*********************************************************//** Initialitze condition variable */ UNIV_INLINE void os_cond_init( /*=========*/ os_cond_t* cond) /*!< in: condition variable. */ { ut_a(cond); #ifdef __WIN__ ut_a(initialize_condition_variable != NULL); initialize_condition_variable(cond); #else ut_a(pthread_cond_init(cond, NULL) == 0); #endif } /*********************************************************//** Do a timed wait on condition variable. @return TRUE if timed out, FALSE otherwise */ UNIV_INLINE ibool os_cond_wait_timed( /*===============*/ os_cond_t* cond, /*!< in: condition variable. */ os_fast_mutex_t* mutex, /*!< in: fast mutex */ #ifndef __WIN__ const struct timespec* abstime /*!< in: timeout */ #else DWORD time_in_ms /*!< in: timeout in milliseconds*/ #endif /* !__WIN__ */ ) { #ifdef __WIN__ BOOL ret; DWORD err; ut_a(sleep_condition_variable != NULL); ret = sleep_condition_variable(cond, mutex, time_in_ms); if (!ret) { err = GetLastError(); /* From http://msdn.microsoft.com/en-us/library/ms686301%28VS.85%29.aspx, "Condition variables are subject to spurious wakeups (those not associated with an explicit wake) and stolen wakeups (another thread manages to run before the woken thread)." Check for both types of timeouts. Conditions are checked by the caller.*/ if ((err == WAIT_TIMEOUT) || (err == ERROR_TIMEOUT)) { return(TRUE); } } ut_a(ret); return(FALSE); #else int ret; ret = pthread_cond_timedwait(cond, mutex, abstime); switch (ret) { case 0: case ETIMEDOUT: /* We play it safe by checking for EINTR even though according to the POSIX documentation it can't return EINTR. */ case EINTR: break; default: fprintf(stderr, " InnoDB: pthread_cond_timedwait() returned: " "%d: abstime={%lu,%lu}\n", ret, (ulong) abstime->tv_sec, (ulong) abstime->tv_nsec); ut_error; } return(ret == ETIMEDOUT); #endif } /*********************************************************//** Wait on condition variable */ UNIV_INLINE void os_cond_wait( /*=========*/ os_cond_t* cond, /*!< in: condition variable. */ os_fast_mutex_t* mutex) /*!< in: fast mutex */ { ut_a(cond); ut_a(mutex); #ifdef __WIN__ ut_a(sleep_condition_variable != NULL); ut_a(sleep_condition_variable(cond, mutex, INFINITE)); #else ut_a(pthread_cond_wait(cond, mutex) == 0); #endif } /*********************************************************//** Wakes all threads waiting for condition variable */ UNIV_INLINE void os_cond_broadcast( /*==============*/ os_cond_t* cond) /*!< in: condition variable. */ { ut_a(cond); #ifdef __WIN__ ut_a(wake_all_condition_variable != NULL); wake_all_condition_variable(cond); #else ut_a(pthread_cond_broadcast(cond) == 0); #endif } /*********************************************************//** Wakes one thread waiting for condition variable */ UNIV_INLINE void os_cond_signal( /*==========*/ os_cond_t* cond) /*!< in: condition variable. */ { ut_a(cond); #ifdef __WIN__ ut_a(wake_condition_variable != NULL); wake_condition_variable(cond); #else ut_a(pthread_cond_signal(cond) == 0); #endif } /*********************************************************//** Destroys condition variable */ UNIV_INLINE void os_cond_destroy( /*============*/ os_cond_t* cond) /*!< in: condition variable. */ { #ifdef __WIN__ /* Do nothing */ #else ut_a(pthread_cond_destroy(cond) == 0); #endif } /*********************************************************//** On Windows (Vista and later), load function pointers for condition variable handling. Those functions are not available in prior versions, so we have to use them via runtime loading, as long as we support XP. */ static void os_cond_module_init(void) /*=====================*/ { #ifdef __WIN__ HMODULE h_dll; if (!srv_use_native_conditions) return; h_dll = GetModuleHandle("kernel32"); initialize_condition_variable = (InitializeConditionVariableProc) GetProcAddress(h_dll, "InitializeConditionVariable"); sleep_condition_variable = (SleepConditionVariableCSProc) GetProcAddress(h_dll, "SleepConditionVariableCS"); wake_all_condition_variable = (WakeAllConditionVariableProc) GetProcAddress(h_dll, "WakeAllConditionVariable"); wake_condition_variable = (WakeConditionVariableProc) GetProcAddress(h_dll, "WakeConditionVariable"); /* When using native condition variables, check function pointers */ ut_a(initialize_condition_variable); ut_a(sleep_condition_variable); ut_a(wake_all_condition_variable); ut_a(wake_condition_variable); #endif } /*********************************************************//** Initializes global event and OS 'slow' mutex lists. */ UNIV_INTERN void os_sync_init(void) /*==============*/ { UT_LIST_INIT(os_event_list); UT_LIST_INIT(os_mutex_list); os_sync_mutex = NULL; os_sync_mutex_inited = FALSE; /* Now for Windows only */ os_cond_module_init(); os_sync_mutex = os_mutex_create(); os_sync_mutex_inited = TRUE; } /*********************************************************//** Frees created events and OS 'slow' mutexes. */ UNIV_INTERN void os_sync_free(void) /*==============*/ { os_event_t event; os_mutex_t mutex; os_sync_free_called = TRUE; event = UT_LIST_GET_FIRST(os_event_list); while (event) { os_event_free(event); event = UT_LIST_GET_FIRST(os_event_list); } mutex = UT_LIST_GET_FIRST(os_mutex_list); while (mutex) { if (mutex == os_sync_mutex) { /* Set the flag to FALSE so that we do not try to reserve os_sync_mutex any more in remaining freeing operations in shutdown */ os_sync_mutex_inited = FALSE; } os_mutex_free(mutex); mutex = UT_LIST_GET_FIRST(os_mutex_list); } os_sync_free_called = FALSE; } /*********************************************************//** Creates an event semaphore, i.e., a semaphore which may just have two states: signaled and nonsignaled. The created event is manual reset: it must be reset explicitly by calling sync_os_reset_event. @return the event handle */ UNIV_INTERN os_event_t os_event_create( /*============*/ const char* name) /*!< in: the name of the event, if NULL the event is created without a name */ { os_event_t event; #ifdef __WIN__ if(!srv_use_native_conditions) { event = ut_malloc(sizeof(struct os_event_struct)); event->handle = CreateEvent(NULL, TRUE, FALSE, (LPCTSTR) name); if (!event->handle) { fprintf(stderr, "InnoDB: Could not create a Windows event" " semaphore; Windows error %lu\n", (ulong) GetLastError()); } } else /* Windows with condition variables */ #endif { UT_NOT_USED(name); event = ut_malloc(sizeof(struct os_event_struct)); os_fast_mutex_init(&(event->os_mutex)); os_cond_init(&(event->cond_var)); event->is_set = FALSE; /* We return this value in os_event_reset(), which can then be be used to pass to the os_event_wait_low(). The value of zero is reserved in os_event_wait_low() for the case when the caller does not want to pass any signal_count value. To distinguish between the two cases we initialize signal_count to 1 here. */ event->signal_count = 1; } /* The os_sync_mutex can be NULL because during startup an event can be created [ because it's embedded in the mutex/rwlock ] before this module has been initialized */ if (os_sync_mutex != NULL) { os_mutex_enter(os_sync_mutex); } /* Put to the list of events */ UT_LIST_ADD_FIRST(os_event_list, os_event_list, event); os_event_count++; if (os_sync_mutex != NULL) { os_mutex_exit(os_sync_mutex); } return(event); } /**********************************************************//** Sets an event semaphore to the signaled state: lets waiting threads proceed. */ UNIV_INTERN void os_event_set( /*=========*/ os_event_t event) /*!< in: event to set */ { ut_a(event); #ifdef __WIN__ if (!srv_use_native_conditions) { ut_a(SetEvent(event->handle)); return; } #endif ut_a(event); os_fast_mutex_lock(&(event->os_mutex)); if (event->is_set) { /* Do nothing */ } else { event->is_set = TRUE; event->signal_count += 1; os_cond_broadcast(&(event->cond_var)); } os_fast_mutex_unlock(&(event->os_mutex)); } /**********************************************************//** Resets an event semaphore to the nonsignaled state. Waiting threads will stop to wait for the event. The return value should be passed to os_even_wait_low() if it is desired that this thread should not wait in case of an intervening call to os_event_set() between this os_event_reset() and the os_event_wait_low() call. See comments for os_event_wait_low(). @return current signal_count. */ UNIV_INTERN ib_int64_t os_event_reset( /*===========*/ os_event_t event) /*!< in: event to reset */ { ib_int64_t ret = 0; ut_a(event); #ifdef __WIN__ if(!srv_use_native_conditions) { ut_a(ResetEvent(event->handle)); return(0); } #endif os_fast_mutex_lock(&(event->os_mutex)); if (!event->is_set) { /* Do nothing */ } else { event->is_set = FALSE; } ret = event->signal_count; os_fast_mutex_unlock(&(event->os_mutex)); return(ret); } /**********************************************************//** Frees an event object, without acquiring the global lock. */ static void os_event_free_internal( /*===================*/ os_event_t event) /*!< in: event to free */ { #ifdef __WIN__ if(!srv_use_native_conditions) { ut_a(event); ut_a(CloseHandle(event->handle)); } else #endif { ut_a(event); /* This is to avoid freeing the mutex twice */ os_fast_mutex_free(&(event->os_mutex)); os_cond_destroy(&(event->cond_var)); } /* Remove from the list of events */ UT_LIST_REMOVE(os_event_list, os_event_list, event); os_event_count--; ut_free(event); } /**********************************************************//** Frees an event object. */ UNIV_INTERN void os_event_free( /*==========*/ os_event_t event) /*!< in: event to free */ { ut_a(event); #ifdef __WIN__ if(!srv_use_native_conditions){ ut_a(CloseHandle(event->handle)); } else /*Windows with condition variables */ #endif { os_fast_mutex_free(&(event->os_mutex)); os_cond_destroy(&(event->cond_var)); } /* Remove from the list of events */ os_mutex_enter(os_sync_mutex); UT_LIST_REMOVE(os_event_list, os_event_list, event); os_event_count--; os_mutex_exit(os_sync_mutex); ut_free(event); } /**********************************************************//** Waits for an event object until it is in the signaled state. Typically, if the event has been signalled after the os_event_reset() we'll return immediately because event->is_set == TRUE. There are, however, situations (e.g.: sync_array code) where we may lose this information. For example: thread A calls os_event_reset() thread B calls os_event_set() [event->is_set == TRUE] thread C calls os_event_reset() [event->is_set == FALSE] thread A calls os_event_wait() [infinite wait!] thread C calls os_event_wait() [infinite wait!] Where such a scenario is possible, to avoid infinite wait, the value returned by os_event_reset() should be passed in as reset_sig_count. */ UNIV_INTERN void os_event_wait_low( /*==============*/ os_event_t event, /*!< in: event to wait */ ib_int64_t reset_sig_count)/*!< in: zero or the value returned by previous call of os_event_reset(). */ { #ifdef __WIN__ if(!srv_use_native_conditions) { DWORD err; ut_a(event); UT_NOT_USED(reset_sig_count); /* Specify an infinite wait */ err = WaitForSingleObject(event->handle, INFINITE); ut_a(err == WAIT_OBJECT_0); return; } #endif os_fast_mutex_lock(&event->os_mutex); if (!reset_sig_count) { reset_sig_count = event->signal_count; } while (!event->is_set && event->signal_count == reset_sig_count) { os_cond_wait(&(event->cond_var), &(event->os_mutex)); /* Solaris manual said that spurious wakeups may occur: we have to check if the event really has been signaled after we came here to wait */ } os_fast_mutex_unlock(&event->os_mutex); } /**********************************************************//** Waits for an event object until it is in the signaled state or a timeout is exceeded. @return 0 if success, OS_SYNC_TIME_EXCEEDED if timeout was exceeded */ UNIV_INTERN ulint os_event_wait_time_low( /*===================*/ os_event_t event, /*!< in: event to wait */ ulint time_in_usec, /*!< in: timeout in microseconds, or OS_SYNC_INFINITE_TIME */ ib_int64_t reset_sig_count) /*!< in: zero or the value returned by previous call of os_event_reset(). */ { ibool timed_out = FALSE; #ifdef __WIN__ DWORD time_in_ms; if (!srv_use_native_conditions) { DWORD err; ut_a(event); if (time_in_usec != OS_SYNC_INFINITE_TIME) { time_in_ms = time_in_usec / 1000; err = WaitForSingleObject(event->handle, time_in_ms); } else { err = WaitForSingleObject(event->handle, INFINITE); } if (err == WAIT_OBJECT_0) { return(0); } else if ((err == WAIT_TIMEOUT) || (err == ERROR_TIMEOUT)) { return(OS_SYNC_TIME_EXCEEDED); } ut_error; /* Dummy value to eliminate compiler warning. */ return(42); } else { ut_a(sleep_condition_variable != NULL); if (time_in_usec != OS_SYNC_INFINITE_TIME) { time_in_ms = time_in_usec / 1000; } else { time_in_ms = INFINITE; } } #else struct timespec abstime; if (time_in_usec != OS_SYNC_INFINITE_TIME) { struct timeval tv; int ret; ulint sec; ulint usec; ret = ut_usectime(&sec, &usec); ut_a(ret == 0); tv.tv_sec = sec; tv.tv_usec = usec; tv.tv_usec += time_in_usec; if ((ulint) tv.tv_usec >= MICROSECS_IN_A_SECOND) { tv.tv_sec += time_in_usec / MICROSECS_IN_A_SECOND; tv.tv_usec %= MICROSECS_IN_A_SECOND; } abstime.tv_sec = tv.tv_sec; abstime.tv_nsec = tv.tv_usec * 1000; } else { abstime.tv_nsec = 999999999; abstime.tv_sec = (time_t) ULINT_MAX; } ut_a(abstime.tv_nsec <= 999999999); #endif /* __WIN__ */ os_fast_mutex_lock(&event->os_mutex); if (!reset_sig_count) { reset_sig_count = event->signal_count; } do { if (event->is_set || event->signal_count != reset_sig_count) { break; } timed_out = os_cond_wait_timed( &event->cond_var, &event->os_mutex, #ifndef __WIN__ &abstime #else time_in_ms #endif /* !__WIN__ */ ); } while (!timed_out); os_fast_mutex_unlock(&event->os_mutex); return(timed_out ? OS_SYNC_TIME_EXCEEDED : 0); } /*********************************************************//** Creates an operating system mutex semaphore. Because these are slow, the mutex semaphore of InnoDB itself (mutex_t) should be used where possible. @return the mutex handle */ UNIV_INTERN os_mutex_t os_mutex_create(void) /*=================*/ { os_fast_mutex_t* mutex; os_mutex_t mutex_str; mutex = ut_malloc(sizeof(os_fast_mutex_t)); os_fast_mutex_init(mutex); mutex_str = ut_malloc(sizeof(os_mutex_str_t)); mutex_str->handle = mutex; mutex_str->count = 0; mutex_str->event = os_event_create(NULL); if (UNIV_LIKELY(os_sync_mutex_inited)) { /* When creating os_sync_mutex itself we cannot reserve it */ os_mutex_enter(os_sync_mutex); } UT_LIST_ADD_FIRST(os_mutex_list, os_mutex_list, mutex_str); os_mutex_count++; if (UNIV_LIKELY(os_sync_mutex_inited)) { os_mutex_exit(os_sync_mutex); } return(mutex_str); } /**********************************************************//** Acquires ownership of a mutex semaphore. */ UNIV_INTERN void os_mutex_enter( /*===========*/ os_mutex_t mutex) /*!< in: mutex to acquire */ { os_fast_mutex_lock(mutex->handle); (mutex->count)++; ut_a(mutex->count == 1); } /**********************************************************//** Releases ownership of a mutex. */ UNIV_INTERN void os_mutex_exit( /*==========*/ os_mutex_t mutex) /*!< in: mutex to release */ { ut_a(mutex); ut_a(mutex->count == 1); (mutex->count)--; os_fast_mutex_unlock(mutex->handle); } /**********************************************************//** Frees a mutex object. */ UNIV_INTERN void os_mutex_free( /*==========*/ os_mutex_t mutex) /*!< in: mutex to free */ { ut_a(mutex); if (UNIV_LIKELY(!os_sync_free_called)) { os_event_free_internal(mutex->event); } if (UNIV_LIKELY(os_sync_mutex_inited)) { os_mutex_enter(os_sync_mutex); } UT_LIST_REMOVE(os_mutex_list, os_mutex_list, mutex); os_mutex_count--; if (UNIV_LIKELY(os_sync_mutex_inited)) { os_mutex_exit(os_sync_mutex); } os_fast_mutex_free(mutex->handle); ut_free(mutex->handle); ut_free(mutex); } /*********************************************************//** Initializes an operating system fast mutex semaphore. */ UNIV_INTERN void os_fast_mutex_init( /*===============*/ os_fast_mutex_t* fast_mutex) /*!< in: fast mutex */ { #ifdef __WIN__ ut_a(fast_mutex); InitializeCriticalSection((LPCRITICAL_SECTION) fast_mutex); #else ut_a(0 == pthread_mutex_init(fast_mutex, MY_MUTEX_INIT_FAST)); #endif if (UNIV_LIKELY(os_sync_mutex_inited)) { /* When creating os_sync_mutex itself (in Unix) we cannot reserve it */ os_mutex_enter(os_sync_mutex); } os_fast_mutex_count++; if (UNIV_LIKELY(os_sync_mutex_inited)) { os_mutex_exit(os_sync_mutex); } } /**********************************************************//** Acquires ownership of a fast mutex. */ UNIV_INTERN void os_fast_mutex_lock( /*===============*/ os_fast_mutex_t* fast_mutex) /*!< in: mutex to acquire */ { #ifdef __WIN__ EnterCriticalSection((LPCRITICAL_SECTION) fast_mutex); #else pthread_mutex_lock(fast_mutex); #endif } /**********************************************************//** Releases ownership of a fast mutex. */ UNIV_INTERN void os_fast_mutex_unlock( /*=================*/ os_fast_mutex_t* fast_mutex) /*!< in: mutex to release */ { #ifdef __WIN__ LeaveCriticalSection(fast_mutex); #else pthread_mutex_unlock(fast_mutex); #endif } /**********************************************************//** Frees a mutex object. */ UNIV_INTERN void os_fast_mutex_free( /*===============*/ os_fast_mutex_t* fast_mutex) /*!< in: mutex to free */ { #ifdef __WIN__ ut_a(fast_mutex); DeleteCriticalSection((LPCRITICAL_SECTION) fast_mutex); #else int ret; ret = pthread_mutex_destroy(fast_mutex); if (UNIV_UNLIKELY(ret != 0)) { ut_print_timestamp(stderr); fprintf(stderr, " InnoDB: error: return value %lu when calling\n" "InnoDB: pthread_mutex_destroy().\n", (ulint)ret); fprintf(stderr, "InnoDB: Byte contents of the pthread mutex at %p:\n", (void*) fast_mutex); ut_print_buf(stderr, fast_mutex, sizeof(os_fast_mutex_t)); putc('\n', stderr); } #endif if (UNIV_LIKELY(os_sync_mutex_inited)) { /* When freeing the last mutexes, we have already freed os_sync_mutex */ os_mutex_enter(os_sync_mutex); } ut_ad(os_fast_mutex_count > 0); os_fast_mutex_count--; if (UNIV_LIKELY(os_sync_mutex_inited)) { os_mutex_exit(os_sync_mutex); } }