/* Copyright (c) 2000, 2014, Oracle and/or its affiliates. Copyright (c) 2011, 2016, MariaDB 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 02110-1335 USA */ /***************************************************************************** ** The following is a simple implementation of posix conditions *****************************************************************************/ #if defined(_WIN32) #undef SAFE_MUTEX /* Avoid safe_mutex redefinitions */ #include "mysys_priv.h" #include #include #include /* Windows native condition variables. We use runtime loading / function pointers, because they are not available on XP */ /* Prototypes and function pointers for condition variable functions */ typedef void (WINAPI * InitializeConditionVariableProc) (PCONDITION_VARIABLE ConditionVariable); typedef BOOL (WINAPI * SleepConditionVariableCSProc) (PCONDITION_VARIABLE ConditionVariable, PCRITICAL_SECTION CriticalSection, DWORD dwMilliseconds); typedef void (WINAPI * WakeAllConditionVariableProc) (PCONDITION_VARIABLE ConditionVariable); typedef void (WINAPI * WakeConditionVariableProc) (PCONDITION_VARIABLE ConditionVariable); static InitializeConditionVariableProc my_InitializeConditionVariable; static SleepConditionVariableCSProc my_SleepConditionVariableCS; static WakeAllConditionVariableProc my_WakeAllConditionVariable; static WakeConditionVariableProc my_WakeConditionVariable; /** Indicates if we have native condition variables, initialized first time pthread_cond_init is called. */ static BOOL have_native_conditions= FALSE; /** Check if native conditions can be used, load function pointers */ static void check_native_cond_availability(void) { HMODULE module= GetModuleHandle("kernel32"); my_InitializeConditionVariable= (InitializeConditionVariableProc) GetProcAddress(module, "InitializeConditionVariable"); my_SleepConditionVariableCS= (SleepConditionVariableCSProc) GetProcAddress(module, "SleepConditionVariableCS"); my_WakeAllConditionVariable= (WakeAllConditionVariableProc) GetProcAddress(module, "WakeAllConditionVariable"); my_WakeConditionVariable= (WakeConditionVariableProc) GetProcAddress(module, "WakeConditionVariable"); if (my_InitializeConditionVariable) have_native_conditions= TRUE; } /** Convert abstime to milliseconds */ static DWORD get_milliseconds(const struct timespec *abstime) { struct timespec current_time; long long ms; if (abstime == NULL) return INFINITE; set_timespec_nsec(current_time, 0); ms= (abstime->tv_sec - current_time.tv_sec)*1000LL + (abstime->tv_nsec - current_time.tv_nsec)/1000000LL; if(ms < 0 ) ms= 0; if(ms > UINT_MAX) ms= INFINITE; return (DWORD)ms; } /* Old (pre-vista) implementation using events */ static int legacy_cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr) { cond->waiting= 0; InitializeCriticalSection(&cond->lock_waiting); cond->events[SIGNAL]= CreateEvent(NULL, /* no security */ FALSE, /* auto-reset event */ FALSE, /* non-signaled initially */ NULL); /* unnamed */ /* Create a manual-reset event. */ cond->events[BROADCAST]= CreateEvent(NULL, /* no security */ TRUE, /* manual-reset */ FALSE, /* non-signaled initially */ NULL); /* unnamed */ cond->broadcast_block_event= CreateEvent(NULL, /* no security */ TRUE, /* manual-reset */ TRUE, /* signaled initially */ NULL); /* unnamed */ if( cond->events[SIGNAL] == NULL || cond->events[BROADCAST] == NULL || cond->broadcast_block_event == NULL ) return ENOMEM; return 0; } static int legacy_cond_destroy(pthread_cond_t *cond) { DeleteCriticalSection(&cond->lock_waiting); if (CloseHandle(cond->events[SIGNAL]) == 0 || CloseHandle(cond->events[BROADCAST]) == 0 || CloseHandle(cond->broadcast_block_event) == 0) return EINVAL; return 0; } static int legacy_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, struct timespec *abstime) { int result; DWORD timeout; timeout= get_milliseconds(abstime); /* Block access if previous broadcast hasn't finished. This is just for safety and should normally not affect the total time spent in this function. */ WaitForSingleObject(cond->broadcast_block_event, INFINITE); EnterCriticalSection(&cond->lock_waiting); cond->waiting++; LeaveCriticalSection(&cond->lock_waiting); LeaveCriticalSection(mutex); result= WaitForMultipleObjects(2, cond->events, FALSE, timeout); EnterCriticalSection(&cond->lock_waiting); cond->waiting--; if (cond->waiting == 0) { /* We're the last waiter to be notified or to stop waiting, so reset the manual event. */ /* Close broadcast gate */ ResetEvent(cond->events[BROADCAST]); /* Open block gate */ SetEvent(cond->broadcast_block_event); } LeaveCriticalSection(&cond->lock_waiting); EnterCriticalSection(mutex); return result == WAIT_TIMEOUT ? ETIMEDOUT : 0; } static int legacy_cond_signal(pthread_cond_t *cond) { EnterCriticalSection(&cond->lock_waiting); if(cond->waiting > 0) SetEvent(cond->events[SIGNAL]); LeaveCriticalSection(&cond->lock_waiting); return 0; } static int legacy_cond_broadcast(pthread_cond_t *cond) { EnterCriticalSection(&cond->lock_waiting); /* The mutex protect us from broadcasting if there isn't any thread waiting to open the block gate after this call has closed it. */ if(cond->waiting > 0) { /* Close block gate */ ResetEvent(cond->broadcast_block_event); /* Open broadcast gate */ SetEvent(cond->events[BROADCAST]); } LeaveCriticalSection(&cond->lock_waiting); return 0; } /* Posix API functions. Just choose between native and legacy implementation. */ int pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr) { /* Once initialization is used here rather than in my_init(), to 1) avoid my_init() pitfalls- undefined order in which initialization should run 2) be potentially useful C++ (in static constructors that run before main()) 3) just to simplify the API. Also, the overhead of my_pthread_once is very small. */ static my_pthread_once_t once_control= MY_PTHREAD_ONCE_INIT; my_pthread_once(&once_control, check_native_cond_availability); if (have_native_conditions) { my_InitializeConditionVariable(&cond->native_cond); return 0; } else return legacy_cond_init(cond, attr); } int pthread_cond_destroy(pthread_cond_t *cond) { if (have_native_conditions) return 0; /* no destroy function */ else return legacy_cond_destroy(cond); } int pthread_cond_broadcast(pthread_cond_t *cond) { if (have_native_conditions) { my_WakeAllConditionVariable(&cond->native_cond); return 0; } else return legacy_cond_broadcast(cond); } int pthread_cond_signal(pthread_cond_t *cond) { if (have_native_conditions) { my_WakeConditionVariable(&cond->native_cond); return 0; } else return legacy_cond_signal(cond); } int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, const struct timespec *abstime) { if (have_native_conditions) { DWORD timeout= get_milliseconds(abstime); if (!my_SleepConditionVariableCS(&cond->native_cond, mutex, timeout)) return ETIMEDOUT; return 0; } else return legacy_cond_timedwait(cond, mutex, abstime); } int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) { return pthread_cond_timedwait(cond, mutex, NULL); } int pthread_attr_init(pthread_attr_t *connect_att) { connect_att->dwStackSize = 0; connect_att->dwCreatingFlag = 0; return 0; } int pthread_attr_setstacksize(pthread_attr_t *connect_att,DWORD stack) { connect_att->dwStackSize=stack; return 0; } int pthread_attr_destroy(pthread_attr_t *connect_att) { bzero((uchar*) connect_att,sizeof(*connect_att)); return 0; } #endif /* __WIN__ */