/* $Header$ */ /* * tclWinThread.c -- * * This file implements the Windows-specific thread operations. * * Copyright (c) 1998 by Sun Microsystems, Inc. * Copyright (c) 1999 by Scriptics Corporation * * See the file "license.terms" for information on usage and redistribution * of this file, and for a DISCLAIMER OF ALL WARRANTIES. * * RCS: @(#) $Id: tclwinthrd.c,v 1.1.1.1 2001/06/13 04:50:42 dtashley Exp $ */ #include "tclWinInt.h" #include #include #include #include /* * This is the master lock used to serialize access to other * serialization data structures. */ static CRITICAL_SECTION masterLock; static int init = 0; #define MASTER_LOCK EnterCriticalSection(&masterLock) #define MASTER_UNLOCK LeaveCriticalSection(&masterLock) /* * This is the master lock used to serialize initialization and finalization * of Tcl as a whole. */ static CRITICAL_SECTION initLock; /* * allocLock is used by Tcl's version of malloc for synchronization. * For obvious reasons, cannot use any dyamically allocated storage. */ static CRITICAL_SECTION allocLock; static Tcl_Mutex allocLockPtr = (Tcl_Mutex) &allocLock; /* * Condition variables are implemented with a combination of a * per-thread Windows Event and a per-condition waiting queue. * The idea is that each thread has its own Event that it waits * on when it is doing a ConditionWait; it uses the same event for * all condition variables because it only waits on one at a time. * Each condition variable has a queue of waiting threads, and a * mutex used to serialize access to this queue. * * Special thanks to David Nichols and * Jim Davidson for advice on the Condition Variable implementation. */ /* * The per-thread event and queue pointers. */ typedef struct ThreadSpecificData { HANDLE condEvent; /* Per-thread condition event */ struct ThreadSpecificData *nextPtr; /* Queue pointers */ struct ThreadSpecificData *prevPtr; int flags; /* See flags below */ } ThreadSpecificData; static Tcl_ThreadDataKey dataKey; /* * State bits for the thread. * WIN_THREAD_UNINIT Uninitialized. Must be zero because * of the way ThreadSpecificData is created. * WIN_THREAD_RUNNING Running, not waiting. * WIN_THREAD_BLOCKED Waiting, or trying to wait. * WIN_THREAD_DEAD Dying - no per-thread event anymore. */ #define WIN_THREAD_UNINIT 0x0 #define WIN_THREAD_RUNNING 0x1 #define WIN_THREAD_BLOCKED 0x2 #define WIN_THREAD_DEAD 0x4 /* * The per condition queue pointers and the * Mutex used to serialize access to the queue. */ typedef struct WinCondition { CRITICAL_SECTION condLock; /* Lock to serialize queuing on the condition */ struct ThreadSpecificData *firstPtr; /* Queue pointers */ struct ThreadSpecificData *lastPtr; } WinCondition; static void FinalizeConditionEvent(ClientData data); /* *---------------------------------------------------------------------- * * Tcl_CreateThread -- * * This procedure creates a new thread. * * Results: * TCL_OK if the thread could be created. The thread ID is * returned in a parameter. * * Side effects: * A new thread is created. * *---------------------------------------------------------------------- */ int Tcl_CreateThread(idPtr, proc, clientData, stackSize, flags) Tcl_ThreadId *idPtr; /* Return, the ID of the thread */ Tcl_ThreadCreateProc proc; /* Main() function of the thread */ ClientData clientData; /* The one argument to Main() */ int stackSize; /* Size of stack for the new thread */ int flags; /* Flags controlling behaviour of * the new thread */ { unsigned long code; code = _beginthreadex(NULL, stackSize, proc, clientData, 0, (unsigned *)idPtr); if (code == 0) { return TCL_ERROR; } else { return TCL_OK; } } /* *---------------------------------------------------------------------- * * TclpThreadExit -- * * This procedure terminates the current thread. * * Results: * None. * * Side effects: * This procedure terminates the current thread. * *---------------------------------------------------------------------- */ void TclpThreadExit(status) int status; { _endthreadex((DWORD)status); } /* *---------------------------------------------------------------------- * * Tcl_GetCurrentThread -- * * This procedure returns the ID of the currently running thread. * * Results: * A thread ID. * * Side effects: * None. * *---------------------------------------------------------------------- */ Tcl_ThreadId Tcl_GetCurrentThread() { return (Tcl_ThreadId)GetCurrentThreadId(); } /* *---------------------------------------------------------------------- * * TclpInitLock * * This procedure is used to grab a lock that serializes initialization * and finalization of Tcl. On some platforms this may also initialize * the mutex used to serialize creation of more mutexes and thread * local storage keys. * * Results: * None. * * Side effects: * Acquire the initialization mutex. * *---------------------------------------------------------------------- */ void TclpInitLock() { if (!init) { /* * There is a fundamental race here that is solved by creating * the first Tcl interpreter in a single threaded environment. * Once the interpreter has been created, it is safe to create * more threads that create interpreters in parallel. */ init = 1; InitializeCriticalSection(&initLock); InitializeCriticalSection(&masterLock); } EnterCriticalSection(&initLock); } /* *---------------------------------------------------------------------- * * TclpInitUnlock * * This procedure is used to release a lock that serializes initialization * and finalization of Tcl. * * Results: * None. * * Side effects: * Release the initialization mutex. * *---------------------------------------------------------------------- */ void TclpInitUnlock() { LeaveCriticalSection(&initLock); } /* *---------------------------------------------------------------------- * * TclpMasterLock * * This procedure is used to grab a lock that serializes creation * of mutexes, condition variables, and thread local storage keys. * * This lock must be different than the initLock because the * initLock is held during creation of syncronization objects. * * Results: * None. * * Side effects: * Acquire the master mutex. * *---------------------------------------------------------------------- */ void TclpMasterLock() { if (!init) { /* * There is a fundamental race here that is solved by creating * the first Tcl interpreter in a single threaded environment. * Once the interpreter has been created, it is safe to create * more threads that create interpreters in parallel. */ init = 1; InitializeCriticalSection(&initLock); InitializeCriticalSection(&masterLock); } EnterCriticalSection(&masterLock); } /* *---------------------------------------------------------------------- * * Tcl_GetAllocMutex * * This procedure returns a pointer to a statically initialized * mutex for use by the memory allocator. The alloctor must * use this lock, because all other locks are allocated... * * Results: * A pointer to a mutex that is suitable for passing to * Tcl_MutexLock and Tcl_MutexUnlock. * * Side effects: * None. * *---------------------------------------------------------------------- */ Tcl_Mutex * Tcl_GetAllocMutex() { #ifdef TCL_THREADS InitializeCriticalSection(&allocLock); return &allocLockPtr; #else return NULL; #endif } #ifdef TCL_THREADS /* *---------------------------------------------------------------------- * * TclpMasterUnlock * * This procedure is used to release a lock that serializes creation * and deletion of synchronization objects. * * Results: * None. * * Side effects: * Release the master mutex. * *---------------------------------------------------------------------- */ void TclpMasterUnlock() { LeaveCriticalSection(&masterLock); } /* *---------------------------------------------------------------------- * * Tcl_MutexLock -- * * This procedure is invoked to lock a mutex. This is a self * initializing mutex that is automatically finalized during * Tcl_Finalize. * * Results: * None. * * Side effects: * May block the current thread. The mutex is aquired when * this returns. * *---------------------------------------------------------------------- */ void Tcl_MutexLock(mutexPtr) Tcl_Mutex *mutexPtr; /* The lock */ { CRITICAL_SECTION *csPtr; if (*mutexPtr == NULL) { MASTER_LOCK; /* * Double inside master lock check to avoid a race. */ if (*mutexPtr == NULL) { csPtr = (CRITICAL_SECTION *)ckalloc(sizeof(CRITICAL_SECTION)); InitializeCriticalSection(csPtr); *mutexPtr = (Tcl_Mutex)csPtr; TclRememberMutex(mutexPtr); } MASTER_UNLOCK; } csPtr = *((CRITICAL_SECTION **)mutexPtr); EnterCriticalSection(csPtr); } /* *---------------------------------------------------------------------- * * Tcl_MutexUnlock -- * * This procedure is invoked to unlock a mutex. * * Results: * None. * * Side effects: * The mutex is released when this returns. * *---------------------------------------------------------------------- */ void Tcl_MutexUnlock(mutexPtr) Tcl_Mutex *mutexPtr; /* The lock */ { CRITICAL_SECTION *csPtr = *((CRITICAL_SECTION **)mutexPtr); LeaveCriticalSection(csPtr); } /* *---------------------------------------------------------------------- * * TclpFinalizeMutex -- * * This procedure is invoked to clean up one mutex. This is only * safe to call at the end of time. * * Results: * None. * * Side effects: * The mutex list is deallocated. * *---------------------------------------------------------------------- */ void TclpFinalizeMutex(mutexPtr) Tcl_Mutex *mutexPtr; { CRITICAL_SECTION *csPtr = *(CRITICAL_SECTION **)mutexPtr; if (csPtr != NULL) { ckfree((char *)csPtr); *mutexPtr = NULL; } } /* *---------------------------------------------------------------------- * * TclpThreadDataKeyInit -- * * This procedure initializes a thread specific data block key. * Each thread has table of pointers to thread specific data. * all threads agree on which table entry is used by each module. * this is remembered in a "data key", that is just an index into * this table. To allow self initialization, the interface * passes a pointer to this key and the first thread to use * the key fills in the pointer to the key. The key should be * a process-wide static. * * Results: * None. * * Side effects: * Will allocate memory the first time this process calls for * this key. In this case it modifies its argument * to hold the pointer to information about the key. * *---------------------------------------------------------------------- */ void TclpThreadDataKeyInit(keyPtr) Tcl_ThreadDataKey *keyPtr; /* Identifier for the data chunk, * really (DWORD **) */ { DWORD *indexPtr; MASTER_LOCK; if (*keyPtr == NULL) { indexPtr = (DWORD *)ckalloc(sizeof(DWORD)); *indexPtr = TlsAlloc(); *keyPtr = (Tcl_ThreadDataKey)indexPtr; TclRememberDataKey(keyPtr); } MASTER_UNLOCK; } /* *---------------------------------------------------------------------- * * TclpThreadDataKeyGet -- * * This procedure returns a pointer to a block of thread local storage. * * Results: * A thread-specific pointer to the data structure, or NULL * if the memory has not been assigned to this key for this thread. * * Side effects: * None. * *---------------------------------------------------------------------- */ VOID * TclpThreadDataKeyGet(keyPtr) Tcl_ThreadDataKey *keyPtr; /* Identifier for the data chunk, * really (DWORD **) */ { DWORD *indexPtr = *(DWORD **)keyPtr; if (indexPtr == NULL) { return NULL; } else { return (VOID *) TlsGetValue(*indexPtr); } } /* *---------------------------------------------------------------------- * * TclpThreadDataKeySet -- * * This procedure sets the pointer to a block of thread local storage. * * Results: * None. * * Side effects: * Sets up the thread so future calls to TclpThreadDataKeyGet with * this key will return the data pointer. * *---------------------------------------------------------------------- */ void TclpThreadDataKeySet(keyPtr, data) Tcl_ThreadDataKey *keyPtr; /* Identifier for the data chunk, * really (pthread_key_t **) */ VOID *data; /* Thread local storage */ { DWORD *indexPtr = *(DWORD **)keyPtr; TlsSetValue(*indexPtr, (void *)data); } /* *---------------------------------------------------------------------- * * TclpFinalizeThreadData -- * * This procedure cleans up the thread-local storage. This is * called once for each thread. * * Results: * None. * * Side effects: * Frees up the memory. * *---------------------------------------------------------------------- */ void TclpFinalizeThreadData(keyPtr) Tcl_ThreadDataKey *keyPtr; { VOID *result; DWORD *indexPtr; if (*keyPtr != NULL) { indexPtr = *(DWORD **)keyPtr; result = (VOID *)TlsGetValue(*indexPtr); if (result != NULL) { ckfree((char *)result); TlsSetValue(*indexPtr, (void *)NULL); } } } /* *---------------------------------------------------------------------- * * TclpFinalizeThreadDataKey -- * * This procedure is invoked to clean up one key. This is a * process-wide storage identifier. The thread finalization code * cleans up the thread local storage itself. * * This assumes the master lock is held. * * Results: * None. * * Side effects: * The key is deallocated. * *---------------------------------------------------------------------- */ void TclpFinalizeThreadDataKey(keyPtr) Tcl_ThreadDataKey *keyPtr; { DWORD *indexPtr; if (*keyPtr != NULL) { indexPtr = *(DWORD **)keyPtr; TlsFree(*indexPtr); ckfree((char *)indexPtr); *keyPtr = NULL; } } /* *---------------------------------------------------------------------- * * Tcl_ConditionWait -- * * This procedure is invoked to wait on a condition variable. * The mutex is automically released as part of the wait, and * automatically grabbed when the condition is signaled. * * The mutex must be held when this procedure is called. * * Results: * None. * * Side effects: * May block the current thread. The mutex is aquired when * this returns. Will allocate memory for a HANDLE * and initialize this the first time this Tcl_Condition is used. * *---------------------------------------------------------------------- */ void Tcl_ConditionWait(condPtr, mutexPtr, timePtr) Tcl_Condition *condPtr; /* Really (WinCondition **) */ Tcl_Mutex *mutexPtr; /* Really (CRITICAL_SECTION **) */ Tcl_Time *timePtr; /* Timeout on waiting period */ { WinCondition *winCondPtr; /* Per-condition queue head */ CRITICAL_SECTION *csPtr; /* Caller's Mutex, after casting */ DWORD wtime; /* Windows time value */ int timeout; /* True if we got a timeout */ int doExit = 0; /* True if we need to do exit setup */ ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); if (tsdPtr->flags & WIN_THREAD_DEAD) { /* * No more per-thread event on which to wait. */ return; } /* * Self initialize the two parts of the contition. * The per-condition and per-thread parts need to be * handled independently. */ if (tsdPtr->flags == WIN_THREAD_UNINIT) { MASTER_LOCK; /* * Create the per-thread event and queue pointers. */ if (tsdPtr->flags == WIN_THREAD_UNINIT) { tsdPtr->condEvent = CreateEvent(NULL, TRUE /* manual reset */, FALSE /* non signaled */, NULL); tsdPtr->nextPtr = NULL; tsdPtr->prevPtr = NULL; tsdPtr->flags = WIN_THREAD_RUNNING; doExit = 1; } MASTER_UNLOCK; if (doExit) { /* * Create a per-thread exit handler to clean up the condEvent. * We must be careful do do this outside the Master Lock * because Tcl_CreateThreadExitHandler uses its own * ThreadSpecificData, and initializing that may drop * back into the Master Lock. */ Tcl_CreateThreadExitHandler(FinalizeConditionEvent, (ClientData) tsdPtr); } } if (*condPtr == NULL) { MASTER_LOCK; /* * Initialize the per-condition queue pointers and Mutex. */ if (*condPtr == NULL) { winCondPtr = (WinCondition *)ckalloc(sizeof(WinCondition)); InitializeCriticalSection(&winCondPtr->condLock); winCondPtr->firstPtr = NULL; winCondPtr->lastPtr = NULL; *condPtr = (Tcl_Condition)winCondPtr; TclRememberCondition(condPtr); } MASTER_UNLOCK; } csPtr = *((CRITICAL_SECTION **)mutexPtr); winCondPtr = *((WinCondition **)condPtr); if (timePtr == NULL) { wtime = INFINITE; } else { wtime = timePtr->sec * 1000 + timePtr->usec / 1000; } /* * Queue the thread on the condition, using * the per-condition lock for serialization. */ tsdPtr->flags = WIN_THREAD_BLOCKED; tsdPtr->nextPtr = NULL; EnterCriticalSection(&winCondPtr->condLock); tsdPtr->prevPtr = winCondPtr->lastPtr; /* A: */ winCondPtr->lastPtr = tsdPtr; if (tsdPtr->prevPtr != NULL) { tsdPtr->prevPtr->nextPtr = tsdPtr; } if (winCondPtr->firstPtr == NULL) { winCondPtr->firstPtr = tsdPtr; } /* * Unlock the caller's mutex and wait for the condition, or a timeout. * There is a minor issue here in that we don't count down the * timeout if we get notified, but another thread grabs the condition * before we do. In that race condition we'll wait again for the * full timeout. Timed waits are dubious anyway. Either you have * the locking protocol wrong and are masking a deadlock, * or you are using conditions to pause your thread. */ LeaveCriticalSection(csPtr); timeout = 0; while (!timeout && (tsdPtr->flags & WIN_THREAD_BLOCKED)) { ResetEvent(tsdPtr->condEvent); LeaveCriticalSection(&winCondPtr->condLock); if (WaitForSingleObject(tsdPtr->condEvent, wtime) == WAIT_TIMEOUT) { timeout = 1; } EnterCriticalSection(&winCondPtr->condLock); } /* * Be careful on timeouts because the signal might arrive right around * time time limit and someone else could have taken us off the queue. */ if (timeout) { if (tsdPtr->flags & WIN_THREAD_RUNNING) { timeout = 0; } else { /* * When dequeuing, we can leave the tsdPtr->nextPtr * and tsdPtr->prevPtr with dangling pointers because * they are reinitialilzed w/out reading them when the * thread is enqueued later. */ if (winCondPtr->firstPtr == tsdPtr) { winCondPtr->firstPtr = tsdPtr->nextPtr; } else { tsdPtr->prevPtr->nextPtr = tsdPtr->nextPtr; } if (winCondPtr->lastPtr == tsdPtr) { winCondPtr->lastPtr = tsdPtr->prevPtr; } else { tsdPtr->nextPtr->prevPtr = tsdPtr->prevPtr; } tsdPtr->flags = WIN_THREAD_RUNNING; } } LeaveCriticalSection(&winCondPtr->condLock); EnterCriticalSection(csPtr); } /* *---------------------------------------------------------------------- * * Tcl_ConditionNotify -- * * This procedure is invoked to signal a condition variable. * * The mutex must be held during this call to avoid races, * but this interface does not enforce that. * * Results: * None. * * Side effects: * May unblock another thread. * *---------------------------------------------------------------------- */ void Tcl_ConditionNotify(condPtr) Tcl_Condition *condPtr; { WinCondition *winCondPtr; ThreadSpecificData *tsdPtr; if (condPtr != NULL) { winCondPtr = *((WinCondition **)condPtr); /* * Loop through all the threads waiting on the condition * and notify them (i.e., broadcast semantics). The queue * manipulation is guarded by the per-condition coordinating mutex. */ EnterCriticalSection(&winCondPtr->condLock); while (winCondPtr->firstPtr != NULL) { tsdPtr = winCondPtr->firstPtr; winCondPtr->firstPtr = tsdPtr->nextPtr; if (winCondPtr->lastPtr == tsdPtr) { winCondPtr->lastPtr = NULL; } tsdPtr->flags = WIN_THREAD_RUNNING; tsdPtr->nextPtr = NULL; tsdPtr->prevPtr = NULL; /* Not strictly necessary, see A: */ SetEvent(tsdPtr->condEvent); } LeaveCriticalSection(&winCondPtr->condLock); } else { /* * Noone has used the condition variable, so there are no waiters. */ } } /* *---------------------------------------------------------------------- * * FinalizeConditionEvent -- * * This procedure is invoked to clean up the per-thread * event used to implement condition waiting. * This is only safe to call at the end of time. * * Results: * None. * * Side effects: * The per-thread event is closed. * *---------------------------------------------------------------------- */ static void FinalizeConditionEvent(data) ClientData data; { ThreadSpecificData *tsdPtr = (ThreadSpecificData *)data; tsdPtr->flags = WIN_THREAD_DEAD; CloseHandle(tsdPtr->condEvent); } /* *---------------------------------------------------------------------- * * TclpFinalizeCondition -- * * This procedure is invoked to clean up a condition variable. * This is only safe to call at the end of time. * * This assumes the Master Lock is held. * * Results: * None. * * Side effects: * The condition variable is deallocated. * *---------------------------------------------------------------------- */ void TclpFinalizeCondition(condPtr) Tcl_Condition *condPtr; { WinCondition *winCondPtr = *(WinCondition **)condPtr; /* * Note - this is called long after the thread-local storage is * reclaimed. The per-thread condition waiting event is * reclaimed earlier in a per-thread exit handler, which is * called before thread local storage is reclaimed. */ if (winCondPtr != NULL) { ckfree((char *)winCondPtr); *condPtr = NULL; } } #endif /* TCL_THREADS */ /* End of tclwinthrd.c */