/* * tclUnixNotify.c -- * * This file contains the implementation of the select-based * Unix-specific notifier, which is the lowest-level part of the * Tcl event loop. This file works together with * ../generic/tclNotify.c. * * Copyright (c) 1995-1997 Sun Microsystems, Inc. * * See the file "license.terms" for information on usage and redistribution * of this file, and for a DISCLAIMER OF ALL WARRANTIES. * * RCS: @(#) tclUnixNotfy.c,v 1.5 2003/01/21 19:40:21 hunt Exp */ #include "tclInt.h" #include "tclPort.h" #include <signal.h> extern TclStubs tclStubs; /* * This structure is used to keep track of the notifier info for a * a registered file. */ typedef struct FileHandler { int fd; int mask; /* Mask of desired events: TCL_READABLE, * etc. */ int readyMask; /* Mask of events that have been seen since the * last time file handlers were invoked for * this file. */ Tcl_FileProc *proc; /* Procedure to call, in the style of * Tcl_CreateFileHandler. */ ClientData clientData; /* Argument to pass to proc. */ struct FileHandler *nextPtr;/* Next in list of all files we care about. */ } FileHandler; /* * The following structure is what is added to the Tcl event queue when * file handlers are ready to fire. */ typedef struct FileHandlerEvent { Tcl_Event header; /* Information that is standard for * all events. */ int fd; /* File descriptor that is ready. Used * to find the FileHandler structure for * the file (can't point directly to the * FileHandler structure because it could * go away while the event is queued). */ } FileHandlerEvent; /* * The following static structure contains the state information for the * select based implementation of the Tcl notifier. One of these structures * is created for each thread that is using the notifier. */ typedef struct ThreadSpecificData { FileHandler *firstFileHandlerPtr; /* Pointer to head of file handler list. */ fd_mask checkMasks[3*MASK_SIZE]; /* This array is used to build up the masks * to be used in the next call to select. * Bits are set in response to calls to * Tcl_CreateFileHandler. */ fd_mask readyMasks[3*MASK_SIZE]; /* This array reflects the readable/writable * conditions that were found to exist by the * last call to select. */ int numFdBits; /* Number of valid bits in checkMasks * (one more than highest fd for which * Tcl_WatchFile has been called). */ #ifdef TCL_THREADS int onList; /* True if it is in this list */ unsigned int pollState; /* pollState is used to implement a polling * handshake between each thread and the * notifier thread. Bits defined below. */ struct ThreadSpecificData *nextPtr, *prevPtr; /* All threads that are currently waiting on * an event have their ThreadSpecificData * structure on a doubly-linked listed formed * from these pointers. You must hold the * notifierMutex lock before accessing these * fields. */ Tcl_Condition waitCV; /* Any other thread alerts a notifier * that an event is ready to be processed * by signaling this condition variable. */ int eventReady; /* True if an event is ready to be processed. * Used as condition flag together with * waitCV above. */ #endif } ThreadSpecificData; static Tcl_ThreadDataKey dataKey; #ifdef TCL_THREADS /* * The following static indicates the number of threads that have * initialized notifiers. * * You must hold the notifierMutex lock before accessing this variable. */ static int notifierCount = 0; /* * The following variable points to the head of a doubly-linked list of * of ThreadSpecificData structures for all threads that are currently * waiting on an event. * * You must hold the notifierMutex lock before accessing this list. */ static ThreadSpecificData *waitingListPtr = NULL; /* * The notifier thread spends all its time in select() waiting for a * file descriptor associated with one of the threads on the waitingListPtr * list to do something interesting. But if the contents of the * waitingListPtr list ever changes, we need to wake up and restart * the select() system call. You can wake up the notifier thread by * writing a single byte to the file descriptor defined below. This * file descriptor is the input-end of a pipe and the notifier thread is * listening for data on the output-end of the same pipe. Hence writing * to this file descriptor will cause the select() system call to return * and wake up the notifier thread. * * You must hold the notifierMutex lock before accessing this list. */ static int triggerPipe = -1; /* * The notifierMutex locks access to all of the global notifier state. */ TCL_DECLARE_MUTEX(notifierMutex) /* * The notifier thread signals the notifierCV when it has finished * initializing the triggerPipe and right before the notifier * thread terminates. */ static Tcl_Condition notifierCV; /* * The pollState bits * POLL_WANT is set by each thread before it waits on its condition * variable. It is checked by the notifier before it does * select. * POLL_DONE is set by the notifier if it goes into select after * seeing POLL_WANT. The idea is to ensure it tries a select * with the same bits the initial thread had set. */ #define POLL_WANT 0x1 #define POLL_DONE 0x2 /* * This is the thread ID of the notifier thread that does select. */ static Tcl_ThreadId notifierThread; #endif /* * Static routines defined in this file. */ #ifdef TCL_THREADS static void NotifierThreadProc _ANSI_ARGS_((ClientData clientData)); #endif static int FileHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr, int flags)); /* *---------------------------------------------------------------------- * * Tcl_InitNotifier -- * * Initializes the platform specific notifier state. * * Results: * Returns a handle to the notifier state for this thread.. * * Side effects: * None. * *---------------------------------------------------------------------- */ ClientData Tcl_InitNotifier() { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); #ifdef TCL_THREADS tsdPtr->eventReady = 0; /* * Start the Notifier thread if necessary. */ Tcl_MutexLock(¬ifierMutex); if (notifierCount == 0) { if (Tcl_CreateThread(¬ifierThread, NotifierThreadProc, NULL, TCL_THREAD_STACK_DEFAULT, TCL_THREAD_NOFLAGS) != TCL_OK) { panic("Tcl_InitNotifier: unable to start notifier thread"); } } notifierCount++; /* * Wait for the notifier pipe to be created. */ while (triggerPipe < 0) { Tcl_ConditionWait(¬ifierCV, ¬ifierMutex, NULL); } Tcl_MutexUnlock(¬ifierMutex); #endif return (ClientData) tsdPtr; } /* *---------------------------------------------------------------------- * * Tcl_FinalizeNotifier -- * * This function is called to cleanup the notifier state before * a thread is terminated. * * Results: * None. * * Side effects: * May terminate the background notifier thread if this is the * last notifier instance. * *---------------------------------------------------------------------- */ void Tcl_FinalizeNotifier(clientData) ClientData clientData; /* Not used. */ { #ifdef TCL_THREADS ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); Tcl_MutexLock(¬ifierMutex); notifierCount--; /* * If this is the last thread to use the notifier, close the notifier * pipe and wait for the background thread to terminate. */ if (notifierCount == 0) { if (triggerPipe < 0) { panic("Tcl_FinalizeNotifier: notifier pipe not initialized"); } /* * Send "q" message to the notifier thread so that it will * terminate. The notifier will return from its call to select() * and notice that a "q" message has arrived, it will then close * its side of the pipe and terminate its thread. Note the we can * not just close the pipe and check for EOF in the notifier * thread because if a background child process was created with * exec, select() would not register the EOF on the pipe until the * child processes had terminated. [Bug: 4139] */ write(triggerPipe, "q", 1); close(triggerPipe); Tcl_ConditionWait(¬ifierCV, ¬ifierMutex, NULL); } /* * Clean up any synchronization objects in the thread local storage. */ Tcl_ConditionFinalize(&(tsdPtr->waitCV)); Tcl_MutexUnlock(¬ifierMutex); #endif } /* *---------------------------------------------------------------------- * * Tcl_AlertNotifier -- * * Wake up the specified notifier from any thread. This routine * is called by the platform independent notifier code whenever * the Tcl_ThreadAlert routine is called. This routine is * guaranteed not to be called on a given notifier after * Tcl_FinalizeNotifier is called for that notifier. * * Results: * None. * * Side effects: * Signals the notifier condition variable for the specified * notifier. * *---------------------------------------------------------------------- */ void Tcl_AlertNotifier(clientData) ClientData clientData; { #ifdef TCL_THREADS ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData; Tcl_MutexLock(¬ifierMutex); tsdPtr->eventReady = 1; Tcl_ConditionNotify(&tsdPtr->waitCV); Tcl_MutexUnlock(¬ifierMutex); #endif } /* *---------------------------------------------------------------------- * * Tcl_SetTimer -- * * This procedure sets the current notifier timer value. This * interface is not implemented in this notifier because we are * always running inside of Tcl_DoOneEvent. * * Results: * None. * * Side effects: * None. * *---------------------------------------------------------------------- */ void Tcl_SetTimer(timePtr) Tcl_Time *timePtr; /* Timeout value, may be NULL. */ { /* * The interval timer doesn't do anything in this implementation, * because the only event loop is via Tcl_DoOneEvent, which passes * timeout values to Tcl_WaitForEvent. */ if (tclStubs.tcl_SetTimer != Tcl_SetTimer) { tclStubs.tcl_SetTimer(timePtr); } } /* *---------------------------------------------------------------------- * * Tcl_ServiceModeHook -- * * This function is invoked whenever the service mode changes. * * Results: * None. * * Side effects: * None. * *---------------------------------------------------------------------- */ void Tcl_ServiceModeHook(mode) int mode; /* Either TCL_SERVICE_ALL, or * TCL_SERVICE_NONE. */ { } /* *---------------------------------------------------------------------- * * Tcl_CreateFileHandler -- * * This procedure registers a file handler with the select notifier. * * Results: * None. * * Side effects: * Creates a new file handler structure. * *---------------------------------------------------------------------- */ void Tcl_CreateFileHandler(fd, mask, proc, clientData) int fd; /* Handle of stream to watch. */ int mask; /* OR'ed combination of TCL_READABLE, * TCL_WRITABLE, and TCL_EXCEPTION: * indicates conditions under which * proc should be called. */ Tcl_FileProc *proc; /* Procedure to call for each * selected event. */ ClientData clientData; /* Arbitrary data to pass to proc. */ { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); FileHandler *filePtr; int index, bit; if (tclStubs.tcl_CreateFileHandler != Tcl_CreateFileHandler) { tclStubs.tcl_CreateFileHandler(fd, mask, proc, clientData); return; } for (filePtr = tsdPtr->firstFileHandlerPtr; filePtr != NULL; filePtr = filePtr->nextPtr) { if (filePtr->fd == fd) { break; } } if (filePtr == NULL) { filePtr = (FileHandler*) ckalloc(sizeof(FileHandler)); filePtr->fd = fd; filePtr->readyMask = 0; filePtr->nextPtr = tsdPtr->firstFileHandlerPtr; tsdPtr->firstFileHandlerPtr = filePtr; } filePtr->proc = proc; filePtr->clientData = clientData; filePtr->mask = mask; /* * Update the check masks for this file. */ index = fd/(NBBY*sizeof(fd_mask)); bit = 1 << (fd%(NBBY*sizeof(fd_mask))); if (mask & TCL_READABLE) { tsdPtr->checkMasks[index] |= bit; } else { tsdPtr->checkMasks[index] &= ~bit; } if (mask & TCL_WRITABLE) { (tsdPtr->checkMasks+MASK_SIZE)[index] |= bit; } else { (tsdPtr->checkMasks+MASK_SIZE)[index] &= ~bit; } if (mask & TCL_EXCEPTION) { (tsdPtr->checkMasks+2*(MASK_SIZE))[index] |= bit; } else { (tsdPtr->checkMasks+2*(MASK_SIZE))[index] &= ~bit; } if (tsdPtr->numFdBits <= fd) { tsdPtr->numFdBits = fd+1; } } /* *---------------------------------------------------------------------- * * Tcl_DeleteFileHandler -- * * Cancel a previously-arranged callback arrangement for * a file. * * Results: * None. * * Side effects: * If a callback was previously registered on file, remove it. * *---------------------------------------------------------------------- */ void Tcl_DeleteFileHandler(fd) int fd; /* Stream id for which to remove callback procedure. */ { FileHandler *filePtr, *prevPtr; int index, bit, i; unsigned long flags; ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); if (tclStubs.tcl_DeleteFileHandler != Tcl_DeleteFileHandler) { tclStubs.tcl_DeleteFileHandler(fd); return; } /* * Find the entry for the given file (and return if there isn't one). */ for (prevPtr = NULL, filePtr = tsdPtr->firstFileHandlerPtr; ; prevPtr = filePtr, filePtr = filePtr->nextPtr) { if (filePtr == NULL) { return; } if (filePtr->fd == fd) { break; } } /* * Update the check masks for this file. */ index = fd/(NBBY*sizeof(fd_mask)); bit = 1 << (fd%(NBBY*sizeof(fd_mask))); if (filePtr->mask & TCL_READABLE) { tsdPtr->checkMasks[index] &= ~bit; } if (filePtr->mask & TCL_WRITABLE) { (tsdPtr->checkMasks+MASK_SIZE)[index] &= ~bit; } if (filePtr->mask & TCL_EXCEPTION) { (tsdPtr->checkMasks+2*(MASK_SIZE))[index] &= ~bit; } /* * Find current max fd. */ if (fd+1 == tsdPtr->numFdBits) { for (tsdPtr->numFdBits = 0; index >= 0; index--) { flags = tsdPtr->checkMasks[index] | (tsdPtr->checkMasks+MASK_SIZE)[index] | (tsdPtr->checkMasks+2*(MASK_SIZE))[index]; if (flags) { for (i = (NBBY*sizeof(fd_mask)); i > 0; i--) { if (flags & (((unsigned long)1) << (i-1))) { break; } } tsdPtr->numFdBits = index * (NBBY*sizeof(fd_mask)) + i; break; } } } /* * Clean up information in the callback record. */ if (prevPtr == NULL) { tsdPtr->firstFileHandlerPtr = filePtr->nextPtr; } else { prevPtr->nextPtr = filePtr->nextPtr; } ckfree((char *) filePtr); } /* *---------------------------------------------------------------------- * * FileHandlerEventProc -- * * This procedure is called by Tcl_ServiceEvent when a file event * reaches the front of the event queue. This procedure is * responsible for actually handling the event by invoking the * callback for the file handler. * * Results: * Returns 1 if the event was handled, meaning it should be removed * from the queue. Returns 0 if the event was not handled, meaning * it should stay on the queue. The only time the event isn't * handled is if the TCL_FILE_EVENTS flag bit isn't set. * * Side effects: * Whatever the file handler's callback procedure does. * *---------------------------------------------------------------------- */ static int FileHandlerEventProc(evPtr, flags) Tcl_Event *evPtr; /* Event to service. */ int flags; /* Flags that indicate what events to * handle, such as TCL_FILE_EVENTS. */ { int mask; FileHandler *filePtr; FileHandlerEvent *fileEvPtr = (FileHandlerEvent *) evPtr; ThreadSpecificData *tsdPtr; if (!(flags & TCL_FILE_EVENTS)) { return 0; } /* * Search through the file handlers to find the one whose handle matches * the event. We do this rather than keeping a pointer to the file * handler directly in the event, so that the handler can be deleted * while the event is queued without leaving a dangling pointer. */ tsdPtr = TCL_TSD_INIT(&dataKey); for (filePtr = tsdPtr->firstFileHandlerPtr; filePtr != NULL; filePtr = filePtr->nextPtr) { if (filePtr->fd != fileEvPtr->fd) { continue; } /* * The code is tricky for two reasons: * 1. The file handler's desired events could have changed * since the time when the event was queued, so AND the * ready mask with the desired mask. * 2. The file could have been closed and re-opened since * the time when the event was queued. This is why the * ready mask is stored in the file handler rather than * the queued event: it will be zeroed when a new * file handler is created for the newly opened file. */ mask = filePtr->readyMask & filePtr->mask; filePtr->readyMask = 0; if (mask != 0) { (*filePtr->proc)(filePtr->clientData, mask); } break; } return 1; } /* *---------------------------------------------------------------------- * * Tcl_WaitForEvent -- * * This function is called by Tcl_DoOneEvent to wait for new * events on the message queue. If the block time is 0, then * Tcl_WaitForEvent just polls without blocking. * * Results: * Returns -1 if the select would block forever, otherwise * returns 0. * * Side effects: * Queues file events that are detected by the select. * *---------------------------------------------------------------------- */ int Tcl_WaitForEvent(timePtr) Tcl_Time *timePtr; /* Maximum block time, or NULL. */ { FileHandler *filePtr; FileHandlerEvent *fileEvPtr; struct timeval timeout, *timeoutPtr; int bit, index, mask; #ifdef TCL_THREADS int waitForFiles; #else int numFound; #endif ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); if (tclStubs.tcl_WaitForEvent != Tcl_WaitForEvent) { return tclStubs.tcl_WaitForEvent(timePtr); } /* * Set up the timeout structure. Note that if there are no events to * check for, we return with a negative result rather than blocking * forever. */ if (timePtr) { timeout.tv_sec = timePtr->sec; timeout.tv_usec = timePtr->usec; timeoutPtr = &timeout; #ifndef TCL_THREADS } else if (tsdPtr->numFdBits == 0) { /* * If there are no threads, no timeout, and no fds registered, * then there are no events possible and we must avoid deadlock. * Note that this is not entirely correct because there might * be a signal that could interrupt the select call, but we * don't handle that case if we aren't using threads. */ return -1; #endif } else { timeoutPtr = NULL; } #ifdef TCL_THREADS /* * Place this thread on the list of interested threads, signal the * notifier thread, and wait for a response or a timeout. */ Tcl_MutexLock(¬ifierMutex); waitForFiles = (tsdPtr->numFdBits > 0); if (timePtr != NULL && timePtr->sec == 0 && timePtr->usec == 0) { /* * Cannot emulate a polling select with a polling condition variable. * Instead, pretend to wait for files and tell the notifier * thread what we are doing. The notifier thread makes sure * it goes through select with its select mask in the same state * as ours currently is. We block until that happens. */ waitForFiles = 1; tsdPtr->pollState = POLL_WANT; timePtr = NULL; } else { tsdPtr->pollState = 0; } if (waitForFiles) { /* * Add the ThreadSpecificData structure of this thread to the list * of ThreadSpecificData structures of all threads that are waiting * on file events. */ tsdPtr->nextPtr = waitingListPtr; if (waitingListPtr) { waitingListPtr->prevPtr = tsdPtr; } tsdPtr->prevPtr = 0; waitingListPtr = tsdPtr; tsdPtr->onList = 1; write(triggerPipe, "", 1); } memset((VOID *) tsdPtr->readyMasks, 0, 3*MASK_SIZE*sizeof(fd_mask)); if (!tsdPtr->eventReady) { Tcl_ConditionWait(&tsdPtr->waitCV, ¬ifierMutex, timePtr); } tsdPtr->eventReady = 0; if (waitForFiles && tsdPtr->onList) { /* * Remove the ThreadSpecificData structure of this thread from the * waiting list. Alert the notifier thread to recompute its select * masks - skipping this caused a hang when trying to close a pipe * which the notifier thread was still doing a select on. */ if (tsdPtr->prevPtr) { tsdPtr->prevPtr->nextPtr = tsdPtr->nextPtr; } else { waitingListPtr = tsdPtr->nextPtr; } if (tsdPtr->nextPtr) { tsdPtr->nextPtr->prevPtr = tsdPtr->prevPtr; } tsdPtr->nextPtr = tsdPtr->prevPtr = NULL; tsdPtr->onList = 0; write(triggerPipe, "", 1); } #else memcpy((VOID *) tsdPtr->readyMasks, (VOID *) tsdPtr->checkMasks, 3*MASK_SIZE*sizeof(fd_mask)); numFound = select(tsdPtr->numFdBits, (SELECT_MASK *) &tsdPtr->readyMasks[0], (SELECT_MASK *) &tsdPtr->readyMasks[MASK_SIZE], (SELECT_MASK *) &tsdPtr->readyMasks[2*MASK_SIZE], timeoutPtr); /* * Some systems don't clear the masks after an error, so * we have to do it here. */ if (numFound == -1) { memset((VOID *) tsdPtr->readyMasks, 0, 3*MASK_SIZE*sizeof(fd_mask)); } #endif /* * Queue all detected file events before returning. */ for (filePtr = tsdPtr->firstFileHandlerPtr; (filePtr != NULL); filePtr = filePtr->nextPtr) { index = filePtr->fd / (NBBY*sizeof(fd_mask)); bit = 1 << (filePtr->fd % (NBBY*sizeof(fd_mask))); mask = 0; if (tsdPtr->readyMasks[index] & bit) { mask |= TCL_READABLE; } if ((tsdPtr->readyMasks+MASK_SIZE)[index] & bit) { mask |= TCL_WRITABLE; } if ((tsdPtr->readyMasks+2*(MASK_SIZE))[index] & bit) { mask |= TCL_EXCEPTION; } if (!mask) { continue; } /* * Don't bother to queue an event if the mask was previously * non-zero since an event must still be on the queue. */ if (filePtr->readyMask == 0) { fileEvPtr = (FileHandlerEvent *) ckalloc( sizeof(FileHandlerEvent)); fileEvPtr->header.proc = FileHandlerEventProc; fileEvPtr->fd = filePtr->fd; Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL); } filePtr->readyMask = mask; } #ifdef TCL_THREADS Tcl_MutexUnlock(¬ifierMutex); #endif return 0; } #ifdef TCL_THREADS /* *---------------------------------------------------------------------- * * NotifierThreadProc -- * * This routine is the initial (and only) function executed by the * special notifier thread. Its job is to wait for file descriptors * to become readable or writable or to have an exception condition * and then to notify other threads who are interested in this * information by signalling a condition variable. Other threads * can signal this notifier thread of a change in their interests * by writing a single byte to a special pipe that the notifier * thread is monitoring. * * Result: * None. Once started, this routine never exits. It dies with * the overall process. * * Side effects: * The trigger pipe used to signal the notifier thread is created * when the notifier thread first starts. * *---------------------------------------------------------------------- */ static void NotifierThreadProc(clientData) ClientData clientData; /* Not used. */ { ThreadSpecificData *tsdPtr; fd_mask masks[3*MASK_SIZE]; long *maskPtr = (long *)masks; /* masks[] cast to type long[] */ int fds[2]; int i, status, index, bit, numFdBits, found, receivePipe, word; struct timeval poll = {0., 0.}, *timePtr; int maskSize = 3 * ((MASK_SIZE) / sizeof(long)) * sizeof(fd_mask); char buf[2]; if (pipe(fds) != 0) { panic("NotifierThreadProc: could not create trigger pipe."); } receivePipe = fds[0]; #ifndef USE_FIONBIO status = fcntl(receivePipe, F_GETFL); status |= O_NONBLOCK; if (fcntl(receivePipe, F_SETFL, status) < 0) { panic("NotifierThreadProc: could not make receive pipe non blocking."); } status = fcntl(fds[1], F_GETFL); status |= O_NONBLOCK; if (fcntl(fds[1], F_SETFL, status) < 0) { panic("NotifierThreadProc: could not make trigger pipe non blocking."); } #else if (ioctl(receivePipe, (int) FIONBIO, &status) < 0) { panic("NotifierThreadProc: could not make receive pipe non blocking."); } if (ioctl(fds[1], (int) FIONBIO, &status) < 0) { panic("NotifierThreadProc: could not make trigger pipe non blocking."); } #endif /* * Install the write end of the pipe into the global variable. */ Tcl_MutexLock(¬ifierMutex); triggerPipe = fds[1]; /* * Signal any threads that are waiting. */ Tcl_ConditionNotify(¬ifierCV); Tcl_MutexUnlock(¬ifierMutex); /* * Look for file events and report them to interested threads. */ while (1) { /* * Set up the select mask to include the receive pipe. */ memset((VOID *)masks, 0, 3*MASK_SIZE*sizeof(fd_mask)); numFdBits = receivePipe + 1; index = receivePipe / (NBBY*sizeof(fd_mask)); bit = 1 << (receivePipe % (NBBY*sizeof(fd_mask))); masks[index] |= bit; /* * Add in the check masks from all of the waiting notifiers. */ Tcl_MutexLock(¬ifierMutex); timePtr = NULL; for (tsdPtr = waitingListPtr; tsdPtr; tsdPtr = tsdPtr->nextPtr) { for (i = 0; i < maskSize; i++) { maskPtr[i] |= ((long*)tsdPtr->checkMasks)[i]; } if (tsdPtr->numFdBits > numFdBits) { numFdBits = tsdPtr->numFdBits; } if (tsdPtr->pollState & POLL_WANT) { /* * Here we make sure we go through select() with the same * mask bits that were present when the thread tried to poll. */ tsdPtr->pollState |= POLL_DONE; timePtr = &poll; } } Tcl_MutexUnlock(¬ifierMutex); maskSize = 3 * ((MASK_SIZE) / sizeof(long)) * sizeof(fd_mask); if (select(numFdBits, (SELECT_MASK *) &masks[0], (SELECT_MASK *) &masks[MASK_SIZE], (SELECT_MASK *) &masks[2*MASK_SIZE], timePtr) == -1) { /* * Try again immediately on an error. */ continue; } /* * Alert any threads that are waiting on a ready file descriptor. */ Tcl_MutexLock(¬ifierMutex); for (tsdPtr = waitingListPtr; tsdPtr; tsdPtr = tsdPtr->nextPtr) { found = 0; for (i = 0; i < maskSize; i++) { word = maskPtr[i] & ((long*)tsdPtr->checkMasks)[i]; found |= word; (((long*)(tsdPtr->readyMasks))[i]) = word; } if (found || (tsdPtr->pollState & POLL_DONE)) { tsdPtr->eventReady = 1; if (tsdPtr->onList) { /* * Remove the ThreadSpecificData structure of this * thread from the waiting list. This prevents us from * continuously spining on select until the other * threads runs and services the file event. */ if (tsdPtr->prevPtr) { tsdPtr->prevPtr->nextPtr = tsdPtr->nextPtr; } else { waitingListPtr = tsdPtr->nextPtr; } if (tsdPtr->nextPtr) { tsdPtr->nextPtr->prevPtr = tsdPtr->prevPtr; } tsdPtr->nextPtr = tsdPtr->prevPtr = NULL; tsdPtr->onList = 0; tsdPtr->pollState = 0; } Tcl_ConditionNotify(&tsdPtr->waitCV); } } Tcl_MutexUnlock(¬ifierMutex); /* * Consume the next byte from the notifier pipe if the pipe was * readable. Note that there may be multiple bytes pending, but * to avoid a race condition we only read one at a time. */ if (masks[index] & bit) { i = read(receivePipe, buf, 1); if ((i == 0) || ((i == 1) && (buf[0] == 'q'))) { /* * Someone closed the write end of the pipe or sent us a * Quit message [Bug: 4139] and then closed the write end * of the pipe so we need to shut down the notifier thread. */ break; } } } /* * Clean up the read end of the pipe and signal any threads waiting on * termination of the notifier thread. */ close(receivePipe); Tcl_MutexLock(¬ifierMutex); triggerPipe = -1; Tcl_ConditionNotify(¬ifierCV); Tcl_MutexUnlock(¬ifierMutex); } #endif