tclUnixNotfy.c Go to the documentation of this file. /* * 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: @(#) $Id: tclUnixNotfy.c,v 1.32 2006/08/21 01:08:03 das Exp $ */ #include "tclInt.h" #ifndef HAVE_COREFOUNDATION /* Darwin/Mac OS X CoreFoundation notifier is * in tclMacOSXNotify.c */ #include <signal.h> /* * This code does deep stub magic to allow replacement of the notifier at * runtime. */ extern TclStubs tclStubs; extern Tcl_NotifierProcs tclOriginalNotifier; /* * This structure is used to keep track of the notifier info for 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; /* Function 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 structure contains a set of select() masks to track readable, * writable, and exceptional conditions. */ typedef struct SelectMasks { fd_set readable; fd_set writable; fd_set exceptional; } SelectMasks; /* * 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. */ SelectMasks checkMasks; /* This structure 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. */ SelectMasks readyMasks; /* 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 * 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(ClientData clientData); #endif static int FileHandlerEventProc(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(void) { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); #ifdef TCL_THREADS tsdPtr->eventReady = 0; /* * Start the Notifier thread if necessary. */ Tcl_MutexLock(&notifierMutex); if (notifierCount == 0) { if (TclpThreadCreate(&notifierThread, NotifierThreadProc, NULL, TCL_THREAD_STACK_DEFAULT, TCL_THREAD_JOINABLE) != TCL_OK) { Tcl_Panic("Tcl_InitNotifier: unable to start notifier thread"); } } notifierCount++; /* * Wait for the notifier pipe to be created. */ while (triggerPipe < 0) { Tcl_ConditionWait(&notifierCV, &notifierMutex, NULL); } Tcl_MutexUnlock(&notifierMutex); #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) /* Not used. */ { #ifdef TCL_THREADS ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); Tcl_MutexLock(&notifierMutex); 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) { int result; if (triggerPipe < 0) { Tcl_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] [Bug: 1222872] */ write(triggerPipe, "q", 1); close(triggerPipe); while(triggerPipe >= 0) { Tcl_ConditionWait(&notifierCV, &notifierMutex, NULL); } result = Tcl_JoinThread(notifierThread, NULL); if (result) { Tcl_Panic("Tcl_FinalizeNotifier: unable to join notifier thread"); } } /* * Clean up any synchronization objects in the thread local storage. */ Tcl_ConditionFinalize(&(tsdPtr->waitCV)); Tcl_MutexUnlock(&notifierMutex); #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) { #ifdef TCL_THREADS ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData; Tcl_MutexLock(&notifierMutex); tsdPtr->eventReady = 1; Tcl_ConditionNotify(&tsdPtr->waitCV); Tcl_MutexUnlock(&notifierMutex); #endif }  /* *---------------------------------------------------------------------- * * Tcl_SetTimer -- * * This function 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( 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 != tclOriginalNotifier.setTimerProc) { tclStubs.tcl_SetTimer(timePtr); } }  /* *---------------------------------------------------------------------- * * Tcl_ServiceModeHook -- * * This function is invoked whenever the service mode changes. * * Results: * None. * * Side effects: * None. * *---------------------------------------------------------------------- */ void Tcl_ServiceModeHook( int mode) /* Either TCL_SERVICE_ALL, or * TCL_SERVICE_NONE. */ { }  /* *---------------------------------------------------------------------- * * Tcl_CreateFileHandler -- * * This function registers a file handler with the select notifier. * * Results: * None. * * Side effects: * Creates a new file handler structure. * *---------------------------------------------------------------------- */ void Tcl_CreateFileHandler( 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, /* Function to call for each selected * event. */ ClientData clientData) /* Arbitrary data to pass to proc. */ { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); FileHandler *filePtr; if (tclStubs.tcl_CreateFileHandler != tclOriginalNotifier.createFileHandlerProc) { 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. */ if (mask & TCL_READABLE) { FD_SET(fd, &(tsdPtr->checkMasks.readable)); } else { FD_CLR(fd, &(tsdPtr->checkMasks.readable)); } if (mask & TCL_WRITABLE) { FD_SET(fd, &(tsdPtr->checkMasks.writable)); } else { FD_CLR(fd, &(tsdPtr->checkMasks.writable)); } if (mask & TCL_EXCEPTION) { FD_SET(fd, &(tsdPtr->checkMasks.exceptional)); } else { FD_CLR(fd, &(tsdPtr->checkMasks.exceptional)); } 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( int fd) /* Stream id for which to remove callback * function. */ { FileHandler *filePtr, *prevPtr; int i; ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); if (tclStubs.tcl_DeleteFileHandler != tclOriginalNotifier.deleteFileHandlerProc) { 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. */ if (filePtr->mask & TCL_READABLE) { FD_CLR(fd, &(tsdPtr->checkMasks.readable)); } if (filePtr->mask & TCL_WRITABLE) { FD_CLR(fd, &(tsdPtr->checkMasks.writable)); } if (filePtr->mask & TCL_EXCEPTION) { FD_CLR(fd, &(tsdPtr->checkMasks.exceptional)); } /* * Find current max fd. */ if (fd+1 == tsdPtr->numFdBits) { tsdPtr->numFdBits = 0; for (i = fd-1; i >= 0; i--) { if (FD_ISSET(i, &(tsdPtr->checkMasks.readable)) || FD_ISSET(i, &(tsdPtr->checkMasks.writable)) || FD_ISSET(i, &(tsdPtr->checkMasks.exceptional))) { tsdPtr->numFdBits = i+1; 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 function is called by Tcl_ServiceEvent when a file event reaches * the front of the event queue. This function 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 function does. * *---------------------------------------------------------------------- */ static int FileHandlerEventProc( 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( Tcl_Time *timePtr) /* Maximum block time, or NULL. */ { FileHandler *filePtr; FileHandlerEvent *fileEvPtr; int mask; Tcl_Time myTime; #ifdef TCL_THREADS int waitForFiles; Tcl_Time *myTimePtr; #else /* * Impl. notes: timeout & timeoutPtr are used if, and only if threads are * not enabled. They are the arguments for the regular select() used when * the core is not thread-enabled. */ struct timeval timeout, *timeoutPtr; int numFound; #endif /* TCL_THREADS */ ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); if (tclStubs.tcl_WaitForEvent != tclOriginalNotifier.waitForEventProc) { 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 != NULL) { /* * TIP #233 (Virtualized Time). Is virtual time in effect? And do we * actually have something to scale? If yes to both then we call the * handler to do this scaling. */ myTime.sec = timePtr->sec; myTime.usec = timePtr->usec; if (myTime.sec != 0 || myTime.usec != 0) { (*tclScaleTimeProcPtr) (&myTime, tclTimeClientData); } #ifdef TCL_THREADS myTimePtr = &myTime; #else timeout.tv_sec = myTime.sec; timeout.tv_usec = myTime.usec; timeoutPtr = &timeout; #endif /* TCL_THREADS */ #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 /* !TCL_THREADS */ } else { #ifdef TCL_THREADS myTimePtr = NULL; #else timeoutPtr = NULL; #endif /* TCL_THREADS */ } #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(&notifierMutex); waitForFiles = (tsdPtr->numFdBits > 0); if (myTimePtr != NULL && myTimePtr->sec == 0 && (myTimePtr->usec == 0 #if defined(__APPLE__) && defined(__LP64__) /* * On 64-bit Darwin, pthread_cond_timedwait() appears to have a bug * that causes it to wait forever when passed an absolute time which * has already been exceeded by the system time; as a workaround, * when given a very brief timeout, just do a poll. [Bug 1457797] */ || myTimePtr->usec < 10 #endif )) { /* * 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; myTimePtr = 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); } FD_ZERO(&(tsdPtr->readyMasks.readable)); FD_ZERO(&(tsdPtr->readyMasks.writable)); FD_ZERO(&(tsdPtr->readyMasks.exceptional)); if (!tsdPtr->eventReady) { Tcl_ConditionWait(&tsdPtr->waitCV, &notifierMutex, myTimePtr); } 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 tsdPtr->readyMasks = tsdPtr->checkMasks; numFound = select(tsdPtr->numFdBits, &(tsdPtr->readyMasks.readable), &(tsdPtr->readyMasks.writable), &(tsdPtr->readyMasks.exceptional), timeoutPtr); /* * Some systems don't clear the masks after an error, so we have to do it * here. */ if (numFound == -1) { FD_ZERO(&(tsdPtr->readyMasks.readable)); FD_ZERO(&(tsdPtr->readyMasks.writable)); FD_ZERO(&(tsdPtr->readyMasks.exceptional)); } #endif /* TCL_THREADS */ /* * Queue all detected file events before returning. */ for (filePtr = tsdPtr->firstFileHandlerPtr; (filePtr != NULL); filePtr = filePtr->nextPtr) { mask = 0; if (FD_ISSET(filePtr->fd, &(tsdPtr->readyMasks.readable))) { mask |= TCL_READABLE; } if (FD_ISSET(filePtr->fd, &(tsdPtr->readyMasks.writable))) { mask |= TCL_WRITABLE; } if (FD_ISSET(filePtr->fd, &(tsdPtr->readyMasks.exceptional))) { 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(&notifierMutex); #endif /* TCL_THREADS */ 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) /* Not used. */ { ThreadSpecificData *tsdPtr; fd_set readableMask; fd_set writableMask; fd_set exceptionalMask; int fds[2]; int i, status, numFdBits = 0, receivePipe; long found; struct timeval poll = {0., 0.}, *timePtr; char buf[2]; if (pipe(fds) != 0) { Tcl_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) { Tcl_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) { Tcl_Panic("NotifierThreadProc: could not make trigger pipe non blocking"); } #else if (ioctl(receivePipe, (int) FIONBIO, &status) < 0) { Tcl_Panic("NotifierThreadProc: could not make receive pipe non blocking"); } if (ioctl(fds[1], (int) FIONBIO, &status) < 0) { Tcl_Panic("NotifierThreadProc: could not make trigger pipe non blocking"); } #endif /* FIONBIO */ /* * Install the write end of the pipe into the global variable. */ Tcl_MutexLock(&notifierMutex); triggerPipe = fds[1]; /* * Signal any threads that are waiting. */ Tcl_ConditionNotify(&notifierCV); Tcl_MutexUnlock(&notifierMutex); /* * Look for file events and report them to interested threads. */ while (1) { FD_ZERO(&readableMask); FD_ZERO(&writableMask); FD_ZERO(&exceptionalMask); /* * Compute the logical OR of the select masks from all the waiting * notifiers. */ Tcl_MutexLock(&notifierMutex); timePtr = NULL; for (tsdPtr = waitingListPtr; tsdPtr; tsdPtr = tsdPtr->nextPtr) { for (i = tsdPtr->numFdBits-1; i >= 0; --i) { if (FD_ISSET(i, &(tsdPtr->checkMasks.readable))) { FD_SET(i, &readableMask); } if (FD_ISSET(i, &(tsdPtr->checkMasks.writable))) { FD_SET(i, &writableMask); } if (FD_ISSET(i, &(tsdPtr->checkMasks.exceptional))) { FD_SET(i, &exceptionalMask); } } 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(&notifierMutex); /* * Set up the select mask to include the receive pipe. */ if (receivePipe >= numFdBits) { numFdBits = receivePipe + 1; } FD_SET(receivePipe, &readableMask); if (select(numFdBits, &readableMask, &writableMask, &exceptionalMask, timePtr) == -1) { /* * Try again immediately on an error. */ continue; } /* * Alert any threads that are waiting on a ready file descriptor. */ Tcl_MutexLock(&notifierMutex); for (tsdPtr = waitingListPtr; tsdPtr; tsdPtr = tsdPtr->nextPtr) { found = 0; for (i = tsdPtr->numFdBits-1; i >= 0; --i) { if (FD_ISSET(i, &(tsdPtr->checkMasks.readable)) && FD_ISSET(i, &readableMask)) { FD_SET(i, &(tsdPtr->readyMasks.readable)); found = 1; } if (FD_ISSET(i, &(tsdPtr->checkMasks.writable)) && FD_ISSET(i, &writableMask)) { FD_SET(i, &(tsdPtr->readyMasks.writable)); found = 1; } if (FD_ISSET(i, &(tsdPtr->checkMasks.exceptional)) && FD_ISSET(i, &exceptionalMask)) { FD_SET(i, &(tsdPtr->readyMasks.exceptional)); found = 1; } } 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(&notifierMutex); /* * 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 (FD_ISSET(receivePipe, &readableMask)) { 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(&notifierMutex); triggerPipe = -1; Tcl_ConditionNotify(&notifierCV); Tcl_MutexUnlock(&notifierMutex); TclpThreadExit (0); } #endif /* TCL_THREADS */ #endif /* HAVE_COREFOUNDATION */  /* * Local Variables: * mode: c * c-basic-offset: 4 * fill-column: 78 * End: */

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