/* * tclMacOSXNotify.c -- * * This file contains the implementation of a merged CFRunLoop/select() * based 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. * Copyright 2001, Apple Computer, Inc. * Copyright (c) 2005 Tcl Core Team. * Copyright (c) 2005-2006 Daniel A. Steffen * * See the file "license.terms" for information on usage and redistribution of * this file, and for a DISCLAIMER OF ALL WARRANTIES. * * RCS: @(#) $Id: tclMacOSXNotify.c,v 1.1.2.10 2007/01/19 01:05:50 das Exp $ */ #include "tclInt.h" #include "tclPort.h" #ifdef HAVE_COREFOUNDATION /* Traditional unix select-based notifier is * in tclUnixNotfy.c */ #include #include 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). */ 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 * notifierLock before accessing these * fields. */ CFRunLoopSourceRef runLoopSource; /* Any other thread alerts a notifier that an * event is ready to be processed by signaling * this CFRunLoopSource. */ CFRunLoopRef runLoop; /* This thread's CFRunLoop, needs to be woken * up whenever the runLoopSource is * signaled. */ int eventReady; /* True if an event is ready to be * processed. */ } ThreadSpecificData; static Tcl_ThreadDataKey dataKey; /* * The following static indicates the number of threads that have initialized * notifiers. * * You must hold the notifierInitLock 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 notifierLock 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 notifierLock lock before writing to the pipe. */ static int triggerPipe = -1; static int receivePipe = -1; /* Output end of triggerPipe */ /* * We use Darwin-native spinlocks instead of pthread mutexes for notifier * locking: this radically simplifies the implementation and lowers overhead. * Note that these are not pure spinlocks, they employ various strategies to * back off, making them immune to most priority-inversion livelocks (c.f. man * 3 OSSpinLockLock). */ #if defined(HAVE_LIBKERN_OSATOMIC_H) && defined(HAVE_OSSPINLOCKLOCK) /* * Use OSSpinLock API where available (Tiger or later). */ #include #if defined(HAVE_WEAK_IMPORT) && MAC_OS_X_VERSION_MIN_REQUIRED < 1040 /* * Support for weakly importing spinlock API. */ #define WEAK_IMPORT_SPINLOCKLOCK #if MAC_OS_X_VERSION_MAX_ALLOWED >= 1050 #define VOLATILE volatile #else #define VOLATILE #endif extern void OSSpinLockLock(VOLATILE OSSpinLock *lock) WEAK_IMPORT_ATTRIBUTE; extern void OSSpinLockUnlock(VOLATILE OSSpinLock *lock) WEAK_IMPORT_ATTRIBUTE; extern void _spin_lock(VOLATILE OSSpinLock *lock) WEAK_IMPORT_ATTRIBUTE; extern void _spin_unlock(VOLATILE OSSpinLock *lock) WEAK_IMPORT_ATTRIBUTE; static void (* lockLock)(VOLATILE OSSpinLock *lock) = NULL; static void (* lockUnlock)(VOLATILE OSSpinLock *lock) = NULL; #undef VOLATILE static pthread_once_t spinLockLockInitControl = PTHREAD_ONCE_INIT; static void SpinLockLockInit(void) { lockLock = OSSpinLockLock != NULL ? OSSpinLockLock : _spin_lock; lockUnlock = OSSpinLockUnlock != NULL ? OSSpinLockUnlock : _spin_unlock; if (lockLock == NULL || lockUnlock == NULL) { Tcl_Panic("SpinLockLockInit: no spinlock API available"); } } #define SpinLockLock(p) lockLock(p) #define SpinLockUnlock(p) lockUnlock(p) #else #define SpinLockLock(p) OSSpinLockLock(p) #define SpinLockUnlock(p) OSSpinLockUnlock(p) #endif /* HAVE_WEAK_IMPORT */ #else /* * Otherwise, use commpage spinlock SPI directly. */ typedef uint32_t OSSpinLock; extern void _spin_lock(OSSpinLock *lock); extern void _spin_unlock(OSSpinLock *lock); #define SpinLockLock(p) _spin_lock(p) #define SpinLockUnlock(p) _spin_unlock(p) #endif /* HAVE_LIBKERN_OSATOMIC_H && HAVE_OSSPINLOCKLOCK */ /* * These spinlocks lock access to the global notifier state. */ static OSSpinLock notifierInitLock = 0; static OSSpinLock notifierLock = 0; /* * Macros abstracting notifier locking/unlocking */ #define LOCK_NOTIFIER_INIT SpinLockLock(¬ifierInitLock) #define UNLOCK_NOTIFIER_INIT SpinLockUnlock(¬ifierInitLock) #define LOCK_NOTIFIER SpinLockLock(¬ifierLock) #define UNLOCK_NOTIFIER SpinLockUnlock(¬ifierLock) /* * 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 pthread_t notifierThread; /* * Custom run loop mode containing only the run loop source for the * notifier thread. */ #ifndef TCL_EVENTS_ONLY_RUN_LOOP_MODE #define TCL_EVENTS_ONLY_RUN_LOOP_MODE "com.tcltk.tclEventsOnlyRunLoopMode" #endif #ifdef __CONSTANT_CFSTRINGS__ #define tclEventsOnlyRunLoopMode CFSTR(TCL_EVENTS_ONLY_RUN_LOOP_MODE) #else static CFStringRef tclEventsOnlyRunLoopMode = NULL; #endif /* * Static routines defined in this file. */ static void NotifierThreadProc(ClientData clientData); static int FileHandlerEventProc(Tcl_Event *evPtr, int flags); #ifdef HAVE_PTHREAD_ATFORK static int atForkInit = 0; static void AtForkPrepare(void); static void AtForkParent(void); static void AtForkChild(void); #if defined(HAVE_WEAK_IMPORT) && MAC_OS_X_VERSION_MIN_REQUIRED < 1040 /* Support for weakly importing pthread_atfork. */ #define WEAK_IMPORT_PTHREAD_ATFORK extern int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void)) WEAK_IMPORT_ATTRIBUTE; #endif /* HAVE_WEAK_IMPORT */ #endif /* HAVE_PTHREAD_ATFORK */ /* *---------------------------------------------------------------------- * * 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); tsdPtr->eventReady = 0; #ifdef WEAK_IMPORT_SPINLOCKLOCK /* * Initialize support for weakly imported spinlock API. */ if (pthread_once(&spinLockLockInitControl, SpinLockLockInit)) { Tcl_Panic("Tcl_InitNotifier: pthread_once failed"); } #endif #ifndef __CONSTANT_CFSTRINGS__ if (!tclEventsOnlyRunLoopMode) { tclEventsOnlyRunLoopMode = CFSTR(TCL_EVENTS_ONLY_RUN_LOOP_MODE); } #endif /* * Initialize CFRunLoopSource and add it to CFRunLoop of this thread. */ if (!tsdPtr->runLoop) { CFRunLoopRef runLoop = CFRunLoopGetCurrent(); CFRunLoopSourceRef runLoopSource; CFRunLoopSourceContext runLoopSourceContext; bzero(&runLoopSourceContext, sizeof(CFRunLoopSourceContext)); runLoopSourceContext.info = tsdPtr; runLoopSource = CFRunLoopSourceCreate(NULL, 0, &runLoopSourceContext); if (!runLoopSource) { Tcl_Panic("Tcl_InitNotifier: could not create CFRunLoopSource"); } CFRunLoopAddSource(runLoop, runLoopSource, kCFRunLoopCommonModes); CFRunLoopAddSource(runLoop, runLoopSource, tclEventsOnlyRunLoopMode); tsdPtr->runLoopSource = runLoopSource; tsdPtr->runLoop = runLoop; } LOCK_NOTIFIER_INIT; #ifdef HAVE_PTHREAD_ATFORK /* * Install pthread_atfork handlers to reinitialize the notifier in the * child of a fork. */ if ( #ifdef WEAK_IMPORT_PTHREAD_ATFORK pthread_atfork != NULL && #endif !atForkInit) { int result = pthread_atfork(AtForkPrepare, AtForkParent, AtForkChild); if (result) { Tcl_Panic("Tcl_InitNotifier: pthread_atfork failed"); } atForkInit = 1; } #endif if (notifierCount == 0) { int fds[2], status; /* * Initialize trigger pipe. */ if (pipe(fds) != 0) { Tcl_Panic("Tcl_InitNotifier: could not create trigger pipe"); } status = fcntl(fds[0], F_GETFL); status |= O_NONBLOCK; if (fcntl(fds[0], F_SETFL, status) < 0) { Tcl_Panic("Tcl_InitNotifier: 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("Tcl_InitNotifier: could not make trigger pipe non blocking"); } receivePipe = fds[0]; triggerPipe = fds[1]; /* * Create notifier thread lazily in Tcl_WaitForEvent() to avoid * interfering with fork() followed immediately by execve() * (cannot execve() when more than one thread is present). */ notifierThread = 0; } notifierCount++; UNLOCK_NOTIFIER_INIT; 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. */ { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); LOCK_NOTIFIER_INIT; 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); if (notifierThread) { result = pthread_join(notifierThread, NULL); if (result) { Tcl_Panic("Tcl_FinalizeNotifier: unable to join notifier thread"); } notifierThread = 0; } close(receivePipe); triggerPipe = -1; } UNLOCK_NOTIFIER_INIT; LOCK_NOTIFIER; /* for concurrency with Tcl_AlertNotifier */ if (tsdPtr->runLoop) { tsdPtr->runLoop = NULL; /* * Remove runLoopSource from all CFRunLoops and release it. */ CFRunLoopSourceInvalidate(tsdPtr->runLoopSource); CFRelease(tsdPtr->runLoopSource); tsdPtr->runLoopSource = NULL; } UNLOCK_NOTIFIER; } /* *---------------------------------------------------------------------- * * 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; { ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData; LOCK_NOTIFIER; if (tsdPtr->runLoop) { tsdPtr->eventReady = 1; CFRunLoopSourceSignal(tsdPtr->runLoopSource); CFRunLoopWakeUp(tsdPtr->runLoop); } UNLOCK_NOTIFIER; } /* *---------------------------------------------------------------------- * * 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(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 != 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(mode) 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(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; /* 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(fd) 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(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; int mask; int waitForFiles; ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); if (tclStubs.tcl_WaitForEvent != tclOriginalNotifier.waitForEventProc) { return tclStubs.tcl_WaitForEvent(timePtr); } /* * Start notifier thread if necessary. */ LOCK_NOTIFIER_INIT; if (!notifierThread) { int result; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM); pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE); pthread_attr_setstacksize(&attr, 60 * 1024); result = pthread_create(¬ifierThread, &attr, (void * (*)(void *))NotifierThreadProc, NULL); pthread_attr_destroy(&attr); if (result || !notifierThread) { Tcl_Panic("Tcl_WaitForEvent: unable to start notifier thread"); } } UNLOCK_NOTIFIER_INIT; /* * Place this thread on the list of interested threads, signal the * notifier thread, and wait for a response or a timeout. */ LOCK_NOTIFIER; 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); } FD_ZERO(&(tsdPtr->readyMasks.readable)); FD_ZERO(&(tsdPtr->readyMasks.writable)); FD_ZERO(&(tsdPtr->readyMasks.exceptional)); if (!tsdPtr->eventReady) { CFTimeInterval waitTime; CFStringRef runLoopMode; if (timePtr == NULL) { waitTime = 1.0e10; /* Wait forever, as per CFRunLoop.c */ } else { waitTime = timePtr->sec + 1.0e-6 * timePtr->usec; } /* * If the run loop is already running (e.g. if Tcl_WaitForEvent was * called recursively), re-run it in a custom run loop mode containing * only the source for the notifier thread, otherwise wakeups from other * sources added to the common run loop modes might get lost. */ if ((runLoopMode = CFRunLoopCopyCurrentMode(tsdPtr->runLoop))) { CFRelease(runLoopMode); runLoopMode = tclEventsOnlyRunLoopMode; } else { runLoopMode = kCFRunLoopDefaultMode; } UNLOCK_NOTIFIER; CFRunLoopRunInMode(runLoopMode, waitTime, TRUE); LOCK_NOTIFIER; } 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); } /* * 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; } UNLOCK_NOTIFIER; return 0; } /* *---------------------------------------------------------------------- * * 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_set readableMask; fd_set writableMask; fd_set exceptionalMask; int i, numFdBits = 0; long found; struct timeval poll = {0., 0.}, *timePtr; char buf[2]; /* * 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. */ LOCK_NOTIFIER; 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; } } UNLOCK_NOTIFIER; /* * 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. */ LOCK_NOTIFIER; 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; } if (tsdPtr->runLoop) { CFRunLoopSourceSignal(tsdPtr->runLoopSource); CFRunLoopWakeUp(tsdPtr->runLoop); } } } UNLOCK_NOTIFIER; /* * 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; } } } pthread_exit (0); } #ifdef HAVE_PTHREAD_ATFORK /* *---------------------------------------------------------------------- * * AtForkPrepare -- * * Lock the notifier in preparation for a fork. * * Results: * None. * * Side effects: * None. * *---------------------------------------------------------------------- */ static void AtForkPrepare(void) { LOCK_NOTIFIER_INIT; LOCK_NOTIFIER; } /* *---------------------------------------------------------------------- * * AtForkParent -- * * Unlock the notifier in the parent after a fork. * * Results: * None. * * Side effects: * None. * *---------------------------------------------------------------------- */ static void AtForkParent(void) { UNLOCK_NOTIFIER; UNLOCK_NOTIFIER_INIT; } /* *---------------------------------------------------------------------- * * AtForkChild -- * * Unlock and reinstall the notifier in the child after a fork. * * Results: * None. * * Side effects: * None. * *---------------------------------------------------------------------- */ static void AtForkChild(void) { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); UNLOCK_NOTIFIER; UNLOCK_NOTIFIER_INIT; if (tsdPtr->runLoop) { tsdPtr->runLoop = NULL; CFRunLoopSourceInvalidate(tsdPtr->runLoopSource); CFRelease(tsdPtr->runLoopSource); tsdPtr->runLoopSource = NULL; } if (notifierCount > 0) { notifierCount = 0; /* * Assume that the return value of Tcl_InitNotifier in the child will * be identical to the one stored as clientData in tclNotify.c's * ThreadSpecificData by the parent's TclInitNotifier, so discard the * return value here. This assumption may require the fork() to be * executed in the main thread of the parent, otherwise * Tcl_AlertNotifier may break in the child. */ Tcl_InitNotifier(); } } #endif /* HAVE_PTHREAD_ATFORK */ #endif /* HAVE_COREFOUNDATION */