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+/*
+ * 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 2005, Tcl Core Team.
+ *
+ * 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 1.1.2.2 2005/05/14 20:52:31 das Exp $
+ */
+
+#ifdef HAVE_COREFOUNDATION /* Traditional unix select-based notifier
+ * is in tclUnixNotfy.c */
+#include "tclInt.h"
+#include "tclPort.h"
+#include <CoreFoundation/CoreFoundation.h>
+#include <pthread.h>
+
+extern TclStubs tclStubs;
+extern Tcl_NotifierProcs tclOriginalNotifier;
+
+/*
+ * 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 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
+ * 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 <libkern/OSAtomic.h>
+#else
+/* Otherwise, use commpage spinlock SPI directly */
+typedef uint32_t OSSpinLock;
+extern void _spin_lock(OSSpinLock *lock);
+extern void _spin_unlock(OSSpinLock *lock);
+#define OSSpinLockLock(p) _spin_lock(p)
+#define OSSpinLockUnlock(p) _spin_unlock(p)
+#endif
+
+/*
+ * 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 OSSpinLockLock(&notifierInitLock)
+#define UNLOCK_NOTIFIER_INIT OSSpinLockUnlock(&notifierInitLock)
+#define LOCK_NOTIFIER OSSpinLockLock(&notifierLock)
+#define UNLOCK_NOTIFIER OSSpinLockUnlock(&notifierLock)
+
+/*
+ * 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;
+
+/*
+ * Static routines defined in this file.
+ */
+
+static void NotifierThreadProc(ClientData clientData);
+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()
+{
+ ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+
+ tsdPtr->eventReady = 0;
+
+ /*
+ * 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);
+ CFRelease(runLoopSource);
+ tsdPtr->runLoopSource = runLoopSource;
+ tsdPtr->runLoop = runLoop;
+ }
+
+ /*
+ * Initialize trigger pipe and start the Notifier thread if necessary.
+ */
+
+ LOCK_NOTIFIER_INIT;
+ if (notifierCount == 0) {
+ int fds[2], status, result;
+ pthread_attr_t attr;
+
+ 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];
+
+ 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(&notifierThread, &attr, (void * (*)(void *))NotifierThreadProc, NULL);
+ pthread_attr_destroy(&attr);
+ if (result) {
+ Tcl_Panic("Tcl_InitNotifier: unable to start notifier thread.");
+ }
+ }
+ 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]
+ */
+ write(triggerPipe, "q", 1);
+ close(triggerPipe);
+
+ result = pthread_join(notifierThread, NULL);
+ if (result) {
+ Tcl_Panic("Tcl_FinalizeNotifier: unable to join notifier thread.");
+ }
+
+ 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);
+ 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 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 != 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 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;
+
+ 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 procedure. */
+{
+ 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 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;
+ int mask;
+ int waitForFiles;
+ ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+
+ if (tclStubs.tcl_WaitForEvent != tclOriginalNotifier.waitForEventProc) {
+ return tclStubs.tcl_WaitForEvent(timePtr);
+ }
+
+ /*
+ * 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;
+
+ if (timePtr == NULL) {
+ waitTime = 1.0e10; /* Wait forever, as per CFRunLoop.c */
+ } else {
+ waitTime = timePtr->sec + 1.0e-6 * timePtr->usec;
+ }
+ UNLOCK_NOTIFIER;
+ CFRunLoopRunInMode(kCFRunLoopDefaultMode, 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);
+}
+
+#endif /* HAVE_COREFOUNDATION */