/* * tclSelectNotfy.c -- * * This file contains the implementation of the select()-based generic * Unix notifier, which is the lowest-level part of the Tcl event loop. * This file works together with generic/tclNotify.c. * * Copyright © 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. */ #include "tclInt.h" #ifndef HAVE_COREFOUNDATION /* Darwin/Mac OS X CoreFoundation notifier is * in tclMacOSXNotify.c */ #if (!defined(NOTIFIER_EPOLL) && !defined(NOTIFIER_KQUEUE)) || !TCL_THREADS #include /* * 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 contains a set of select() masks to track readable, * writable, and exception conditions. */ typedef struct { fd_set readable; fd_set writable; fd_set exception; } SelectMasks; /* * The following structure is what is added to the Tcl event queue when file * handlers are ready to fire. */ typedef struct { 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. */ 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). */ #if 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. */ #ifdef __CYGWIN__ void *event; /* Any other thread alerts a notifier that an * event is ready to be processed by sending * this event. */ void *hwnd; /* Messaging window. */ #else /* !__CYGWIN__ */ pthread_cond_t waitCV; /* Any other thread alerts a notifier that an * event is ready to be processed by signaling * this condition variable. */ #endif /* __CYGWIN__ */ int waitCVinitialized; /* Variable to flag initialization of the * structure. */ int eventReady; /* True if an event is ready to be processed. * Used as condition flag together with waitCV * above. */ #endif /* TCL_THREADS */ } ThreadSpecificData; static Tcl_ThreadDataKey dataKey; #if 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 writing to the pipe. */ static int triggerPipe = -1; /* * The notifierMutex locks access to all of the global notifier state. */ static pthread_mutex_t notifierInitMutex = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t notifierMutex = PTHREAD_MUTEX_INITIALIZER; /* * The following static indicates if the notifier thread is running. * * You must hold the notifierInitMutex before accessing this variable. */ static int notifierThreadRunning = 0; /* * The notifier thread signals the notifierCV when it has finished * initializing the triggerPipe and right before the notifier thread * terminates. */ static pthread_cond_t notifierCV = PTHREAD_COND_INITIALIZER; /* * 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 /* TCL_THREADS */ /* * Static routines defined in this file. */ #if TCL_THREADS static TCL_NORETURN void NotifierThreadProc(ClientData clientData); #if defined(HAVE_PTHREAD_ATFORK) static int atForkInit = 0; static void AtForkChild(void); #endif /* HAVE_PTHREAD_ATFORK */ #endif /* TCL_THREADS */ static int FileHandlerEventProc(Tcl_Event *evPtr, int flags); /* * Import of critical bits of Windows API when building threaded with Cygwin. */ #if defined(__CYGWIN__) #ifdef __cplusplus extern "C" { #endif typedef struct { void *hwnd; /* Messaging window. */ unsigned int *message; /* Message payload. */ size_t wParam; /* Event-specific "word" parameter. */ size_t lParam; /* Event-specific "long" parameter. */ int time; /* Event timestamp. */ int x; /* Event location (where meaningful). */ int y; int lPrivate; } MSG; typedef struct { unsigned int style; void *lpfnWndProc; int cbClsExtra; int cbWndExtra; void *hInstance; void *hIcon; void *hCursor; void *hbrBackground; const void *lpszMenuName; const void *lpszClassName; } WNDCLASSW; #ifdef __clang__ #pragma clang diagnostic ignored "-Wignored-attributes" #endif extern void __stdcall CloseHandle(void *); extern void *__stdcall CreateEventW(void *, unsigned char, unsigned char, void *); extern void *__stdcall CreateWindowExW(void *, const void *, const void *, unsigned int, int, int, int, int, void *, void *, void *, void *); extern unsigned int __stdcall DefWindowProcW(void *, int, void *, void *); extern unsigned char __stdcall DestroyWindow(void *); extern int __stdcall DispatchMessageW(const MSG *); extern unsigned char __stdcall GetMessageW(MSG *, void *, int, int); extern void __stdcall MsgWaitForMultipleObjects(unsigned int, void *, unsigned char, unsigned int, unsigned int); extern unsigned char __stdcall PeekMessageW(MSG *, void *, int, int, int); extern unsigned char __stdcall PostMessageW(void *, unsigned int, void *, void *); extern void __stdcall PostQuitMessage(int); extern void *__stdcall RegisterClassW(const WNDCLASSW *); extern unsigned char __stdcall ResetEvent(void *); extern unsigned char __stdcall TranslateMessage(const MSG *); /* * Threaded-cygwin specific constants and functions in this file: */ static const wchar_t className[] = L"TclNotifier"; static unsigned int __stdcall NotifierProc(void *hwnd, unsigned int message, void *wParam, void *lParam); #ifdef __cplusplus } #endif #endif /* TCL_THREADS && __CYGWIN__ */ #include "tclUnixNotfy.c" /* *---------------------------------------------------------------------- * * 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) { if (tclNotifierHooks.initNotifierProc) { return tclNotifierHooks.initNotifierProc(); } else { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); #if TCL_THREADS tsdPtr->eventReady = 0; /* * Initialize thread specific condition variable for this thread. */ if (tsdPtr->waitCVinitialized == 0) { #ifdef __CYGWIN__ WNDCLASSW clazz; clazz.style = 0; clazz.cbClsExtra = 0; clazz.cbWndExtra = 0; clazz.hInstance = TclWinGetTclInstance(); clazz.hbrBackground = NULL; clazz.lpszMenuName = NULL; clazz.lpszClassName = className; clazz.lpfnWndProc = (void *)NotifierProc; clazz.hIcon = NULL; clazz.hCursor = NULL; RegisterClassW(&clazz); tsdPtr->hwnd = CreateWindowExW(NULL, clazz.lpszClassName, clazz.lpszClassName, 0, 0, 0, 0, 0, NULL, NULL, clazz.hInstance, NULL); tsdPtr->event = CreateEventW(NULL, 1 /* manual */, 0 /* !signaled */, NULL); #else pthread_cond_init(&tsdPtr->waitCV, NULL); #endif /* __CYGWIN__ */ tsdPtr->waitCVinitialized = 1; } pthread_mutex_lock(¬ifierInitMutex); #if defined(HAVE_PTHREAD_ATFORK) /* * Install pthread_atfork handlers to clean up the notifier in the * child of a fork. */ if (!atForkInit) { int result = pthread_atfork(NULL, NULL, AtForkChild); if (result) { Tcl_Panic("Tcl_InitNotifier: pthread_atfork failed"); } atForkInit = 1; } #endif /* HAVE_PTHREAD_ATFORK */ notifierCount++; pthread_mutex_unlock(¬ifierInitMutex); #endif /* TCL_THREADS */ return 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) { if (tclNotifierHooks.finalizeNotifierProc) { tclNotifierHooks.finalizeNotifierProc(clientData); return; } else { #if TCL_THREADS ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); pthread_mutex_lock(¬ifierInitMutex); 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 && triggerPipe != -1) { if (write(triggerPipe, "q", 1) != 1) { Tcl_Panic("Tcl_FinalizeNotifier: %s", "unable to write 'q' to triggerPipe"); } close(triggerPipe); pthread_mutex_lock(¬ifierMutex); while(triggerPipe != -1) { pthread_cond_wait(¬ifierCV, ¬ifierMutex); } pthread_mutex_unlock(¬ifierMutex); if (notifierThreadRunning) { int result = pthread_join((pthread_t) notifierThread, NULL); if (result) { Tcl_Panic("Tcl_FinalizeNotifier: %s", "unable to join notifier thread"); } notifierThreadRunning = 0; } } /* * Clean up any synchronization objects in the thread local storage. */ #ifdef __CYGWIN__ DestroyWindow(tsdPtr->hwnd); CloseHandle(tsdPtr->event); #else /* __CYGWIN__ */ pthread_cond_destroy(&tsdPtr->waitCV); #endif /* __CYGWIN__ */ tsdPtr->waitCVinitialized = 0; pthread_mutex_unlock(¬ifierInitMutex); #endif /* TCL_THREADS */ } } /* *---------------------------------------------------------------------- * * 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. */ { if (tclNotifierHooks.createFileHandlerProc) { tclNotifierHooks.createFileHandlerProc(fd, mask, proc, clientData); return; } else { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); FileHandler *filePtr; for (filePtr = tsdPtr->firstFileHandlerPtr; filePtr != NULL; filePtr = filePtr->nextPtr) { if (filePtr->fd == fd) { break; } } if (filePtr == NULL) { filePtr = (FileHandler *)Tcl_Alloc(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.exception); } else { FD_CLR(fd, &tsdPtr->checkMasks.exception); } 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. */ { if (tclNotifierHooks.deleteFileHandlerProc) { tclNotifierHooks.deleteFileHandlerProc(fd); return; } else { FileHandler *filePtr, *prevPtr; int i; ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); /* * 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.exception); } /* * Find current max fd. */ if (fd+1 == tsdPtr->numFdBits) { int 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.exception)) { numFdBits = i+1; break; } } tsdPtr->numFdBits = numFdBits; } /* * Clean up information in the callback record. */ if (prevPtr == NULL) { tsdPtr->firstFileHandlerPtr = filePtr->nextPtr; } else { prevPtr->nextPtr = filePtr->nextPtr; } Tcl_Free(filePtr); } } #if defined(__CYGWIN__) static unsigned int __stdcall NotifierProc( void *hwnd, unsigned int message, void *wParam, void *lParam) { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); if (message != 1024) { return DefWindowProcW(hwnd, message, wParam, lParam); } /* * Process all of the runnable events. */ tsdPtr->eventReady = 1; Tcl_ServiceAll(); return 0; } #endif /* TCL_THREADS && __CYGWIN__ */ /* *---------------------------------------------------------------------- * * 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( const Tcl_Time *timePtr) /* Maximum block time, or NULL. */ { if (tclNotifierHooks.waitForEventProc) { return tclNotifierHooks.waitForEventProc(timePtr); } else { FileHandler *filePtr; int mask; Tcl_Time vTime; ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); #if TCL_THREADS int waitForFiles; # ifdef __CYGWIN__ MSG msg; # endif /* __CYGWIN__ */ #else /* !TCL_THREADS */ /* * 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 */ /* * 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. */ if (timePtr->sec != 0 || timePtr->usec != 0) { vTime = *timePtr; tclScaleTimeProcPtr(&vTime, tclTimeClientData); timePtr = &vTime; } #if !TCL_THREADS timeout.tv_sec = timePtr->sec; timeout.tv_usec = timePtr->usec; timeoutPtr = &timeout; } 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; } else { timeoutPtr = NULL; #endif /* !TCL_THREADS */ } #if TCL_THREADS /* * Start notifier thread and place this thread on the list of * interested threads, signal the notifier thread, and wait for a * response or a timeout. */ StartNotifierThread("Tcl_WaitForEvent"); pthread_mutex_lock(¬ifierMutex); if (timePtr != NULL && timePtr->sec == 0 && (timePtr->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] */ || timePtr->usec < 10 #endif /* __APPLE__ && __LP64__ */ )) { /* * 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 { waitForFiles = (tsdPtr->numFdBits > 0); 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; if ((write(triggerPipe, "", 1) == -1) && (errno != EAGAIN)) { Tcl_Panic("Tcl_WaitForEvent: %s", "unable to write to triggerPipe"); } } FD_ZERO(&tsdPtr->readyMasks.readable); FD_ZERO(&tsdPtr->readyMasks.writable); FD_ZERO(&tsdPtr->readyMasks.exception); if (!tsdPtr->eventReady) { #ifdef __CYGWIN__ if (!PeekMessageW(&msg, NULL, 0, 0, 0)) { unsigned int timeout; if (timePtr) { timeout = timePtr->sec * 1000 + timePtr->usec / 1000; } else { timeout = 0xFFFFFFFF; } pthread_mutex_unlock(¬ifierMutex); MsgWaitForMultipleObjects(1, &tsdPtr->event, 0, timeout, 1279); pthread_mutex_lock(¬ifierMutex); } #else /* !__CYGWIN__ */ if (timePtr != NULL) { Tcl_Time now; struct timespec ptime; Tcl_GetTime(&now); ptime.tv_sec = timePtr->sec + now.sec + (timePtr->usec + now.usec) / 1000000; ptime.tv_nsec = 1000 * ((timePtr->usec + now.usec) % 1000000); pthread_cond_timedwait(&tsdPtr->waitCV, ¬ifierMutex, &ptime); } else { pthread_cond_wait(&tsdPtr->waitCV, ¬ifierMutex); } #endif /* __CYGWIN__ */ } tsdPtr->eventReady = 0; #ifdef __CYGWIN__ while (PeekMessageW(&msg, NULL, 0, 0, 0)) { /* * Retrieve and dispatch the message. */ unsigned int result = GetMessageW(&msg, NULL, 0, 0); if (result == 0) { PostQuitMessage(msg.wParam); /* What to do here? */ } else if (result != (unsigned int) -1) { TranslateMessage(&msg); DispatchMessageW(&msg); } } ResetEvent(tsdPtr->event); #endif /* __CYGWIN__ */ 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; if ((write(triggerPipe, "", 1) == -1) && (errno != EAGAIN)) { Tcl_Panic("Tcl_WaitForEvent: %s", "unable to write to triggerPipe"); } } #else /* !TCL_THREADS */ tsdPtr->readyMasks = tsdPtr->checkMasks; numFound = select(tsdPtr->numFdBits, &tsdPtr->readyMasks.readable, &tsdPtr->readyMasks.writable, &tsdPtr->readyMasks.exception, 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.exception); } #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.exception)) { 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) { FileHandlerEvent *fileEvPtr = (FileHandlerEvent *)Tcl_Alloc(sizeof(FileHandlerEvent)); fileEvPtr->header.proc = FileHandlerEventProc; fileEvPtr->fd = filePtr->fd; Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL); } filePtr->readyMask = mask; } #if TCL_THREADS pthread_mutex_unlock(¬ifierMutex); #endif /* TCL_THREADS */ 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. * *---------------------------------------------------------------------- */ #if TCL_THREADS static TCL_NORETURN void NotifierThreadProc( TCL_UNUSED(ClientData)) { ThreadSpecificData *tsdPtr; fd_set readableMask; fd_set writableMask; fd_set exceptionMask; int i; int fds[2], receivePipe; long found; struct timeval poll = {0, 0}, *timePtr; char buf[2]; int numFdBits = 0; if (pipe(fds) != 0) { Tcl_Panic("NotifierThreadProc: %s", "could not create trigger pipe"); } receivePipe = fds[0]; if (TclUnixSetBlockingMode(receivePipe, TCL_MODE_NONBLOCKING) < 0) { Tcl_Panic("NotifierThreadProc: %s", "could not make receive pipe non blocking"); } if (TclUnixSetBlockingMode(fds[1], TCL_MODE_NONBLOCKING) < 0) { Tcl_Panic("NotifierThreadProc: %s", "could not make trigger pipe non blocking"); } if (fcntl(receivePipe, F_SETFD, FD_CLOEXEC) < 0) { Tcl_Panic("NotifierThreadProc: %s", "could not make receive pipe close-on-exec"); } if (fcntl(fds[1], F_SETFD, FD_CLOEXEC) < 0) { Tcl_Panic("NotifierThreadProc: %s", "could not make trigger pipe close-on-exec"); } /* * Install the write end of the pipe into the global variable. */ pthread_mutex_lock(¬ifierMutex); triggerPipe = fds[1]; /* * Signal any threads that are waiting. */ pthread_cond_broadcast(¬ifierCV); pthread_mutex_unlock(¬ifierMutex); /* * Look for file events and report them to interested threads. */ while (1) { FD_ZERO(&readableMask); FD_ZERO(&writableMask); FD_ZERO(&exceptionMask); /* * Compute the logical OR of the masks from all the waiting * notifiers. */ pthread_mutex_lock(¬ifierMutex); 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.exception)) { FD_SET(i, &exceptionMask); } } 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; } } pthread_mutex_unlock(¬ifierMutex); /* * Set up the mask to include the receive pipe. */ if (receivePipe >= numFdBits) { numFdBits = receivePipe + 1; } FD_SET(receivePipe, &readableMask); if (select(numFdBits, &readableMask, &writableMask, &exceptionMask, timePtr) == -1) { /* * Try again immediately on an error. */ continue; } /* * Alert any threads that are waiting on a ready file descriptor. */ pthread_mutex_lock(¬ifierMutex); 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.exception) && FD_ISSET(i, &exceptionMask)) { FD_SET(i, &tsdPtr->readyMasks.exception); found = 1; } } if (found || (tsdPtr->pollState & POLL_DONE)) { AlertSingleThread(tsdPtr); } } pthread_mutex_unlock(¬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. */ do { i = read(receivePipe, buf, 1); if (i <= 0) { break; } else 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; } } while (1); if ((i == 0) || (buf[0] == 'q')) { break; } } /* * Clean up the read end of the pipe and signal any threads waiting on * termination of the notifier thread. */ close(receivePipe); pthread_mutex_lock(¬ifierMutex); triggerPipe = -1; pthread_cond_broadcast(¬ifierCV); pthread_mutex_unlock(¬ifierMutex); TclpThreadExit(0); } #endif /* TCL_THREADS */ #endif /* (!NOTIFIER_EPOLL && !NOTIFIER_KQUEUE) || !TCL_THREADS */ #endif /* !HAVE_COREFOUNDATION */ /* * Local Variables: * mode: c * c-basic-offset: 4 * fill-column: 78 * End: */