/* * tclEpollNotfy.c -- * * This file contains the implementation of the epoll()-based * Linux-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. * Copyright (c) 2016 Lucio Andrés Illanes Albornoz * * See the file "license.terms" for information on usage and redistribution * of this file, and for a DISCLAIMER OF ALL WARRANTIES. */ #ifdef NOTIFIER_EPOLL #define _GNU_SOURCE /* For pipe2(2) */ #include "tclInt.h" #ifndef HAVE_COREFOUNDATION /* Darwin/Mac OS X CoreFoundation notifier is * in tclMacOSXNotify.c */ #include #include #include #ifdef HAVE_EVENTFD #include #endif /* HAVE_EVENTFD */ #include #include /* * This structure is used to keep track of the notifier info for a registered * file. */ struct PlatformEventData; 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. */ LIST_ENTRY(FileHandler) readyNode; /* Next/previous in list of FileHandlers asso- * ciated with regular files (S_IFREG) that are * ready for I/O. */ struct PlatformEventData *pedPtr; /* Pointer to PlatformEventData associating this * FileHandler with epoll(7) events. */ } FileHandler; /* * The following structure associates a FileHandler and the thread that owns it * with the file descriptors of interest and their event masks passed to epoll_ctl(2) * and their corresponding event(s) returned by epoll_wait(2). */ struct ThreadSpecificData; struct PlatformEventData { FileHandler *filePtr; struct ThreadSpecificData *tsdPtr; }; /* * 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 * epoll based implementation of the Tcl notifier. One of these structures is * created for each thread that is using the notifier. */ LIST_HEAD(PlatformReadyFileHandlerList, FileHandler); typedef struct ThreadSpecificData { FileHandler *firstFileHandlerPtr; /* Pointer to head of file handler list. */ struct PlatformReadyFileHandlerList firstReadyFileHandlerPtr; /* Pointer to head of list of FileHandlers * associated with regular files (S_IFREG) * that are ready for I/O. */ pthread_mutex_t notifierMutex; /* Mutex protecting notifier termination in * PlatformEventsFinalize. */ #ifdef HAVE_EVENTFD int triggerEventFd; /* eventfd(2) used by other threads to wake * up this thread for inter-thread IPC. */ #else int triggerPipe[2]; /* pipe(2) used by other threads to wake * up this thread for inter-thread IPC. */ #endif /* HAVE_EVENTFD */ int eventsFd; /* epoll(7) file descriptor used to wait for fds */ struct epoll_event *readyEvents; /* Pointer to at most maxReadyEvents events * returned by epoll_wait(2). */ size_t maxReadyEvents; /* Count of epoll_events in readyEvents. */ } ThreadSpecificData; static Tcl_ThreadDataKey dataKey; void PlatformEventsControl(FileHandler *filePtr, ThreadSpecificData *tsdPtr, int op, int isNew); static void PlatformEventsFinalize(void); void PlatformEventsInit(void); static int PlatformEventsTranslate(struct epoll_event *event); static int PlatformEventsWait(struct epoll_event *events, size_t numEvents, struct timeval *timePtr); #include "tclUnixNotfy.c" /* *---------------------------------------------------------------------- * * Tcl_InitNotifier -- * * Initializes the platform specific notifier state. * * Results: * Returns a handle to the notifier state for this thread. * * Side effects: * If no initNotifierProc notifier hook exists, PlatformEventsInit * is called. * *---------------------------------------------------------------------- */ ClientData Tcl_InitNotifier(void) { if (tclNotifierHooks.initNotifierProc) { return tclNotifierHooks.initNotifierProc(); } else { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); PlatformEventsInit(); return tsdPtr; } } /* *---------------------------------------------------------------------- * * Tcl_FinalizeNotifier -- * * This function is called to cleanup the notifier state before a thread * is terminated. * * Results: * None. * * Side effects: * If no finalizeNotifierProc notifier hook exists, PlatformEvents- * Finalize is called. * *---------------------------------------------------------------------- */ void Tcl_FinalizeNotifier( ClientData clientData) /* Not used. */ { if (tclNotifierHooks.finalizeNotifierProc) { tclNotifierHooks.finalizeNotifierProc(clientData); return; } else { PlatformEventsFinalize(); } } /* *---------------------------------------------------------------------- * * PlatformEventsControl -- * * This function registers interest for the file descriptor and the mask * of TCL_* bits associated with filePtr on the epoll file descriptor * associated with tsdPtr. * Future calls to epoll_wait will return filePtr and tsdPtr alongside with * the event registered here via the PlatformEventData struct. * * Results: * None. * * Side effects: * If adding a new file descriptor, a PlatformEventData struct will be * allocated and associated with filePtr. * fstat is called on the file descriptor; if it is associated with * a regular file (S_IFREG,) filePtr is considered to be ready for I/O * and added to or deleted from the corresponding list in tsdPtr. * If it is not associated with a regular file, the file descriptor is * added, modified concerning its mask of events of interest, or deleted * from the epoll file descriptor of the calling thread. * *---------------------------------------------------------------------- */ void PlatformEventsControl( FileHandler *filePtr, ThreadSpecificData *tsdPtr, int op, int isNew) { struct epoll_event newEvent; struct PlatformEventData *newPedPtr; struct stat fdStat; newEvent.events = 0; if (filePtr->mask & (TCL_READABLE | TCL_EXCEPTION)) { newEvent.events |= EPOLLIN; } if (filePtr->mask & TCL_WRITABLE) { newEvent.events |= EPOLLOUT; } if (isNew) { newPedPtr = ckalloc(sizeof(*newPedPtr)); newPedPtr->filePtr = filePtr; newPedPtr->tsdPtr = tsdPtr; filePtr->pedPtr = newPedPtr; } newEvent.data.ptr = filePtr->pedPtr; /* * N.B. As discussed in Tcl_WaitForEvent(), epoll(7) does not sup- * port regular files (S_IFREG.) Therefore, filePtr is in these * cases simply added or deleted from the list of FileHandlers * associated with regular files belonging to tsdPtr. */ if (fstat(filePtr->fd, &fdStat) == -1) { Tcl_Panic("fstat: %s", strerror(errno)); } else if ((fdStat.st_mode & S_IFMT) == S_IFREG) { switch (op) { case EPOLL_CTL_ADD: if (isNew) { LIST_INSERT_HEAD(&tsdPtr->firstReadyFileHandlerPtr, filePtr, readyNode); } break; case EPOLL_CTL_DEL: LIST_REMOVE(filePtr, readyNode); break; } return; } else if (epoll_ctl(tsdPtr->eventsFd, op, filePtr->fd, &newEvent) == -1) { Tcl_Panic("epoll_ctl: %s", strerror(errno)); } } /* *---------------------------------------------------------------------- * * PlatformEventsFinalize -- * * This function closes the eventfd and the epoll file descriptor and * frees the epoll_event structs owned by the thread of the caller. * The above operations are protected by tsdPtr->notifierMutex, which * is destroyed thereafter. * * Results: * None. * * Side effects: * While tsdPtr->notifierMutex is held: * The per-thread eventfd(2) is closed, if non-zero, and set to -1. * The per-thread epoll(7) fd is closed, if non-zero, and set to 0. * The per-thread epoll_event structs are freed, if any, and set to 0. * * tsdPtr->notifierMutex is destroyed. * *---------------------------------------------------------------------- */ void PlatformEventsFinalize( void) { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); pthread_mutex_lock(&tsdPtr->notifierMutex); #ifdef HAVE_EVENTFD if (tsdPtr->triggerEventFd) { close(tsdPtr->triggerEventFd); tsdPtr->triggerEventFd = -1; } #else if (tsdPtr->triggerPipe[0]) { close(tsdPtr->triggerPipe[0]); tsdPtr->triggerPipe[0] = -1; } if (tsdPtr->triggerPipe[1]) { close(tsdPtr->triggerPipe[1]); tsdPtr->triggerPipe[1] = -1; } #endif /* HAVE_EVENTFD */ if (tsdPtr->eventsFd > 0) { close(tsdPtr->eventsFd); tsdPtr->eventsFd = 0; } if (tsdPtr->readyEvents) { ckfree(tsdPtr->readyEvents); tsdPtr->maxReadyEvents = 0; } pthread_mutex_unlock(&tsdPtr->notifierMutex); if ((errno = pthread_mutex_destroy(&tsdPtr->notifierMutex))) { Tcl_Panic("pthread_mutex_destroy: %s", strerror(errno)); } } /* *---------------------------------------------------------------------- * * PlatformEventsInit -- * * This function abstracts creating a kqueue fd via the epoll_create * system call and allocating memory for the epoll_event structs in * tsdPtr for the thread of the caller. * * Results: * None. * * Side effects: * The following per-thread entities are initialised: * notifierMutex is initialised. * The eventfd(2) is created w/ EFD_CLOEXEC and EFD_NONBLOCK. * The epoll(7) fd is created w/ EPOLL_CLOEXEC. * A FileHandler struct is allocated and initialised for the event- * fd(2), registering interest for TCL_READABLE on it via Platform- * EventsControl(). * readyEvents and maxReadyEvents are initialised with 512 epoll_events. * *---------------------------------------------------------------------- */ void PlatformEventsInit( void) { ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); FileHandler *filePtr; errno = pthread_mutex_init(&tsdPtr->notifierMutex, NULL); if (errno) { Tcl_Panic("Tcl_InitNotifier: %s", "could not create mutex"); } filePtr = ckalloc(sizeof(*filePtr)); #ifdef HAVE_EVENTFD if ((tsdPtr->triggerEventFd = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK)) <= 0) { Tcl_Panic("Tcl_InitNotifier: %s", "could not create trigger eventfd"); } filePtr->fd = tsdPtr->triggerEventFd; #else if (pipe2(tsdPtr->triggerPipe, O_CLOEXEC | O_NONBLOCK) != 0) { Tcl_Panic("Tcl_InitNotifier: %s", "could not create trigger pipe"); } filePtr->fd = tsdPtr->triggerPipe[0]; #endif if ((tsdPtr->eventsFd = epoll_create1(EPOLL_CLOEXEC)) == -1) { Tcl_Panic("epoll_create1: %s", strerror(errno)); } filePtr->mask = TCL_READABLE; PlatformEventsControl(filePtr, tsdPtr, EPOLL_CTL_ADD, 1); if (!tsdPtr->readyEvents) { tsdPtr->maxReadyEvents = 512; tsdPtr->readyEvents = ckalloc(tsdPtr->maxReadyEvents * sizeof(tsdPtr->readyEvents[0])); } LIST_INIT(&tsdPtr->firstReadyFileHandlerPtr); } /* *---------------------------------------------------------------------- * * PlatformEventsTranslate -- * * This function translates the platform-specific mask of returned * events in eventPtr to a mask of TCL_* bits. * * Results: * Returns the translated mask. * * Side effects: * None. * *---------------------------------------------------------------------- */ int PlatformEventsTranslate( struct epoll_event *eventPtr) { int mask; mask = 0; if (eventPtr->events & (EPOLLIN | EPOLLHUP)) { mask |= TCL_READABLE; } if (eventPtr->events & EPOLLOUT) { mask |= TCL_WRITABLE; } if (eventPtr->events & EPOLLERR) { mask |= TCL_EXCEPTION; } return mask; } /* *---------------------------------------------------------------------- * * PlatformEventsWait -- * * This function abstracts waiting for I/O events via epoll_wait. * * Results: * Returns -1 if epoll_wait failed. Returns 0 if polling and if no * events became available whilst polling. Returns a pointer to and * the count of all returned events in all other cases. * * Side effects: * gettimeofday(2), epoll_wait(2), and gettimeofday(2) are called, * in the specified order. * If timePtr specifies a positive value, it is updated to reflect * the amount of time that has passed; if its value would {under, * over}flow, it is set to zero. * *---------------------------------------------------------------------- */ int PlatformEventsWait( struct epoll_event *events, size_t numEvents, struct timeval *timePtr) { int numFound; struct timeval tv0, tv1, tv_delta; int timeout; ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); /* * If timePtr is NULL, epoll_wait(2) will wait indefinitely. If it * specifies a timeout of {0,0}, epoll_wait(2) will poll. Otherwise, * the timeout will simply be converted to milliseconds. */ if (!timePtr) { timeout = -1; } else if (!timePtr->tv_sec && !timePtr->tv_usec) { timeout = 0; } else { timeout = (int)timePtr->tv_sec; } /* * Call (and possibly block on) epoll_wait(2) and substract the delta * of gettimeofday(2) before and after the call from timePtr if the * latter is not NULL. Return the number of events returned by epoll_wait(2). */ gettimeofday(&tv0, NULL); numFound = epoll_wait(tsdPtr->eventsFd, events, (int)numEvents, timeout); gettimeofday(&tv1, NULL); if (timePtr && (timePtr->tv_sec && timePtr->tv_usec)) { timersub(&tv1, &tv0, &tv_delta); if (!timercmp(&tv_delta, timePtr, >)) { timersub(timePtr, &tv_delta, timePtr); } else { timePtr->tv_sec = 0; timePtr->tv_usec = 0; } } return numFound; } /* *---------------------------------------------------------------------- * * Tcl_CreateFileHandler -- * * This function registers a file handler with the epoll notifier * of the thread of the caller. * * Results: * None. * * Side effects: * Creates a new file handler structure. * PlatformEventsControl() is called for the 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. */ { int isNew; 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 = ckalloc(sizeof(FileHandler)); filePtr->fd = fd; filePtr->readyMask = 0; filePtr->nextPtr = tsdPtr->firstFileHandlerPtr; tsdPtr->firstFileHandlerPtr = filePtr; isNew = 1; } else { isNew = 0; } filePtr->proc = proc; filePtr->clientData = clientData; filePtr->mask = mask; PlatformEventsControl(filePtr, tsdPtr, isNew ? EPOLL_CTL_ADD : EPOLL_CTL_MOD, isNew); } } /* *---------------------------------------------------------------------- * * Tcl_DeleteFileHandler -- * * Cancel a previously-arranged callback arrangement for a file on * the epoll file descriptor of the thread of the caller. * * Results: * None. * * Side effects: * If a callback was previously registered on file, remove it. * PlatformEventsControl() is called for the file handler structure. * The PlatformEventData struct associated with the new file handler * structure is freed. * *---------------------------------------------------------------------- */ void Tcl_DeleteFileHandler( int fd) /* Stream id for which to remove callback * function. */ { if (tclNotifierHooks.deleteFileHandlerProc) { tclNotifierHooks.deleteFileHandlerProc(fd); return; } else { FileHandler *filePtr, *prevPtr; 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. */ PlatformEventsControl(filePtr, tsdPtr, EPOLL_CTL_DEL, 0); if (filePtr->pedPtr) { ckfree(filePtr->pedPtr); } /* * Clean up information in the callback record. */ if (prevPtr == NULL) { tsdPtr->firstFileHandlerPtr = filePtr->nextPtr; } else { prevPtr->nextPtr = filePtr->nextPtr; } ckfree(filePtr); } } /* *---------------------------------------------------------------------- * * 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. * The waiting logic is implemented in PlatformEventsWait. * * Results: * Returns -1 if PlatformEventsWait() would block forever, otherwise * returns 0. * * Side effects: * Queues file events that are detected by PlatformEventsWait(). * *---------------------------------------------------------------------- */ 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; /* * Impl. notes: timeout & timeoutPtr are used if, and only if threads * are not enabled. They are the arguments for the regular epoll_wait() * used when the core is not thread-enabled. */ struct timeval timeout, *timeoutPtr; int numFound, numEvent; struct PlatformEventData *pedPtr; ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); int numQueued; ssize_t i; /* * 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; } timeout.tv_sec = timePtr->sec; timeout.tv_usec = timePtr->usec; timeoutPtr = &timeout; } else { timeoutPtr = NULL; } /* * Walk the list of FileHandlers associated with regular files * (S_IFREG) belonging to tsdPtr, queue Tcl events for them, and * update their mask of events of interest. * As epoll(7) does not support regular files, the behaviour of * {select,poll}(2) is simply simulated here: fds associated with * regular files are added to this list by PlatformEventsControl() * and processed here before calling (and possibly blocking) on * PlatformEventsWait(). */ numQueued = 0; LIST_FOREACH(filePtr, &tsdPtr->firstReadyFileHandlerPtr, readyNode) { mask = 0; if (filePtr->mask & TCL_READABLE) { mask |= TCL_READABLE; } if (filePtr->mask & TCL_WRITABLE) { mask |= TCL_WRITABLE; } /* * 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 = ckalloc(sizeof(FileHandlerEvent)); fileEvPtr->header.proc = FileHandlerEventProc; fileEvPtr->fd = filePtr->fd; Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL); numQueued++; } filePtr->readyMask = mask; } /* * If any events were queued in the above loop, force PlatformEvents- * Wait() to poll as there already are events that need to be processed * at this point. */ if (numQueued) { timeout.tv_sec = 0; timeout.tv_usec = 0; timeoutPtr = &timeout; } /* * Wait or poll for new events, queue Tcl events for the FileHandlers * corresponding to them, and update the FileHandlers' mask of events * of interest registered by the last call to Tcl_CreateFileHandler(). * * Events for the eventfd(2)/trigger pipe are processed here in order * to facilitate inter-thread IPC. If another thread intends to wake * up this thread whilst it's blocking on PlatformEventsWait(), it * write(2)s to the eventfd(2)/trigger pipe (see Tcl_AlertNotifier(),) * which in turn will cause PlatformEventsWait() to return immediately. */ numFound = PlatformEventsWait(tsdPtr->readyEvents, tsdPtr->maxReadyEvents, timeoutPtr); for (numEvent = 0; numEvent < numFound; numEvent++) { pedPtr = tsdPtr->readyEvents[numEvent].data.ptr; filePtr = pedPtr->filePtr; mask = PlatformEventsTranslate(&tsdPtr->readyEvents[numEvent]); #ifdef HAVE_EVENTFD if (filePtr->fd == tsdPtr->triggerEventFd) { uint64_t eventFdVal; i = read(tsdPtr->triggerEventFd, &eventFdVal, sizeof(eventFdVal)); if ((i != sizeof(eventFdVal)) && (errno != EAGAIN)) { #else if (filePtr->fd == tsdPtr->triggerPipe[0]) { char triggerPipeVal; i = read(tsdPtr->triggerPipe[0], &triggerPipeVal, sizeof(triggerPipeVal)); if ((i != sizeof(triggerPipeVal)) && (errno != EAGAIN)) { #endif Tcl_Panic("Tcl_WaitForEvent: " "read from %p->triggerEventFd: %s", (void *)tsdPtr, strerror(errno)); } else { continue; } } 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 = ckalloc(sizeof(FileHandlerEvent)); fileEvPtr->header.proc = FileHandlerEventProc; fileEvPtr->fd = filePtr->fd; Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL); } filePtr->readyMask = mask; } return 0; } } #endif /* !HAVE_COREFOUNDATION */ #endif /* NOTIFIER_EPOLL */ /* * Local Variables: * mode: c * c-basic-offset: 4 * fill-column: 78 * End: */