diff options
Diffstat (limited to 'exp_poll.c')
| -rw-r--r-- | exp_poll.c | 526 |
1 files changed, 526 insertions, 0 deletions
diff --git a/exp_poll.c b/exp_poll.c new file mode 100644 index 0000000..69324b0 --- /dev/null +++ b/exp_poll.c @@ -0,0 +1,526 @@ +/* exp_poll.c - This file contains UNIX specific procedures for + * poll-based notifier, which is the lowest-level part of the Tcl + * event loop. This file works together with ../generic/tclNotify.c. + * + * Design and implementation of this program was paid for by U.S. tax + * dollars. Therefore it is public domain. However, the author and + * NIST would appreciate credit if this program or parts of it are + * used. + * + * Written by Don Libes, NIST, 2/6/90 + * Rewritten by Don Libes, 2/96 for new Tcl notifier paradigm. + * Rewritten again by Don Libes, 8/97 for yet another Tcl notifier paradigm. + */ + +#include "tclInt.h" +#include "tclPort.h" +#include <signal.h> + +#include <poll.h> +#include <sys/types.h> + +#ifdef HAVE_UNISTD_H +# include <unistd.h> +#endif + +/* Some systems require that the poll array be non-empty so provide a + * 1-elt array for starters. It will be ignored as soon as it grows + * larger. + */ + +static struct pollfd initialFdArray; +static struct pollfd *fdArray = &initialFdArray; +static int fdsInUse = 0; /* space in use */ +static int fdsMaxSpace = 1; /* space that has actually been allocated */ + +/* + * tclUnixNotify.c -- + * + * This file contains the implementation of the select-based + * Unix-specific notifier, which is the lowest-level part of the + * Tcl event loop. This file works together with + * ../generic/tclNotify.c. + * + * Copyright (c) 1995-1997 Sun Microsystems, Inc. + * + * See the file "license.terms" for information on usage and redistribution + * of this file, and for a DISCLAIMER OF ALL WARRANTIES. + * + * SCCS: @(#) tclUnixNotfy.c 1.42 97/07/02 20:55:44 + */ + +/* + * 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. */ + int pollArrayIndex; /* index into poll array */ + 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 static structure contains the state information for the + * select based implementation of the Tcl notifier. + */ + +static struct { + FileHandler *firstFileHandlerPtr; + /* Pointer to head of file handler list. */ + fd_mask checkMasks[3*MASK_SIZE]; + /* This array 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. */ + fd_mask readyMasks[3*MASK_SIZE]; + /* 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). */ +} notifier; + +/* + * The following static indicates whether this module has been initialized. + */ + +static int initialized = 0; + +/* + * Static routines defined in this file. + */ + +static void InitNotifier _ANSI_ARGS_((void)); +static void NotifierExitHandler _ANSI_ARGS_(( + ClientData clientData)); +static int FileHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr, + int flags)); + +/* + *---------------------------------------------------------------------- + * + * InitNotifier -- + * + * Initializes the notifier state. + * + * Results: + * None. + * + * Side effects: + * Creates a new exit handler. + * + *---------------------------------------------------------------------- + */ + +static void +InitNotifier() +{ + initialized = 1; + memset(¬ifier, 0, sizeof(notifier)); + Tcl_CreateExitHandler(NotifierExitHandler, NULL); +} + +/* + *---------------------------------------------------------------------- + * + * NotifierExitHandler -- + * + * This function is called to cleanup the notifier state before + * Tcl is unloaded. + * + * Results: + * None. + * + * Side effects: + * Destroys the notifier window. + * + *---------------------------------------------------------------------- + */ + +static void +NotifierExitHandler(clientData) + ClientData clientData; /* Not used. */ +{ + initialized = 0; +} + +/* + *---------------------------------------------------------------------- + * + * 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. + */ +} + +/* + *---------------------------------------------------------------------- + * + * Tcl_CreateFileHandler -- + * + * This procedure registers a file handler with the Xt notifier. + * + * Results: + * None. + * + * Side effects: + * Creates a new file handler structure and registers one or more + * input procedures with Xt. + * + *---------------------------------------------------------------------- + */ + +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. */ +{ + FileHandler *filePtr; + int index, bit; + int cur_fd_index; + + if (!initialized) { + InitNotifier(); + } + + for (filePtr = notifier.firstFileHandlerPtr; filePtr != NULL; + filePtr = filePtr->nextPtr) { + if (filePtr->fd == fd) { + break; + } + } + if (filePtr == NULL) { + filePtr = (FileHandler*) ckalloc(sizeof(FileHandler)); /* MLK */ + filePtr->fd = fd; + filePtr->readyMask = 0; + filePtr->nextPtr = notifier.firstFileHandlerPtr; + notifier.firstFileHandlerPtr = filePtr; + } + filePtr->proc = proc; + filePtr->clientData = clientData; + filePtr->pollArrayIndex = fdsInUse; + cur_fd_index = fdsInUse; + + fdsInUse++; + if (fdsInUse > fdsMaxSpace) { + if (fdArray != &initialFdArray) ckfree((char *)fdArray); + fdArray = (struct pollfd *)ckalloc(fdsInUse*sizeof(struct pollfd)); + fdsMaxSpace = fdsInUse; + } + + fdArray[cur_fd_index].fd = fd; + + /* I know that POLLIN/OUT is right. But I have no idea if POLLPRI + * corresponds well to TCL_EXCEPTION. + */ + + if (mask & TCL_READABLE) { + fdArray[cur_fd_index].events = POLLIN; + } + if (mask & TCL_WRITABLE) { + fdArray[cur_fd_index].events = POLLOUT; + } + if (mask & TCL_EXCEPTION) { + fdArray[cur_fd_index].events = POLLPRI; + } +} + +/* + *---------------------------------------------------------------------- + * + * 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, *lastPtr; + int index, bit, mask, i; + int cur_fd_index; + + if (!initialized) { + InitNotifier(); + } + + /* + * Find the entry for the given file (and return if there + * isn't one). + */ + + for (prevPtr = NULL, filePtr = notifier.firstFileHandlerPtr; ; + prevPtr = filePtr, filePtr = filePtr->nextPtr) { + if (filePtr == NULL) { + return; + } + if (filePtr->fd == fd) { + break; + } + } + + /* + * Clean up information in the callback record. + */ + + if (prevPtr == NULL) { + notifier.firstFileHandlerPtr = filePtr->nextPtr; + } else { + prevPtr->nextPtr = filePtr->nextPtr; + } + + /* back to poll-specific code - DEL */ + + cur_fd_index = filePtr->pollArrayIndex; + fdsInUse--; + + /* if this one is last, do nothing special */ + /* else swap with one at end of array */ + + if (cur_fd_index != fdsInUse) { + int lastfd_in_array = fdArray[fdsInUse].fd; + memcpy(&fdArray[cur_fd_index],&fdArray[fdsInUse],sizeof(struct pollfd)); + + /* update index to reflect new location in array */ + /* first find link corresponding to last element in array */ + + for (lastPtr = notifier.firstFileHandlerPtr; filePtr; lastPtr = lastPtr->nextPtr) { + if (lastPtr->fd == lastfd_in_array) { + lastPtr->pollArrayIndex = cur_fd_index; + break; + } + } + } + + fdsInUse--; + + 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. */ +{ + FileHandler *filePtr; + FileHandlerEvent *fileEvPtr = (FileHandlerEvent *) evPtr; + int mask; + + 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. + */ + + for (filePtr = notifier.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 timeout; + struct timeval *timeoutPtr; + + int bit, index, mask, numFound; + + if (!initialized) { + InitNotifier(); + } + + /* + * 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) { + timeout = timePtr->sec*1000 + timePtr->usec/1000; + + } else if (notifier.numFdBits == 0) { + return -1; + } else { + timeoutPtr = NULL; + } + + numFound = poll(fdArray,fdsInUse,timeout); + + /* + * Queue all detected file events before returning. + */ + + for (filePtr = notifier.firstFileHandlerPtr; + (filePtr != NULL) && (numFound > 0); + filePtr = filePtr->nextPtr) { + index = filePtr->pollArrayIndex; + mask = 0; + + if (fdArray[index].revents & POLLIN) { + mask |= TCL_READABLE; + } + if (fdArray[index].revents & POLLOUT) { + mask |= TCL_WRITABLE; + } + /* I have no idea if this is right ... */ + if (fdArray[index].revents & (POLLPRI|POLLERR|POLLHUP|POLLNVAL)) { + mask |= TCL_EXCEPTION; + } + + if (!mask) { + continue; + } else { + numFound--; + } + + /* + * 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; + } + return 0; +} + |