/* * tclNotify.c -- * * This file implements the generic portion of the Tcl notifier. * The notifier is lowest-level part of the event system. It * manages an event queue that holds Tcl_Event structures. The * platform specific portion of the notifier is defined in the * tcl*Notify.c files in each platform directory. * * Copyright (c) 1995-1997 Sun Microsystems, Inc. * Copyright (c) 1998 by Scriptics Corporation. * * See the file "license.terms" for information on usage and redistribution * of this file, and for a DISCLAIMER OF ALL WARRANTIES. * * RCS: @(#) $Id: tclNotify.c,v 1.2 2001/09/14 01:43:01 zlaski Exp $ */ #include "tclInt.h" #include "tclPort.h" /* * The following static indicates whether this module has been initialized. */ static int initialized = 0; /* * For each event source (created with Tcl_CreateEventSource) there * is a structure of the following type: */ typedef struct EventSource { Tcl_EventSetupProc *setupProc; Tcl_EventCheckProc *checkProc; ClientData clientData; struct EventSource *nextPtr; } EventSource; /* * The following structure keeps track of the state of the notifier. * The first three elements keep track of the event queue. In addition to * the first (next to be serviced) and last events in the queue, we keep * track of a "marker" event. This provides a simple priority mechanism * whereby events can be inserted at the front of the queue but behind all * other high-priority events already in the queue (this is used for things * like a sequence of Enter and Leave events generated during a grab in * Tk). */ static struct { Tcl_Event *firstEventPtr; /* First pending event, or NULL if none. */ Tcl_Event *lastEventPtr; /* Last pending event, or NULL if none. */ Tcl_Event *markerEventPtr; /* Last high-priority event in queue, or * NULL if none. */ int serviceMode; /* One of TCL_SERVICE_NONE or * TCL_SERVICE_ALL. */ int blockTimeSet; /* 0 means there is no maximum block * time: block forever. */ Tcl_Time blockTime; /* If blockTimeSet is 1, gives the * maximum elapsed time for the next block. */ int inTraversal; /* 1 if Tcl_SetMaxBlockTime is being * called during an event source traversal. */ EventSource *firstEventSourcePtr; /* Pointer to first event source in * global list of event sources. */ } notifier; /* * Declarations for functions used in this file. */ static void InitNotifier _ANSI_ARGS_((void)); static void NotifierExitHandler _ANSI_ARGS_((ClientData clientData)); /* *---------------------------------------------------------------------- * * InitNotifier -- * * This routine is called to initialize the notifier module. * * Results: * None. * * Side effects: * Creates an exit handler and initializes static data. * *---------------------------------------------------------------------- */ static void InitNotifier() { initialized = 1; memset(¬ifier, 0, sizeof(notifier)); notifier.serviceMode = TCL_SERVICE_NONE; Tcl_CreateExitHandler(NotifierExitHandler, NULL); } /* *---------------------------------------------------------------------- * * NotifierExitHandler -- * * This routine is called during Tcl finalization. * * Results: * None. * * Side effects: * Clears the notifier intialization flag. * *---------------------------------------------------------------------- */ static void NotifierExitHandler(clientData) ClientData clientData; /* Not used. */ { initialized = 0; } /* *---------------------------------------------------------------------- * * Tcl_CreateEventSource -- * * This procedure is invoked to create a new source of events. * The source is identified by a procedure that gets invoked * during Tcl_DoOneEvent to check for events on that source * and queue them. * * * Results: * None. * * Side effects: * SetupProc and checkProc will be invoked each time that Tcl_DoOneEvent * runs out of things to do. SetupProc will be invoked before * Tcl_DoOneEvent calls select or whatever else it uses to wait * for events. SetupProc typically calls functions like Tcl_WatchFile * or Tcl_SetMaxBlockTime to indicate what to wait for. * * CheckProc is called after select or whatever operation was actually * used to wait. It figures out whether anything interesting actually * happened (e.g. by calling Tcl_FileReady), and then calls * Tcl_QueueEvent to queue any events that are ready. * * Each of these procedures is passed two arguments, e.g. * (*checkProc)(ClientData clientData, int flags)); * ClientData is the same as the clientData argument here, and flags * is a combination of things like TCL_FILE_EVENTS that indicates * what events are of interest: setupProc and checkProc use flags * to figure out whether their events are relevant or not. * *---------------------------------------------------------------------- */ void Tcl_CreateEventSource(setupProc, checkProc, clientData) Tcl_EventSetupProc *setupProc; /* Procedure to invoke to figure out * what to wait for. */ Tcl_EventCheckProc *checkProc; /* Procedure to call after waiting * to see what happened. */ ClientData clientData; /* One-word argument to pass to * setupProc and checkProc. */ { EventSource *sourcePtr; if (!initialized) { InitNotifier(); } sourcePtr = (EventSource *) ckalloc(sizeof(EventSource)); sourcePtr->setupProc = setupProc; sourcePtr->checkProc = checkProc; sourcePtr->clientData = clientData; sourcePtr->nextPtr = notifier.firstEventSourcePtr; notifier.firstEventSourcePtr = sourcePtr; } /* *---------------------------------------------------------------------- * * Tcl_DeleteEventSource -- * * This procedure is invoked to delete the source of events * given by proc and clientData. * * Results: * None. * * Side effects: * The given event source is cancelled, so its procedure will * never again be called. If no such source exists, nothing * happens. * *---------------------------------------------------------------------- */ void Tcl_DeleteEventSource(setupProc, checkProc, clientData) Tcl_EventSetupProc *setupProc; /* Procedure to invoke to figure out * what to wait for. */ Tcl_EventCheckProc *checkProc; /* Procedure to call after waiting * to see what happened. */ ClientData clientData; /* One-word argument to pass to * setupProc and checkProc. */ { EventSource *sourcePtr, *prevPtr; for (sourcePtr = notifier.firstEventSourcePtr, prevPtr = NULL; sourcePtr != NULL; prevPtr = sourcePtr, sourcePtr = sourcePtr->nextPtr) { if ((sourcePtr->setupProc != setupProc) || (sourcePtr->checkProc != checkProc) || (sourcePtr->clientData != clientData)) { continue; } if (prevPtr == NULL) { notifier.firstEventSourcePtr = sourcePtr->nextPtr; } else { prevPtr->nextPtr = sourcePtr->nextPtr; } ckfree((char *) sourcePtr); return; } } /* *---------------------------------------------------------------------- * * Tcl_QueueEvent -- * * Insert an event into the Tk event queue at one of three * positions: the head, the tail, or before a floating marker. * Events inserted before the marker will be processed in * first-in-first-out order, but before any events inserted at * the tail of the queue. Events inserted at the head of the * queue will be processed in last-in-first-out order. * * Results: * None. * * Side effects: * None. * *---------------------------------------------------------------------- */ void Tcl_QueueEvent(evPtr, position) Tcl_Event* evPtr; /* Event to add to queue. The storage * space must have been allocated the caller * with malloc (ckalloc), and it becomes * the property of the event queue. It * will be freed after the event has been * handled. */ Tcl_QueuePosition position; /* One of TCL_QUEUE_TAIL, TCL_QUEUE_HEAD, * TCL_QUEUE_MARK. */ { if (!initialized) { InitNotifier(); } if (position == TCL_QUEUE_TAIL) { /* * Append the event on the end of the queue. */ evPtr->nextPtr = NULL; if (notifier.firstEventPtr == NULL) { notifier.firstEventPtr = evPtr; } else { notifier.lastEventPtr->nextPtr = evPtr; } notifier.lastEventPtr = evPtr; } else if (position == TCL_QUEUE_HEAD) { /* * Push the event on the head of the queue. */ evPtr->nextPtr = notifier.firstEventPtr; if (notifier.firstEventPtr == NULL) { notifier.lastEventPtr = evPtr; } notifier.firstEventPtr = evPtr; } else if (position == TCL_QUEUE_MARK) { /* * Insert the event after the current marker event and advance * the marker to the new event. */ if (notifier.markerEventPtr == NULL) { evPtr->nextPtr = notifier.firstEventPtr; notifier.firstEventPtr = evPtr; } else { evPtr->nextPtr = notifier.markerEventPtr->nextPtr; notifier.markerEventPtr->nextPtr = evPtr; } notifier.markerEventPtr = evPtr; if (evPtr->nextPtr == NULL) { notifier.lastEventPtr = evPtr; } } } /* *---------------------------------------------------------------------- * * Tcl_DeleteEvents -- * * Calls a procedure for each event in the queue and deletes those * for which the procedure returns 1. Events for which the * procedure returns 0 are left in the queue. * * Results: * None. * * Side effects: * Potentially removes one or more events from the event queue. * *---------------------------------------------------------------------- */ void Tcl_DeleteEvents(proc, clientData) Tcl_EventDeleteProc *proc; /* The procedure to call. */ ClientData clientData; /* type-specific data. */ { Tcl_Event *evPtr, *prevPtr, *hold; if (!initialized) { InitNotifier(); } for (prevPtr = (Tcl_Event *) NULL, evPtr = notifier.firstEventPtr; evPtr != (Tcl_Event *) NULL; ) { if ((*proc) (evPtr, clientData) == 1) { if (notifier.firstEventPtr == evPtr) { notifier.firstEventPtr = evPtr->nextPtr; if (evPtr->nextPtr == NULL) { notifier.lastEventPtr = prevPtr; } if (notifier.markerEventPtr == evPtr) { notifier.markerEventPtr = prevPtr; } } else { prevPtr->nextPtr = evPtr->nextPtr; } hold = evPtr; evPtr = evPtr->nextPtr; ckfree((char *) hold); } else { prevPtr = evPtr; evPtr = evPtr->nextPtr; } } } /* *---------------------------------------------------------------------- * * Tcl_ServiceEvent -- * * Process one event from the event queue, or invoke an * asynchronous event handler. * * Results: * The return value is 1 if the procedure actually found an event * to process. If no processing occurred, then 0 is returned. * * Side effects: * Invokes all of the event handlers for the highest priority * event in the event queue. May collapse some events into a * single event or discard stale events. * *---------------------------------------------------------------------- */ int Tcl_ServiceEvent(flags) int flags; /* Indicates what events should be processed. * May be any combination of TCL_WINDOW_EVENTS * TCL_FILE_EVENTS, TCL_TIMER_EVENTS, or other * flags defined elsewhere. Events not * matching this will be skipped for processing * later. */ { Tcl_Event *evPtr, *prevPtr; Tcl_EventProc *proc; if (!initialized) { InitNotifier(); } /* * Asynchronous event handlers are considered to be the highest * priority events, and so must be invoked before we process events * on the event queue. */ if (Tcl_AsyncReady()) { (void) Tcl_AsyncInvoke((Tcl_Interp *) NULL, 0); return 1; } /* * No event flags is equivalent to TCL_ALL_EVENTS. */ if ((flags & TCL_ALL_EVENTS) == 0) { flags |= TCL_ALL_EVENTS; } /* * Loop through all the events in the queue until we find one * that can actually be handled. */ for (evPtr = notifier.firstEventPtr; evPtr != NULL; evPtr = evPtr->nextPtr) { /* * Call the handler for the event. If it actually handles the * event then free the storage for the event. There are two * tricky things here, but stemming from the fact that the event * code may be re-entered while servicing the event: * * 1. Set the "proc" field to NULL. This is a signal to ourselves * that we shouldn't reexecute the handler if the event loop * is re-entered. * 2. When freeing the event, must search the queue again from the * front to find it. This is because the event queue could * change almost arbitrarily while handling the event, so we * can't depend on pointers found now still being valid when * the handler returns. */ proc = evPtr->proc; evPtr->proc = NULL; if ((proc != NULL) && (*proc)(evPtr, flags)) { if (notifier.firstEventPtr == evPtr) { notifier.firstEventPtr = evPtr->nextPtr; if (evPtr->nextPtr == NULL) { notifier.lastEventPtr = NULL; } if (notifier.markerEventPtr == evPtr) { notifier.markerEventPtr = NULL; } } else { for (prevPtr = notifier.firstEventPtr; prevPtr->nextPtr != evPtr; prevPtr = prevPtr->nextPtr) { /* Empty loop body. */ } prevPtr->nextPtr = evPtr->nextPtr; if (evPtr->nextPtr == NULL) { notifier.lastEventPtr = prevPtr; } if (notifier.markerEventPtr == evPtr) { notifier.markerEventPtr = prevPtr; } } ckfree((char *) evPtr); return 1; } else { /* * The event wasn't actually handled, so we have to restore * the proc field to allow the event to be attempted again. */ evPtr->proc = proc; } /* * The handler for this event asked to defer it. Just go on to * the next event. */ continue; } return 0; } /* *---------------------------------------------------------------------- * * Tcl_GetServiceMode -- * * This routine returns the current service mode of the notifier. * * Results: * Returns either TCL_SERVICE_ALL or TCL_SERVICE_NONE. * * Side effects: * None. * *---------------------------------------------------------------------- */ int Tcl_GetServiceMode() { if (!initialized) { InitNotifier(); } return notifier.serviceMode; } /* *---------------------------------------------------------------------- * * Tcl_SetServiceMode -- * * This routine sets the current service mode of the notifier. * * Results: * Returns the previous service mode. * * Side effects: * None. * *---------------------------------------------------------------------- */ int Tcl_SetServiceMode(mode) int mode; /* New service mode: TCL_SERVICE_ALL or * TCL_SERVICE_NONE */ { int oldMode; if (!initialized) { InitNotifier(); } oldMode = notifier.serviceMode; notifier.serviceMode = mode; return oldMode; } /* *---------------------------------------------------------------------- * * Tcl_SetMaxBlockTime -- * * This procedure is invoked by event sources to tell the notifier * how long it may block the next time it blocks. The timePtr * argument gives a maximum time; the actual time may be less if * some other event source requested a smaller time. * * Results: * None. * * Side effects: * May reduce the length of the next sleep in the notifier. * *---------------------------------------------------------------------- */ void Tcl_SetMaxBlockTime(timePtr) Tcl_Time *timePtr; /* Specifies a maximum elapsed time for * the next blocking operation in the * event notifier. */ { if (!initialized) { InitNotifier(); } if (!notifier.blockTimeSet || (timePtr->sec < notifier.blockTime.sec) || ((timePtr->sec == notifier.blockTime.sec) && (timePtr->usec < notifier.blockTime.usec))) { notifier.blockTime = *timePtr; notifier.blockTimeSet = 1; } /* * If we are called outside an event source traversal, set the * timeout immediately. */ if (!notifier.inTraversal) { if (notifier.blockTimeSet) { Tcl_SetTimer(¬ifier.blockTime); } else { Tcl_SetTimer(NULL); } } } /* *---------------------------------------------------------------------- * * Tcl_DoOneEvent -- * * Process a single event of some sort. If there's no work to * do, wait for an event to occur, then process it. * * Results: * The return value is 1 if the procedure actually found an event * to process. If no processing occurred, then 0 is returned (this * can happen if the TCL_DONT_WAIT flag is set or if there are no * event handlers to wait for in the set specified by flags). * * Side effects: * May delay execution of process while waiting for an event, * unless TCL_DONT_WAIT is set in the flags argument. Event * sources are invoked to check for and queue events. Event * handlers may produce arbitrary side effects. * *---------------------------------------------------------------------- */ int Tcl_DoOneEvent(flags) int flags; /* Miscellaneous flag values: may be any * combination of TCL_DONT_WAIT, * TCL_WINDOW_EVENTS, TCL_FILE_EVENTS, * TCL_TIMER_EVENTS, TCL_IDLE_EVENTS, or * others defined by event sources. */ { int result = 0, oldMode; EventSource *sourcePtr; Tcl_Time *timePtr; if (!initialized) { InitNotifier(); } /* * The first thing we do is to service any asynchronous event * handlers. */ if (Tcl_AsyncReady()) { (void) Tcl_AsyncInvoke((Tcl_Interp *) NULL, 0); return 1; } /* * No event flags is equivalent to TCL_ALL_EVENTS. */ if ((flags & TCL_ALL_EVENTS) == 0) { flags |= TCL_ALL_EVENTS; } /* * Set the service mode to none so notifier event routines won't * try to service events recursively. */ oldMode = notifier.serviceMode; notifier.serviceMode = TCL_SERVICE_NONE; /* * The core of this procedure is an infinite loop, even though * we only service one event. The reason for this is that we * may be processing events that don't do anything inside of Tcl. */ while (1) { /* * If idle events are the only things to service, skip the * main part of the loop and go directly to handle idle * events (i.e. don't wait even if TCL_DONT_WAIT isn't set). */ if ((flags & TCL_ALL_EVENTS) == TCL_IDLE_EVENTS) { flags = TCL_IDLE_EVENTS|TCL_DONT_WAIT; goto idleEvents; } /* * Ask Tcl to service a queued event, if there are any. */ if (Tcl_ServiceEvent(flags)) { result = 1; break; } /* * If TCL_DONT_WAIT is set, be sure to poll rather than * blocking, otherwise reset the block time to infinity. */ if (flags & TCL_DONT_WAIT) { notifier.blockTime.sec = 0; notifier.blockTime.usec = 0; notifier.blockTimeSet = 1; } else { notifier.blockTimeSet = 0; } /* * Set up all the event sources for new events. This will * cause the block time to be updated if necessary. */ notifier.inTraversal = 1; for (sourcePtr = notifier.firstEventSourcePtr; sourcePtr != NULL; sourcePtr = sourcePtr->nextPtr) { if (sourcePtr->setupProc) { (sourcePtr->setupProc)(sourcePtr->clientData, flags); } } notifier.inTraversal = 0; if ((flags & TCL_DONT_WAIT) || notifier.blockTimeSet) { timePtr = ¬ifier.blockTime; } else { timePtr = NULL; } /* * Wait for a new event or a timeout. If Tcl_WaitForEvent * returns -1, we should abort Tcl_DoOneEvent. */ result = Tcl_WaitForEvent(timePtr); if (result < 0) { result = 0; break; } /* * Check all the event sources for new events. */ for (sourcePtr = notifier.firstEventSourcePtr; sourcePtr != NULL; sourcePtr = sourcePtr->nextPtr) { if (sourcePtr->checkProc) { (sourcePtr->checkProc)(sourcePtr->clientData, flags); } } /* * Check for events queued by the notifier or event sources. */ if (Tcl_ServiceEvent(flags)) { result = 1; break; } /* * We've tried everything at this point, but nobody we know * about had anything to do. Check for idle events. If none, * either quit or go back to the top and try again. */ idleEvents: if (flags & TCL_IDLE_EVENTS) { if (TclServiceIdle()) { result = 1; break; } } if (flags & TCL_DONT_WAIT) { break; } /* * If Tcl_WaitForEvent has returned 1, * indicating that one system event has been dispatched * (and thus that some Tcl code might have been indirectly executed), * we break out of the loop. * We do this to give VwaitCmd for instance a chance to check * if that system event had the side effect of changing the * variable (so the vwait can return and unwind properly). * * NB: We will process idle events if any first, because * otherwise we might never do the idle events if the notifier * always gets system events. */ if (result) { break; } } notifier.serviceMode = oldMode; return result; } /* *---------------------------------------------------------------------- * * Tcl_ServiceAll -- * * This routine checks all of the event sources, processes * events that are on the Tcl event queue, and then calls the * any idle handlers. Platform specific notifier callbacks that * generate events should call this routine before returning to * the system in order to ensure that Tcl gets a chance to * process the new events. * * Results: * Returns 1 if an event or idle handler was invoked, else 0. * * Side effects: * Anything that an event or idle handler may do. * *---------------------------------------------------------------------- */ int Tcl_ServiceAll() { int result = 0; EventSource *sourcePtr; if (!initialized) { InitNotifier(); } if (notifier.serviceMode == TCL_SERVICE_NONE) { return result; } /* * We need to turn off event servicing like we to in Tcl_DoOneEvent, * to avoid recursive calls. */ notifier.serviceMode = TCL_SERVICE_NONE; /* * Check async handlers first. */ if (Tcl_AsyncReady()) { (void) Tcl_AsyncInvoke((Tcl_Interp *) NULL, 0); } /* * Make a single pass through all event sources, queued events, * and idle handlers. Note that we wait to update the notifier * timer until the end so we can avoid multiple changes. */ notifier.inTraversal = 1; notifier.blockTimeSet = 0; for (sourcePtr = notifier.firstEventSourcePtr; sourcePtr != NULL; sourcePtr = sourcePtr->nextPtr) { if (sourcePtr->setupProc) { (sourcePtr->setupProc)(sourcePtr->clientData, TCL_ALL_EVENTS); } } for (sourcePtr = notifier.firstEventSourcePtr; sourcePtr != NULL; sourcePtr = sourcePtr->nextPtr) { if (sourcePtr->checkProc) { (sourcePtr->checkProc)(sourcePtr->clientData, TCL_ALL_EVENTS); } } while (Tcl_ServiceEvent(0)) { result = 1; } if (TclServiceIdle()) { result = 1; } if (!notifier.blockTimeSet) { Tcl_SetTimer(NULL); } else { Tcl_SetTimer(¬ifier.blockTime); } notifier.inTraversal = 0; notifier.serviceMode = TCL_SERVICE_ALL; return result; }