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Diffstat (limited to 'contrib/tcl/generic/tclNotify.c')
| -rw-r--r-- | contrib/tcl/generic/tclNotify.c | 578 |
1 files changed, 578 insertions, 0 deletions
diff --git a/contrib/tcl/generic/tclNotify.c b/contrib/tcl/generic/tclNotify.c new file mode 100644 index 0000000..0745591 --- /dev/null +++ b/contrib/tcl/generic/tclNotify.c @@ -0,0 +1,578 @@ +/* + * tclNotify.c -- + * + * This file provides the parts of the Tcl event notifier that are + * the same on all platforms, plus a few other parts that are used + * on more than one platform but not all. + * + * The notifier is the lowest-level part of the event system. It + * manages an event queue that holds Tcl_Event structures and a list + * of event sources that can add events to the queue. It also + * contains the procedure Tcl_DoOneEvent that invokes the event + * sources and blocks to wait for new events, but Tcl_DoOneEvent + * is in the platform-specific part of the notifier (in files like + * tclUnixNotify.c). + * + * Copyright (c) 1995 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: @(#) tclNotify.c 1.6 96/02/29 09:20:10 + */ + +#include "tclInt.h" +#include "tclPort.h" + +/* + * The following variable records the address of the first event + * source in the list of all event sources for the application. + * This variable is accessed by the notifier to traverse the list + * and invoke each event source. + */ + +TclEventSource *tclFirstEventSourcePtr = NULL; + +/* + * The following variables indicate how long to block in the event + * notifier the next time it blocks (default: block forever). + */ + +static int blockTimeSet = 0; /* 0 means there is no maximum block + * time: block forever. */ +static Tcl_Time blockTime; /* If blockTimeSet is 1, gives the + * maximum elapsed time for the next block. */ + +/* + * The following variables 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 Tcl_Event *firstEventPtr = NULL; + /* First pending event, or NULL if none. */ +static Tcl_Event *lastEventPtr = NULL; + /* Last pending event, or NULL if none. */ +static Tcl_Event *markerEventPtr = NULL; + /* Last high-priority event in queue, or + * NULL if none. */ + +/* + * Prototypes for procedures used only in this file: + */ + +static int ServiceEvent _ANSI_ARGS_((int flags)); + +/* + *---------------------------------------------------------------------- + * + * 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. */ +{ + TclEventSource *sourcePtr; + + sourcePtr = (TclEventSource *) ckalloc(sizeof(TclEventSource)); + sourcePtr->setupProc = setupProc; + sourcePtr->checkProc = checkProc; + sourcePtr->clientData = clientData; + sourcePtr->nextPtr = tclFirstEventSourcePtr; + tclFirstEventSourcePtr = 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. */ +{ + TclEventSource *sourcePtr, *prevPtr; + + for (sourcePtr = tclFirstEventSourcePtr, prevPtr = NULL; + sourcePtr != NULL; + prevPtr = sourcePtr, sourcePtr = sourcePtr->nextPtr) { + if ((sourcePtr->setupProc != setupProc) + || (sourcePtr->checkProc != checkProc) + || (sourcePtr->clientData != clientData)) { + continue; + } + if (prevPtr == NULL) { + tclFirstEventSourcePtr = 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 (position == TCL_QUEUE_TAIL) { + /* + * Append the event on the end of the queue. + */ + + evPtr->nextPtr = NULL; + if (firstEventPtr == NULL) { + firstEventPtr = evPtr; + } else { + lastEventPtr->nextPtr = evPtr; + } + lastEventPtr = evPtr; + } else if (position == TCL_QUEUE_HEAD) { + /* + * Push the event on the head of the queue. + */ + + evPtr->nextPtr = firstEventPtr; + if (firstEventPtr == NULL) { + lastEventPtr = evPtr; + } + 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 (markerEventPtr == NULL) { + evPtr->nextPtr = firstEventPtr; + firstEventPtr = evPtr; + } else { + evPtr->nextPtr = markerEventPtr->nextPtr; + markerEventPtr->nextPtr = evPtr; + } + markerEventPtr = evPtr; + if (evPtr->nextPtr == NULL) { + 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; + + for (prevPtr = (Tcl_Event *) NULL, evPtr = firstEventPtr; + evPtr != (Tcl_Event *) NULL; + ) { + if ((*proc) (evPtr, clientData) == 1) { + if (firstEventPtr == evPtr) { + firstEventPtr = evPtr->nextPtr; + if (evPtr->nextPtr == (Tcl_Event *) NULL) { + lastEventPtr = (Tcl_Event *) NULL; + } + } else { + prevPtr->nextPtr = evPtr->nextPtr; + } + hold = evPtr; + evPtr = evPtr->nextPtr; + ckfree((char *) hold); + } else { + prevPtr = evPtr; + evPtr = evPtr->nextPtr; + } + } +} + +/* + *---------------------------------------------------------------------- + * + * ServiceEvent -- + * + * Process one event from the event queue. This routine is called + * by the notifier whenever it wants Tk to process an event. + * + * 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. + * + *---------------------------------------------------------------------- + */ + +static int +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; + + /* + * 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 = 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 (firstEventPtr == evPtr) { + firstEventPtr = evPtr->nextPtr; + if (evPtr->nextPtr == NULL) { + lastEventPtr = NULL; + } + } else { + for (prevPtr = firstEventPtr; prevPtr->nextPtr != evPtr; + prevPtr = prevPtr->nextPtr) { + /* Empty loop body. */ + } + prevPtr->nextPtr = evPtr->nextPtr; + if (evPtr->nextPtr == NULL) { + lastEventPtr = prevPtr; + } + } + if (markerEventPtr == evPtr) { + markerEventPtr = NULL; + } + 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_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 (!blockTimeSet || (timePtr->sec < blockTime.sec) + || ((timePtr->sec == blockTime.sec) + && (timePtr->usec < blockTime.usec))) { + blockTime = *timePtr; + blockTimeSet = 1; + } +} + +/* + *---------------------------------------------------------------------- + * + * 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. */ +{ + TclEventSource *sourcePtr; + Tcl_Time *timePtr; + + /* + * No event flags is equivalent to TCL_ALL_EVENTS. + */ + + if ((flags & TCL_ALL_EVENTS) == 0) { + flags |= TCL_ALL_EVENTS; + } + + /* + * The core of this procedure is an infinite loop, even though + * we only service one event. The reason for this is that we + * might think we have an event ready (e.g. the connection to + * the server becomes readable), but then we might discover that + * there's nothing interesting on that connection, so no event + * was serviced. Or, the select operation could return prematurely + * due to a signal. The easiest thing in both these cases is + * just to loop back and try again. + */ + + while (1) { + + /* + * The first thing we do is to service any asynchronous event + * handlers. + */ + + if (Tcl_AsyncReady()) { + (void) Tcl_AsyncInvoke((Tcl_Interp *) NULL, 0); + return 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_IDLE_EVENTS) { + flags = TCL_IDLE_EVENTS|TCL_DONT_WAIT; + goto idleEvents; + } + + /* + * Ask Tk to service a queued event, if there are any. + */ + + if (ServiceEvent(flags)) { + return 1; + } + + /* + * There are no events already queued. Invoke all of the + * event sources to give them a chance to setup for the wait. + */ + + blockTimeSet = 0; + for (sourcePtr = tclFirstEventSourcePtr; sourcePtr != NULL; + sourcePtr = sourcePtr->nextPtr) { + (*sourcePtr->setupProc)(sourcePtr->clientData, flags); + } + if ((flags & TCL_DONT_WAIT) || + ((flags & TCL_IDLE_EVENTS) && TclIdlePending())) { + /* + * Don't block: there are idle events waiting, or we don't + * care about idle events anyway, or the caller asked us not + * to block. + */ + + blockTime.sec = 0; + blockTime.usec = 0; + timePtr = &blockTime; + } else if (blockTimeSet) { + timePtr = &blockTime; + } else { + timePtr = NULL; + } + + /* + * Wait until an event occurs or the timer expires. + */ + + if (Tcl_WaitForEvent(timePtr) == TCL_ERROR) { + return 0; + } + + /* + * Give each of the event sources a chance to queue events, + * then call ServiceEvent and give it another chance to + * service events. + */ + + for (sourcePtr = tclFirstEventSourcePtr; sourcePtr != NULL; + sourcePtr = sourcePtr->nextPtr) { + (*sourcePtr->checkProc)(sourcePtr->clientData, flags); + } + if (ServiceEvent(flags)) { + return 1; + } + + /* + * We've tried everything at this point, but nobody 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) && TclServiceIdle()) { + return 1; + } + if (flags & TCL_DONT_WAIT) { + return 0; + } + } +} |
