/*
* 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.
*
* RCS: @(#) $Id: tclUnixNotfy.c,v 1.11.2.2 2003/07/16 22:09:48 hobbs Exp $
*/
#if 0
#include "tclInt.h"
#include "tclPort.h"
#else
#include "tkPort.h"
#include "Lang.h"
#endif
#include <signal.h>
#ifdef _LANG
#include <errno.h>
#endif
#ifdef TCL_EVENT_IMPLEMENT
#ifndef _LANG
extern TclStubs tclStubs;
#else
#include "tkEvent_f.h"
#endif
extern Tcl_NotifierProcs tclOriginalNotifier;
#ifndef MASK_SIZE
/* under Cygwin we use tclUnix but tkWin.
So bring in some "tkUnixPort.h" definitions
*/
#ifdef HAVE_SYS_SELECT_H
# include <sys/select.h>
#endif
/*
* The following macro defines the number of fd_masks in an fd_set:
*/
#ifndef FD_SETSIZE
# ifdef OPEN_MAX
# define FD_SETSIZE OPEN_MAX
# else
# define FD_SETSIZE 256
# endif
#endif
#if !defined(howmany)
# define howmany(x, y) (((x)+((y)-1))/(y))
#endif
#ifndef NFDBITS
# define NFDBITS NBBY*sizeof(fd_mask)
#endif
#define MASK_SIZE howmany(FD_SETSIZE, NFDBITS)
#endif
/*
* 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. */
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 structure contains a set of select() masks to track
* readable, writable, and exceptional conditions.
*/
typedef struct SelectMasks {
fd_set readable;
fd_set writable;
fd_set exceptional;
} SelectMasks;
/*
* 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). */
#ifdef 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. */
Tcl_Condition waitCV; /* Any other thread alerts a notifier
* that an event is ready to be processed
* by signaling this condition variable. */
int eventReady; /* True if an event is ready to be processed.
* Used as condition flag together with
* waitCV above. */
#endif
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;
#ifdef 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
* 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 accessing this list.
*/
static int triggerPipe = -1;
/*
* The notifierMutex locks access to all of the global notifier state.
*/
TCL_DECLARE_MUTEX(notifierMutex)
/*
* The notifier thread signals the notifierCV when it has finished
* initializing the triggerPipe and right before the notifier
* thread terminates.
*/
static Tcl_Condition notifierCV;
/*
* 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
/*
* Static routines defined in this file.
*/
#ifdef TCL_THREADS
static void NotifierThreadProc _ANSI_ARGS_((ClientData clientData));
#endif
static int FileHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr,
int flags));
/*
*----------------------------------------------------------------------
*
* 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()
{
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
#ifdef TCL_THREADS
tsdPtr->eventReady = 0;
/*
* Start the Notifier thread if necessary.
*/
Tcl_MutexLock(¬ifierMutex);
if (notifierCount == 0) {
if (Tcl_CreateThread(¬ifierThread, NotifierThreadProc, NULL,
TCL_THREAD_STACK_DEFAULT, TCL_THREAD_NOFLAGS) != TCL_OK) {
panic("Tcl_InitNotifier: unable to start notifier thread");
}
}
notifierCount++;
/*
* Wait for the notifier pipe to be created.
*/
while (triggerPipe < 0) {
Tcl_ConditionWait(¬ifierCV, ¬ifierMutex, NULL);
}
Tcl_MutexUnlock(¬ifierMutex);
#endif
return (ClientData) 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 clientData; /* Not used. */
{
#ifdef TCL_THREADS
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
Tcl_MutexLock(¬ifierMutex);
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) {
if (triggerPipe < 0) {
panic("Tcl_FinalizeNotifier: notifier pipe not initialized");
}
/*
* Send "q" message to the notifier thread so that it will
* terminate. The notifier will return from its call to select()
* and notice that a "q" message has arrived, it will then close
* its side of the pipe and terminate its thread. Note the we can
* not just close the pipe and check for EOF in the notifier
* thread because if a background child process was created with
* exec, select() would not register the EOF on the pipe until the
* child processes had terminated. [Bug: 4139]
*/
write(triggerPipe, "q", 1);
close(triggerPipe);
Tcl_ConditionWait(¬ifierCV, ¬ifierMutex, NULL);
}
/*
* Clean up any synchronization objects in the thread local storage.
*/
Tcl_ConditionFinalize(&(tsdPtr->waitCV));
Tcl_MutexUnlock(¬ifierMutex);
#endif
}
/*
*----------------------------------------------------------------------
*
* Tcl_AlertNotifier --
*
* Wake up the specified notifier from any thread. This routine
* is called by the platform independent notifier code whenever
* the Tcl_ThreadAlert routine is called. This routine is
* guaranteed not to be called on a given notifier after
* Tcl_FinalizeNotifier is called for that notifier.
*
* Results:
* None.
*
* Side effects:
* Signals the notifier condition variable for the specified
* notifier.
*
*----------------------------------------------------------------------
*/
void
Tcl_AlertNotifier(clientData)
ClientData clientData;
{
#ifdef TCL_THREADS
ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData;
Tcl_MutexLock(¬ifierMutex);
tsdPtr->eventReady = 1;
Tcl_ConditionNotify(&tsdPtr->waitCV);
Tcl_MutexUnlock(¬ifierMutex);
#endif
}
/*
*----------------------------------------------------------------------
*
* 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.
*/
if (tclStubs.tcl_SetTimer != tclOriginalNotifier.setTimerProc) {
tclStubs.tcl_SetTimer(timePtr);
}
}
/*
*----------------------------------------------------------------------
*
* Tcl_ServiceModeHook --
*
* This function is invoked whenever the service mode changes.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
void
Tcl_ServiceModeHook(mode)
int mode; /* Either TCL_SERVICE_ALL, or
* TCL_SERVICE_NONE. */
{
}
/*
*----------------------------------------------------------------------
*
* Tcl_CreateFileHandler --
*
* This procedure registers a file handler with the select notifier.
*
* Results:
* None.
*
* Side effects:
* Creates a new file handler structure.
*
*----------------------------------------------------------------------
*/
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. */
{
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
FileHandler *filePtr;
if (tclStubs.tcl_CreateFileHandler != tclOriginalNotifier.createFileHandlerProc) {
tclStubs.tcl_CreateFileHandler(fd, mask, proc, clientData);
return;
}
for (filePtr = tsdPtr->firstFileHandlerPtr; filePtr != NULL;
filePtr = filePtr->nextPtr) {
if (filePtr->fd == fd) {
break;
}
}
if (filePtr == NULL) {
filePtr = (FileHandler*) ckalloc(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.exceptional) );
} else {
FD_CLR( fd, &(tsdPtr->checkMasks.exceptional) );
}
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(fd)
int fd; /* Stream id for which to remove callback procedure. */
{
FileHandler *filePtr, *prevPtr;
int i;
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
if (tclStubs.tcl_DeleteFileHandler != tclOriginalNotifier.deleteFileHandlerProc) {
tclStubs.tcl_DeleteFileHandler(fd);
return;
}
/*
* 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.exceptional) );
}
/*
* Find current max fd.
*/
if (fd+1 == tsdPtr->numFdBits) {
tsdPtr->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.exceptional ) ) ) {
tsdPtr->numFdBits = i+1;
break;
}
}
}
/*
* Clean up information in the callback record.
*/
if (prevPtr == NULL) {
tsdPtr->firstFileHandlerPtr = filePtr->nextPtr;
} else {
prevPtr->nextPtr = filePtr->nextPtr;
}
ckfree((char *) filePtr);
}
#if defined(__EMX__) && (defined(__WIN32__) || defined(__PM__))
/* Backdoor into processing of events when from Tk. */
int (*Tcl_WaitForEventProc)(int, fd_mask *, Tcl_Time *) = NULL;
#endif
/*
*----------------------------------------------------------------------
*
* 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. */
{
int mask;
FileHandler *filePtr;
FileHandlerEvent *fileEvPtr = (FileHandlerEvent *) evPtr;
ThreadSpecificData *tsdPtr;
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.
*/
tsdPtr = TCL_TSD_INIT(&dataKey);
for (filePtr = tsdPtr->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;
struct timeval timeout, *timeoutPtr;
int mask;
#ifdef TCL_THREADS
int waitForFiles;
#else
int numFound;
#endif
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
if (tclStubs.tcl_WaitForEvent != tclOriginalNotifier.waitForEventProc) {
return tclStubs.tcl_WaitForEvent(timePtr);
}
/*
* 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.tv_sec = timePtr->sec;
timeout.tv_usec = timePtr->usec;
timeoutPtr = &timeout;
#ifndef TCL_THREADS
} 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;
#endif
} else {
timeoutPtr = NULL;
}
#ifdef TCL_THREADS
/*
* Place this thread on the list of interested threads, signal the
* notifier thread, and wait for a response or a timeout.
*/
Tcl_MutexLock(¬ifierMutex);
waitForFiles = (tsdPtr->numFdBits > 0);
if (timePtr != NULL && timePtr->sec == 0 && timePtr->usec == 0) {
/*
* 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 {
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;
write(triggerPipe, "", 1);
}
FD_ZERO( &(tsdPtr->readyMasks.readable) );
FD_ZERO( &(tsdPtr->readyMasks.writable) );
FD_ZERO( &(tsdPtr->readyMasks.exceptional) );
if (!tsdPtr->eventReady) {
Tcl_ConditionWait(&tsdPtr->waitCV, ¬ifierMutex, timePtr);
}
tsdPtr->eventReady = 0;
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;
write(triggerPipe, "", 1);
}
#else
tsdPtr->readyMasks = tsdPtr->checkMasks;
numFound = select( tsdPtr->numFdBits,
&(tsdPtr->readyMasks.readable),
&(tsdPtr->readyMasks.writable),
&(tsdPtr->readyMasks.exceptional),
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.exceptional ) );
}
#ifdef _LANG
/*
* Language-specific check for signals
*/
if (numFound == -1 && errno == EINTR) {
LangAsyncCheck();
}
#endif
#endif
/*
* 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.exceptional) ) ) {
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) {
fileEvPtr = (FileHandlerEvent *) ckalloc(
sizeof(FileHandlerEvent));
fileEvPtr->header.proc = FileHandlerEventProc;
fileEvPtr->fd = filePtr->fd;
Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL);
}
filePtr->readyMask = mask;
}
#ifdef TCL_THREADS
Tcl_MutexUnlock(¬ifierMutex);
#endif
return 0;
}
#ifdef TCL_THREADS
/*
*----------------------------------------------------------------------
*
* 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.
*
*----------------------------------------------------------------------
*/
static void
NotifierThreadProc(clientData)
ClientData clientData; /* Not used. */
{
ThreadSpecificData *tsdPtr;
fd_set readableMask;
fd_set writableMask;
fd_set exceptionalMask;
int fds[2];
int i, status, numFdBits, receivePipe;
long found;
struct timeval poll = {0., 0.}, *timePtr;
char buf[2];
if (pipe(fds) != 0) {
panic("NotifierThreadProc: could not create trigger pipe.");
}
receivePipe = fds[0];
#ifndef USE_FIONBIO
status = fcntl(receivePipe, F_GETFL);
status |= O_NONBLOCK;
if (fcntl(receivePipe, F_SETFL, status) < 0) {
panic("NotifierThreadProc: could not make receive pipe non blocking.");
}
status = fcntl(fds[1], F_GETFL);
status |= O_NONBLOCK;
if (fcntl(fds[1], F_SETFL, status) < 0) {
panic("NotifierThreadProc: could not make trigger pipe non blocking.");
}
#else
if (ioctl(receivePipe, (int) FIONBIO, &status) < 0) {
panic("NotifierThreadProc: could not make receive pipe non blocking.");
}
if (ioctl(fds[1], (int) FIONBIO, &status) < 0) {
panic("NotifierThreadProc: could not make trigger pipe non blocking.");
}
#endif
/*
* Install the write end of the pipe into the global variable.
*/
Tcl_MutexLock(¬ifierMutex);
triggerPipe = fds[1];
/*
* Signal any threads that are waiting.
*/
Tcl_ConditionNotify(¬ifierCV);
Tcl_MutexUnlock(¬ifierMutex);
/*
* Look for file events and report them to interested threads.
*/
while (1) {
FD_ZERO( &readableMask );
FD_ZERO( &writableMask );
FD_ZERO( &exceptionalMask );
/*
* Compute the logical OR of the select masks from all the
* waiting notifiers.
*/
Tcl_MutexLock(¬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.exceptional) ) ) {
FD_SET( i, &exceptionalMask );
}
}
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;
}
}
Tcl_MutexUnlock(¬ifierMutex);
/*
* Set up the select mask to include the receive pipe.
*/
if ( receivePipe >= numFdBits ) {
numFdBits = receivePipe + 1;
}
FD_SET( receivePipe, &readableMask );
if ( select( numFdBits, &readableMask, &writableMask,
&exceptionalMask, timePtr) == -1 ) {
/*
* Try again immediately on an error.
*/
continue;
}
/*
* Alert any threads that are waiting on a ready file descriptor.
*/
Tcl_MutexLock(¬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.exceptional) )
&& FD_ISSET( i, &exceptionalMask ) ) {
FD_SET( i, &(tsdPtr->readyMasks.exceptional) );
found = 1;
}
}
if (found || (tsdPtr->pollState & POLL_DONE)) {
tsdPtr->eventReady = 1;
if (tsdPtr->onList) {
/*
* Remove the ThreadSpecificData structure of this
* thread from the waiting list. This prevents us from
* continuously spining on select until the other
* threads runs and services the file event.
*/
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;
tsdPtr->pollState = 0;
}
Tcl_ConditionNotify(&tsdPtr->waitCV);
}
}
Tcl_MutexUnlock(¬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.
*/
if ( FD_ISSET( receivePipe, &readableMask ) ) {
i = read(receivePipe, buf, 1);
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;
}
}
}
/*
* Clean up the read end of the pipe and signal any threads waiting on
* termination of the notifier thread.
*/
close(receivePipe);
Tcl_MutexLock(¬ifierMutex);
triggerPipe = -1;
Tcl_ConditionNotify(¬ifierCV);
Tcl_MutexUnlock(¬ifierMutex);
}
#endif
#endif