/*
* tclSelectNotfy.c --
*
* This file contains the implementation of the select()-based generic
* Unix notifier, which is the lowest-level part of the Tcl event loop.
* This file works together with generic/tclNotify.c.
*
* Copyright © 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.
*/
#include "tclInt.h"
#ifndef HAVE_COREFOUNDATION /* Darwin/Mac OS X CoreFoundation notifier is
* in tclMacOSXNotify.c */
#if (!defined(NOTIFIER_EPOLL) && !defined(NOTIFIER_KQUEUE)) || !TCL_THREADS
#include <signal.h>
/*
* This structure is used to keep track of the notifier info for 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; /* 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. */
} FileHandler;
/*
* The following structure contains a set of select() masks to track readable,
* writable, and exception conditions.
*/
typedef struct {
fd_set readable;
fd_set writable;
fd_set exception;
} SelectMasks;
/*
* 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
* 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). */
#if 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. */
#ifdef __CYGWIN__
void *event; /* Any other thread alerts a notifier that an
* event is ready to be processed by sending
* this event. */
void *hwnd; /* Messaging window. */
#else /* !__CYGWIN__ */
pthread_cond_t waitCV; /* Any other thread alerts a notifier that an
* event is ready to be processed by signaling
* this condition variable. */
#endif /* __CYGWIN__ */
int waitCVinitialized; /* Variable to flag initialization of the
* structure. */
int eventReady; /* True if an event is ready to be processed.
* Used as condition flag together with waitCV
* above. */
#endif /* TCL_THREADS */
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;
#if 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
* 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 writing to the pipe.
*/
static int triggerPipe = -1;
/*
* The notifierMutex locks access to all of the global notifier state.
*/
static pthread_mutex_t notifierInitMutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t notifierMutex = PTHREAD_MUTEX_INITIALIZER;
/*
* The following static indicates if the notifier thread is running.
*
* You must hold the notifierInitMutex before accessing this variable.
*/
static int notifierThreadRunning = 0;
/*
* The notifier thread signals the notifierCV when it has finished
* initializing the triggerPipe and right before the notifier thread
* terminates.
*/
static pthread_cond_t notifierCV = PTHREAD_COND_INITIALIZER;
/*
* 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 /* TCL_THREADS */
/*
* Static routines defined in this file.
*/
#if TCL_THREADS
static TCL_NORETURN void NotifierThreadProc(ClientData clientData);
#if defined(HAVE_PTHREAD_ATFORK)
static int atForkInit = 0;
static void AtForkChild(void);
#endif /* HAVE_PTHREAD_ATFORK */
#endif /* TCL_THREADS */
static int FileHandlerEventProc(Tcl_Event *evPtr, int flags);
/*
* Import of critical bits of Windows API when building threaded with Cygwin.
*/
#if defined(__CYGWIN__)
#ifdef __cplusplus
extern "C" {
#endif
typedef struct {
void *hwnd; /* Messaging window. */
unsigned int *message; /* Message payload. */
size_t wParam; /* Event-specific "word" parameter. */
size_t lParam; /* Event-specific "long" parameter. */
int time; /* Event timestamp. */
int x; /* Event location (where meaningful). */
int y;
int lPrivate;
} MSG;
typedef struct {
unsigned int style;
void *lpfnWndProc;
int cbClsExtra;
int cbWndExtra;
void *hInstance;
void *hIcon;
void *hCursor;
void *hbrBackground;
const void *lpszMenuName;
const void *lpszClassName;
} WNDCLASSW;
#ifdef __clang__
#pragma clang diagnostic ignored "-Wignored-attributes"
#endif
extern void __stdcall CloseHandle(void *);
extern void *__stdcall CreateEventW(void *, unsigned char, unsigned char,
void *);
extern void *__stdcall CreateWindowExW(void *, const void *, const void *,
unsigned int, int, int, int, int, void *, void *,
void *, void *);
extern unsigned int __stdcall DefWindowProcW(void *, int, void *, void *);
extern unsigned char __stdcall DestroyWindow(void *);
extern int __stdcall DispatchMessageW(const MSG *);
extern unsigned char __stdcall GetMessageW(MSG *, void *, int, int);
extern void __stdcall MsgWaitForMultipleObjects(unsigned int, void *,
unsigned char, unsigned int, unsigned int);
extern unsigned char __stdcall PeekMessageW(MSG *, void *, int, int, int);
extern unsigned char __stdcall PostMessageW(void *, unsigned int, void *,
void *);
extern void __stdcall PostQuitMessage(int);
extern void *__stdcall RegisterClassW(const WNDCLASSW *);
extern unsigned char __stdcall ResetEvent(void *);
extern unsigned char __stdcall TranslateMessage(const MSG *);
/*
* Threaded-cygwin specific constants and functions in this file:
*/
static const wchar_t className[] = L"TclNotifier";
static unsigned int __stdcall NotifierProc(void *hwnd, unsigned int message,
void *wParam, void *lParam);
#ifdef __cplusplus
}
#endif
#endif /* TCL_THREADS && __CYGWIN__ */
/*
* Incorporate the base notifier implementation.
*/
#include "tclUnixNotfy.c"
/*
*----------------------------------------------------------------------
*
* TclpInitNotifier --
*
* Initializes the platform specific notifier state.
*
* Results:
* Returns a handle to the notifier state for this thread.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
ClientData
TclpInitNotifier(void)
{
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
#if TCL_THREADS
tsdPtr->eventReady = 0;
/*
* Initialize thread specific condition variable for this thread.
*/
if (tsdPtr->waitCVinitialized == 0) {
#ifdef __CYGWIN__
WNDCLASSW clazz;
clazz.style = 0;
clazz.cbClsExtra = 0;
clazz.cbWndExtra = 0;
clazz.hInstance = TclWinGetTclInstance();
clazz.hbrBackground = NULL;
clazz.lpszMenuName = NULL;
clazz.lpszClassName = className;
clazz.lpfnWndProc = (void *) NotifierProc;
clazz.hIcon = NULL;
clazz.hCursor = NULL;
RegisterClassW(&clazz);
tsdPtr->hwnd = CreateWindowExW(NULL, clazz.lpszClassName,
clazz.lpszClassName, 0, 0, 0, 0, 0, NULL, NULL,
clazz.hInstance, NULL);
tsdPtr->event = CreateEventW(NULL, 1 /* manual */,
0 /* !signaled */, NULL);
#else /* !__CYGWIN__ */
pthread_cond_init(&tsdPtr->waitCV, NULL);
#endif /* __CYGWIN__ */
tsdPtr->waitCVinitialized = 1;
}
pthread_mutex_lock(¬ifierInitMutex);
#if defined(HAVE_PTHREAD_ATFORK)
/*
* Install pthread_atfork handlers to clean up the notifier in the child
* of a fork.
*/
if (!atForkInit) {
int result = pthread_atfork(NULL, NULL, AtForkChild);
if (result) {
Tcl_Panic("Tcl_InitNotifier: %s", "pthread_atfork failed");
}
atForkInit = 1;
}
#endif /* HAVE_PTHREAD_ATFORK */
notifierCount++;
pthread_mutex_unlock(¬ifierInitMutex);
#endif /* TCL_THREADS */
return tsdPtr;
}
/*
*----------------------------------------------------------------------
*
* TclpFinalizeNotifier --
*
* 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
TclpFinalizeNotifier(
ClientData clientData)
{
#if TCL_THREADS
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
pthread_mutex_lock(¬ifierInitMutex);
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 && triggerPipe != -1) {
if (write(triggerPipe, "q", 1) != 1) {
Tcl_Panic("Tcl_FinalizeNotifier: %s",
"unable to write 'q' to triggerPipe");
}
close(triggerPipe);
pthread_mutex_lock(¬ifierMutex);
while(triggerPipe != -1) {
pthread_cond_wait(¬ifierCV, ¬ifierMutex);
}
pthread_mutex_unlock(¬ifierMutex);
if (notifierThreadRunning) {
int result = pthread_join((pthread_t) notifierThread, NULL);
if (result) {
Tcl_Panic("Tcl_FinalizeNotifier: %s",
"unable to join notifier thread");
}
notifierThreadRunning = 0;
}
}
/*
* Clean up any synchronization objects in the thread local storage.
*/
#ifdef __CYGWIN__
DestroyWindow(tsdPtr->hwnd);
CloseHandle(tsdPtr->event);
#else /* !__CYGWIN__ */
pthread_cond_destroy(&tsdPtr->waitCV);
#endif /* __CYGWIN__ */
tsdPtr->waitCVinitialized = 0;
pthread_mutex_unlock(¬ifierInitMutex);
#endif /* TCL_THREADS */
}
/*
*----------------------------------------------------------------------
*
* TclpCreateFileHandler --
*
* This function registers a file handler with the select notifier.
*
* Results:
* None.
*
* Side effects:
* Creates a new file handler structure.
*
*----------------------------------------------------------------------
*/
void
TclpCreateFileHandler(
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. */
{
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
FileHandler *filePtr = LookUpFileHandler(tsdPtr, fd, NULL);
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.exception);
} else {
FD_CLR(fd, &tsdPtr->checkMasks.exception);
}
if (tsdPtr->numFdBits <= fd) {
tsdPtr->numFdBits = fd + 1;
}
}
/*
*----------------------------------------------------------------------
*
* TclpDeleteFileHandler --
*
* Cancel a previously-arranged callback arrangement for a file.
*
* Results:
* None.
*
* Side effects:
* If a callback was previously registered on file, remove it.
*
*----------------------------------------------------------------------
*/
void
TclpDeleteFileHandler(
int fd) /* Stream id for which to remove callback
* function. */
{
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
FileHandler *filePtr, *prevPtr;
int i;
/*
* Find the entry for the given file (and return if there isn't one).
*/
filePtr = LookUpFileHandler(tsdPtr, fd, &prevPtr);
if (filePtr == NULL) {
return;
}
/*
* 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.exception);
}
/*
* Find current max fd.
*/
if (fd + 1 == tsdPtr->numFdBits) {
int 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.exception)) {
numFdBits = i + 1;
break;
}
}
tsdPtr->numFdBits = numFdBits;
}
/*
* Clean up information in the callback record.
*/
if (prevPtr == NULL) {
tsdPtr->firstFileHandlerPtr = filePtr->nextPtr;
} else {
prevPtr->nextPtr = filePtr->nextPtr;
}
ckfree(filePtr);
}
#if defined(__CYGWIN__)
static unsigned int __stdcall
NotifierProc(
void *hwnd,
unsigned int message,
void *wParam,
void *lParam)
{
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
if (message != 1024) {
return DefWindowProcW(hwnd, message, wParam, lParam);
}
/*
* Process all of the runnable events.
*/
tsdPtr->eventReady = 1;
Tcl_ServiceAll();
return 0;
}
#endif /* TCL_THREADS && __CYGWIN__ */
/*
*----------------------------------------------------------------------
*
* TclpWaitForEvent --
*
* 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
TclpWaitForEvent(
const Tcl_Time *timePtr) /* Maximum block time, or NULL. */
{
FileHandler *filePtr;
int mask;
Tcl_Time vTime;
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
#if TCL_THREADS
int waitForFiles;
# ifdef __CYGWIN__
MSG msg;
# endif /* __CYGWIN__ */
#else /* !TCL_THREADS */
/*
* Impl. notes: timeout & timeoutPtr are used if, and only if threads are
* not enabled. They are the arguments for the regular select() used when
* the core is not thread-enabled.
*/
struct timeval timeout, *timeoutPtr;
int numFound;
#endif /* TCL_THREADS */
/*
* 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;
TclScaleTime(&vTime);
timePtr = &vTime;
}
#if !TCL_THREADS
timeout.tv_sec = timePtr->sec;
timeout.tv_usec = timePtr->usec;
timeoutPtr = &timeout;
} 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;
} else {
timeoutPtr = NULL;
#endif /* !TCL_THREADS */
}
#if TCL_THREADS
/*
* Start notifier thread and place this thread on the list of interested
* threads, signal the notifier thread, and wait for a response or a
* timeout.
*/
StartNotifierThread("Tcl_WaitForEvent");
pthread_mutex_lock(¬ifierMutex);
if (timePtr != NULL && timePtr->sec == 0 && (timePtr->usec == 0
#if defined(__APPLE__) && defined(__LP64__)
/*
* On 64-bit Darwin, pthread_cond_timedwait() appears to have a
* bug that causes it to wait forever when passed an absolute time
* which has already been exceeded by the system time; as a
* workaround, when given a very brief timeout, just do a poll.
* [Bug 1457797]
*/
|| timePtr->usec < 10
#endif /* __APPLE__ && __LP64__ */
)) {
/*
* 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 {
waitForFiles = (tsdPtr->numFdBits > 0);
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;
if ((write(triggerPipe, "", 1) == -1) && (errno != EAGAIN)) {
Tcl_Panic("Tcl_WaitForEvent: %s",
"unable to write to triggerPipe");
}
}
FD_ZERO(&tsdPtr->readyMasks.readable);
FD_ZERO(&tsdPtr->readyMasks.writable);
FD_ZERO(&tsdPtr->readyMasks.exception);
if (!tsdPtr->eventReady) {
#ifdef __CYGWIN__
if (!PeekMessageW(&msg, NULL, 0, 0, 0)) {
unsigned int timeout;
if (timePtr) {
timeout = timePtr->sec * 1000 + timePtr->usec / 1000;
} else {
timeout = 0xFFFFFFFF;
}
pthread_mutex_unlock(¬ifierMutex);
MsgWaitForMultipleObjects(1, &tsdPtr->event, 0, timeout, 1279);
pthread_mutex_lock(¬ifierMutex);
}
#else /* !__CYGWIN__ */
if (timePtr != NULL) {
Tcl_Time now;
struct timespec ptime;
Tcl_GetTime(&now);
ptime.tv_sec = timePtr->sec + now.sec +
(timePtr->usec + now.usec) / 1000000;
ptime.tv_nsec = 1000 * ((timePtr->usec + now.usec) % 1000000);
pthread_cond_timedwait(&tsdPtr->waitCV, ¬ifierMutex, &ptime);
} else {
pthread_cond_wait(&tsdPtr->waitCV, ¬ifierMutex);
}
#endif /* __CYGWIN__ */
}
tsdPtr->eventReady = 0;
#ifdef __CYGWIN__
while (PeekMessageW(&msg, NULL, 0, 0, 0)) {
/*
* Retrieve and dispatch the message.
*/
unsigned int result = GetMessageW(&msg, NULL, 0, 0);
if (result == 0) {
PostQuitMessage(msg.wParam);
/* What to do here? */
} else if (result != (unsigned int) -1) {
TranslateMessage(&msg);
DispatchMessageW(&msg);
}
}
ResetEvent(tsdPtr->event);
#endif /* __CYGWIN__ */
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;
if ((write(triggerPipe, "", 1) == -1) && (errno != EAGAIN)) {
Tcl_Panic("Tcl_WaitForEvent: %s",
"unable to write to triggerPipe");
}
}
#else /* !TCL_THREADS */
tsdPtr->readyMasks = tsdPtr->checkMasks;
numFound = select(tsdPtr->numFdBits, &tsdPtr->readyMasks.readable,
&tsdPtr->readyMasks.writable, &tsdPtr->readyMasks.exception,
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.exception);
}
#endif /* TCL_THREADS */
/*
* 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.exception)) {
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) {
FileHandlerEvent *fileEvPtr =
(FileHandlerEvent *) ckalloc(sizeof(FileHandlerEvent));
fileEvPtr->header.proc = FileHandlerEventProc;
fileEvPtr->fd = filePtr->fd;
Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL);
}
filePtr->readyMask = mask;
}
#if TCL_THREADS
pthread_mutex_unlock(¬ifierMutex);
#endif /* TCL_THREADS */
return 0;
}
/*
*----------------------------------------------------------------------
*
* 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 normally never exits and usually dies
* with the overall process, but it can be shut down if the Tcl library
* is finalized.
*
* Side effects:
* The trigger pipe used to signal the notifier thread is created when
* the notifier thread first starts.
*
*----------------------------------------------------------------------
*/
#if TCL_THREADS
static TCL_NORETURN void
NotifierThreadProc(
TCL_UNUSED(ClientData))
{
ThreadSpecificData *tsdPtr;
fd_set readableMask;
fd_set writableMask;
fd_set exceptionMask;
int i;
int fds[2], receivePipe;
long found;
struct timeval poll = {0, 0}, *timePtr;
char buf[2];
int numFdBits = 0;
if (pipe(fds) != 0) {
Tcl_Panic("NotifierThreadProc: %s", "could not create trigger pipe");
}
receivePipe = fds[0];
if (TclUnixSetBlockingMode(receivePipe, TCL_MODE_NONBLOCKING) < 0) {
Tcl_Panic("NotifierThreadProc: %s",
"could not make receive pipe non blocking");
}
if (TclUnixSetBlockingMode(fds[1], TCL_MODE_NONBLOCKING) < 0) {
Tcl_Panic("NotifierThreadProc: %s",
"could not make trigger pipe non blocking");
}
if (fcntl(receivePipe, F_SETFD, FD_CLOEXEC) < 0) {
Tcl_Panic("NotifierThreadProc: %s",
"could not make receive pipe close-on-exec");
}
if (fcntl(fds[1], F_SETFD, FD_CLOEXEC) < 0) {
Tcl_Panic("NotifierThreadProc: %s",
"could not make trigger pipe close-on-exec");
}
/*
* Install the write end of the pipe into the global variable.
*/
pthread_mutex_lock(¬ifierMutex);
triggerPipe = fds[1];
/*
* Signal any threads that are waiting.
*/
pthread_cond_broadcast(¬ifierCV);
pthread_mutex_unlock(¬ifierMutex);
/*
* Look for file events and report them to interested threads.
*/
while (1) {
FD_ZERO(&readableMask);
FD_ZERO(&writableMask);
FD_ZERO(&exceptionMask);
/*
* Compute the logical OR of the masks from all the waiting
* notifiers.
*/
pthread_mutex_lock(¬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.exception)) {
FD_SET(i, &exceptionMask);
}
}
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;
}
}
pthread_mutex_unlock(¬ifierMutex);
/*
* Set up the mask to include the receive pipe.
*/
if (receivePipe >= numFdBits) {
numFdBits = receivePipe + 1;
}
FD_SET(receivePipe, &readableMask);
if (select(numFdBits, &readableMask, &writableMask, &exceptionMask,
timePtr) == -1) {
/*
* Try again immediately on an error.
*/
continue;
}
/*
* Alert any threads that are waiting on a ready file descriptor.
*/
pthread_mutex_lock(¬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.exception)
&& FD_ISSET(i, &exceptionMask)) {
FD_SET(i, &tsdPtr->readyMasks.exception);
found = 1;
}
}
if (found || (tsdPtr->pollState & POLL_DONE)) {
AlertSingleThread(tsdPtr);
}
}
pthread_mutex_unlock(¬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.
*/
do {
i = read(receivePipe, buf, 1);
if (i <= 0) {
break;
} else 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;
}
} while (1);
if ((i == 0) || (buf[0] == 'q')) {
break;
}
}
/*
* Clean up the read end of the pipe and signal any threads waiting on
* termination of the notifier thread.
*/
close(receivePipe);
pthread_mutex_lock(¬ifierMutex);
triggerPipe = -1;
pthread_cond_broadcast(¬ifierCV);
pthread_mutex_unlock(¬ifierMutex);
TclpThreadExit(0);
}
#endif /* TCL_THREADS */
#endif /* (!NOTIFIER_EPOLL && !NOTIFIER_KQUEUE) || !TCL_THREADS */
#else
TCL_MAC_EMPTY_FILE(unix_tclSelectNotfy_c)
#endif /* !HAVE_COREFOUNDATION */
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/