/*
* tclUnixNotfy.c --
*
* This file contains subroutines shared by all notifier backend
* implementations on *nix platforms. It is *included* by the epoll,
* kqueue and select notifier implementation files.
*
* Copyright © 1995-1997 Sun Microsystems, Inc.
* Copyright © 2016 Lucio Andrés Illanes Albornoz <l.illanes@gmx.de>
* Copyright © 2021 Donal K. Fellows
*
* See the file "license.terms" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*/
#include <poll.h>
#include "tclInt.h"
#ifndef HAVE_COREFOUNDATION /* Darwin/Mac OS X CoreFoundation notifier is
* in tclMacOSXNotify.c */
#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 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 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 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). */
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. */
#if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_PTHREAD_CONDATTR_SETCLOCK)
int useMonoTime; /* When true use CLOCK_MONOTONIC */
#endif
#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. */
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;
/*
* 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;
/*
* Static routines defined in this file.
*/
static int FileHandlerEventProc(Tcl_Event *evPtr, int flags);
#if !TCL_THREADS
# undef NOTIFIER_EPOLL
# undef NOTIFIER_KQUEUE
# define NOTIFIER_SELECT
#elif !defined(NOTIFIER_EPOLL) && !defined(NOTIFIER_KQUEUE)
# define NOTIFIER_SELECT
static TCL_NORETURN void NotifierThreadProc(void *clientData);
# if defined(HAVE_PTHREAD_ATFORK)
static void AtForkChild(void);
# endif /* HAVE_PTHREAD_ATFORK */
/*
*----------------------------------------------------------------------
*
* StartNotifierThread --
*
* Start a notifier thread and wait for the notifier pipe to be created.
*
* Results:
* None.
*
* Side effects:
* Running Thread.
*
*----------------------------------------------------------------------
*/
static void
StartNotifierThread(
const char *proc)
{
if (!notifierThreadRunning) {
pthread_mutex_lock(¬ifierInitMutex);
if (!notifierThreadRunning) {
if (TclpThreadCreate(¬ifierThread, NotifierThreadProc, NULL,
TCL_THREAD_STACK_DEFAULT, TCL_THREAD_JOINABLE) != TCL_OK) {
Tcl_Panic("%s: unable to start notifier thread", proc);
}
pthread_mutex_lock(¬ifierMutex);
/*
* Wait for the notifier pipe to be created.
*/
while (triggerPipe < 0) {
pthread_cond_wait(¬ifierCV, ¬ifierMutex);
}
pthread_mutex_unlock(¬ifierMutex);
notifierThreadRunning = 1;
}
pthread_mutex_unlock(¬ifierInitMutex);
}
}
/*
*----------------------------------------------------------------------
*
* 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(void)
{
if (tclNotifierHooks.initNotifierProc) {
return tclNotifierHooks.initNotifierProc();
} else {
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
tsdPtr->eventReady = 0;
/*
* Initialize thread specific condition variable for this thread.
*/
if (tsdPtr->waitCVinitialized == 0) {
#ifdef __CYGWIN__
WNDCLASS class;
class.style = 0;
class.cbClsExtra = 0;
class.cbWndExtra = 0;
class.hInstance = TclWinGetTclInstance();
class.hbrBackground = NULL;
class.lpszMenuName = NULL;
class.lpszClassName = className;
class.lpfnWndProc = NotifierProc;
class.hIcon = NULL;
class.hCursor = NULL;
RegisterClassW(&class);
tsdPtr->hwnd = CreateWindowExW(NULL, class.lpszClassName,
class.lpszClassName, 0, 0, 0, 0, 0, NULL, NULL,
TclWinGetTclInstance(), NULL);
tsdPtr->event = CreateEventW(NULL, 1 /* manual */,
0 /* !signaled */, NULL);
#else
#if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_PTHREAD_CONDATTR_SETCLOCK)
pthread_condattr_t attr;
pthread_condattr_init(&attr);
tsdPtr->useMonoTime =
pthread_condattr_setclock(&attr, CLOCK_MONOTONIC) == 0;
if (tsdPtr->useMonoTime) {
if (pthread_cond_init(&tsdPtr->waitCV, &attr)) {
tsdPtr->useMonoTime = 0;
pthread_cond_init(&tsdPtr->waitCV, NULL);
}
} else {
pthread_cond_init(&tsdPtr->waitCV, NULL);
}
pthread_condattr_destroy(&attr);
#else
pthread_cond_init(&tsdPtr->waitCV, NULL);
#endif
#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: pthread_atfork failed");
}
atForkInit = 1;
}
#endif /* HAVE_PTHREAD_ATFORK */
notifierCount++;
pthread_mutex_unlock(¬ifierInitMutex);
return 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) /* Not used. */
{
if (tclNotifierHooks.finalizeNotifierProc) {
tclNotifierHooks.finalizeNotifierProc(clientData);
return;
} else {
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) {
if (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: 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);
}
}
/*
*----------------------------------------------------------------------
*
* Tcl_AlertNotifier --
#endif /* NOTIFIER_SELECT */
/*
*----------------------------------------------------------------------
*
* TclpAlertNotifier --
*
* 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:
* select(2) notifier:
* signals the notifier condition variable for the specified
* notifier.
* epoll(7) notifier:
* write(2)s to the eventfd(2) of the specified thread.
* kqueue(2) notifier:
* write(2)s to the trigger pipe(2) of the specified thread.
*
*----------------------------------------------------------------------
*/
void
TclpAlertNotifier(
void *clientData)
{
#ifdef NOTIFIER_SELECT
#if TCL_THREADS
ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData;
pthread_mutex_lock(¬ifierMutex);
tsdPtr->eventReady = 1;
# ifdef __CYGWIN__
PostMessageW(tsdPtr->hwnd, 1024, 0, 0);
# else
pthread_cond_broadcast(&tsdPtr->waitCV);
# endif /* __CYGWIN__ */
pthread_mutex_unlock(¬ifierMutex);
#else
(void)clientData;
#endif /* TCL_THREADS */
#else /* !NOTIFIER_SELECT */
ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData;
#if defined(NOTIFIER_EPOLL) && defined(HAVE_EVENTFD)
uint64_t eventFdVal = 1;
if (write(tsdPtr->triggerEventFd, &eventFdVal,
sizeof(eventFdVal)) != sizeof(eventFdVal)) {
Tcl_Panic("Tcl_AlertNotifier: unable to write to %p->triggerEventFd",
tsdPtr);
}
#else
if (write(tsdPtr->triggerPipe[1], "", 1) != 1) {
Tcl_Panic("Tcl_AlertNotifier: unable to write to %p->triggerPipe",
tsdPtr);
}
#endif /* NOTIFIER_EPOLL && HAVE_EVENTFD */
#endif /* NOTIFIER_SELECT */
}
/*
*----------------------------------------------------------------------
*
* LookUpFileHandler --
*
* Look up the file handler structure (and optionally the previous one in
* the chain) associated with a file descriptor.
*
* Returns:
* A pointer to the file handler, or NULL if it can't be found.
*
* Side effects:
* If prevPtrPtr is non-NULL, it will be written to if the file handler
* is found.
*
*----------------------------------------------------------------------
*/
static inline FileHandler *
LookUpFileHandler(
ThreadSpecificData *tsdPtr, /* Where to look things up. */
int fd, /* What we are looking for. */
FileHandler **prevPtrPtr) /* If non-NULL, where to report the previous
* pointer. */
{
FileHandler *filePtr, *prevPtr;
/*
* 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 NULL;
}
if (filePtr->fd == fd) {
break;
}
}
/*
* Report what we've found to our caller.
*/
if (prevPtrPtr) {
*prevPtrPtr = prevPtr;
}
return filePtr;
}
/*
*----------------------------------------------------------------------
*
* TclpSetTimer --
*
* This function 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
TclpSetTimer(
TCL_UNUSED(const Tcl_Time *)) /* Timeout value, may be NULL. */
{
/*
* The interval timer doesn't do anything in this implementation, because
* the only event loop is via Tcl_DoOneEvent, which passes timeout values
* to Tcl_WaitForEvent.
*/
}
/*
*----------------------------------------------------------------------
*
* Tcl_ServiceModeHook --
*
* This function is invoked whenever the service mode changes.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
void
TclpServiceModeHook(
int mode) /* Either TCL_SERVICE_ALL, or
* TCL_SERVICE_NONE. */
{
if (mode == TCL_SERVICE_ALL) {
#ifdef NOTIFIER_SELECT
#if TCL_THREADS
StartNotifierThread("Tcl_ServiceModeHook");
#endif
#endif /* NOTIFIER_SELECT */
}
}
/*
*----------------------------------------------------------------------
*
* FileHandlerEventProc --
*
* This function is called by Tcl_ServiceEvent when a file event reaches
* the front of the event queue. This function 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 function does.
*
*----------------------------------------------------------------------
*/
static int
FileHandlerEventProc(
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;
}
#if defined(__CYGWIN__)
static DWORD __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 /* __CYGWIN__ */
/*
*----------------------------------------------------------------------
*
* 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(
const Tcl_Time *timePtr) /* Maximum block time, or NULL. */
{
if (tclNotifierHooks.waitForEventProc) {
return tclNotifierHooks.waitForEventProc(timePtr);
} else {
FileHandler *filePtr;
int mask;
Tcl_Time vTime;
int waitForFiles;
# ifdef __CYGWIN__
MSG msg;
# endif /* __CYGWIN__ */
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
/*
* 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;
tclScaleTimeProcPtr(&vTime, tclTimeClientData);
timePtr = &vTime;
}
}
/*
* 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)) {
DWORD 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
if (timePtr != NULL) {
struct timespec ptime;
#if defined(HAVE_CLOCK_GETTIME) && defined(HAVE_PTHREAD_CONDATTR_SETCLOCK)
if (tsdPtr->useMonoTime) {
clock_gettime(CLOCK_MONOTONIC, &ptime);
} else {
clock_gettime(CLOCK_REALTIME, &ptime);
}
ptime.tv_sec += timePtr->sec +
(timePtr->usec * 1000 + ptime.tv_nsec) / 1000000000;
ptime.tv_nsec = (timePtr->usec * 1000 + ptime.tv_nsec) %
1000000000;
#else
Tcl_Time now;
Tcl_GetTime(&now);
ptime.tv_sec = timePtr->sec + now.sec +
(timePtr->usec + now.usec) / 1000000;
ptime.tv_nsec = 1000 * ((timePtr->usec + now.usec) % 1000000);
#endif
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.
*/
DWORD result = GetMessageW(&msg, NULL, 0, 0);
if (result == 0) {
PostQuitMessage(msg.wParam);
/* What to do here? */
} else if (result != (DWORD) -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");
}
}
/*
* 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 =
ckalloc(sizeof(FileHandlerEvent));
fileEvPtr->header.proc = FileHandlerEventProc;
fileEvPtr->fd = filePtr->fd;
Tcl_QueueEvent((Tcl_Event *) fileEvPtr, TCL_QUEUE_TAIL);
}
filePtr->readyMask = mask;
}
pthread_mutex_unlock(¬ifierMutex);
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 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 TCL_NORETURN void
NotifierThreadProc(
ClientData clientData) /* Not used. */
{
ThreadSpecificData *tsdPtr;
fd_set readableMask;
fd_set writableMask;
fd_set exceptionMask;
int fds[2];
int i, numFdBits = 0, receivePipe;
long found;
struct timeval poll = {0., 0.}, *timePtr;
char buf[2];
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 select 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 select 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)) {
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;
}
#ifdef __CYGWIN__
PostMessageW(tsdPtr->hwnd, 1024, 0, 0);
#else /* __CYGWIN__ */
pthread_cond_broadcast(&tsdPtr->waitCV);
#endif /* __CYGWIN__ */
}
}
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.
*/
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);
pthread_mutex_lock(¬ifierMutex);
triggerPipe = -1;
pthread_cond_broadcast(¬ifierCV);
pthread_mutex_unlock(¬ifierMutex);
TclpThreadExit(0);
}
#if defined(HAVE_PTHREAD_ATFORK)
/*
*----------------------------------------------------------------------
*
* AtForkChild --
*
* Unlock and reinstall the notifier in the child after a fork.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
static void
AtForkChild(void)
{
if (notifierThreadRunning == 1) {
pthread_cond_destroy(¬ifierCV);
}
pthread_mutex_init(¬ifierInitMutex, NULL);
pthread_mutex_init(¬ifierMutex, NULL);
pthread_cond_init(¬ifierCV, NULL);
#ifdef NOTIFIER_SELECT
asyncPending = 0;
#endif
/*
* notifierThreadRunning == 1: thread is running, (there might be data in
* notifier lists)
* atForkInit == 0: InitNotifier was never called
* notifierCount != 0: unbalanced InitNotifier() / FinalizeNotifier calls
* waitingListPtr != 0: there are threads currently waiting for events.
*/
if (atForkInit == 1) {
notifierCount = 0;
if (notifierThreadRunning == 1) {
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
notifierThreadRunning = 0;
close(triggerPipe);
triggerPipe = -1;
#ifdef NOTIFIER_SELECT
close(otherPipe);
otherPipe = -1;
#endif
/*
* The waitingListPtr might contain event info from multiple
* threads, which are invalid here, so setting it to NULL is not
* unreasonable.
*/
waitingListPtr = NULL;
/*
* The tsdPtr from before the fork is copied as well. But since we
* are paranoiac, we don't trust its condvar and reset it.
*/
#ifdef __CYGWIN__
DestroyWindow(tsdPtr->hwnd);
tsdPtr->hwnd = CreateWindowExW(NULL, className,
className, 0, 0, 0, 0, 0, NULL, NULL,
TclWinGetTclInstance(), NULL);
ResetEvent(tsdPtr->event);
#else /* !__CYGWIN__ */
pthread_cond_destroy(&tsdPtr->waitCV);
pthread_cond_init(&tsdPtr->waitCV, NULL);
#endif /* __CYGWIN__ */
/*
* In case, we had multiple threads running before the fork,
* make sure, we don't try to reach out to their thread local data.
*/
tsdPtr->nextPtr = tsdPtr->prevPtr = NULL;
/*
* The list of registered event handlers at fork time is in
* tsdPtr->firstFileHandlerPtr;
*/
}
}
Tcl_InitNotifier();
#ifdef NOTIFIER_SELECT
/*
* Restart the notifier thread for signal handling.
*/
StartNotifierThread("AtForkChild");
#endif
}
#endif /* HAVE_PTHREAD_ATFORK */
#endif /* TCL_THREADS */
#endif /* NOTIFIER_SELECT */
/*
*----------------------------------------------------------------------
*
* TclpNotifierData --
*
* This function returns a void pointer to be associated
* with a Tcl_AsyncHandler.
*
* Results:
* For the epoll and kqueue notifiers, this function returns the
* thread specific data. Otherwise NULL.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
void *
TclpNotifierData(void)
{
#if defined(NOTIFIER_EPOLL) || defined(NOTIFIER_KQUEUE)
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
return tsdPtr;
#else
return NULL;
#endif
}
/*
*----------------------------------------------------------------------
*
* TclUnixWaitForFile --
*
* This function waits synchronously for a file to become readable or
* writable, with an optional timeout.
*
* Results:
* The return value is an OR'ed combination of TCL_READABLE,
* TCL_WRITABLE, and TCL_EXCEPTION, indicating the conditions that are
* present on file at the time of the return. This function will not
* return until either "timeout" milliseconds have elapsed or at least
* one of the conditions given by mask has occurred for file (a return
* value of 0 means that a timeout occurred). No normal events will be
* serviced during the execution of this function.
*
* Side effects:
* Time passes.
*
*----------------------------------------------------------------------
*/
#ifndef HAVE_COREFOUNDATION /* Darwin/Mac OS X CoreFoundation notifier is
* in tclMacOSXNotify.c */
int
TclUnixWaitForFile(
int fd, /* Handle for file on which to wait. */
int mask, /* What to wait for: OR'ed combination of
* TCL_READABLE, TCL_WRITABLE, and
* TCL_EXCEPTION. */
int timeout) /* Maximum amount of time to wait for one of
* the conditions in mask to occur, in
* milliseconds. A value of 0 means don't wait
* at all, and a value of -1 means wait
* forever. */
{
Tcl_Time abortTime = {0, 0}, now; /* silence gcc 4 warning */
struct timeval blockTime, *timeoutPtr;
struct pollfd pollFds[1];
int numFound, result = 0, pollTimeout;
/*
* If there is a non-zero finite timeout, compute the time when we give
* up.
*/
if (timeout > 0) {
Tcl_GetTime(&now);
abortTime.sec = now.sec + timeout / 1000;
abortTime.usec = now.usec + (timeout % 1000) * 1000;
if (abortTime.usec >= 1000000) {
abortTime.usec -= 1000000;
abortTime.sec += 1;
}
timeoutPtr = &blockTime;
} else if (timeout == 0) {
timeoutPtr = &blockTime;
blockTime.tv_sec = 0;
blockTime.tv_usec = 0;
} else {
timeoutPtr = NULL;
}
/*
* Setup the pollfd structure for the fd.
*/
pollFds[0].fd = fd;
pollFds[0].events = pollFds[0].revents = 0;
if (mask & TCL_READABLE) {
pollFds[0].events |= (POLLIN | POLLHUP);
}
if (mask & TCL_WRITABLE) {
pollFds[0].events |= POLLOUT;
}
if (mask & TCL_EXCEPTION) {
pollFds[0].events |= POLLERR;
}
/*
* Loop in a mini-event loop of our own, waiting for either the file to
* become ready or a timeout to occur.
*/
do {
if (timeout > 0) {
blockTime.tv_sec = abortTime.sec - now.sec;
blockTime.tv_usec = abortTime.usec - now.usec;
if (blockTime.tv_usec < 0) {
blockTime.tv_sec -= 1;
blockTime.tv_usec += 1000000;
}
if (blockTime.tv_sec < 0) {
blockTime.tv_sec = 0;
blockTime.tv_usec = 0;
}
}
/*
* Wait for the event or a timeout.
*/
if (!timeoutPtr) {
pollTimeout = -1;
} else if (!timeoutPtr->tv_sec && !timeoutPtr->tv_usec) {
pollTimeout = 0;
} else {
pollTimeout = (int) timeoutPtr->tv_sec * 1000;
if (timeoutPtr->tv_usec) {
pollTimeout += (int) timeoutPtr->tv_usec / 1000;
}
}
numFound = poll(pollFds, 1, pollTimeout);
if (numFound == 1) {
result = 0;
if (pollFds[0].revents & (POLLIN | POLLHUP)) {
result |= TCL_READABLE;
}
if (pollFds[0].revents & POLLOUT) {
result |= TCL_WRITABLE;
}
if (pollFds[0].revents & POLLERR) {
result |= TCL_EXCEPTION;
}
if (result) {
break;
}
}
if (timeout == 0) {
break;
}
if (timeout < 0) {
continue;
}
/*
* The select returned early, so we need to recompute the timeout.
*/
Tcl_GetTime(&now);
} while ((abortTime.sec > now.sec)
|| (abortTime.sec == now.sec && abortTime.usec > now.usec));
return result;
}
#endif /* !HAVE_COREFOUNDATION */
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/