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-rw-r--r--macosx/tclMacOSXNotify.c138
1 files changed, 104 insertions, 34 deletions
diff --git a/macosx/tclMacOSXNotify.c b/macosx/tclMacOSXNotify.c
index bdda1ce..f9cd046 100644
--- a/macosx/tclMacOSXNotify.c
+++ b/macosx/tclMacOSXNotify.c
@@ -13,7 +13,7 @@
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
- * RCS: @(#) $Id: tclMacOSXNotify.c,v 1.1.2.6 2006/05/27 05:23:04 das Exp $
+ * RCS: @(#) $Id: tclMacOSXNotify.c,v 1.1.2.7 2006/07/20 06:21:42 das Exp $
*/
#include "tclInt.h"
@@ -164,6 +164,32 @@ static int receivePipe = -1; /* Output end of triggerPipe */
#include <libkern/OSAtomic.h>
+#if defined(HAVE_WEAK_IMPORT) && MAC_OS_X_VERSION_MIN_REQUIRED < 1040
+/*
+ * Support for weakly importing spinlock API.
+ */
+#define WEAK_IMPORT_SPINLOCKLOCK
+extern void OSSpinLockLock(OSSpinLock *lock) WEAK_IMPORT_ATTRIBUTE;
+extern void OSSpinLockUnlock(OSSpinLock *lock) WEAK_IMPORT_ATTRIBUTE;
+extern void _spin_lock(OSSpinLock *lock) WEAK_IMPORT_ATTRIBUTE;
+extern void _spin_unlock(OSSpinLock *lock) WEAK_IMPORT_ATTRIBUTE;
+static void (* lockLock)(OSSpinLock *lock) = NULL;
+static void (* lockUnlock)(OSSpinLock *lock) = NULL;
+static pthread_once_t spinLockLockInitControl = PTHREAD_ONCE_INIT;
+static void SpinLockLockInit(void) {
+ lockLock = OSSpinLockLock != NULL ? OSSpinLockLock : _spin_lock;
+ lockUnlock = OSSpinLockUnlock != NULL ? OSSpinLockUnlock : _spin_unlock;
+ if (lockLock == NULL || lockUnlock == NULL) {
+ Tcl_Panic("SpinLockLockInit: no spinlock API available.");
+ }
+}
+#define SpinLockLock(p) lockLock(p)
+#define SpinLockUnlock(p) lockUnlock(p)
+#else
+#define SpinLockLock(p) OSSpinLockLock(p)
+#define SpinLockUnlock(p) OSSpinLockUnlock(p)
+#endif /* HAVE_WEAK_IMPORT */
+
#else
/*
* Otherwise, use commpage spinlock SPI directly.
@@ -172,8 +198,8 @@ static int receivePipe = -1; /* Output end of triggerPipe */
typedef uint32_t OSSpinLock;
extern void _spin_lock(OSSpinLock *lock);
extern void _spin_unlock(OSSpinLock *lock);
-#define OSSpinLockLock(p) _spin_lock(p)
-#define OSSpinLockUnlock(p) _spin_unlock(p)
+#define SpinLockLock(p) _spin_lock(p)
+#define SpinLockUnlock(p) _spin_unlock(p)
#endif /* HAVE_LIBKERN_OSATOMIC_H && HAVE_OSSPINLOCKLOCK */
@@ -188,10 +214,10 @@ static OSSpinLock notifierLock = 0;
* Macros abstracting notifier locking/unlocking
*/
-#define LOCK_NOTIFIER_INIT OSSpinLockLock(&notifierInitLock)
-#define UNLOCK_NOTIFIER_INIT OSSpinLockUnlock(&notifierInitLock)
-#define LOCK_NOTIFIER OSSpinLockLock(&notifierLock)
-#define UNLOCK_NOTIFIER OSSpinLockUnlock(&notifierLock)
+#define LOCK_NOTIFIER_INIT SpinLockLock(&notifierInitLock)
+#define UNLOCK_NOTIFIER_INIT SpinLockUnlock(&notifierInitLock)
+#define LOCK_NOTIFIER SpinLockLock(&notifierLock)
+#define UNLOCK_NOTIFIER SpinLockUnlock(&notifierLock)
/*
* The pollState bits
@@ -223,7 +249,13 @@ static int atForkInit = 0;
static void AtForkPrepare(void);
static void AtForkParent(void);
static void AtForkChild(void);
-#endif
+#if defined(HAVE_WEAK_IMPORT) && MAC_OS_X_VERSION_MIN_REQUIRED < 1040
+/* Support for weakly importing pthread_atfork. */
+#define WEAK_IMPORT_PTHREAD_ATFORK
+extern int pthread_atfork(void (*prepare)(void), void (*parent)(void),
+ void (*child)(void)) WEAK_IMPORT_ATTRIBUTE;
+#endif /* HAVE_WEAK_IMPORT */
+#endif /* HAVE_PTHREAD_ATFORK */
/*
*----------------------------------------------------------------------
@@ -248,8 +280,17 @@ Tcl_InitNotifier(void)
tsdPtr->eventReady = 0;
+#ifdef WEAK_IMPORT_SPINLOCKLOCK
+ /*
+ * Initialize support for weakly imported spinlock API.
+ */
+ if (pthread_once(&spinLockLockInitControl, SpinLockLockInit)) {
+ Tcl_Panic("Tcl_InitNotifier: pthread_once failed.");
+ }
+#endif
+
/*
- * Initialize CFRunLoopSource and add it to CFRunLoop of this thread
+ * Initialize CFRunLoopSource and add it to CFRunLoop of this thread.
*/
if (!tsdPtr->runLoop) {
@@ -268,28 +309,31 @@ Tcl_InitNotifier(void)
tsdPtr->runLoop = runLoop;
}
- /*
- * Initialize trigger pipe and start the Notifier thread if necessary.
- */
-
LOCK_NOTIFIER_INIT;
#ifdef HAVE_PTHREAD_ATFORK
/*
- * Install pthread_atfork handlers to reinstall the notifier thread in the
+ * Install pthread_atfork handlers to reinitialize the notifier in the
* child of a fork.
*/
- if (!atForkInit) {
+ if (
+#ifdef WEAK_IMPORT_PTHREAD_ATFORK
+ pthread_atfork != NULL &&
+#endif
+ !atForkInit) {
int result = pthread_atfork(AtForkPrepare, AtForkParent, AtForkChild);
if (result) {
- Tcl_Panic("Tcl_InitNotifier: pthread_atfork failed");
+ Tcl_Panic("Tcl_InitNotifier: pthread_atfork failed.");
}
atForkInit = 1;
}
#endif
if (notifierCount == 0) {
- int fds[2], status, result;
- pthread_attr_t attr;
+ int fds[2], status;
+
+ /*
+ * Initialize trigger pipe.
+ */
if (pipe(fds) != 0) {
Tcl_Panic("Tcl_InitNotifier: could not create trigger pipe.");
@@ -309,16 +353,13 @@ Tcl_InitNotifier(void)
receivePipe = fds[0];
triggerPipe = fds[1];
- pthread_attr_init(&attr);
- pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
- pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
- pthread_attr_setstacksize(&attr, 60 * 1024);
- result = pthread_create(&notifierThread, &attr,
- (void * (*)(void *))NotifierThreadProc, NULL);
- pthread_attr_destroy(&attr);
- if (result) {
- Tcl_Panic("Tcl_InitNotifier: unable to start notifier thread.");
- }
+ /*
+ * Create notifier thread lazily in Tcl_WaitForEvent() to avoid
+ * interfering with fork() followed immediately by execve()
+ * (cannot execve() when more than one thread is present).
+ */
+
+ notifierThread = 0;
}
notifierCount++;
UNLOCK_NOTIFIER_INIT;
@@ -379,9 +420,12 @@ Tcl_FinalizeNotifier(clientData)
write(triggerPipe, "q", 1);
close(triggerPipe);
- result = pthread_join(notifierThread, NULL);
- if (result) {
- Tcl_Panic("Tcl_FinalizeNotifier: unable to join notifier thread.");
+ if (notifierThread) {
+ result = pthread_join(notifierThread, NULL);
+ if (result) {
+ Tcl_Panic("Tcl_FinalizeNotifier: unable to join notifier thread.");
+ }
+ notifierThread = 0;
}
close(receivePipe);
@@ -764,6 +808,28 @@ Tcl_WaitForEvent(timePtr)
}
/*
+ * Start notifier thread if necessary.
+ */
+
+ LOCK_NOTIFIER_INIT;
+ if (!notifierThread) {
+ int result;
+ pthread_attr_t attr;
+
+ pthread_attr_init(&attr);
+ pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
+ pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+ pthread_attr_setstacksize(&attr, 60 * 1024);
+ result = pthread_create(&notifierThread, &attr,
+ (void * (*)(void *))NotifierThreadProc, NULL);
+ pthread_attr_destroy(&attr);
+ if (result || !notifierThread) {
+ Tcl_Panic("Tcl_WaitForEvent: unable to start notifier thread.");
+ }
+ }
+ UNLOCK_NOTIFIER_INIT;
+
+ /*
* Place this thread on the list of interested threads, signal the
* notifier thread, and wait for a response or a timeout.
*/
@@ -1138,9 +1204,13 @@ AtForkChild(void)
}
if (notifierCount > 0) {
notifierCount = 0;
- /* Note that Tcl_FinalizeNotifier does not use its clientData
- * parameter, so discard return value of Tcl_InitNotifier here and
- * leave stale clientData in tclNotify.c's ThreadSpecificData.
+ /*
+ * Assume that the return value of Tcl_InitNotifier() in the child
+ * will be identical to the one stored as clientData in tclNotify.c's
+ * ThreadSpecificData by the parent's TclInitNotifier(), so discard
+ * the return value here. This assumption may require the fork() to
+ * be executed in the main thread of the parent, otherwise
+ * Tcl_AlertNotifier() may break in the child.
*/
Tcl_InitNotifier();
}
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