Proposed fix for [ba44e415a0]: "Use of mutexLock causes problem with reactive event handling in AndroWish".bug_ba44e415a0

This basically undoes the retry mechamism in Tcl_MutexLock, introduced in [9f8b7bea53]. Does this retry mechamism hurt more than it helps? Feedback requested.

1 files changed, 5 insertions, 46 deletions

diff --git a/unix/tclUnixThrd.c b/unix/tclUnixThrd.c
index ae81c5f..0e8070d 100644
--- a/unix/tclUnixThrd.c
+++ b/unix/tclUnixThrd.c
@@ -22,19 +22,6 @@ typedef struct ThreadSpecificData {
 static Tcl_ThreadDataKey dataKey;
 
 /*
- * This is the number of milliseconds to wait between internal retries in
- * the Tcl_MutexLock function.  This value must be greater than zero and
- * should be a suitable value for the given platform.
- *
- * TODO: This may need to be dynamically determined, based on the relative
- *       performance of the running process.
- */
-
-#ifndef TCL_MUTEX_LOCK_SLEEP_TIME
-#  define TCL_MUTEX_LOCK_SLEEP_TIME	(25)
-#endif
-
-/*
  * masterLock is used to serialize creation of mutexes, condition variables,
  * and thread local storage. This is the only place that can count on the
  * ability to statically initialize the mutex.
@@ -58,13 +45,6 @@ static pthread_mutex_t allocLock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t *allocLockPtr = &allocLock;
 
 /*
- * The mutexLock serializes Tcl_MutexLock. This is necessary to prevent
- * races when finalizing a mutex that some other thread may want to lock.
- */
-
-static pthread_mutex_t mutexLock = PTHREAD_MUTEX_INITIALIZER;
-
-/*
  * These are for the critical sections inside this file.
  */
 
@@ -380,7 +360,6 @@ TclpMasterUnlock(void)
     pthread_mutex_unlock(&masterLock);
 #endif
 }
-
 
 /*
  *----------------------------------------------------------------------
@@ -457,32 +436,12 @@ retry:
 	}
 	MASTER_UNLOCK;
     }
-    while (1) {
-	pthread_mutex_lock(&mutexLock);
-	pmutexPtr = *((pthread_mutex_t **)mutexPtr);
-	if (pmutexPtr == NULL) {
-	    pthread_mutex_unlock(&mutexLock);
-	    goto retry;
-	}
-	if (pthread_mutex_trylock(pmutexPtr) == 0) {
-	    pthread_mutex_unlock(&mutexLock);
-	    return;
-	}
-	pthread_mutex_unlock(&mutexLock);
-	/*
-	 * BUGBUG: All core and Thread package tests pass when usleep()
-	 *         is used; however, the Thread package tests hang at
-	 *         various places when Tcl_Sleep() is used, typically
-	 *         while running test "thread-17.8", "thread-17.9", or
-	 *         "thread-17.11a".  Really, what we want here is just
-	 *         to yield to other threads for a while.
-	 */
-#ifdef HAVE_USLEEP
-	usleep(TCL_MUTEX_LOCK_SLEEP_TIME * 1000);
-#else
-	Tcl_Sleep(TCL_MUTEX_LOCK_SLEEP_TIME);
-#endif
+
+    pmutexPtr = *((pthread_mutex_t **)mutexPtr);
+    if (pmutexPtr == NULL) {
+	goto retry;
     }
+    pthread_mutex_lock(pmutexPtr);
 }
 
 /*