1 files changed, 346 insertions, 0 deletions
diff --git a/nsprpub/pr/src/threads/prmon.c b/nsprpub/pr/src/threads/prmon.c
new file mode 100644
index 000000000..36be8a941
--- /dev/null
+++ b/nsprpub/pr/src/threads/prmon.c
@@ -0,0 +1,346 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "primpl.h"
+
+/************************************************************************/
+
+/*
+ * Notifies just get posted to the monitor. The actual notification is done
+ * when the monitor is fully exited so that MP systems don't contend for a
+ * monitor that they can't enter.
+ */
+static void _PR_PostNotifyToMonitor(PRMonitor *mon, PRBool broadcast)
+{
+    PR_ASSERT(mon != NULL);
+    PR_ASSERT_CURRENT_THREAD_IN_MONITOR(mon);
+
+    /* mon->notifyTimes is protected by the monitor, so we don't need to
+     * acquire mon->lock.
+     */
+    if (broadcast)
+        mon->notifyTimes = -1;
+    else if (mon->notifyTimes != -1)
+        mon->notifyTimes += 1;
+}
+
+static void _PR_PostNotifiesFromMonitor(PRCondVar *cv, PRIntn times)
+{
+    PRStatus rv;
+
+    /*
+     * Time to actually notify any waits that were affected while the monitor
+     * was entered.
+     */
+    PR_ASSERT(cv != NULL);
+    PR_ASSERT(times != 0);
+    if (times == -1) {
+        rv = PR_NotifyAllCondVar(cv);
+        PR_ASSERT(rv == PR_SUCCESS);
+    } else {
+        while (times-- > 0) {
+            rv = PR_NotifyCondVar(cv);
+            PR_ASSERT(rv == PR_SUCCESS);
+        }
+    }
+}
+
+/*
+** Create a new monitor.
+*/
+PR_IMPLEMENT(PRMonitor*) PR_NewMonitor()
+{
+    PRMonitor *mon;
+    PRStatus rv;
+
+    if (!_pr_initialized) _PR_ImplicitInitialization();
+
+    mon = PR_NEWZAP(PRMonitor);
+    if (mon == NULL) {
+        PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
+        return NULL;
+    }
+
+    rv = _PR_InitLock(&mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+    if (rv != PR_SUCCESS)
+        goto error1;
+
+    mon->owner = NULL;
+
+    rv = _PR_InitCondVar(&mon->entryCV, &mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+    if (rv != PR_SUCCESS)
+        goto error2;
+
+    rv = _PR_InitCondVar(&mon->waitCV, &mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+    if (rv != PR_SUCCESS)
+        goto error3;
+
+    mon->notifyTimes = 0;
+    mon->entryCount = 0;
+    mon->name = NULL;
+    return mon;
+
+error3:
+    _PR_FreeCondVar(&mon->entryCV);
+error2:
+    _PR_FreeLock(&mon->lock);
+error1:
+    PR_Free(mon);
+    return NULL;
+}
+
+PR_IMPLEMENT(PRMonitor*) PR_NewNamedMonitor(const char* name)
+{
+    PRMonitor* mon = PR_NewMonitor();
+    if (mon)
+        mon->name = name;
+    return mon;
+}
+
+/*
+** Destroy a monitor. There must be no thread waiting on the monitor's
+** condition variable. The caller is responsible for guaranteeing that the
+** monitor is no longer in use.
+*/
+PR_IMPLEMENT(void) PR_DestroyMonitor(PRMonitor *mon)
+{
+    PR_ASSERT(mon != NULL);
+    _PR_FreeCondVar(&mon->waitCV);
+    _PR_FreeCondVar(&mon->entryCV);
+    _PR_FreeLock(&mon->lock);
+#if defined(DEBUG)
+    memset(mon, 0xaf, sizeof(PRMonitor));
+#endif
+    PR_Free(mon);
+}
+
+/*
+** Enter the lock associated with the monitor.
+*/
+PR_IMPLEMENT(void) PR_EnterMonitor(PRMonitor *mon)
+{
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    PRStatus rv;
+
+    PR_ASSERT(mon != NULL);
+    PR_Lock(&mon->lock);
+    if (mon->entryCount != 0) {
+        if (mon->owner == me)
+            goto done;
+        while (mon->entryCount != 0) {
+            rv = PR_WaitCondVar(&mon->entryCV, PR_INTERVAL_NO_TIMEOUT);
+            PR_ASSERT(rv == PR_SUCCESS);
+        }
+    }
+    /* and now I have the monitor */
+    PR_ASSERT(mon->notifyTimes == 0);
+    PR_ASSERT(mon->owner == NULL);
+    mon->owner = me;
+
+done:
+    mon->entryCount += 1;
+    rv = PR_Unlock(&mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+}
+
+/*
+** Test and then enter the lock associated with the monitor if it's not
+** already entered by some other thread. Return PR_FALSE if some other
+** thread owned the lock at the time of the call.
+*/
+PR_IMPLEMENT(PRBool) PR_TestAndEnterMonitor(PRMonitor *mon)
+{
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    PRStatus rv;
+
+    PR_ASSERT(mon != NULL);
+    PR_Lock(&mon->lock);
+    if (mon->entryCount != 0) {
+        if (mon->owner == me)
+            goto done;
+        rv = PR_Unlock(&mon->lock);
+        PR_ASSERT(rv == PR_SUCCESS);
+        return PR_FALSE;
+    }
+    /* and now I have the monitor */
+    PR_ASSERT(mon->notifyTimes == 0);
+    PR_ASSERT(mon->owner == NULL);
+    mon->owner = me;
+
+done:
+    mon->entryCount += 1;
+    rv = PR_Unlock(&mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+    return PR_TRUE;
+}
+
+/*
+** Exit the lock associated with the monitor once.
+*/
+PR_IMPLEMENT(PRStatus) PR_ExitMonitor(PRMonitor *mon)
+{
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    PRStatus rv;
+
+    PR_ASSERT(mon != NULL);
+    PR_Lock(&mon->lock);
+    /* the entries should be > 0 and we'd better be the owner */
+    PR_ASSERT(mon->entryCount > 0);
+    PR_ASSERT(mon->owner == me);
+    if (mon->entryCount == 0 || mon->owner != me)
+    {
+        rv = PR_Unlock(&mon->lock);
+        PR_ASSERT(rv == PR_SUCCESS);
+        return PR_FAILURE;
+    }
+
+    mon->entryCount -= 1;  /* reduce by one */
+    if (mon->entryCount == 0)
+    {
+        /* and if it transitioned to zero - notify an entry waiter */
+        /* make the owner unknown */
+        mon->owner = NULL;
+        if (mon->notifyTimes != 0) {
+            _PR_PostNotifiesFromMonitor(&mon->waitCV, mon->notifyTimes);
+            mon->notifyTimes = 0;
+        }
+        rv = PR_NotifyCondVar(&mon->entryCV);
+        PR_ASSERT(rv == PR_SUCCESS);
+    }
+    rv = PR_Unlock(&mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+    return PR_SUCCESS;
+}
+
+/*
+** Return the number of times that the current thread has entered the
+** lock. Returns zero if the current thread has not entered the lock.
+*/
+PR_IMPLEMENT(PRIntn) PR_GetMonitorEntryCount(PRMonitor *mon)
+{
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    PRStatus rv;
+    PRIntn count = 0;
+
+    PR_Lock(&mon->lock);
+    if (mon->owner == me)
+        count = mon->entryCount;
+    rv = PR_Unlock(&mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+    return count;
+}
+
+PR_IMPLEMENT(void) PR_AssertCurrentThreadInMonitor(PRMonitor *mon)
+{
+#if defined(DEBUG) || defined(FORCE_PR_ASSERT)
+    PRStatus rv;
+
+    PR_Lock(&mon->lock);
+    PR_ASSERT(mon->entryCount != 0 &&
+              mon->owner == _PR_MD_CURRENT_THREAD());
+    rv = PR_Unlock(&mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+#endif
+}
+
+/*
+** Wait for a notify on the condition variable. Sleep for "ticks" amount
+** of time (if "tick" is 0 then the sleep is indefinite). While
+** the thread is waiting it exits the monitors lock (as if it called
+** PR_ExitMonitor as many times as it had called PR_EnterMonitor).  When
+** the wait has finished the thread regains control of the monitors lock
+** with the same entry count as before the wait began.
+**
+** The thread waiting on the monitor will be resumed when the monitor is
+** notified (assuming the thread is the next in line to receive the
+** notify) or when the "ticks" elapses.
+**
+** Returns PR_FAILURE if the caller has not locked the lock associated
+** with the condition variable.
+** This routine can return PR_PENDING_INTERRUPT_ERROR if the waiting thread
+** has been interrupted.
+*/
+PR_IMPLEMENT(PRStatus) PR_Wait(PRMonitor *mon, PRIntervalTime ticks)
+{
+    PRStatus rv;
+    PRUint32 saved_entries;
+    PRThread *saved_owner;
+
+    PR_ASSERT(mon != NULL);
+    PR_Lock(&mon->lock);
+    /* the entries better be positive */
+    PR_ASSERT(mon->entryCount > 0);
+    /* and it better be owned by us */
+    PR_ASSERT(mon->owner == _PR_MD_CURRENT_THREAD());  /* XXX return failure */
+
+    /* tuck these away 'till later */
+    saved_entries = mon->entryCount;
+    mon->entryCount = 0;
+    saved_owner = mon->owner;
+    mon->owner = NULL;
+    /* If we have pending notifies, post them now. */
+    if (mon->notifyTimes != 0) {
+        _PR_PostNotifiesFromMonitor(&mon->waitCV, mon->notifyTimes);
+        mon->notifyTimes = 0;
+    }
+    rv = PR_NotifyCondVar(&mon->entryCV);
+    PR_ASSERT(rv == PR_SUCCESS);
+
+    rv = PR_WaitCondVar(&mon->waitCV, ticks);
+    PR_ASSERT(rv == PR_SUCCESS);
+
+    while (mon->entryCount != 0) {
+        rv = PR_WaitCondVar(&mon->entryCV, PR_INTERVAL_NO_TIMEOUT);
+        PR_ASSERT(rv == PR_SUCCESS);
+    }
+    PR_ASSERT(mon->notifyTimes == 0);
+    /* reinstate the interesting information */
+    mon->entryCount = saved_entries;
+    mon->owner = saved_owner;
+
+    rv = PR_Unlock(&mon->lock);
+    PR_ASSERT(rv == PR_SUCCESS);
+    return rv;
+}
+
+/*
+** Notify the highest priority thread waiting on the condition
+** variable. If a thread is waiting on the condition variable (using
+** PR_Wait) then it is awakened and begins waiting on the monitor's lock.
+*/
+PR_IMPLEMENT(PRStatus) PR_Notify(PRMonitor *mon)
+{
+    _PR_PostNotifyToMonitor(mon, PR_FALSE);
+    return PR_SUCCESS;
+}
+
+/*
+** Notify all of the threads waiting on the condition variable. All of
+** threads are notified in turn. The highest priority thread will
+** probably acquire the monitor first when the monitor is exited.
+*/
+PR_IMPLEMENT(PRStatus) PR_NotifyAll(PRMonitor *mon)
+{
+    _PR_PostNotifyToMonitor(mon, PR_TRUE);
+    return PR_SUCCESS;
+}
+
+/************************************************************************/
+
+PRUint32 _PR_MonitorToString(PRMonitor *mon, char *buf, PRUint32 buflen)
+{
+    PRUint32 nb;
+
+    if (mon->owner) {
+	nb = PR_snprintf(buf, buflen, "[%p] owner=%d[%p] count=%ld",
+			 mon, mon->owner->id, mon->owner, mon->entryCount);
+    } else {
+	nb = PR_snprintf(buf, buflen, "[%p]", mon);
+    }
+    return nb;
+}