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-rw-r--r--nsprpub/pr/src/threads/combined/prulock.c457
1 files changed, 457 insertions, 0 deletions
diff --git a/nsprpub/pr/src/threads/combined/prulock.c b/nsprpub/pr/src/threads/combined/prulock.c
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+/* -*- 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"
+
+#if defined(WIN95)
+/*
+** Some local variables report warnings on Win95 because the code paths
+** using them are conditioned on HAVE_CUSTOME_USER_THREADS.
+** The pragma suppresses the warning.
+**
+*/
+#pragma warning(disable : 4101)
+#endif
+
+
+void _PR_InitLocks(void)
+{
+ _PR_MD_INIT_LOCKS();
+}
+
+/*
+** Deal with delayed interrupts/requested reschedule during interrupt
+** re-enables.
+*/
+void _PR_IntsOn(_PRCPU *cpu)
+{
+ PRUintn missed, pri, i;
+ _PRInterruptTable *it;
+ PRThread *me;
+
+ PR_ASSERT(cpu); /* Global threads don't have CPUs */
+ PR_ASSERT(_PR_MD_GET_INTSOFF() > 0);
+ me = _PR_MD_CURRENT_THREAD();
+ PR_ASSERT(!(me->flags & _PR_IDLE_THREAD));
+
+ /*
+ ** Process delayed interrupts. This logic is kinda scary because we
+ ** need to avoid losing an interrupt (it's ok to delay an interrupt
+ ** until later).
+ **
+ ** There are two missed state words. _pr_ints.where indicates to the
+ ** interrupt handler which state word is currently safe for
+ ** modification.
+ **
+ ** This code scans both interrupt state words, using the where flag
+ ** to indicate to the interrupt which state word is safe for writing.
+ ** If an interrupt comes in during a scan the other word will be
+ ** modified. This modification will be noticed during the next
+ ** iteration of the loop or during the next call to this routine.
+ */
+ for (i = 0; i < 2; i++) {
+ cpu->where = (1 - i);
+ missed = cpu->u.missed[i];
+ if (missed != 0) {
+ cpu->u.missed[i] = 0;
+ for (it = _pr_interruptTable; it->name; it++) {
+ if (missed & it->missed_bit) {
+ PR_LOG(_pr_sched_lm, PR_LOG_MIN,
+ ("IntsOn[0]: %s intr", it->name));
+ (*it->handler)();
+ }
+ }
+ }
+ }
+
+ if (cpu->u.missed[3] != 0) {
+ _PRCPU *cpu;
+
+ _PR_THREAD_LOCK(me);
+ me->state = _PR_RUNNABLE;
+ pri = me->priority;
+
+ cpu = me->cpu;
+ _PR_RUNQ_LOCK(cpu);
+ _PR_ADD_RUNQ(me, cpu, pri);
+ _PR_RUNQ_UNLOCK(cpu);
+ _PR_THREAD_UNLOCK(me);
+ _PR_MD_SWITCH_CONTEXT(me);
+ }
+}
+
+/*
+** Unblock the first runnable waiting thread. Skip over
+** threads that are trying to be suspended
+** Note: Caller must hold _PR_LOCK_LOCK()
+*/
+void _PR_UnblockLockWaiter(PRLock *lock)
+{
+ PRThread *t = NULL;
+ PRThread *me;
+ PRCList *q;
+
+ q = lock->waitQ.next;
+ PR_ASSERT(q != &lock->waitQ);
+ while (q != &lock->waitQ) {
+ /* Unblock first waiter */
+ t = _PR_THREAD_CONDQ_PTR(q);
+
+ /*
+ ** We are about to change the thread's state to runnable and for local
+ ** threads, we are going to assign a cpu to it. So, protect thread's
+ ** data structure.
+ */
+ _PR_THREAD_LOCK(t);
+
+ if (t->flags & _PR_SUSPENDING) {
+ q = q->next;
+ _PR_THREAD_UNLOCK(t);
+ continue;
+ }
+
+ /* Found a runnable thread */
+ PR_ASSERT(t->state == _PR_LOCK_WAIT);
+ PR_ASSERT(t->wait.lock == lock);
+ t->wait.lock = 0;
+ PR_REMOVE_LINK(&t->waitQLinks); /* take it off lock's waitQ */
+
+ /*
+ ** If this is a native thread, nothing else to do except to wake it
+ ** up by calling the machine dependent wakeup routine.
+ **
+ ** If this is a local thread, we need to assign it a cpu and
+ ** put the thread on that cpu's run queue. There are two cases to
+ ** take care of. If the currently running thread is also a local
+ ** thread, we just assign our own cpu to that thread and put it on
+ ** the cpu's run queue. If the the currently running thread is a
+ ** native thread, we assign the primordial cpu to it (on NT,
+ ** MD_WAKEUP handles the cpu assignment).
+ */
+
+ if ( !_PR_IS_NATIVE_THREAD(t) ) {
+
+ t->state = _PR_RUNNABLE;
+
+ me = _PR_MD_CURRENT_THREAD();
+
+ _PR_AddThreadToRunQ(me, t);
+ _PR_THREAD_UNLOCK(t);
+ } else {
+ t->state = _PR_RUNNING;
+ _PR_THREAD_UNLOCK(t);
+ }
+ _PR_MD_WAKEUP_WAITER(t);
+ break;
+ }
+ return;
+}
+
+/************************************************************************/
+
+
+PR_IMPLEMENT(PRLock*) PR_NewLock(void)
+{
+ PRLock *lock;
+
+ if (!_pr_initialized) {
+ _PR_ImplicitInitialization();
+ }
+
+ lock = PR_NEWZAP(PRLock);
+ if (lock) {
+ if (_PR_InitLock(lock) != PR_SUCCESS) {
+ PR_DELETE(lock);
+ return NULL;
+ }
+ }
+ return lock;
+}
+
+PRStatus _PR_InitLock(PRLock *lock)
+{
+ if (_PR_MD_NEW_LOCK(&lock->ilock) != PR_SUCCESS) {
+ return PR_FAILURE;
+ }
+ PR_INIT_CLIST(&lock->links);
+ PR_INIT_CLIST(&lock->waitQ);
+ return PR_SUCCESS;
+}
+
+/*
+** Destroy the given lock "lock". There is no point in making this race
+** free because if some other thread has the pointer to this lock all
+** bets are off.
+*/
+PR_IMPLEMENT(void) PR_DestroyLock(PRLock *lock)
+{
+ _PR_FreeLock(lock);
+ PR_DELETE(lock);
+}
+
+void _PR_FreeLock(PRLock *lock)
+{
+ PR_ASSERT(lock->owner == 0);
+ _PR_MD_FREE_LOCK(&lock->ilock);
+}
+
+extern PRThread *suspendAllThread;
+/*
+** Lock the lock.
+*/
+PR_IMPLEMENT(void) PR_Lock(PRLock *lock)
+{
+ PRThread *me = _PR_MD_CURRENT_THREAD();
+ PRIntn is;
+ PRThread *t;
+ PRCList *q;
+
+ PR_ASSERT(me != suspendAllThread);
+ PR_ASSERT(!(me->flags & _PR_IDLE_THREAD));
+ PR_ASSERT(lock != NULL);
+#ifdef _PR_GLOBAL_THREADS_ONLY
+ _PR_MD_LOCK(&lock->ilock);
+ PR_ASSERT(lock->owner == 0);
+ lock->owner = me;
+ return;
+#else /* _PR_GLOBAL_THREADS_ONLY */
+
+ if (_native_threads_only) {
+ _PR_MD_LOCK(&lock->ilock);
+ PR_ASSERT(lock->owner == 0);
+ lock->owner = me;
+ return;
+ }
+
+ if (!_PR_IS_NATIVE_THREAD(me)) {
+ _PR_INTSOFF(is);
+ }
+
+ PR_ASSERT(_PR_IS_NATIVE_THREAD(me) || _PR_MD_GET_INTSOFF() != 0);
+
+retry:
+ _PR_LOCK_LOCK(lock);
+ if (lock->owner == 0) {
+ /* Just got the lock */
+ lock->owner = me;
+ lock->priority = me->priority;
+ /* Add the granted lock to this owning thread's lock list */
+ PR_APPEND_LINK(&lock->links, &me->lockList);
+ _PR_LOCK_UNLOCK(lock);
+ if (!_PR_IS_NATIVE_THREAD(me)) {
+ _PR_FAST_INTSON(is);
+ }
+ return;
+ }
+
+ /* If this thread already owns this lock, then it is a deadlock */
+ PR_ASSERT(lock->owner != me);
+
+ PR_ASSERT(_PR_IS_NATIVE_THREAD(me) || _PR_MD_GET_INTSOFF() != 0);
+
+#if 0
+ if (me->priority > lock->owner->priority) {
+ /*
+ ** Give the lock owner a priority boost until we get the
+ ** lock. Record the priority we boosted it to.
+ */
+ lock->boostPriority = me->priority;
+ _PR_SetThreadPriority(lock->owner, me->priority);
+ }
+#endif
+
+ /*
+ Add this thread to the asked for lock's list of waiting threads. We
+ add this thread thread in the right priority order so when the unlock
+ occurs, the thread with the higher priority will get the lock.
+ */
+ q = lock->waitQ.next;
+ if (q == &lock->waitQ || _PR_THREAD_CONDQ_PTR(q)->priority ==
+ _PR_THREAD_CONDQ_PTR(lock->waitQ.prev)->priority) {
+ /*
+ * If all the threads in the lock waitQ have the same priority,
+ * then avoid scanning the list: insert the element at the end.
+ */
+ q = &lock->waitQ;
+ } else {
+ /* Sort thread into lock's waitQ at appropriate point */
+ /* Now scan the list for where to insert this entry */
+ while (q != &lock->waitQ) {
+ t = _PR_THREAD_CONDQ_PTR(lock->waitQ.next);
+ if (me->priority > t->priority) {
+ /* Found a lower priority thread to insert in front of */
+ break;
+ }
+ q = q->next;
+ }
+ }
+ PR_INSERT_BEFORE(&me->waitQLinks, q);
+
+ /*
+ Now grab the threadLock since we are about to change the state. We have
+ to do this since a PR_Suspend or PR_SetThreadPriority type call that takes
+ a PRThread* as an argument could be changing the state of this thread from
+ a thread running on a different cpu.
+ */
+
+ _PR_THREAD_LOCK(me);
+ me->state = _PR_LOCK_WAIT;
+ me->wait.lock = lock;
+ _PR_THREAD_UNLOCK(me);
+
+ _PR_LOCK_UNLOCK(lock);
+
+ _PR_MD_WAIT(me, PR_INTERVAL_NO_TIMEOUT);
+ goto retry;
+
+#endif /* _PR_GLOBAL_THREADS_ONLY */
+}
+
+/*
+** Unlock the lock.
+*/
+PR_IMPLEMENT(PRStatus) PR_Unlock(PRLock *lock)
+{
+ PRCList *q;
+ PRThreadPriority pri, boost;
+ PRIntn is;
+ PRThread *me = _PR_MD_CURRENT_THREAD();
+
+ PR_ASSERT(lock != NULL);
+ PR_ASSERT(lock->owner == me);
+ PR_ASSERT(me != suspendAllThread);
+ PR_ASSERT(!(me->flags & _PR_IDLE_THREAD));
+ if (lock->owner != me) {
+ return PR_FAILURE;
+ }
+
+#ifdef _PR_GLOBAL_THREADS_ONLY
+ lock->owner = 0;
+ _PR_MD_UNLOCK(&lock->ilock);
+ return PR_SUCCESS;
+#else /* _PR_GLOBAL_THREADS_ONLY */
+
+ if (_native_threads_only) {
+ lock->owner = 0;
+ _PR_MD_UNLOCK(&lock->ilock);
+ return PR_SUCCESS;
+ }
+
+ if (!_PR_IS_NATIVE_THREAD(me)) {
+ _PR_INTSOFF(is);
+ }
+ _PR_LOCK_LOCK(lock);
+
+ /* Remove the lock from the owning thread's lock list */
+ PR_REMOVE_LINK(&lock->links);
+ pri = lock->priority;
+ boost = lock->boostPriority;
+ if (boost > pri) {
+ /*
+ ** We received a priority boost during the time we held the lock.
+ ** We need to figure out what priority to move to by scanning
+ ** down our list of lock's that we are still holding and using
+ ** the highest boosted priority found.
+ */
+ q = me->lockList.next;
+ while (q != &me->lockList) {
+ PRLock *ll = _PR_LOCK_PTR(q);
+ if (ll->boostPriority > pri) {
+ pri = ll->boostPriority;
+ }
+ q = q->next;
+ }
+ if (pri != me->priority) {
+ _PR_SetThreadPriority(me, pri);
+ }
+ }
+
+ /* Unblock the first waiting thread */
+ q = lock->waitQ.next;
+ if (q != &lock->waitQ) {
+ _PR_UnblockLockWaiter(lock);
+ }
+ lock->boostPriority = PR_PRIORITY_LOW;
+ lock->owner = 0;
+ _PR_LOCK_UNLOCK(lock);
+ if (!_PR_IS_NATIVE_THREAD(me)) {
+ _PR_INTSON(is);
+ }
+ return PR_SUCCESS;
+#endif /* _PR_GLOBAL_THREADS_ONLY */
+}
+
+/*
+** If the current thread owns |lock|, this assertion is guaranteed to
+** succeed. Otherwise, the behavior of this function is undefined.
+*/
+PR_IMPLEMENT(void) PR_AssertCurrentThreadOwnsLock(PRLock *lock)
+{
+ PRThread *me = _PR_MD_CURRENT_THREAD();
+ PR_ASSERT(lock->owner == me);
+}
+
+/*
+** Test and then lock the lock if it's not already locked by some other
+** thread. Return PR_FALSE if some other thread owned the lock at the
+** time of the call.
+*/
+PR_IMPLEMENT(PRBool) PR_TestAndLock(PRLock *lock)
+{
+ PRThread *me = _PR_MD_CURRENT_THREAD();
+ PRBool rv = PR_FALSE;
+ PRIntn is;
+
+#ifdef _PR_GLOBAL_THREADS_ONLY
+ is = _PR_MD_TEST_AND_LOCK(&lock->ilock);
+ if (is == 0) {
+ lock->owner = me;
+ return PR_TRUE;
+ }
+ return PR_FALSE;
+#else /* _PR_GLOBAL_THREADS_ONLY */
+
+#ifndef _PR_LOCAL_THREADS_ONLY
+ if (_native_threads_only) {
+ is = _PR_MD_TEST_AND_LOCK(&lock->ilock);
+ if (is == 0) {
+ lock->owner = me;
+ return PR_TRUE;
+ }
+ return PR_FALSE;
+ }
+#endif
+
+ if (!_PR_IS_NATIVE_THREAD(me)) {
+ _PR_INTSOFF(is);
+ }
+
+ _PR_LOCK_LOCK(lock);
+ if (lock->owner == 0) {
+ /* Just got the lock */
+ lock->owner = me;
+ lock->priority = me->priority;
+ /* Add the granted lock to this owning thread's lock list */
+ PR_APPEND_LINK(&lock->links, &me->lockList);
+ rv = PR_TRUE;
+ }
+ _PR_LOCK_UNLOCK(lock);
+
+ if (!_PR_IS_NATIVE_THREAD(me)) {
+ _PR_INTSON(is);
+ }
+ return rv;
+#endif /* _PR_GLOBAL_THREADS_ONLY */
+}
+
+/************************************************************************/
+/************************************************************************/
+/***********************ROUTINES FOR DCE EMULATION***********************/
+/************************************************************************/
+/************************************************************************/
+PR_IMPLEMENT(PRStatus) PRP_TryLock(PRLock *lock)
+{
+ return (PR_TestAndLock(lock)) ? PR_SUCCESS : PR_FAILURE;
+}