diff options
Diffstat (limited to 'nsprpub/pr/src/threads/combined/prulock.c')
| -rw-r--r-- | nsprpub/pr/src/threads/combined/prulock.c | 446 |
1 files changed, 446 insertions, 0 deletions
diff --git a/nsprpub/pr/src/threads/combined/prulock.c b/nsprpub/pr/src/threads/combined/prulock.c new file mode 100644 index 000000000..8b2f41eec --- /dev/null +++ b/nsprpub/pr/src/threads/combined/prulock.c @@ -0,0 +1,446 @@ +/* -*- 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; } |