diff options
Diffstat (limited to 'nsprpub/pr/src/bthreads/btmon.c')
| -rw-r--r-- | nsprpub/pr/src/bthreads/btmon.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/nsprpub/pr/src/bthreads/btmon.c b/nsprpub/pr/src/bthreads/btmon.c new file mode 100644 index 000000000..bd05e73dc --- /dev/null +++ b/nsprpub/pr/src/bthreads/btmon.c @@ -0,0 +1,201 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* 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 <kernel/OS.h> + +#include "primpl.h" + +/* +** Create a new monitor. Monitors are re-entrant locks with a single built-in +** condition variable. +** +** This may fail if memory is tight or if some operating system resource +** is low. +*/ +PR_IMPLEMENT(PRMonitor*) + PR_NewMonitor (void) +{ + PRMonitor *mon; + PRCondVar *cvar; + PRLock *lock; + + mon = PR_NEWZAP( PRMonitor ); + if( mon ) + { + lock = PR_NewLock(); + if( !lock ) + { + PR_DELETE( mon ); + return( 0 ); + } + + cvar = PR_NewCondVar( lock ); + if( !cvar ) + { + PR_DestroyLock( lock ); + PR_DELETE( mon ); + return( 0 ); + } + + mon->cvar = cvar; + mon->name = NULL; + } + + return( mon ); +} + +PR_IMPLEMENT(PRMonitor*) PR_NewNamedMonitor(const char* name) +{ + PRMonitor* mon = PR_NewMonitor(); + if( mon ) + { + mon->name = name; + } + return mon; +} + +/* +** Destroy a monitor. The caller is responsible for guaranteeing that the +** monitor is no longer in use. There must be no thread waiting on the +** monitor's condition variable and that the lock is not held. +** +*/ +PR_IMPLEMENT(void) + PR_DestroyMonitor (PRMonitor *mon) +{ + PR_DestroyLock( mon->cvar->lock ); + PR_DestroyCondVar( mon->cvar ); + PR_DELETE( mon ); +} + +/* +** Enter the lock associated with the monitor. If the calling thread currently +** is in the monitor, the call to enter will silently succeed. In either case, +** it will increment the entry count by one. +*/ +PR_IMPLEMENT(void) + PR_EnterMonitor (PRMonitor *mon) +{ + if( mon->cvar->lock->owner == find_thread( NULL ) ) + { + mon->entryCount++; + + } else + { + PR_Lock( mon->cvar->lock ); + mon->entryCount = 1; + } +} + +/* +** Decrement the entry count associated with the monitor. If the decremented +** entry count is zero, the monitor is exited. Returns PR_FAILURE if the +** calling thread has not entered the monitor. +*/ +PR_IMPLEMENT(PRStatus) + PR_ExitMonitor (PRMonitor *mon) +{ + if( mon->cvar->lock->owner != find_thread( NULL ) ) + { + return( PR_FAILURE ); + } + if( --mon->entryCount == 0 ) + { + return( PR_Unlock( mon->cvar->lock ) ); + } + return( PR_SUCCESS ); +} + +/* +** Wait for a notify on the monitor's condition variable. Sleep for "ticks" +** amount of time (if "ticks" is PR_INTERVAL_NO_TIMEOUT then the sleep is +** indefinite). +** +** While the thread is waiting it exits the monitor (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" timeout elapses. +** +** Returns PR_FAILURE if the caller has not entered the monitor. +*/ +PR_IMPLEMENT(PRStatus) + PR_Wait (PRMonitor *mon, PRIntervalTime ticks) +{ + PRUint32 entryCount; + PRUintn status; + PRThread *meThread; + thread_id me = find_thread( NULL ); + meThread = PR_GetCurrentThread(); + + if( mon->cvar->lock->owner != me ) return( PR_FAILURE ); + + entryCount = mon->entryCount; + mon->entryCount = 0; + + status = PR_WaitCondVar( mon->cvar, ticks ); + + mon->entryCount = entryCount; + + return( status ); +} + +/* +** Notify a thread waiting on the monitor's condition variable. If a thread +** is waiting on the condition variable (using PR_Wait) then it is awakened +** and attempts to reenter the monitor. +*/ +PR_IMPLEMENT(PRStatus) + PR_Notify (PRMonitor *mon) +{ + if( mon->cvar->lock->owner != find_thread( NULL ) ) + { + return( PR_FAILURE ); + } + + PR_NotifyCondVar( mon->cvar ); + return( PR_SUCCESS ); +} + +/* +** Notify all of the threads waiting on the monitor's condition variable. +** All of threads waiting on the condition are scheduled to reenter the +** monitor. +*/ +PR_IMPLEMENT(PRStatus) + PR_NotifyAll (PRMonitor *mon) +{ + if( mon->cvar->lock->owner != find_thread( NULL ) ) + { + return( PR_FAILURE ); + } + + PR_NotifyAllCondVar( mon->cvar ); + 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) +{ + return( (mon->cvar->lock->owner == find_thread( NULL )) ? + mon->entryCount : 0 ); +} + +/* +** If the current thread is in |mon|, this assertion is guaranteed to +** succeed. Otherwise, the behavior of this function is undefined. +*/ +PR_IMPLEMENT(void) + PR_AssertCurrentThreadInMonitor(PRMonitor *mon) +{ + PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mon->cvar->lock); +} |