1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/nsprpub/pr/src/bthreads/btmon.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,201 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#include <kernel/OS.h>
1.10 +
1.11 +#include "primpl.h"
1.12 +
1.13 +/*
1.14 +** Create a new monitor. Monitors are re-entrant locks with a single built-in
1.15 +** condition variable.
1.16 +**
1.17 +** This may fail if memory is tight or if some operating system resource
1.18 +** is low.
1.19 +*/
1.20 +PR_IMPLEMENT(PRMonitor*)
1.21 + PR_NewMonitor (void)
1.22 +{
1.23 + PRMonitor *mon;
1.24 + PRCondVar *cvar;
1.25 + PRLock *lock;
1.26 +
1.27 + mon = PR_NEWZAP( PRMonitor );
1.28 + if( mon )
1.29 + {
1.30 + lock = PR_NewLock();
1.31 + if( !lock )
1.32 + {
1.33 + PR_DELETE( mon );
1.34 + return( 0 );
1.35 + }
1.36 +
1.37 + cvar = PR_NewCondVar( lock );
1.38 + if( !cvar )
1.39 + {
1.40 + PR_DestroyLock( lock );
1.41 + PR_DELETE( mon );
1.42 + return( 0 );
1.43 + }
1.44 +
1.45 + mon->cvar = cvar;
1.46 + mon->name = NULL;
1.47 + }
1.48 +
1.49 + return( mon );
1.50 +}
1.51 +
1.52 +PR_IMPLEMENT(PRMonitor*) PR_NewNamedMonitor(const char* name)
1.53 +{
1.54 + PRMonitor* mon = PR_NewMonitor();
1.55 + if( mon )
1.56 + {
1.57 + mon->name = name;
1.58 + }
1.59 + return mon;
1.60 +}
1.61 +
1.62 +/*
1.63 +** Destroy a monitor. The caller is responsible for guaranteeing that the
1.64 +** monitor is no longer in use. There must be no thread waiting on the
1.65 +** monitor's condition variable and that the lock is not held.
1.66 +**
1.67 +*/
1.68 +PR_IMPLEMENT(void)
1.69 + PR_DestroyMonitor (PRMonitor *mon)
1.70 +{
1.71 + PR_DestroyLock( mon->cvar->lock );
1.72 + PR_DestroyCondVar( mon->cvar );
1.73 + PR_DELETE( mon );
1.74 +}
1.75 +
1.76 +/*
1.77 +** Enter the lock associated with the monitor. If the calling thread currently
1.78 +** is in the monitor, the call to enter will silently succeed. In either case,
1.79 +** it will increment the entry count by one.
1.80 +*/
1.81 +PR_IMPLEMENT(void)
1.82 + PR_EnterMonitor (PRMonitor *mon)
1.83 +{
1.84 + if( mon->cvar->lock->owner == find_thread( NULL ) )
1.85 + {
1.86 + mon->entryCount++;
1.87 +
1.88 + } else
1.89 + {
1.90 + PR_Lock( mon->cvar->lock );
1.91 + mon->entryCount = 1;
1.92 + }
1.93 +}
1.94 +
1.95 +/*
1.96 +** Decrement the entry count associated with the monitor. If the decremented
1.97 +** entry count is zero, the monitor is exited. Returns PR_FAILURE if the
1.98 +** calling thread has not entered the monitor.
1.99 +*/
1.100 +PR_IMPLEMENT(PRStatus)
1.101 + PR_ExitMonitor (PRMonitor *mon)
1.102 +{
1.103 + if( mon->cvar->lock->owner != find_thread( NULL ) )
1.104 + {
1.105 + return( PR_FAILURE );
1.106 + }
1.107 + if( --mon->entryCount == 0 )
1.108 + {
1.109 + return( PR_Unlock( mon->cvar->lock ) );
1.110 + }
1.111 + return( PR_SUCCESS );
1.112 +}
1.113 +
1.114 +/*
1.115 +** Wait for a notify on the monitor's condition variable. Sleep for "ticks"
1.116 +** amount of time (if "ticks" is PR_INTERVAL_NO_TIMEOUT then the sleep is
1.117 +** indefinite).
1.118 +**
1.119 +** While the thread is waiting it exits the monitor (as if it called
1.120 +** PR_ExitMonitor as many times as it had called PR_EnterMonitor). When
1.121 +** the wait has finished the thread regains control of the monitors lock
1.122 +** with the same entry count as before the wait began.
1.123 +**
1.124 +** The thread waiting on the monitor will be resumed when the monitor is
1.125 +** notified (assuming the thread is the next in line to receive the
1.126 +** notify) or when the "ticks" timeout elapses.
1.127 +**
1.128 +** Returns PR_FAILURE if the caller has not entered the monitor.
1.129 +*/
1.130 +PR_IMPLEMENT(PRStatus)
1.131 + PR_Wait (PRMonitor *mon, PRIntervalTime ticks)
1.132 +{
1.133 + PRUint32 entryCount;
1.134 + PRUintn status;
1.135 + PRThread *meThread;
1.136 + thread_id me = find_thread( NULL );
1.137 + meThread = PR_GetCurrentThread();
1.138 +
1.139 + if( mon->cvar->lock->owner != me ) return( PR_FAILURE );
1.140 +
1.141 + entryCount = mon->entryCount;
1.142 + mon->entryCount = 0;
1.143 +
1.144 + status = PR_WaitCondVar( mon->cvar, ticks );
1.145 +
1.146 + mon->entryCount = entryCount;
1.147 +
1.148 + return( status );
1.149 +}
1.150 +
1.151 +/*
1.152 +** Notify a thread waiting on the monitor's condition variable. If a thread
1.153 +** is waiting on the condition variable (using PR_Wait) then it is awakened
1.154 +** and attempts to reenter the monitor.
1.155 +*/
1.156 +PR_IMPLEMENT(PRStatus)
1.157 + PR_Notify (PRMonitor *mon)
1.158 +{
1.159 + if( mon->cvar->lock->owner != find_thread( NULL ) )
1.160 + {
1.161 + return( PR_FAILURE );
1.162 + }
1.163 +
1.164 + PR_NotifyCondVar( mon->cvar );
1.165 + return( PR_SUCCESS );
1.166 +}
1.167 +
1.168 +/*
1.169 +** Notify all of the threads waiting on the monitor's condition variable.
1.170 +** All of threads waiting on the condition are scheduled to reenter the
1.171 +** monitor.
1.172 +*/
1.173 +PR_IMPLEMENT(PRStatus)
1.174 + PR_NotifyAll (PRMonitor *mon)
1.175 +{
1.176 + if( mon->cvar->lock->owner != find_thread( NULL ) )
1.177 + {
1.178 + return( PR_FAILURE );
1.179 + }
1.180 +
1.181 + PR_NotifyAllCondVar( mon->cvar );
1.182 + return( PR_SUCCESS );
1.183 +}
1.184 +
1.185 +/*
1.186 +** Return the number of times that the current thread has entered the
1.187 +** lock. Returns zero if the current thread has not entered the lock.
1.188 +*/
1.189 +PR_IMPLEMENT(PRIntn)
1.190 + PR_GetMonitorEntryCount(PRMonitor *mon)
1.191 +{
1.192 + return( (mon->cvar->lock->owner == find_thread( NULL )) ?
1.193 + mon->entryCount : 0 );
1.194 +}
1.195 +
1.196 +/*
1.197 +** If the current thread is in |mon|, this assertion is guaranteed to
1.198 +** succeed. Otherwise, the behavior of this function is undefined.
1.199 +*/
1.200 +PR_IMPLEMENT(void)
1.201 + PR_AssertCurrentThreadInMonitor(PRMonitor *mon)
1.202 +{
1.203 + PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mon->cvar->lock);
1.204 +}
