tor-browser

The Tor Browser
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prmon.h (3240B)

      1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* This Source Code Form is subject to the terms of the Mozilla Public
      3 * License, v. 2.0. If a copy of the MPL was not distributed with this
      4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      5 
      6 #ifndef prmon_h___
      7 #define prmon_h___
      8 
      9 #include "prtypes.h"
     10 #include "prinrval.h"
     11 
     12 PR_BEGIN_EXTERN_C
     13 
     14 typedef struct PRMonitor PRMonitor;
     15 
     16 /*
     17 ** Create a new monitor. Monitors are re-entrant locks with a single built-in
     18 ** condition variable.
     19 **
     20 ** This may fail if memory is tight or if some operating system resource
     21 ** is low.
     22 */
     23 NSPR_API(PRMonitor*) PR_NewMonitor(void);
     24 
     25 /*
     26 ** Destroy a monitor. The caller is responsible for guaranteeing that the
     27 ** monitor is no longer in use. There must be no thread waiting on the monitor's
     28 ** condition variable and that the lock is not held.
     29 **
     30 */
     31 NSPR_API(void) PR_DestroyMonitor(PRMonitor *mon);
     32 
     33 /*
     34 ** Enter the lock associated with the monitor. If the calling thread currently
     35 ** is in the monitor, the call to enter will silently succeed. In either case,
     36 ** it will increment the entry count by one.
     37 */
     38 NSPR_API(void) PR_EnterMonitor(PRMonitor *mon);
     39 
     40 /*
     41 ** Decrement the entry count associated with the monitor. If the decremented
     42 ** entry count is zero, the monitor is exited. Returns PR_FAILURE if the
     43 ** calling thread has not entered the monitor.
     44 */
     45 NSPR_API(PRStatus) PR_ExitMonitor(PRMonitor *mon);
     46 
     47 /*
     48 ** Wait for a notify on the monitor's condition variable. Sleep for "ticks"
     49 ** amount of time (if "ticks" is PR_INTERVAL_NO_TIMEOUT then the sleep is
     50 ** indefinite).
     51 **
     52 ** While the thread is waiting it exits the monitor (as if it called
     53 ** PR_ExitMonitor as many times as it had called PR_EnterMonitor).  When
     54 ** the wait has finished the thread regains control of the monitors lock
     55 ** with the same entry count as before the wait began.
     56 **
     57 ** The thread waiting on the monitor will be resumed when the monitor is
     58 ** notified (assuming the thread is the next in line to receive the
     59 ** notify) or when the "ticks" timeout elapses.
     60 **
     61 ** Returns PR_FAILURE if the caller has not entered the monitor.
     62 */
     63 NSPR_API(PRStatus) PR_Wait(PRMonitor *mon, PRIntervalTime ticks);
     64 
     65 /*
     66 ** Notify a thread waiting on the monitor's condition variable. If a thread
     67 ** is waiting on the condition variable (using PR_Wait) then it is awakened
     68 ** and attempts to reenter the monitor.
     69 */
     70 NSPR_API(PRStatus) PR_Notify(PRMonitor *mon);
     71 
     72 /*
     73 ** Notify all of the threads waiting on the monitor's condition variable.
     74 ** All of threads waiting on the condition are scheduled to reenter the
     75 ** monitor.
     76 */
     77 NSPR_API(PRStatus) PR_NotifyAll(PRMonitor *mon);
     78 
     79 /*
     80 ** PR_ASSERT_CURRENT_THREAD_IN_MONITOR
     81 ** If the current thread is in |mon|, this assertion is guaranteed to
     82 ** succeed.  Otherwise, the behavior of this function is undefined.
     83 */
     84 #if defined(DEBUG) || defined(FORCE_PR_ASSERT)
     85 #define PR_ASSERT_CURRENT_THREAD_IN_MONITOR(/* PRMonitor* */ mon) \
     86    PR_AssertCurrentThreadInMonitor(mon)
     87 #else
     88 #define PR_ASSERT_CURRENT_THREAD_IN_MONITOR(/* PRMonitor* */ mon)
     89 #endif
     90 
     91 /* Don't call this function directly. */
     92 NSPR_API(void) PR_AssertCurrentThreadInMonitor(PRMonitor *mon);
     93 
     94 PR_END_EXTERN_C
     95 
     96 #endif /* prmon_h___ */