nsprpub/pr/include/prmon.h

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  37
  38 #ifndef prmon_h___
  39 #define prmon_h___
  40
  41 #include "prtypes.h"
  42 #include "prinrval.h"
  43
  44 PR_BEGIN_EXTERN_C
  45
  46 typedef struct PRMonitor PRMonitor;
  47
  48 /*
  49 ** Create a new monitor. Monitors are re-entrant locks with a single built-in
  50 ** condition variable.
  51 **
  52 ** This may fail if memory is tight or if some operating system resource
  53 ** is low.
  54 */
  55 NSPR_API(PRMonitor*) PR_NewMonitor(void);
  56
  57 /*
  58 ** Destroy a monitor. The caller is responsible for guaranteeing that the
  59 ** monitor is no longer in use. There must be no thread waiting on the monitor's
  60 ** condition variable and that the lock is not held.
  61 **
  62 */
  63 NSPR_API(void) PR_DestroyMonitor(PRMonitor *mon);
  64
  65 /*
  66 ** Enter the lock associated with the monitor. If the calling thread currently
  67 ** is in the monitor, the call to enter will silently succeed. In either case,
  68 ** it will increment the entry count by one.
  69 */
  70 NSPR_API(void) PR_EnterMonitor(PRMonitor *mon);
  71
  72 /*
  73 ** Decrement the entry count associated with the monitor. If the decremented
  74 ** entry count is zero, the monitor is exited. Returns PR_FAILURE if the
  75 ** calling thread has not entered the monitor.
  76 */
  77 NSPR_API(PRStatus) PR_ExitMonitor(PRMonitor *mon);
  78
  79 /*
  80 ** Wait for a notify on the monitor's condition variable. Sleep for "ticks"
  81 ** amount of time (if "ticks" is PR_INTERVAL_NO_TIMEOUT then the sleep is
  82 ** indefinite).
  83 **
  84 ** While the thread is waiting it exits the monitor (as if it called
  85 ** PR_ExitMonitor as many times as it had called PR_EnterMonitor).  When
  86 ** the wait has finished the thread regains control of the monitors lock
  87 ** with the same entry count as before the wait began.
  88 **
  89 ** The thread waiting on the monitor will be resumed when the monitor is
  90 ** notified (assuming the thread is the next in line to receive the
  91 ** notify) or when the "ticks" timeout elapses.
  92 **
  93 ** Returns PR_FAILURE if the caller has not entered the monitor.
  94 */
  95 NSPR_API(PRStatus) PR_Wait(PRMonitor *mon, PRIntervalTime ticks);
  96
  97 /*
  98 ** Notify a thread waiting on the monitor's condition variable. If a thread
  99 ** is waiting on the condition variable (using PR_Wait) then it is awakened
 100 ** and attempts to reenter the monitor.
 101 */
 102 NSPR_API(PRStatus) PR_Notify(PRMonitor *mon);
 103
 104 /*
 105 ** Notify all of the threads waiting on the monitor's condition variable.
 106 ** All of threads waiting on the condition are scheduled to reenter the
 107 ** monitor.
 108 */
 109 NSPR_API(PRStatus) PR_NotifyAll(PRMonitor *mon);
 110
 111 PR_END_EXTERN_C
 112
 113 #endif /* prmon_h___ */