third_party/npapi/npspy/extern/nspr/obsolete/prsem.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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   3  * The contents of this file are subject to the Mozilla Public
   4  * License Version 1.1 (the "License"); you may not use this file
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  12  *
  13  * The Original Code is the Netscape Portable Runtime (NSPR).
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  15  * The Initial Developer of the Original Code is Netscape
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  24  * "GPL"), in which case the provisions of the GPL are applicable
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  33  */
  34
  35 #ifndef prsem_h___
  36 #define prsem_h___
  37
  38 /*
  39 ** API for counting semaphores. Semaphores are counting synchronizing
  40 ** variables based on a lock and a condition variable.  They are lightweight
  41 ** contention control for a given count of resources.
  42 */
  43 #include "prtypes.h"
  44
  45 PR_BEGIN_EXTERN_C
  46
  47 typedef struct PRSemaphore PRSemaphore;
  48
  49 /*
  50 ** Create a new semaphore object.
  51 */
  52 NSPR_API(PRSemaphore*) PR_NewSem(PRUintn value);
  53
  54 /*
  55 ** Destroy the given semaphore object.
  56 **
  57 */
  58 NSPR_API(void) PR_DestroySem(PRSemaphore *sem);
  59
  60 /*
  61 ** Wait on a Semaphore.
  62 **
  63 ** This routine allows a calling thread to wait or proceed depending upon the
  64 ** state of the semahore sem. The thread can proceed only if the counter value
  65 ** of the semaphore sem is currently greater than 0. If the value of semaphore
  66 ** sem is positive, it is decremented by one and the routine returns immediately
  67 ** allowing the calling thread to continue. If the value of semaphore sem is 0,
  68 ** the calling thread blocks awaiting the semaphore to be released by another
  69 ** thread.
  70 **
  71 ** This routine can return PR_PENDING_INTERRUPT if the waiting thread
  72 ** has been interrupted.
  73 */
  74 NSPR_API(PRStatus) PR_WaitSem(PRSemaphore *sem);
  75
  76 /*
  77 ** This routine increments the counter value of the semaphore. If other threads
  78 ** are blocked for the semaphore, then the scheduler will determine which ONE
  79 ** thread will be unblocked.
  80 */
  81 NSPR_API(void) PR_PostSem(PRSemaphore *sem);
  82
  83 /*
  84 ** Returns the value of the semaphore referenced by sem without affecting
  85 ** the state of the semaphore.  The value represents the semaphore vaule
  86 F** at the time of the call, but may not be the actual value when the
  87 ** caller inspects it.
  88 */
  89 NSPR_API(PRUintn) PR_GetValueSem(PRSemaphore *sem);
  90
  91 PR_END_EXTERN_C
  92
  93 #endif /* prsem_h___ */