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/gecko_api/include/obsolete/prsem.h

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  1. /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  2. /* ***** BEGIN LICENSE BLOCK *****
  3. * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  4. *
  5. * The contents of this file are subject to the Mozilla Public License Version
  6. * 1.1 (the "License"); you may not use this file except in compliance with
  7. * the License. You may obtain a copy of the License at
  8. * http://www.mozilla.org/MPL/
  9. *
  10. * Software distributed under the License is distributed on an "AS IS" basis,
  11. * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12. * for the specific language governing rights and limitations under the
  13. * License.
  14. *
  15. * The Original Code is the Netscape Portable Runtime (NSPR).
  16. *
  17. * The Initial Developer of the Original Code is
  18. * Netscape Communications Corporation.
  19. * Portions created by the Initial Developer are Copyright (C) 1998-2000
  20. * the Initial Developer. All Rights Reserved.
  21. *
  22. * Contributor(s):
  23. *
  24. * Alternatively, the contents of this file may be used under the terms of
  25. * either the GNU General Public License Version 2 or later (the "GPL"), or
  26. * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  27. * in which case the provisions of the GPL or the LGPL are applicable instead
  28. * of those above. If you wish to allow use of your version of this file only
  29. * under the terms of either the GPL or the LGPL, and not to allow others to
  30. * use your version of this file under the terms of the MPL, indicate your
  31. * decision by deleting the provisions above and replace them with the notice
  32. * and other provisions required by the GPL or the LGPL. If you do not delete
  33. * the provisions above, a recipient may use your version of this file under
  34. * the terms of any one of the MPL, the GPL or the LGPL.
  35. *
  36. * ***** END LICENSE BLOCK ***** */
  37. #ifndef prsem_h___
  38. #define prsem_h___
  39. /*
  40. ** API for counting semaphores. Semaphores are counting synchronizing
  41. ** variables based on a lock and a condition variable. They are lightweight
  42. ** contention control for a given count of resources.
  43. */
  44. #include "prtypes.h"
  45. PR_BEGIN_EXTERN_C
  46. typedef struct PRSemaphore PRSemaphore;
  47. /*
  48. ** Create a new semaphore object.
  49. */
  50. NSPR_API(PRSemaphore*) PR_NewSem(PRUintn value);
  51. /*
  52. ** Destroy the given semaphore object.
  53. **
  54. */
  55. NSPR_API(void) PR_DestroySem(PRSemaphore *sem);
  56. /*
  57. ** Wait on a Semaphore.
  58. **
  59. ** This routine allows a calling thread to wait or proceed depending upon the
  60. ** state of the semahore sem. The thread can proceed only if the counter value
  61. ** of the semaphore sem is currently greater than 0. If the value of semaphore
  62. ** sem is positive, it is decremented by one and the routine returns immediately
  63. ** allowing the calling thread to continue. If the value of semaphore sem is 0,
  64. ** the calling thread blocks awaiting the semaphore to be released by another
  65. ** thread.
  66. **
  67. ** This routine can return PR_PENDING_INTERRUPT if the waiting thread
  68. ** has been interrupted.
  69. */
  70. NSPR_API(PRStatus) PR_WaitSem(PRSemaphore *sem);
  71. /*
  72. ** This routine increments the counter value of the semaphore. If other threads
  73. ** are blocked for the semaphore, then the scheduler will determine which ONE
  74. ** thread will be unblocked.
  75. */
  76. NSPR_API(void) PR_PostSem(PRSemaphore *sem);
  77. /*
  78. ** Returns the value of the semaphore referenced by sem without affecting
  79. ** the state of the semaphore. The value represents the semaphore vaule
  80. F** at the time of the call, but may not be the actual value when the
  81. ** caller inspects it.
  82. */
  83. NSPR_API(PRUintn) PR_GetValueSem(PRSemaphore *sem);
  84. PR_END_EXTERN_C
  85. #endif /* prsem_h___ */