include/thread_mpi/lock.h

   1 /*
   2 This source code file is part of thread_mpi.
   3 Written by Sander Pronk, Erik Lindahl, and possibly others.
   4
   5 Copyright (c) 2009, Sander Pronk, Erik Lindahl.
   6 All rights reserved.
   7
   8 Redistribution and use in source and binary forms, with or without
   9 modification, are permitted provided that the following conditions are met:
  10 1) Redistributions of source code must retain the above copyright
  11    notice, this list of conditions and the following disclaimer.
  12 2) Redistributions in binary form must reproduce the above copyright
  13    notice, this list of conditions and the following disclaimer in the
  14    documentation and/or other materials provided with the distribution.
  15 3) Neither the name of the copyright holders nor the
  16    names of its contributors may be used to endorse or promote products
  17    derived from this software without specific prior written permission.
  18
  19 THIS SOFTWARE IS PROVIDED BY US ''AS IS'' AND ANY
  20 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  21 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  22 DISCLAIMED. IN NO EVENT SHALL WE BE LIABLE FOR ANY
  23 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  24 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  25 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  26 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  28 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29
  30 If you want to redistribute modifications, please consider that
  31 scientific software is very special. Version control is crucial -
  32 bugs must be traceable. We will be happy to consider code for
  33 inclusion in the official distribution, but derived work should not
  34 be called official thread_mpi. Details are found in the README & COPYING
  35 files.
  36 */
  37
  38 #ifndef _TMPI_FASTLOCK_H_
  39 #define _TMPI_FASTLOCK_H_
  40
  41 #include "atomic.h"
  42 #include "wait.h"
  43
  44 /** Fast (possibly busy-wait-based) lock type
  45  *
  46  *  This lock type forms an intermediate between the spinlocks and mutexes:
  47  *  it is based on a busy-wait loop, but yields to the scheduler if the lock
  48  *  is locked.  This is therefore the preferred type of  lock for when waits
  49  *  are expected to be reasonably short.
  50  *
  51  *  Variables of this type should be initialized by calling
  52  *  tMPI_Lock_init().
  53  *
  54  * \see
  55  * - tMPI_Lock_init
  56  * - tMPI_Lock_lock
  57  */
  58 typedef struct tMPI_Lock tMPI_Lock_t;
  59 struct tMPI_Lock
  60 {
  61     tMPI_Spinlock_t   lock;      /*!< The underlying spin lock */
  62     TMPI_YIELD_WAIT_DATA
  63 };
  64
  65
  66 /** Initialize lock
  67  *
  68  *  \param lock     Pointer to the new lock.
  69  */
  70 void tMPI_Lock_init(tMPI_Lock_t *lock);
  71
  72
  73 /** Perform yielding, busy-waiting locking
  74   *
  75   *  This function blocks until the lock is locked.
  76   *
  77   *  \param lock  Pointer to previously created lock.
  78   */
  79 void tMPI_Lock_lock(tMPI_Lock_t *lock);
  80
  81 /** Unlock the lock
  82   *
  83   *  \param lock  Pointer to previously created lock.
  84   */
  85 void tMPI_Lock_unlock(tMPI_Lock_t *lock);
  86
  87 /** Try to lock the lock but don't block if it is locked.
  88   *
  89   *  \param lock  Pointer to previously created lock.
  90   */
  91 int tMPI_Lock_trylock(tMPI_Lock_t *lock);
  92
  93 /** Check the status of the lock without affecting its state
  94   *
  95   *  \param lock  Pointer to previously created lock.
  96   */
  97 int tMPI_Lock_islocked(const tMPI_Lock_t *lock);
  98
  99
 100
 101 #endif