libcilkrts/runtime/spin_mutex.h

   1 /* spin_mutex.h                  -*-C++-*-
   2  *
   3  *************************************************************************
   4  *
   5  *  @copyright
   6  *  Copyright (C) 2009-2013, Intel Corporation
   7  *  All rights reserved.
   8  *
   9  *  @copyright
  10  *  Redistribution and use in source and binary forms, with or without
  11  *  modification, are permitted provided that the following conditions
  12  *  are met:
  13  *
  14  *    * Redistributions of source code must retain the above copyright
  15  *      notice, this list of conditions and the following disclaimer.
  16  *    * Redistributions in binary form must reproduce the above copyright
  17  *      notice, this list of conditions and the following disclaimer in
  18  *      the documentation and/or other materials provided with the
  19  *      distribution.
  20  *    * Neither the name of Intel Corporation nor the names of its
  21  *      contributors may be used to endorse or promote products derived
  22  *      from this software without specific prior written permission.
  23  *
  24  *  @copyright
  25  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  26  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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  31  *  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
  32  *  OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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  37  **************************************************************************/
  38
  39 /**
  40  * @file spin_mutex.h
  41  *
  42  * @brief Support for Cilk runtime mutexes.
  43  *
  44  * Cilk runtime mutexes are implemented as simple spin loops.
  45  *
  46  * This file is similar to a worker_mutex, except it does not have an
  47  * owner field.
  48  *
  49  * TBD: This class, worker_mutex, and os_mutex overlap quite a bit in
  50  * functionality.  Can we unify these mutexes somehow?
  51  */
  52 #ifndef INCLUDED_SPIN_MUTEX_DOT_H
  53 #define INCLUDED_SPIN_MUTEX_DOT_H
  54
  55 #include <cilk/common.h>
  56 #include "rts-common.h"
  57 #include "cilk_malloc.h"
  58
  59 __CILKRTS_BEGIN_EXTERN_C
  60
  61 /**
  62  * Mutexes are treated as an abstract data type within the Cilk
  63  * runtime system.  They are implemented as simple spin loops.
  64  */
  65 typedef struct spin_mutex {
  66     /** Mutex spin loop variable. 0 if unowned, 1 if owned. */
  67     volatile int lock;
  68
  69     /** Padding so the mutex takes up a cache line. */
  70     char pad[64/sizeof(int) - 1];
  71 } spin_mutex;
  72
  73
  74 /**
  75  * @brief Create a new Cilk spin_mutex.
  76  *
  77  * @return Returns an initialized spin mutex.
  78  */
  79 COMMON_PORTABLE
  80 spin_mutex* spin_mutex_create();
  81
  82 /**
  83  * @brief Initialize a Cilk spin_mutex.
  84  *
  85  * @param m Spin_Mutex to be initialized.
  86  */
  87 COMMON_PORTABLE
  88 void spin_mutex_init(spin_mutex *m);
  89
  90 /**
  91  * @brief Acquire a Cilk spin_mutex.
  92  *
  93  * If statistics are being gathered, the time spent
  94  * acquiring the spin_mutex will be attributed to the specified worker.
  95  *
  96  * @param m Spin_Mutex to be initialized.
  97  */
  98 COMMON_PORTABLE
  99 void spin_mutex_lock(struct spin_mutex *m);
 100 /**
 101  * @brief Attempt to lock a Cilk spin_mutex and fail if it isn't available.
 102  *
 103  * @param m Spin_Mutex to be acquired.
 104  *
 105  * @return 1 if the spin_mutex was acquired.
 106  * @return 0 if the spin_mutex was not acquired.
 107  */
 108 COMMON_PORTABLE
 109 int spin_mutex_trylock(struct spin_mutex *m);
 110
 111 /**
 112  * @brief Release a Cilk spin_mutex.
 113  *
 114  * @param m Spin_Mutex to be released.
 115  */
 116 COMMON_PORTABLE
 117 void spin_mutex_unlock(struct spin_mutex *m);
 118
 119 /**
 120  * @brief Deallocate a Cilk spin_mutex.  Currently does nothing.
 121  *
 122  * @param m Spin_Mutex to be deallocated.
 123  */
 124 COMMON_PORTABLE
 125 void spin_mutex_destroy(struct spin_mutex *m);
 126
 127 __CILKRTS_END_EXTERN_C
 128
 129 #endif // ! defined(INCLUDED_SPIN_MUTEX_DOT_H)