libcilkrts/runtime/spin_mutex.h

   1 /* spin_mutex.h                  -*-C++-*-
   2  *
   3  *************************************************************************
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  48  **************************************************************************/
  49
  50 /**
  51  * @file spin_mutex.h
  52  *
  53  * @brief Support for Cilk runtime mutexes.
  54  *
  55  * Cilk runtime mutexes are implemented as simple spin loops.
  56  *
  57  * This file is similar to a worker_mutex, except it does not have an
  58  * owner field.
  59  *
  60  * TBD: This class, worker_mutex, and os_mutex overlap quite a bit in
  61  * functionality.  Can we unify these mutexes somehow?
  62  */
  63 #ifndef INCLUDED_SPIN_MUTEX_DOT_H
  64 #define INCLUDED_SPIN_MUTEX_DOT_H
  65
  66 #include <cilk/common.h>
  67 #include "rts-common.h"
  68 #include "cilk_malloc.h"
  69
  70 __CILKRTS_BEGIN_EXTERN_C
  71
  72 /**
  73  * Mutexes are treated as an abstract data type within the Cilk
  74  * runtime system.  They are implemented as simple spin loops.
  75  */
  76 typedef struct spin_mutex {
  77     /** Mutex spin loop variable. 0 if unowned, 1 if owned. */
  78     volatile int lock;
  79
  80     /** Padding so the mutex takes up a cache line. */
  81     char pad[64/sizeof(int) - 1];
  82 } spin_mutex;
  83
  84
  85 /**
  86  * @brief Create a new Cilk spin_mutex.
  87  *
  88  * @return Returns an initialized spin mutex.
  89  */
  90 COMMON_PORTABLE
  91 spin_mutex* spin_mutex_create();
  92
  93 /**
  94  * @brief Initialize a Cilk spin_mutex.
  95  *
  96  * @param m Spin_Mutex to be initialized.
  97  */
  98 COMMON_PORTABLE
  99 void spin_mutex_init(spin_mutex *m);
 100
 101 /**
 102  * @brief Acquire a Cilk spin_mutex.
 103  *
 104  * If statistics are being gathered, the time spent
 105  * acquiring the spin_mutex will be attributed to the specified worker.
 106  *
 107  * @param m Spin_Mutex to be initialized.
 108  */
 109 COMMON_PORTABLE
 110 void spin_mutex_lock(struct spin_mutex *m);
 111 /**
 112  * @brief Attempt to lock a Cilk spin_mutex and fail if it isn't available.
 113  *
 114  * @param m Spin_Mutex to be acquired.
 115  *
 116  * @return 1 if the spin_mutex was acquired.
 117  * @return 0 if the spin_mutex was not acquired.
 118  */
 119 COMMON_PORTABLE
 120 int spin_mutex_trylock(struct spin_mutex *m);
 121
 122 /**
 123  * @brief Release a Cilk spin_mutex.
 124  *
 125  * @param m Spin_Mutex to be released.
 126  */
 127 COMMON_PORTABLE
 128 void spin_mutex_unlock(struct spin_mutex *m);
 129
 130 /**
 131  * @brief Deallocate a Cilk spin_mutex.  Currently does nothing.
 132  *
 133  * @param m Spin_Mutex to be deallocated.
 134  */
 135 COMMON_PORTABLE
 136 void spin_mutex_destroy(struct spin_mutex *m);
 137
 138 __CILKRTS_END_EXTERN_C
 139
 140 #endif // ! defined(INCLUDED_SPIN_MUTEX_DOT_H)