src/thread/pthread/SDL_sysmutex.c
author Ryan C. Gordon
Mon, 23 Jan 2017 12:06:10 -0500
changeset 10837 c2f241c2f6ad
parent 10737 3406a0f8b041
child 11233 554b2c683da2
permissions -rw-r--r--
audio: Fix same bug as last commit, but for _mm_bslli_si128 vs _mm_slli_si128.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2017 Sam Lantinga <slouken@libsdl.org>
     4 
     5   This software is provided 'as-is', without any express or implied
     6   warranty.  In no event will the authors be held liable for any damages
     7   arising from the use of this software.
     8 
     9   Permission is granted to anyone to use this software for any purpose,
    10   including commercial applications, and to alter it and redistribute it
    11   freely, subject to the following restrictions:
    12 
    13   1. The origin of this software must not be misrepresented; you must not
    14      claim that you wrote the original software. If you use this software
    15      in a product, an acknowledgment in the product documentation would be
    16      appreciated but is not required.
    17   2. Altered source versions must be plainly marked as such, and must not be
    18      misrepresented as being the original software.
    19   3. This notice may not be removed or altered from any source distribution.
    20 */
    21 #include "../../SDL_internal.h"
    22 
    23 #include <errno.h>
    24 #include <pthread.h>
    25 
    26 #include "SDL_thread.h"
    27 
    28 #if !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX && \
    29     !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP
    30 #define FAKE_RECURSIVE_MUTEX 1
    31 #endif
    32 
    33 struct SDL_mutex
    34 {
    35     pthread_mutex_t id;
    36 #if FAKE_RECURSIVE_MUTEX
    37     int recursive;
    38     pthread_t owner;
    39 #endif
    40 };
    41 
    42 SDL_mutex *
    43 SDL_CreateMutex(void)
    44 {
    45     SDL_mutex *mutex;
    46     pthread_mutexattr_t attr;
    47 
    48     /* Allocate the structure */
    49     mutex = (SDL_mutex *) SDL_calloc(1, sizeof(*mutex));
    50     if (mutex) {
    51         pthread_mutexattr_init(&attr);
    52 #if SDL_THREAD_PTHREAD_RECURSIVE_MUTEX
    53         pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
    54 #elif SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP
    55         pthread_mutexattr_setkind_np(&attr, PTHREAD_MUTEX_RECURSIVE_NP);
    56 #else
    57         /* No extra attributes necessary */
    58 #endif
    59         if (pthread_mutex_init(&mutex->id, &attr) != 0) {
    60             SDL_SetError("pthread_mutex_init() failed");
    61             SDL_free(mutex);
    62             mutex = NULL;
    63         }
    64     } else {
    65         SDL_OutOfMemory();
    66     }
    67     return (mutex);
    68 }
    69 
    70 void
    71 SDL_DestroyMutex(SDL_mutex * mutex)
    72 {
    73     if (mutex) {
    74         pthread_mutex_destroy(&mutex->id);
    75         SDL_free(mutex);
    76     }
    77 }
    78 
    79 /* Lock the mutex */
    80 int
    81 SDL_LockMutex(SDL_mutex * mutex)
    82 {
    83 #if FAKE_RECURSIVE_MUTEX
    84     pthread_t this_thread;
    85 #endif
    86 
    87     if (mutex == NULL) {
    88         return SDL_SetError("Passed a NULL mutex");
    89     }
    90 
    91 #if FAKE_RECURSIVE_MUTEX
    92     this_thread = pthread_self();
    93     if (mutex->owner == this_thread) {
    94         ++mutex->recursive;
    95     } else {
    96         /* The order of operations is important.
    97            We set the locking thread id after we obtain the lock
    98            so unlocks from other threads will fail.
    99          */
   100         if (pthread_mutex_lock(&mutex->id) == 0) {
   101             mutex->owner = this_thread;
   102             mutex->recursive = 0;
   103         } else {
   104             return SDL_SetError("pthread_mutex_lock() failed");
   105         }
   106     }
   107 #else
   108     if (pthread_mutex_lock(&mutex->id) < 0) {
   109         return SDL_SetError("pthread_mutex_lock() failed");
   110     }
   111 #endif
   112     return 0;
   113 }
   114 
   115 int
   116 SDL_TryLockMutex(SDL_mutex * mutex)
   117 {
   118     int retval;
   119 #if FAKE_RECURSIVE_MUTEX
   120     pthread_t this_thread;
   121 #endif
   122 
   123     if (mutex == NULL) {
   124         return SDL_SetError("Passed a NULL mutex");
   125     }
   126 
   127     retval = 0;
   128 #if FAKE_RECURSIVE_MUTEX
   129     this_thread = pthread_self();
   130     if (mutex->owner == this_thread) {
   131         ++mutex->recursive;
   132     } else {
   133         /* The order of operations is important.
   134          We set the locking thread id after we obtain the lock
   135          so unlocks from other threads will fail.
   136          */
   137         if (pthread_mutex_lock(&mutex->id) == 0) {
   138             mutex->owner = this_thread;
   139             mutex->recursive = 0;
   140         } else if (errno == EBUSY) {
   141             retval = SDL_MUTEX_TIMEDOUT;
   142         } else {
   143             retval = SDL_SetError("pthread_mutex_trylock() failed");
   144         }
   145     }
   146 #else
   147     if (pthread_mutex_trylock(&mutex->id) != 0) {
   148         if (errno == EBUSY) {
   149             retval = SDL_MUTEX_TIMEDOUT;
   150         } else {
   151             retval = SDL_SetError("pthread_mutex_trylock() failed");
   152         }
   153     }
   154 #endif
   155     return retval;
   156 }
   157 
   158 int
   159 SDL_UnlockMutex(SDL_mutex * mutex)
   160 {
   161     if (mutex == NULL) {
   162         return SDL_SetError("Passed a NULL mutex");
   163     }
   164 
   165 #if FAKE_RECURSIVE_MUTEX
   166     /* We can only unlock the mutex if we own it */
   167     if (pthread_self() == mutex->owner) {
   168         if (mutex->recursive) {
   169             --mutex->recursive;
   170         } else {
   171             /* The order of operations is important.
   172                First reset the owner so another thread doesn't lock
   173                the mutex and set the ownership before we reset it,
   174                then release the lock semaphore.
   175              */
   176             mutex->owner = 0;
   177             pthread_mutex_unlock(&mutex->id);
   178         }
   179     } else {
   180         return SDL_SetError("mutex not owned by this thread");
   181     }
   182 
   183 #else
   184     if (pthread_mutex_unlock(&mutex->id) < 0) {
   185         return SDL_SetError("pthread_mutex_unlock() failed");
   186     }
   187 #endif /* FAKE_RECURSIVE_MUTEX */
   188 
   189     return 0;
   190 }
   191 
   192 /* vi: set ts=4 sw=4 expandtab: */