SDL  2.0
SDL_sysmutex.c File Reference
#include "../../SDL_internal.h"
#include "SDL_thread.h"
#include "SDL_systhread_c.h"
+ Include dependency graph for SDL_sysmutex.c:

Go to the source code of this file.

Data Structures

struct  SDL_mutex
 

Functions

SDL_mutexSDL_CreateMutex (void)
 
void SDL_DestroyMutex (SDL_mutex *mutex)
 
int SDL_LockMutex (SDL_mutex *mutex)
 
int SDL_TryLockMutex (SDL_mutex *mutex)
 
int SDL_mutexV (SDL_mutex *mutex)
 

Function Documentation

◆ SDL_CreateMutex()

SDL_mutex* SDL_CreateMutex ( void  )

Create a mutex, initialized unlocked.

Definition at line 38 of file SDL_sysmutex.c.

39 {
41 
42  /* Allocate mutex memory */
43  mutex = (SDL_mutex *) SDL_malloc(sizeof(*mutex));
44  if (mutex) {
45  /* Create the mutex semaphore, with initial value 1 */
47  mutex->recursive = 0;
48  mutex->owner = 0;
49  if (!mutex->sem) {
50  SDL_free(mutex);
51  mutex = NULL;
52  }
53  } else {
55  }
56  return mutex;
57 }

References mutex, NULL, SDL_mutex::owner, SDL_mutex::recursive, SDL_CreateSemaphore, SDL_free, SDL_malloc, SDL_OutOfMemory, and SDL_mutex::sem.

◆ SDL_DestroyMutex()

void SDL_DestroyMutex ( SDL_mutex mutex)

Destroy a mutex.

Definition at line 61 of file SDL_sysmutex.c.

62 {
63  if (mutex) {
64  if (mutex->sem) {
66  }
67  SDL_free(mutex);
68  }
69 }

References mutex, SDL_DestroySemaphore, SDL_free, and SDL_mutex::sem.

◆ SDL_LockMutex()

int SDL_LockMutex ( SDL_mutex mutex)

Definition at line 73 of file SDL_sysmutex.c.

74 {
75 #if SDL_THREADS_DISABLED
76  return 0;
77 #else
78  SDL_threadID this_thread;
79 
80  if (mutex == NULL) {
81  return SDL_SetError("Passed a NULL mutex");
82  }
83 
84  this_thread = SDL_ThreadID();
85  if (mutex->owner == this_thread) {
86  ++mutex->recursive;
87  } else {
88  /* The order of operations is important.
89  We set the locking thread id after we obtain the lock
90  so unlocks from other threads will fail.
91  */
93  mutex->owner = this_thread;
94  mutex->recursive = 0;
95  }
96 
97  return 0;
98 #endif /* SDL_THREADS_DISABLED */
99 }

References mutex, NULL, SDL_mutex::owner, SDL_mutex::recursive, SDL_SemWait, SDL_SetError, SDL_ThreadID, and SDL_mutex::sem.

◆ SDL_mutexV()

int SDL_mutexV ( SDL_mutex mutex)

Definition at line 136 of file SDL_sysmutex.c.

137 {
138 #if SDL_THREADS_DISABLED
139  return 0;
140 #else
141  if (mutex == NULL) {
142  return SDL_SetError("Passed a NULL mutex");
143  }
144 
145  /* If we don't own the mutex, we can't unlock it */
146  if (SDL_ThreadID() != mutex->owner) {
147  return SDL_SetError("mutex not owned by this thread");
148  }
149 
150  if (mutex->recursive) {
151  --mutex->recursive;
152  } else {
153  /* The order of operations is important.
154  First reset the owner so another thread doesn't lock
155  the mutex and set the ownership before we reset it,
156  then release the lock semaphore.
157  */
158  mutex->owner = 0;
160  }
161  return 0;
162 #endif /* SDL_THREADS_DISABLED */
163 }

References mutex, NULL, SDL_mutex::owner, SDL_mutex::recursive, SDL_SemPost, SDL_SetError, SDL_ThreadID, and SDL_mutex::sem.

◆ SDL_TryLockMutex()

int SDL_TryLockMutex ( SDL_mutex mutex)

Try to lock the mutex

Returns
0, SDL_MUTEX_TIMEDOUT, or -1 on error

Definition at line 103 of file SDL_sysmutex.c.

104 {
105 #if SDL_THREADS_DISABLED
106  return 0;
107 #else
108  int retval = 0;
109  SDL_threadID this_thread;
110 
111  if (mutex == NULL) {
112  return SDL_SetError("Passed a NULL mutex");
113  }
114 
115  this_thread = SDL_ThreadID();
116  if (mutex->owner == this_thread) {
117  ++mutex->recursive;
118  } else {
119  /* The order of operations is important.
120  We set the locking thread id after we obtain the lock
121  so unlocks from other threads will fail.
122  */
124  if (retval == 0) {
125  mutex->owner = this_thread;
126  mutex->recursive = 0;
127  }
128  }
129 
130  return retval;
131 #endif /* SDL_THREADS_DISABLED */
132 }

References mutex, NULL, SDL_mutex::owner, SDL_mutex::recursive, retval, SDL_SemWait, SDL_SetError, SDL_ThreadID, and SDL_mutex::sem.

SDL_CreateSemaphore
#define SDL_CreateSemaphore
Definition: SDL_dynapi_overrides.h:264
NULL
#define NULL
Definition: begin_code.h:164
SDL_mutex
Definition: SDL_sysmutex.c:30
mutex
static SDL_mutex * mutex
Definition: testlock.c:23
SDL_SemPost
#define SDL_SemPost
Definition: SDL_dynapi_overrides.h:269
retval
SDL_bool retval
Definition: testgamecontroller.c:65
SDL_free
#define SDL_free
Definition: SDL_dynapi_overrides.h:377
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_mutex::sem
SDL_sem * sem
Definition: SDL_sysmutex.c:33
SDL_mutex::owner
SDL_threadID owner
Definition: SDL_sysmutex.c:32
SDL_threadID
unsigned long SDL_threadID
Definition: SDL_thread.h:49
SDL_SemWait
#define SDL_SemWait
Definition: SDL_dynapi_overrides.h:266
SDL_SetError
#define SDL_SetError
Definition: SDL_dynapi_overrides.h:30
SDL_mutex::recursive
int recursive
Definition: SDL_sysmutex.c:31
SDL_DestroySemaphore
#define SDL_DestroySemaphore
Definition: SDL_dynapi_overrides.h:265
SDL_malloc
#define SDL_malloc
Definition: SDL_dynapi_overrides.h:374
SDL_ThreadID
#define SDL_ThreadID
Definition: SDL_dynapi_overrides.h:475