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.

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

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 */
46  mutex->sem = SDL_CreateSemaphore(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 }
#define SDL_CreateSemaphore
static SDL_mutex * mutex
Definition: testlock.c:23
#define SDL_free
#define NULL
Definition: begin_code.h:164
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_threadID owner
Definition: SDL_sysmutex.c:32
#define SDL_malloc
int recursive
Definition: SDL_sysmutex.c:31
SDL_sem * sem
Definition: SDL_sysmutex.c:33

◆ SDL_DestroyMutex()

void SDL_DestroyMutex ( SDL_mutex mutex)

Destroy a mutex.

Definition at line 61 of file SDL_sysmutex.c.

References SDL_DestroySemaphore, SDL_free, and SDL_mutex::sem.

62 {
63  if (mutex) {
64  if (mutex->sem) {
65  SDL_DestroySemaphore(mutex->sem);
66  }
67  SDL_free(mutex);
68  }
69 }
#define SDL_free
#define SDL_DestroySemaphore
SDL_sem * sem
Definition: SDL_sysmutex.c:33

◆ SDL_LockMutex()

int SDL_LockMutex ( SDL_mutex mutex)

Definition at line 73 of file SDL_sysmutex.c.

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

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  */
92  SDL_SemWait(mutex->sem);
93  mutex->owner = this_thread;
94  mutex->recursive = 0;
95  }
96 
97  return 0;
98 #endif /* SDL_THREADS_DISABLED */
99 }
#define SDL_ThreadID
#define NULL
Definition: begin_code.h:164
#define SDL_SetError
SDL_threadID owner
Definition: SDL_sysmutex.c:32
#define SDL_SemWait
int recursive
Definition: SDL_sysmutex.c:31
SDL_sem * sem
Definition: SDL_sysmutex.c:33
unsigned long SDL_threadID
Definition: SDL_thread.h:49

◆ SDL_mutexV()

int SDL_mutexV ( SDL_mutex mutex)

Definition at line 136 of file SDL_sysmutex.c.

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

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;
159  SDL_SemPost(mutex->sem);
160  }
161  return 0;
162 #endif /* SDL_THREADS_DISABLED */
163 }
#define SDL_ThreadID
#define SDL_SemPost
#define NULL
Definition: begin_code.h:164
#define SDL_SetError
SDL_threadID owner
Definition: SDL_sysmutex.c:32
int recursive
Definition: SDL_sysmutex.c:31
SDL_sem * sem
Definition: SDL_sysmutex.c:33

◆ 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.

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

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  */
123  retval = SDL_SemWait(mutex->sem);
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 }
#define SDL_ThreadID
SDL_bool retval
#define NULL
Definition: begin_code.h:164
#define SDL_SetError
SDL_threadID owner
Definition: SDL_sysmutex.c:32
#define SDL_SemWait
int recursive
Definition: SDL_sysmutex.c:31
SDL_sem * sem
Definition: SDL_sysmutex.c:33
unsigned long SDL_threadID
Definition: SDL_thread.h:49