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SDL_mutex.h File Reference
#include "SDL_stdinc.h"
#include "SDL_error.h"
#include "begin_code.h"
#include "close_code.h"

Go to the source code of this file.

Macros

#define SDL_MUTEX_MAXWAIT   (~(Uint32)0)
 
#define SDL_MUTEX_TIMEDOUT   1
 

Mutex functions

#define SDL_mutexP(m)   SDL_LockMutex(m)
 
#define SDL_mutexV(m)   SDL_UnlockMutex(m)
 
typedef struct SDL_mutex SDL_mutex
 
DECLSPEC SDL_mutex *SDLCALL SDL_CreateMutex (void)
 
DECLSPEC int SDLCALL SDL_LockMutex (SDL_mutex *mutex)
 
DECLSPEC int SDLCALL SDL_TryLockMutex (SDL_mutex *mutex)
 
DECLSPEC int SDLCALL SDL_UnlockMutex (SDL_mutex *mutex)
 
DECLSPEC void SDLCALL SDL_DestroyMutex (SDL_mutex *mutex)
 

Semaphore functions

typedef struct SDL_semaphore SDL_sem
 
DECLSPEC SDL_sem *SDLCALL SDL_CreateSemaphore (Uint32 initial_value)
 
DECLSPEC void SDLCALL SDL_DestroySemaphore (SDL_sem *sem)
 
DECLSPEC int SDLCALL SDL_SemWait (SDL_sem *sem)
 
DECLSPEC int SDLCALL SDL_SemTryWait (SDL_sem *sem)
 
DECLSPEC int SDLCALL SDL_SemWaitTimeout (SDL_sem *sem, Uint32 ms)
 
DECLSPEC int SDLCALL SDL_SemPost (SDL_sem *sem)
 
DECLSPEC Uint32 SDLCALL SDL_SemValue (SDL_sem *sem)
 

Condition variable functions

typedef struct SDL_cond SDL_cond
 
DECLSPEC SDL_cond *SDLCALL SDL_CreateCond (void)
 
DECLSPEC void SDLCALL SDL_DestroyCond (SDL_cond *cond)
 
DECLSPEC int SDLCALL SDL_CondSignal (SDL_cond *cond)
 
DECLSPEC int SDLCALL SDL_CondBroadcast (SDL_cond *cond)
 
DECLSPEC int SDLCALL SDL_CondWait (SDL_cond *cond, SDL_mutex *mutex)
 
DECLSPEC int SDLCALL SDL_CondWaitTimeout (SDL_cond *cond, SDL_mutex *mutex, Uint32 ms)
 

Macro Definition Documentation

#define SDL_MUTEX_MAXWAIT   (~(Uint32)0)

This is the timeout value which corresponds to never time out.

Definition at line 49 of file SDL_mutex.h.

Referenced by SDL_CondWait(), SDL_CondWaitTimeout(), SDL_SemWait(), SDL_SemWaitTimeout(), and SDL_TimerThread().

#define SDL_MUTEX_TIMEDOUT   1

Synchronization functions which can time out return this value if they time out.

Definition at line 44 of file SDL_mutex.h.

Referenced by SDL_CondWaitTimeout(), SDL_SemTryWait(), SDL_SemWaitTimeout(), and SDL_TryLockMutex().

#define SDL_mutexP (   m)    SDL_LockMutex(m)

Lock the mutex.

Returns
0, or -1 on error.

Definition at line 71 of file SDL_mutex.h.

#define SDL_mutexV (   m)    SDL_UnlockMutex(m)

Unlock the mutex.

Returns
0, or -1 on error.
Warning
It is an error to unlock a mutex that has not been locked by the current thread, and doing so results in undefined behavior.

Definition at line 89 of file SDL_mutex.h.

Typedef Documentation

typedef struct SDL_cond SDL_cond

Definition at line 167 of file SDL_mutex.h.

typedef struct SDL_mutex SDL_mutex

Definition at line 59 of file SDL_mutex.h.

typedef struct SDL_semaphore SDL_sem

Definition at line 107 of file SDL_mutex.h.

Function Documentation

DECLSPEC int SDLCALL SDL_CondBroadcast ( SDL_cond cond)

Restart all threads that are waiting on the condition variable.

Returns
0 or -1 on error.

Definition at line 106 of file SDL_syscond.c.

References i, SDL_LockMutex(), SDL_SemPost(), SDL_SemWait(), SDL_SetError(), and SDL_UnlockMutex().

DECLSPEC int SDLCALL SDL_CondSignal ( SDL_cond cond)

Restart one of the threads that are waiting on the condition variable.

Returns
0 or -1 on error.

Definition at line 82 of file SDL_syscond.c.

References SDL_LockMutex(), SDL_SemPost(), SDL_SemWait(), SDL_SetError(), and SDL_UnlockMutex().

Referenced by SDL_DestroySemaphore(), and SDL_SemPost().

DECLSPEC int SDLCALL SDL_CondWait ( SDL_cond cond,
SDL_mutex mutex 
)

Wait on the condition variable, unlocking the provided mutex.

Warning
The mutex must be locked before entering this function!

The mutex is re-locked once the condition variable is signaled.

Returns
0 when it is signaled, or -1 on error.

Definition at line 215 of file SDL_syscond.c.

References SDL_CondWaitTimeout(), SDL_MUTEX_MAXWAIT, and SDL_SetError().

DECLSPEC int SDLCALL SDL_CondWaitTimeout ( SDL_cond cond,
SDL_mutex mutex,
Uint32  ms 
)

Waits for at most ms milliseconds, and returns 0 if the condition variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not signaled in the allotted time, and -1 on error.

Warning
On some platforms this function is implemented by looping with a delay of 1 ms, and so should be avoided if possible.

Definition at line 160 of file SDL_syscond.c.

References NULL, SDL_LockMutex(), SDL_MUTEX_MAXWAIT, SDL_MUTEX_TIMEDOUT, SDL_SemPost(), SDL_SemWait(), SDL_SemWaitTimeout(), SDL_SetError(), and SDL_UnlockMutex().

Referenced by SDL_CondWait(), and SDL_SemWaitTimeout().

DECLSPEC SDL_cond* SDLCALL SDL_CreateCond ( void  )

Create a condition variable.

Typical use of condition variables:

Thread A: SDL_LockMutex(lock); while ( ! condition ) { SDL_CondWait(cond, lock); } SDL_UnlockMutex(lock);

Thread B: SDL_LockMutex(lock); ... condition = true; ... SDL_CondSignal(cond); SDL_UnlockMutex(lock);

There is some discussion whether to signal the condition variable with the mutex locked or not. There is some potential performance benefit to unlocking first on some platforms, but there are some potential race conditions depending on how your code is structured.

In general it's safer to signal the condition variable while the mutex is locked.

Definition at line 42 of file SDL_syscond.c.

References NULL, SDL_CreateMutex(), SDL_CreateSemaphore(), SDL_DestroyCond(), SDL_free(), SDL_malloc(), SDL_OutOfMemory, and SDL_SetError().

Referenced by SDL_CreateSemaphore().

DECLSPEC SDL_sem* SDLCALL SDL_CreateSemaphore ( Uint32  initial_value)

Create a semaphore, initialized with value, returns NULL on failure.

Definition at line 85 of file SDL_syssem.c.

References free, malloc, NULL, SDL_CreateCond(), SDL_CreateMutex(), SDL_DestroySemaphore(), SDL_free(), SDL_malloc(), SDL_OutOfMemory, and SDL_SetError().

Referenced by PSP_EventInit(), SDL_CreateCond(), SDL_CreateMutex(), SDL_CreateThread(), SDL_SYS_JoystickInit(), and SDL_TimerInit().

DECLSPEC void SDLCALL SDL_DestroyCond ( SDL_cond cond)

Destroy a condition variable.

Definition at line 64 of file SDL_syscond.c.

References SDL_DestroyMutex(), SDL_DestroySemaphore(), and SDL_free().

Referenced by SDL_CreateCond(), and SDL_DestroySemaphore().

DECLSPEC int SDLCALL SDL_SemPost ( SDL_sem sem)

Atomically increases the semaphore's count (not blocking).

Returns
0, or -1 on error.

Definition at line 200 of file SDL_syssem.c.

References NULL, SDL_CondSignal(), SDL_LockMutex(), SDL_SetError(), and SDL_UnlockMutex().

Referenced by EventUpdate(), JoystickUpdate(), PSP_PumpEvents(), SDL_AddTimer(), SDL_CondBroadcast(), SDL_CondSignal(), SDL_CondWaitTimeout(), SDL_mutexV(), SDL_RunThread(), SDL_SYS_JoystickUpdate(), and SDL_TimerQuit().

DECLSPEC int SDLCALL SDL_SemTryWait ( SDL_sem sem)

Non-blocking variant of SDL_SemWait().

Returns
0 if the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error.

Definition at line 130 of file SDL_syssem.c.

References SDL_LockMutex(), SDL_MUTEX_TIMEDOUT, SDL_SemWaitTimeout(), SDL_SetError(), and SDL_UnlockMutex().

Referenced by SDL_SemWaitTimeout().

DECLSPEC Uint32 SDLCALL SDL_SemValue ( SDL_sem sem)

Returns the current count of the semaphore.

Definition at line 186 of file SDL_syssem.c.

References NULL, ret, SDL_LockMutex(), SDL_SetError(), and SDL_UnlockMutex().

DECLSPEC int SDLCALL SDL_SemWait ( SDL_sem sem)

This function suspends the calling thread until the semaphore pointed to by sem has a positive count. It then atomically decreases the semaphore count.

Definition at line 180 of file SDL_syssem.c.

References SDL_MUTEX_MAXWAIT, SDL_SemWaitTimeout(), and SDL_SetError().

Referenced by EventUpdate(), JoystickUpdate(), PSP_PumpEvents(), SDL_CondBroadcast(), SDL_CondSignal(), SDL_CondWaitTimeout(), SDL_CreateThread(), SDL_LockMutex(), SDL_mutexP(), SDL_SemWaitTimeout(), SDL_SYS_JoystickUpdate(), and SDL_TryLockMutex().

DECLSPEC int SDLCALL SDL_SemWaitTimeout ( SDL_sem sem,
Uint32  ms 
)

Variant of SDL_SemWait() with a timeout in milliseconds.

Returns
0 if the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in the allotted time, and -1 on error.
Warning
On some platforms this function is implemented by looping with a delay of 1 ms, and so should be avoided if possible.

Definition at line 150 of file SDL_syssem.c.

References NULL, SDL_CondWaitTimeout(), SDL_Delay(), SDL_GetTicks(), SDL_LockMutex(), SDL_MUTEX_MAXWAIT, SDL_MUTEX_TIMEDOUT, SDL_SemTryWait(), SDL_SemWait(), SDL_SetError(), and SDL_UnlockMutex().

Referenced by SDL_CondWaitTimeout(), SDL_SemTryWait(), SDL_SemWait(), and SDL_TimerThread().

DECLSPEC int SDLCALL 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_TIMEDOUT, SDL_SemWait(), SDL_SetError(), and SDL_ThreadID().