SDL 3.0
SDL_thread.h File Reference
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Macros

#define SDL_BeginThreadFunction   NULL
 
#define SDL_EndThreadFunction   NULL
 
#define SDL_CreateThread(fn, name, data)   SDL_CreateThreadRuntime((fn), (name), (data), (SDL_FunctionPointer) (SDL_BeginThreadFunction), (SDL_FunctionPointer) (SDL_EndThreadFunction))
 
#define SDL_CreateThreadWithProperties(props)   SDL_CreateThreadWithPropertiesRuntime((props), (SDL_FunctionPointer) (SDL_BeginThreadFunction), (SDL_FunctionPointer) (SDL_EndThreadFunction))
 
#define SDL_PROP_THREAD_CREATE_ENTRY_FUNCTION_POINTER   "SDL.thread.create.entry_function"
 
#define SDL_PROP_THREAD_CREATE_NAME_STRING   "SDL.thread.create.name"
 
#define SDL_PROP_THREAD_CREATE_USERDATA_POINTER   "SDL.thread.create.userdata"
 
#define SDL_PROP_THREAD_CREATE_STACKSIZE_NUMBER   "SDL.thread.create.stacksize"
 

Typedefs

typedef struct SDL_Thread SDL_Thread
 
typedef Uint64 SDL_ThreadID
 
typedef SDL_AtomicInt SDL_TLSID
 
typedef int(* SDL_ThreadFunction) (void *data)
 
typedef void(* SDL_TLSDestructorCallback) (void *value)
 

Enumerations

enum  SDL_ThreadPriority {
  SDL_THREAD_PRIORITY_LOW ,
  SDL_THREAD_PRIORITY_NORMAL ,
  SDL_THREAD_PRIORITY_HIGH ,
  SDL_THREAD_PRIORITY_TIME_CRITICAL
}
 

Functions

SDL_ThreadSDL_CreateThreadRuntime (SDL_ThreadFunction fn, const char *name, void *data, SDL_FunctionPointer pfnBeginThread, SDL_FunctionPointer pfnEndThread)
 
SDL_ThreadSDL_CreateThreadWithPropertiesRuntime (SDL_PropertiesID props, SDL_FunctionPointer pfnBeginThread, SDL_FunctionPointer pfnEndThread)
 
const char * SDL_GetThreadName (SDL_Thread *thread)
 
SDL_ThreadID SDL_GetCurrentThreadID (void)
 
SDL_ThreadID SDL_GetThreadID (SDL_Thread *thread)
 
bool SDL_SetCurrentThreadPriority (SDL_ThreadPriority priority)
 
void SDL_WaitThread (SDL_Thread *thread, int *status)
 
void SDL_DetachThread (SDL_Thread *thread)
 
void * SDL_GetTLS (SDL_TLSID *id)
 
bool SDL_SetTLS (SDL_TLSID *id, const void *value, SDL_TLSDestructorCallback destructor)
 
void SDL_CleanupTLS (void)
 

Macro Definition Documentation

◆ SDL_BeginThreadFunction

#define SDL_BeginThreadFunction   NULL

Definition at line 278 of file SDL_thread.h.

◆ SDL_CreateThread

#define SDL_CreateThread (   fn,
  name,
  data 
)    SDL_CreateThreadRuntime((fn), (name), (data), (SDL_FunctionPointer) (SDL_BeginThreadFunction), (SDL_FunctionPointer) (SDL_EndThreadFunction))

Definition at line 320 of file SDL_thread.h.

◆ SDL_CreateThreadWithProperties

#define SDL_CreateThreadWithProperties (   props)    SDL_CreateThreadWithPropertiesRuntime((props), (SDL_FunctionPointer) (SDL_BeginThreadFunction), (SDL_FunctionPointer) (SDL_EndThreadFunction))

Definition at line 321 of file SDL_thread.h.

◆ SDL_EndThreadFunction

#define SDL_EndThreadFunction   NULL

Definition at line 284 of file SDL_thread.h.

◆ SDL_PROP_THREAD_CREATE_ENTRY_FUNCTION_POINTER

#define SDL_PROP_THREAD_CREATE_ENTRY_FUNCTION_POINTER   "SDL.thread.create.entry_function"

Definition at line 322 of file SDL_thread.h.

◆ SDL_PROP_THREAD_CREATE_NAME_STRING

#define SDL_PROP_THREAD_CREATE_NAME_STRING   "SDL.thread.create.name"

Definition at line 323 of file SDL_thread.h.

◆ SDL_PROP_THREAD_CREATE_STACKSIZE_NUMBER

#define SDL_PROP_THREAD_CREATE_STACKSIZE_NUMBER   "SDL.thread.create.stacksize"

Definition at line 325 of file SDL_thread.h.

◆ SDL_PROP_THREAD_CREATE_USERDATA_POINTER

#define SDL_PROP_THREAD_CREATE_USERDATA_POINTER   "SDL.thread.create.userdata"

Definition at line 324 of file SDL_thread.h.

Typedef Documentation

◆ SDL_Thread

typedef struct SDL_Thread SDL_Thread

CategoryThread

SDL thread management routines. The SDL thread object.

These are opaque data.

Since
This datatype is available since SDL 3.1.3.
See also
SDL_CreateThread
SDL_WaitThread

Definition at line 58 of file SDL_thread.h.

◆ SDL_ThreadFunction

typedef int(* SDL_ThreadFunction) (void *data)

The function passed to SDL_CreateThread() as the new thread's entry point.

Parameters
datawhat was passed as data to SDL_CreateThread().
Returns
a value that can be reported through SDL_WaitThread().
Since
This datatype is available since SDL 3.1.3.

Definition at line 113 of file SDL_thread.h.

◆ SDL_ThreadID

A unique numeric ID that identifies a thread.

These are different from SDL_Thread objects, which are generally what an application will operate on, but having a way to uniquely identify a thread can be useful at times.

Since
This datatype is available since SDL 3.1.3.
See also
SDL_GetThreadID
SDL_GetCurrentThreadID

Definition at line 72 of file SDL_thread.h.

◆ SDL_TLSDestructorCallback

typedef void(* SDL_TLSDestructorCallback) (void *value)

The callback used to cleanup data passed to SDL_SetTLS.

This is called when a thread exits, to allow an app to free any resources.

Parameters
valuea pointer previously handed to SDL_SetTLS.
Since
This datatype is available since SDL 3.1.3.
See also
SDL_SetTLS

Definition at line 487 of file SDL_thread.h.

◆ SDL_TLSID

Thread local storage ID.

0 is the invalid ID. An app can create these and then set data for these IDs that is unique to each thread.

Since
This datatype is available since SDL 3.1.3.
See also
SDL_GetTLS
SDL_SetTLS

Definition at line 85 of file SDL_thread.h.

Enumeration Type Documentation

◆ SDL_ThreadPriority

The SDL thread priority.

SDL will make system changes as necessary in order to apply the thread priority. Code which attempts to control thread state related to priority should be aware that calling SDL_SetCurrentThreadPriority may alter such state. SDL_HINT_THREAD_PRIORITY_POLICY can be used to control aspects of this behavior.

Since
This enum is available since SDL 3.1.3.
Enumerator
SDL_THREAD_PRIORITY_LOW 
SDL_THREAD_PRIORITY_NORMAL 
SDL_THREAD_PRIORITY_HIGH 
SDL_THREAD_PRIORITY_TIME_CRITICAL 

Definition at line 98 of file SDL_thread.h.

98 {
SDL_ThreadPriority
Definition SDL_thread.h:98
@ SDL_THREAD_PRIORITY_TIME_CRITICAL
Definition SDL_thread.h:102
@ SDL_THREAD_PRIORITY_LOW
Definition SDL_thread.h:99
@ SDL_THREAD_PRIORITY_HIGH
Definition SDL_thread.h:101
@ SDL_THREAD_PRIORITY_NORMAL
Definition SDL_thread.h:100

Function Documentation

◆ SDL_CleanupTLS()

void SDL_CleanupTLS ( void  )
extern

Cleanup all TLS data for this thread.

If you are creating your threads outside of SDL and then calling SDL functions, you should call this function before your thread exits, to properly clean up SDL memory.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.1.3.

◆ SDL_CreateThreadRuntime()

SDL_Thread * SDL_CreateThreadRuntime ( SDL_ThreadFunction  fn,
const char *  name,
void *  data,
SDL_FunctionPointer  pfnBeginThread,
SDL_FunctionPointer  pfnEndThread 
)
extern

The actual entry point for SDL_CreateThread.

Parameters
fnthe SDL_ThreadFunction function to call in the new thread
namethe name of the thread
dataa pointer that is passed to fn
pfnBeginThreadthe C runtime's _beginthreadex (or whatnot). Can be NULL.
pfnEndThreadthe C runtime's _endthreadex (or whatnot). Can be NULL.
Returns
an opaque pointer to the new thread object on success, NULL if the new thread could not be created; call SDL_GetError() for more information.
Since
This function is available since SDL 3.1.3.

◆ SDL_CreateThreadWithPropertiesRuntime()

SDL_Thread * SDL_CreateThreadWithPropertiesRuntime ( SDL_PropertiesID  props,
SDL_FunctionPointer  pfnBeginThread,
SDL_FunctionPointer  pfnEndThread 
)
extern

The actual entry point for SDL_CreateThreadWithProperties.

Parameters
propsthe properties to use
pfnBeginThreadthe C runtime's _beginthreadex (or whatnot). Can be NULL.
pfnEndThreadthe C runtime's _endthreadex (or whatnot). Can be NULL.
Returns
an opaque pointer to the new thread object on success, NULL if the new thread could not be created; call SDL_GetError() for more information.
Since
This function is available since SDL 3.1.3.

◆ SDL_DetachThread()

void SDL_DetachThread ( SDL_Thread thread)
extern

Let a thread clean up on exit without intervention.

A thread may be "detached" to signify that it should not remain until another thread has called SDL_WaitThread() on it. Detaching a thread is useful for long-running threads that nothing needs to synchronize with or further manage. When a detached thread is done, it simply goes away.

There is no way to recover the return code of a detached thread. If you need this, don't detach the thread and instead use SDL_WaitThread().

Once a thread is detached, you should usually assume the SDL_Thread isn't safe to reference again, as it will become invalid immediately upon the detached thread's exit, instead of remaining until someone has called SDL_WaitThread() to finally clean it up. As such, don't detach the same thread more than once.

If a thread has already exited when passed to SDL_DetachThread(), it will stop waiting for a call to SDL_WaitThread() and clean up immediately. It is not safe to detach a thread that might be used with SDL_WaitThread().

You may not call SDL_WaitThread() on a thread that has been detached. Use either that function or this one, but not both, or behavior is undefined.

It is safe to pass NULL to this function; it is a no-op.

Parameters
threadthe SDL_Thread pointer that was returned from the SDL_CreateThread() call that started this thread.
Since
This function is available since SDL 3.1.3.
See also
SDL_CreateThread
SDL_WaitThread

◆ SDL_GetCurrentThreadID()

SDL_ThreadID SDL_GetCurrentThreadID ( void  )
extern

Get the thread identifier for the current thread.

This thread identifier is as reported by the underlying operating system. If SDL is running on a platform that does not support threads the return value will always be zero.

This function also returns a valid thread ID when called from the main thread.

Returns
the ID of the current thread.
Since
This function is available since SDL 3.1.3.
See also
SDL_GetThreadID

◆ SDL_GetThreadID()

SDL_ThreadID SDL_GetThreadID ( SDL_Thread thread)
extern

Get the thread identifier for the specified thread.

This thread identifier is as reported by the underlying operating system. If SDL is running on a platform that does not support threads the return value will always be zero.

Parameters
threadthe thread to query.
Returns
the ID of the specified thread, or the ID of the current thread if thread is NULL.
Since
This function is available since SDL 3.1.3.
See also
SDL_GetCurrentThreadID

◆ SDL_GetThreadName()

const char * SDL_GetThreadName ( SDL_Thread thread)
extern

Get the thread name as it was specified in SDL_CreateThread().

Parameters
threadthe thread to query.
Returns
a pointer to a UTF-8 string that names the specified thread, or NULL if it doesn't have a name.
Since
This function is available since SDL 3.1.3.

◆ SDL_GetTLS()

void * SDL_GetTLS ( SDL_TLSID id)
extern

Get the current thread's value associated with a thread local storage ID.

Parameters
ida pointer to the thread local storage ID, may not be NULL.
Returns
the value associated with the ID for the current thread or NULL if no value has been set; call SDL_GetError() for more information.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.1.3.
See also
SDL_SetTLS

◆ SDL_SetCurrentThreadPriority()

bool SDL_SetCurrentThreadPriority ( SDL_ThreadPriority  priority)
extern

Set the priority for the current thread.

Note that some platforms will not let you alter the priority (or at least, promote the thread to a higher priority) at all, and some require you to be an administrator account. Be prepared for this to fail.

Parameters
prioritythe SDL_ThreadPriority to set.
Returns
true on success or false on failure; call SDL_GetError() for more information.
Since
This function is available since SDL 3.1.3.

◆ SDL_SetTLS()

bool SDL_SetTLS ( SDL_TLSID id,
const void *  value,
SDL_TLSDestructorCallback  destructor 
)
extern

Set the current thread's value associated with a thread local storage ID.

If the thread local storage ID is not initialized (the value is 0), a new ID will be created in a thread-safe way, so all calls using a pointer to the same ID will refer to the same local storage.

Note that replacing a value from a previous call to this function on the same thread does not call the previous value's destructor!

destructor can be NULL; it is assumed that value does not need to be cleaned up if so.

Parameters
ida pointer to the thread local storage ID, may not be NULL.
valuethe value to associate with the ID for the current thread.
destructora function called when the thread exits, to free the value, may be NULL.
Returns
true on success or false on failure; call SDL_GetError() for more information.

\threadsafety It is safe to call this function from any thread.

Since
This function is available since SDL 3.1.3.
See also
SDL_GetTLS

◆ SDL_WaitThread()

void SDL_WaitThread ( SDL_Thread thread,
int *  status 
)
extern

Wait for a thread to finish.

Threads that haven't been detached will remain (as a "zombie") until this function cleans them up. Not doing so is a resource leak.

Once a thread has been cleaned up through this function, the SDL_Thread that references it becomes invalid and should not be referenced again. As such, only one thread may call SDL_WaitThread() on another.

The return code for the thread function is placed in the area pointed to by status, if status is not NULL.

You may not wait on a thread that has been used in a call to SDL_DetachThread(). Use either that function or this one, but not both, or behavior is undefined.

It is safe to pass a NULL thread to this function; it is a no-op.

Note that the thread pointer is freed by this function and is not valid afterward.

Parameters
threadthe SDL_Thread pointer that was returned from the SDL_CreateThread() call that started this thread.
statuspointer to an integer that will receive the value returned from the thread function by its 'return', or NULL to not receive such value back.
Since
This function is available since SDL 3.1.3.
See also
SDL_CreateThread
SDL_DetachThread