Threadsafe initialization helpers (Thread Once)

Data Structures
struct	M_thread_once_t

Macros
#define	M_THREAD_ONCE_STATIC_INITIALIZER   { M_FALSE, M_THREAD_SPINLOCK_STATIC_INITIALIZER }

Functions
M_bool	M_thread_once (M_thread_once_t *once_control, void(*init_routine)(M_uint64 flags), M_uint64 init_flags)
M_bool	M_thread_once_reset (M_thread_once_t *once_control)

Detailed Description

Threadsafe initialization helpers (Thread Once)

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Data Structure Documentation

M_thread_once_t

struct M_thread_once_t

Public struct for M_thread_once, so static initializer can be used

Data Fields
M_bool	initialized
M_thread_spinlock_t	spinlock

Macro Definition Documentation

M_THREAD_ONCE_STATIC_INITIALIZER

#define M_THREAD_ONCE_STATIC_INITIALIZER   { M_FALSE, M_THREAD_SPINLOCK_STATIC_INITIALIZER }

Static initializer for M_thread_once

Function Documentation

M_thread_once()

M_bool M_thread_once	(	M_thread_once_t *	once_control,
		void(*)(M_uint64 flags)	init_routine,
		M_uint64	init_flags
	)

Ensure an initialization routine is performed only once, even if called from multiple threads simultaneously.

Performing initialization in a multi-threaded program can cause race conditions.

Take this code example: static int initialized = 0; if (!initialized) { init_routine(); initialized = 1; }

If two threads where to enter this simultaneously, before init_routine() was complete, they would call it twice. The above code example can be replaced with:

static M_thread_once_t initialized = M_THREAD_ONCE_STATIC_INITIALIZER; M_thread_once(&initialized, init_routine);

Parameters

[in]	once_control	Once control variable passed by reference, and first set to M_THREAD_ONCE_STATIC_INITIALIZER;
[in]	init_routine	Initialization routine to be called if it has not yet been called.
[in]	init_flags	Flags to be passed onto the initialization routine.

Returns

M_TRUE if init routine was just run, M_FALSE if not run (previously run)

M_thread_once_reset()

M_bool M_thread_once_reset

(

M_thread_once_t *

once_control

)

Reset the once_control object back to an uninitialized state. Useful to be called in a destructor so an initialization routine can be re-run.

Parameters

[in]

once_control

Once control variable passed by reference, and first set to M_THREAD_ONCE_STATIC_INITIALIZER;

Returns

M_TRUE if reset, M_FALSE if not initialized.