sanei_thread.h File Reference

Support for forking processes and threading. More...

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Functions
void	sanei_thread_init (void)
	Initialize sanei_thread.
SANE_Bool	sanei_thread_is_forked (void)
	Do we use processes or threads?
SANE_Pid	sanei_thread_begin (int(*func)(void *args), void *args)
	Spawn a new task.
int	sanei_thread_kill (SANE_Pid pid)
	Terminate spawned task.
int	sanei_thread_sendsig (SANE_Pid pid, int sig)
	Send a signal to a task.
SANE_Pid	sanei_thread_waitpid (SANE_Pid pid, int *status)
	Wait for task termination.
SANE_Status	sanei_thread_get_status (SANE_Pid pid)
	Check the current status of the spawned task.

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Detailed Description

Support for forking processes and threading.

Backends should not use fork() directly because fork() does not work correctly on some platforms. Use the functions provided by sanei_thread instead. The build system decides if fork() or threads are used.

Please keep in mind that the behaviour of the child process depends on if it's a process or thread especially concerning variables.

In this file we use "task" as an umbrella term for process and thread.

See also:

sanei.h sanei_backend.h

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Function Documentation

void sanei_thread_init

(

void

)

Initialize sanei_thread.

This function must be called before any other sanei_thread function.

SANE_Bool sanei_thread_is_forked

(

void

)

Do we use processes or threads?

This function can be used to check if processes or threads are used.

Returns:

• SANE_TRUE - if processes are used (fork)
• SANE_FALSE - i threads are used

SANE_Pid sanei_thread_begin	(	int(*)(void *args)	func,
		void *	args
	)

Spawn a new task.

This function should be used to start a new task.

Parameters:

	func()	function to call as child task
	args	argument of the function (only one!)

Returns:

• task id
• -1 if creating the new task failed

int sanei_thread_kill

(

SANE_Pid

pid

)

Terminate spawned task.

This function terminates the task that was created with sanei_thread_begin.

For processes, SIGTERM is sent. If threads are used, pthread_cancel() terminates the task.

Parameters:

pid

- the id of the task

Returns:

• 0 on success
• any other value if an error occured while terminating the task

int sanei_thread_sendsig	(	SANE_Pid	pid,
		int	sig
	)

Send a signal to a task.

This function can be used to send a signal to a task.

For terminating the task, sanei_thread_kill() should be used.

Parameters:

	pid	- the id of the task
	sig	- the signal to send

Returns:

• 0 - on success
• any other value - if an error occured while sending the signal

SANE_Pid sanei_thread_waitpid	(	SANE_Pid	pid,
		int *	status
	)

Wait for task termination.

This function waits until a task that has been terminated by sanei_thread_kill(), sanei_thread_sendsys() or by any other means is finished.

Parameters:

	pid	- the id of the task
	status	- status of the task that has just finished

Returns:

• the pid of the task we have been waiting for

SANE_Status sanei_thread_get_status

(

SANE_Pid

pid

)

Check the current status of the spawned task.

Parameters:

pid

- the id of the task

Returns:

• SANE_STATUS_GOOD - if the task finished without errors
• any other value - if the task finished unexpectantly or hasn't finished yet

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