ACE_Task_Base Class Reference

Direct base class for the ACE_Task template. More...

#include <Task.h>

Inheritance diagram for ACE_Task_Base:

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Collaboration diagram for ACE_Task_Base:

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List of all members.

Public Member Functions
	ACE_Task_Base (ACE_Thread_Manager *=0)
	Constructor.
virtual	~ACE_Task_Base (void)
	Destructor.
virtual int	open (void *args=0)
virtual int	close (u_long flags=0)
virtual int	module_closed (void)
virtual int	put (ACE_Message_Block *, ACE_Time_Value *=0)
virtual int	svc (void)
	Run by a daemon thread to handle deferred processing.
virtual int	activate (long flags=THR_NEW_LWP|THR_JOINABLE|THR_INHERIT_SCHED, int n_threads=1, int force_active=0, long priority=ACE_DEFAULT_THREAD_PRIORITY, int grp_id=-1, ACE_Task_Base *task=0, ACE_hthread_t thread_handles[]=0, void *stack[]=0, size_t stack_size[]=0, ACE_thread_t thread_ids[]=0, const char *thr_name[]=0)
virtual int	wait (void)
virtual int	suspend (void)
	Suspend a task.
virtual int	resume (void)
	Resume a suspended task.
int	grp_id (void) const
	Get the current group id.
void	grp_id (int)
	Set the current group id.
ACE_Thread_Manager *	thr_mgr (void) const
	Get the thread manager associated with this Task.
void	thr_mgr (ACE_Thread_Manager *)
	Set the thread manager associated with this Task.
int	is_reader (void) const
	True if queue is a reader, else false.
int	is_writer (void) const
	True if queue is a writer, else false.
size_t	thr_count (void) const
ACE_thread_t	last_thread (void) const
Static Public Member Functions
static ACE_THR_FUNC_RETURN	svc_run (void *)
	Routine that runs the service routine as a daemon thread.
static void	cleanup (void *object, void *params)
Protected Attributes
size_t	thr_count_
ACE_Thread_Manager *	thr_mgr_
	Multi-threading manager.
u_long	flags_
	ACE_Task flags.
int	grp_id_
	This maintains the group id of the Task.
ACE_thread_t	last_thread_id_
	Holds the thread ID of the last thread to exit svc() in this object.
Private Member Functions
ACE_Task_Base &	operator= (const ACE_Task_Base &)
	ACE_Task_Base (const ACE_Task_Base &)

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Detailed Description

Direct base class for the ACE_Task template.

This class factors out the non-template code in order to reduce template bloat, as well as to make it possible for the ACE_Thread_Manager to store ACE_Task_Base *'s polymorphically.

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Constructor & Destructor Documentation

ACE_BEGIN_VERSIONED_NAMESPACE_DECL ACE_Task_Base::ACE_Task_Base

(

ACE_Thread_Manager *

thr_man = 0

)

Constructor.

ACE_Task_Base::~ACE_Task_Base

(

void

)

[virtual]

Destructor.

ACE_Task_Base::ACE_Task_Base

(

const ACE_Task_Base &

)

[private]

---

Member Function Documentation

int ACE_Task_Base::open

(

void *

args = 0

)

[virtual]

Hook called to initialize a task and prepare it for execution. args can be used to pass arbitrary information into <open>.

Reimplemented in ACE_Stream_Head<>, ACE_Stream_Tail<>, ACE_Thru_Task<>, ACE_Svc_Handler<, >, and ACE_Svc_Handler< ACE_PEER_STREAM_2, ACE_SYNCH_USE >.

int ACE_Task_Base::close

(

u_long

flags = 0

)

[virtual]

Hook called from ACE_Thread_Exit when during thread exit and from the default implementation of <module_closed>. In general, this method shouldn't be called directly by an application, particularly if the <Task> is running as an Active Object. Instead, a special message should be passed into the <Task> via the <put> method defined below, and the <svc> method should interpret this as a flag to shut down the <Task>.

Reimplemented in ACE_Stream_Head<>, ACE_Stream_Tail<>, ACE_Thru_Task<>, ACE_Svc_Handler<, >, and ACE_Svc_Handler< ACE_PEER_STREAM_2, ACE_SYNCH_USE >.

int ACE_Task_Base::module_closed

(

void

)

[virtual]

Hook called during <ACE_Module::close>. The default implementation calls forwards the call to close(1). Please notice the changed value of the default argument of <close>. This allows tasks to differ between the call has been originated from <ACE_Thread_Exit> or from <module_closed>. Be aware that close(0) will be also called when a thread associated with the ACE_Task instance exits.

int ACE_Task_Base::put	(	ACE_Message_Block *	,
		ACE_Time_Value *	= 0
	)			[virtual]

A hook method that can be used to pass a message to a task, where it can be processed immediately or queued for subsequent processing in the <svc> hook method.

Reimplemented in ACE_Stream_Head<>, ACE_Stream_Tail<>, ACE_Thru_Task<>, and ACE_Buffered_Svc_Handler<, >.

int ACE_Task_Base::svc

(

void

)

[virtual]

Run by a daemon thread to handle deferred processing.

Reimplemented in ACE_Asynch_Pseudo_Task, ACE_Proactor_Timer_Handler, ACE_Stream_Head<>, ACE_Stream_Tail<>, ACE_Thru_Task<>, and ACE_Thread_Timer_Queue_Adapter< TQ >.

int ACE_Task_Base::activate	(	long	flags = THR_NEW_LWP | THR_JOINABLE | THR_INHERIT_SCHED,
		int	n_threads = 1,
		int	force_active = 0,
		long	priority = ACE_DEFAULT_THREAD_PRIORITY,
		int	grp_id = -1,
		ACE_Task_Base *	task = 0,
		ACE_hthread_t	thread_handles[] = 0,
		void *	stack[] = 0,
		size_t	stack_size[] = 0,
		ACE_thread_t	thread_ids[] = 0,
		const char *	thr_name[] = 0
	)			[virtual]

Turn the task into an active object, i.e., having n_threads of control, all running at the priority level (see below) with the same grp_id, all of which invoke <Task::svc>. Returns -1 if failure occurs, returns 1 if Task is already an active object and force_active is false (i.e., do *not* create a new thread in this case), and returns 0 if Task was not already an active object and a thread is created successfully or thread is an active object and force_active is true. Note that if force_active is true and there are already threads spawned in this <Task>, the grp_id parameter is ignored and the grp_id of any newly activated thread(s) will inherit the existing grp_id of the existing thread(s) in the <Task>.

The <{flags}> are a bitwise-OR of the following: = BEGIN<INDENT> THR_CANCEL_DISABLE, THR_CANCEL_ENABLE, THR_CANCEL_DEFERRED, THR_CANCEL_ASYNCHRONOUS, THR_BOUND, THR_NEW_LWP, THR_DETACHED, THR_SUSPENDED, THR_DAEMON, THR_JOINABLE, THR_SCHED_FIFO, THR_SCHED_RR, THR_SCHED_DEFAULT, THR_EXPLICIT_SCHED, THR_SCOPE_SYSTEM, THR_SCOPE_PROCESS = END<INDENT> If THR_SCHED_INHERIT is not desirable, applications should specifically pass in THR_EXPLICIT_SCHED.

By default, or if <{priority}> is set to ACE_DEFAULT_THREAD_PRIORITY, an "appropriate" priority value for the given scheduling policy (specified in <{flags}>, e.g., <THR_SCHED_DEFAULT>) is used. This value is calculated dynamically, and is the median value between the minimum and maximum priority values for the given policy. If an explicit value is given, it is used. Note that actual priority values are EXTREMEMLY implementation-dependent, and are probably best avoided.

If thread_handles != 0 it is assumed to be an array of n thread_handles that will be assigned the values of the thread handles being spawned. Returns -1 on failure (errno will explain...), otherwise returns the group id of the threads.

Assigning task allows you to associate the newly spawned threads with an instance of ACE_Task_Base. If task == 0, then the new threads are associated automatically with this ACE_Task_Base. Setting the task argument to value other than this makes the thread manipulating methods, such as wait(), suspend(), resume(), useless. Threads spawned with user specified task value must therefore be manipulated thru ACE_Thread_Manager directly.

If stack != 0 it is assumed to be an array of n pointers to the base of the stacks to use for the threads being spawned. Likewise, if stack_size != 0 it is assumed to be an array of n values indicating how big each of the corresponding stacks are.

Reimplemented in ACE_Thread_Timer_Queue_Adapter< TQ >.

int ACE_Task_Base::wait

(

void

)

[virtual]

Block until there are no more threads running in this task. This method will not wait for either detached or daemon threads; the threads must have been spawned with the THR_JOINABLE flag. Upon successful completion, the threads have been joined, so further attempts to join with any of the waited-for threads will fail.

Return values:

	0	Success.
	-1	Failure (consult errno for further information).

int ACE_Task_Base::suspend

(

void

)

[virtual]

Suspend a task.

Reimplemented from ACE_Service_Object.

int ACE_Task_Base::resume

(

void

)

[virtual]

Resume a suspended task.

Reimplemented from ACE_Service_Object.

ACE_BEGIN_VERSIONED_NAMESPACE_DECL ACE_INLINE int ACE_Task_Base::grp_id

(

void

)

const

Get the current group id.

ACE_INLINE void ACE_Task_Base::grp_id

(

int

identifier

)

Set the current group id.

ACE_INLINE ACE_Thread_Manager * ACE_Task_Base::thr_mgr

(

void

)

const

Get the thread manager associated with this Task.

ACE_INLINE void ACE_Task_Base::thr_mgr

(

ACE_Thread_Manager *

thr_mgr

)

Set the thread manager associated with this Task.

ACE_INLINE int ACE_Task_Base::is_reader

(

void

)

const

True if queue is a reader, else false.

ACE_INLINE int ACE_Task_Base::is_writer

(

void

)

const

True if queue is a writer, else false.

ACE_INLINE size_t ACE_Task_Base::thr_count

(

void

)

const

Returns the number of threads currently running within a task. If we're a passive object this value is 0, else it's greater than 0.

ACE_INLINE ACE_thread_t ACE_Task_Base::last_thread

(

void

)

const

Returns the thread ID of the thread whose exit caused this object's thread count to be decremented to 0.

When a thread spawned in the context of this object (using activate()) returns from its svc() method ACE calls the close() hook. Before it does so, it decrements the number of active threads. If the number of threads is decremented to 0, the thread ID of the current thread is stored for access by this method. If the returned thread ID matches the calling thread's ID, the calling thread knows that there are no other threads still active in the ACE_Task.

Return values:

ACE_thread_t

of the last thread to close. 0 if the last thread is not yet known; for example, if no threads are active, or if multiple threads are active.

ACE_THR_FUNC_RETURN ACE_Task_Base::svc_run

(

void *

args

)

[static]

Routine that runs the service routine as a daemon thread.

void ACE_Task_Base::cleanup	(	void *	object,
		void *	params
	)			[static]

Cleanup hook that is called when a thread exits to gracefully shutdown an ACE_Task.

ACE_Task_Base& ACE_Task_Base::operator=

(

const ACE_Task_Base &

)

[private]

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Member Data Documentation

size_t ACE_Task_Base::thr_count_ [protected]

Count of the number of threads running within the task. If this value is greater than 0 then we're an active object and the value of <thr_count_> is the number of active threads at this instant. If the value == 0, then we're a passive object.

ACE_Thread_Manager* ACE_Task_Base::thr_mgr_ [protected]

Multi-threading manager.

u_long ACE_Task_Base::flags_ [protected]

ACE_Task flags.

int ACE_Task_Base::grp_id_ [protected]

This maintains the group id of the Task.

ACE_thread_t ACE_Task_Base::last_thread_id_ [protected]

Holds the thread ID of the last thread to exit svc() in this object.

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The documentation for this class was generated from the following files:

• Task.h
• Task.cpp
• Task.inl