Reifies a method into a request. Subclasses typically represent necessary state and behavior. More...

#include <Activation_Queue.h>

Inheritance diagram for ACE_Activation_Queue:

Collaboration diagram for ACE_Activation_Queue:

Public Member Functions
	ACE_Activation_Queue (ACE_Message_Queue< ACE_SYNCH > new_queue=0, ACE_Allocator alloc=0, ACE_Allocator *db_alloc=0)
	Constructor.
virtual	~ACE_Activation_Queue (void)
	Destructor.
ACE_Method_Request *	dequeue (ACE_Time_Value *tv=0)
	Dequeue the next available ACE_Method_Request.
int	enqueue (ACE_Method_Request new_method_request, ACE_Time_Value tv=0)
	Enqueue the ACE_Method_Request in priority order.
size_t	method_count (void) const
	Get the current number of method objects in the queue.
int	is_empty (void) const
	Returns 1 if the queue is empty, 0 otherwise.
int	is_full (void) const
	Returns 1 if the queue is full, 0 otherwise.
void	dump (void) const
	Dump the state of an request.
ACE_Message_Queue< ACE_SYNCH > *	queue (void) const
	Get a pointer to the underlying queue.
void	queue (ACE_Message_Queue< ACE_SYNCH > *q)
	Set the pointer to the underlying queue.
Public Attributes
	ACE_ALLOC_HOOK_DECLARE
	Declare the dynamic allocation hooks.
Protected Attributes
ACE_Message_Queue< ACE_SYNCH > *	queue_
	Stores the Method_Requests.
bool	delete_queue_
	Keeps track of whether we need to delete the queue.
Private Attributes
ACE_Allocator *	allocator_
	Allocation strategy of the queue.
ACE_Allocator *	data_block_allocator_
	Allocation strategy of the message blocks.

Detailed Description

Reifies a method into a request. Subclasses typically represent necessary state and behavior.

Maintains a priority-ordered queue of ACE_Method_Request objects. A scheduler class (often derived from ACE_Task) subsequently removes each method request and invokes its call() method.

This class is discussed in depth in the Active Object chapter of POSA2. In that book, it is referred to as an Activation List.

See also:: ACE_Method_Request

Definition at line 52 of file Activation_Queue.h.

Constructor & Destructor Documentation

ACE_Activation_Queue::ACE_Activation_Queue	(	ACE_Message_Queue< ACE_SYNCH > *	new_queue = `0`,
		ACE_Allocator *	alloc = `0`,
		ACE_Allocator *	db_alloc = `0`
	)

Constructor.

Initializes a new activation queue.

Parameters:

	new_queue	The activation queue uses an ACE_Message_Queue to queue and order the method requests. If this argument is 0, a new ACE_Message_Queue is created for this object's use and will be deleted when this object is destroyed. If a non-zero pointer is supplied, the passed object will be used and will not be deleted when this object is destroyed. If an ACE_Task is being created to act as the scheduler, for instance, its ACE_Message_Queue pointer can be passed to this object.
	alloc	Optional, the allocator to use when allocating ACE_Message_Block instances that wrap the method requests queued to this activation queue. Defaults to ACE_Allocator::instance().
	db_alloc	Optional, the allocator to use when allocating data blocks for the ACE_Message_Block instances that wrap the method requests queued to this activation queue. Defaults to ACE_Allocator::instance().

Definition at line 38 of file Activation_Queue.cpp.

  : delete_queue_ (false)
  , allocator_(alloc)
  , data_block_allocator_(db_alloc)
{
  if (this->allocator_ == 0)
    this->allocator_ = ACE_Allocator::instance ();

  if (new_queue)
    this->queue_ = new_queue;
  else
    {
      ACE_NEW (this->queue_,
               ACE_Message_Queue<ACE_SYNCH>);
      this->delete_queue_ = true;
    }
}

ACE_Activation_Queue::~ACE_Activation_Queue ( void ) [virtual]

Destructor.

Definition at line 79 of file Activation_Queue.cpp.

{
  if (this->delete_queue_)
    delete this->queue_;
}

Member Function Documentation

ACE_Method_Request * ACE_Activation_Queue::dequeue ( ACE_Time_Value * tv = 0 )

Dequeue the next available ACE_Method_Request.

Parameters:

tv

If 0, the method will block until a method request is available, else will wait until the absolute time specified in the referenced ACE_Time_Value. This method will return, earlier, however, if queue is closed, deactivated, or when a signal occurs.

Return values:

	Pointer	to the dequeued ACE_Method_Request object.
	0	an error occurs; errno contains further information. If the specified timeout elapses, errno will be `EWOULDBLOCK`.

Definition at line 86 of file Activation_Queue.cpp.

{
  ACE_Message_Block *mb = 0;

  // Dequeue the message.
  if (this->queue_->dequeue_head (mb, tv) != -1)
    {
      // Get the next <Method_Request>.
      ACE_Method_Request *mr =
        reinterpret_cast<ACE_Method_Request *> (mb->base ());
      // Delete the message block.
      mb->release ();
      return mr;
    }
  else
    return 0;
}

void ACE_Activation_Queue::dump ( void ) const

Dump the state of an request.

int ACE_Activation_Queue::enqueue	(	ACE_Method_Request *	new_method_request,
		ACE_Time_Value *	tv = `0`
	)

Enqueue the ACE_Method_Request in priority order.

The priority of the method request is obtained via the priority() method of the queued method request. Priority ordering is determined by the ACE_Message_Queue class; 0 is the lowest priority.

Parameters:

	new_method_request	Pointer to the ACE_Method_Request object to queue. This object's `priority()` method is called to obtain the priority.
	tv	If 0, the method will block until the method request can be queued, else will wait until the absolute time specified in the referenced ACE_Time_Value. This method will return, earlier, however, if queue is closed, deactivated, or when a signal occurs.

Return values:

	>0	The number of method requests on the queue after adding the specified request.
	-1	if an error occurs; errno contains further information. If the specified timeout elapses, errno will be `EWOULDBLOCK`.

Definition at line 105 of file Activation_Queue.cpp.

{
  ACE_Message_Block *mb = 0;

  // We pass sizeof (*mr) here so that flow control will work
  // correctly.  Since we also pass <mr> note that no unnecessary
  // memory is actually allocated -- just the size field is set.
  ACE_NEW_MALLOC_RETURN (mb,
                         static_cast<ACE_Message_Block *> (this->allocator_->malloc (sizeof (ACE_Message_Block))),
                         ACE_Message_Block (sizeof (*mr),    // size
                                            ACE_Message_Block::MB_DATA, // type
                                            0,       // cont
                                            (char *) mr,    // data
                                            0,       // allocator
                                            0,       // locking strategy
                                            mr->priority (), // priority
                                            ACE_Time_Value::zero,     // execution time
                                            ACE_Time_Value::max_time, // absolute time of deadline
                                            this->data_block_allocator_,  // data_block allocator
                                            this->allocator_), // message_block allocator
                         -1);

  // Enqueue in priority order.
  int const result = this->queue_->enqueue_prio (mb, tv);

  // Free ACE_Message_Block if enqueue_prio failed.
  if (result == -1)
      ACE_DES_FREE (mb, this->allocator_->free, ACE_Message_Block);

  return result;
}

int ACE_Activation_Queue::is_empty ( void ) const [inline]

Returns 1 if the queue is empty, 0 otherwise.

Definition at line 20 of file Activation_Queue.inl.

{
  return queue_->is_empty ();
}

int ACE_Activation_Queue::is_full ( void ) const [inline]

Returns 1 if the queue is full, 0 otherwise.

Definition at line 14 of file Activation_Queue.inl.

{
  return queue_->is_full ();
}

size_t ACE_Activation_Queue::method_count ( void ) const [inline]

Get the current number of method objects in the queue.

Definition at line 8 of file Activation_Queue.inl.

{
  return queue_->message_count ();
}

ACE_Message_Queue< ACE_SYNCH > * ACE_Activation_Queue::queue ( void ) const [inline]

Get a pointer to the underlying queue.

Definition at line 26 of file Activation_Queue.inl.

{
  return queue_;
}

void ACE_Activation_Queue::queue ( ACE_Message_Queue< ACE_SYNCH > * q )

Set the pointer to the underlying queue.

Definition at line 59 of file Activation_Queue.cpp.

{
  // Destroy the internal queue if one exist.
  if (this->delete_queue_)
    {
      // Destroy the current queue.
      delete this->queue_;

      // Set the flag to false.  NOTE that the delete_queue_ flag is a
      // flag used to only indicate whether or not if an internal
      // ACE_Message_Queue has been created, therefore, it will not
      // affect the user if the user decided to replace the queue with
      // their own queue no matter how many time they call on this
      // function.
      this->delete_queue_ = false;
    }

  queue_ = q;
}