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TAO_Queued_Message Class Reference

Represent messages queued in the outgoing data path of the TAO_Transport class. More...

#include <Queued_Message.h>

Inheritance diagram for TAO_Queued_Message:

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Collaboration diagram for TAO_Queued_Message:

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List of all members.

Public Methods

 TAO_Queued_Message (ACE_Allocator *alloc=0, int is_heap_allocated=0)
 Constructor. More...

virtual ~TAO_Queued_Message (void)
 Destructor. More...

Intrusive list manipulation
The messages are put in a doubled linked list (for easy insertion and removal). To minimize memory allocations the list is intrusive, i.e. each element in the list contains the pointers for the next and previous element.

The following methods are used to manipulate this implicit list.

Todo:
: We should implement this as a base template, something like: template<class T> Intrusive_Node { public: void next (T *); T* next () const; private: T* next_; }; and use it as follows: class TAO_Queued_Message : public Intrusive_Node<TAO_Queued_Message> { };


virtual TAO_Queued_Message * next (void) const
 Set/get the next element in the list. More...

virtual TAO_Queued_Message * prev (void) const
 Set/get the previous element in the list. More...

virtual void remove_from_list (TAO_Queued_Message *&head, TAO_Queued_Message *&tail)
 Remove this element from the list. More...

virtual void push_back (TAO_Queued_Message *&head, TAO_Queued_Message *&tail)
 Insert the current element at the tail of the queue. More...

virtual void push_front (TAO_Queued_Message *&head, TAO_Queued_Message *&tail)
 Insert the current element at the head of the queue. More...

Template Methods
virtual size_t message_length (void) const=0
 Return the length of the message. More...

virtual int all_data_sent (void) const=0
 Return 1 if all the data has been sent. More...

virtual void fill_iov (int iovcnt_max, int &iovcnt, iovec iov[]) const=0
 Fill up an io vector using the connects of the message. More...

virtual void bytes_transferred (size_t &byte_count)=0
 Update the internal state, data has been sent. More...

virtual TAO_Queued_Message * clone (ACE_Allocator *allocator)=0
 Clone this element. More...

virtual void destroy (void)=0
 Reclaim resources. More...


Protected Attributes

ACE_Allocatorallocator_
int is_heap_created_

Private Attributes

TAO_Queued_Message * next_
 Implement an intrusive double-linked list for the message queue. More...

TAO_Queued_Message * prev_

Detailed Description

Represent messages queued in the outgoing data path of the TAO_Transport class.

Please read the documentation in the TAO_Transport class to find out more about the design of the outgoing data path.

In some configurations TAO needs to maintain a per-connection queue of outgoing messages. This queue is drained by the pluggable protocols framework, normally under control of the ACE_Reactor, but other configurations are conceivable. The elements in the queue may may removed early, for example, because the application can specify timeouts for each message, or because the underlying connection is broken.

In many cases the message corresponds to some application request, the application may be blocked waiting for the request to be sent, even more importantlyl, the ORB can be configured to use the Leader/Followers strategy, in which case one of the waiting threads can be required to wake up before its message completes each message may contain a 'Sent_Notifier'

NOTE:

The contents of the ACE_Message_Block may have been allocated from TSS storage, in that case we cannot steal them. However, we do not need to perform a deep copy all the time, for example, in a twoway request the sending thread blocks until the data goes out. The queued message can borrow the memory as it will be deallocated by the sending thread when it finishes. Oneways and asynchronous calls are another story.

Todo:
: Change the ORB to allocate oneway and AMI buffer from global memory, to avoid the data copy in this path. What happens if the there is no queueing? Can we check that before allocating the memory?

Definition at line 65 of file Queued_Message.h.


Constructor & Destructor Documentation

TAO_Queued_Message::TAO_Queued_Message ACE_Allocator   alloc = 0,
int    is_heap_allocated = 0
 

Constructor.

Definition at line 13 of file Queued_Message.cpp.

00015   : allocator_ (alloc)
00016   , is_heap_created_ (is_heap_allocated)
00017   , next_ (0)
00018   , prev_ (0)
00019 {
00020 }

TAO_Queued_Message::~TAO_Queued_Message void    [virtual]
 

Destructor.

Definition at line 22 of file Queued_Message.cpp.

00023 {
00024 }


Member Function Documentation

virtual int TAO_Queued_Message::all_data_sent void    const [pure virtual]
 

Return 1 if all the data has been sent.

Implemented in TAO_Asynch_Queued_Message.

Referenced by TAO_Transport::cleanup_queue, TAO_Reactive_Flushing_Strategy::flush_message, and TAO_Block_Flushing_Strategy::flush_message.

virtual void TAO_Queued_Message::bytes_transferred size_t &    byte_count [pure virtual]
 

Update the internal state, data has been sent.

After the TAO_Transport class completes a successful (or partially successful) I/O operation it must update the state of all the messages queued. This callback method is used by each message to update its state and determine if all the data has been sent already.

Parameters:
byte_count  The number of bytes succesfully sent. The TAO_Queued_Message should decrement this value by the number of bytes that must still be sent.
Returns:
Returns 1 if the TAO_Queued_Message has any more data to send.

Implemented in TAO_Asynch_Queued_Message.

Referenced by TAO_Transport::cleanup_queue.

virtual TAO_Queued_Message* TAO_Queued_Message::clone ACE_Allocator   allocator [pure virtual]
 

Clone this element.

Implemented in TAO_Asynch_Queued_Message.

virtual void TAO_Queued_Message::destroy void    [pure virtual]
 

Reclaim resources.

Reliable messages are allocated from the stack, thus they do not be deallocated. Asynchronous (SYNC_NONE) messages are allocated from the heap (or a pool), they need to be reclaimed explicitly.

Implemented in TAO_Asynch_Queued_Message.

Referenced by TAO_Transport::cleanup_queue, and TAO_Transport::send_connection_closed_notifications_i.

virtual void TAO_Queued_Message::fill_iov int    iovcnt_max,
int &    iovcnt,
iovec    iov[]
const [pure virtual]
 

Fill up an io vector using the connects of the message.

Different versions of this class represent the message using either a single buffer, or a message block. This method allows a derived class to fill up the contents of an io vector, the TAO_Transport class uses this method to group as many messages as possible in an iovector before sending them to the OS I/O subsystem.

Parameters:
iovcnt_max  The number of elements in iov
iovcnt  The number of elements already used by iov, this method should update this counter
iov  The io vector

Implemented in TAO_Asynch_Queued_Message.

Referenced by TAO_Transport::drain_queue_i.

virtual size_t TAO_Queued_Message::message_length void    const [pure virtual]
 

Return the length of the message.

If the message has been partially sent it returns the number of bytes that are still not sent.

Implemented in TAO_Asynch_Queued_Message.

Referenced by TAO_Transport::check_buffering_constraints_i, and TAO_Transport::cleanup_queue.

ACE_INLINE TAO_Queued_Message * TAO_Queued_Message::next void    const [virtual]
 

Set/get the next element in the list.

Definition at line 5 of file Queued_Message.inl.

References next_.

Referenced by TAO_Transport::check_buffering_constraints_i, TAO_Transport::drain_queue_i, TAO_Transport::send_connection_closed_notifications_i, TAO_Transport::send_message_block_chain_i, TAO_Transport::send_synch_message_helper_i, and TAO_Transport::send_synchronous_message_i.

00006 {
00007   return this->next_;
00008 }

ACE_INLINE TAO_Queued_Message * TAO_Queued_Message::prev void    const [virtual]
 

Set/get the previous element in the list.

Definition at line 11 of file Queued_Message.inl.

References prev_.

Referenced by TAO_Transport::send_message_block_chain_i, TAO_Transport::send_synch_message_helper_i, and TAO_Transport::send_synchronous_message_i.

00012 {
00013   return this->prev_;
00014 }

void TAO_Queued_Message::push_back TAO_Queued_Message *&    head,
TAO_Queued_Message *&    tail
[virtual]
 

Insert the current element at the tail of the queue.

Definition at line 45 of file Queued_Message.cpp.

References next_, and prev_.

Referenced by TAO_Transport::send_message_block_chain_i, TAO_Transport::send_message_shared_i, TAO_Transport::send_reply_message_i, and TAO_Transport::send_synchronous_message_i.

00047 {
00048   if (tail == 0)
00049     {
00050       tail = this;
00051       head = this;
00052       this->next_ = 0;
00053       this->prev_ = 0;
00054       return;
00055     }
00056 
00057   tail->next_ = this;
00058   this->prev_ = tail;
00059   this->next_ = 0;
00060   tail = this;
00061 }

void TAO_Queued_Message::push_front TAO_Queued_Message *&    head,
TAO_Queued_Message *&    tail
[virtual]
 

Insert the current element at the head of the queue.

Definition at line 64 of file Queued_Message.cpp.

References next_, and prev_.

Referenced by TAO_Transport::send_synchronous_message_i.

00066 {
00067   if (head == 0)
00068     {
00069       tail = this;
00070       head = this;
00071       this->next_ = 0;
00072       this->prev_ = 0;
00073       return;
00074     }
00075 
00076   head->prev_ = this;
00077   this->next_ = head;
00078   this->prev_ = 0;
00079   head = this;
00080 }

void TAO_Queued_Message::remove_from_list TAO_Queued_Message *&    head,
TAO_Queued_Message *&    tail
[virtual]
 

Remove this element from the list.

Definition at line 27 of file Queued_Message.cpp.

References next_, and prev_.

Referenced by TAO_Transport::cleanup_queue, TAO_Transport::send_message_block_chain_i, TAO_Transport::send_reply_message_i, TAO_Transport::send_synch_message_helper_i, and TAO_Transport::send_synchronous_message_i.

00029 {
00030   if (this->prev_ != 0)
00031     this->prev_->next_ = this->next_;
00032   else
00033     head = this->next_;
00034 
00035   if (this->next_ != 0)
00036     this->next_->prev_ = this->prev_;
00037   else
00038     tail = this->prev_;
00039 
00040   this->next_ = 0;
00041   this->prev_ = 0;
00042 }


Member Data Documentation

ACE_Allocator* TAO_Queued_Message::allocator_ [protected]
 

Definition at line 194 of file Queued_Message.h.

Referenced by TAO_Synch_Queued_Message::destroy, and TAO_Asynch_Queued_Message::destroy.

int TAO_Queued_Message::is_heap_created_ [protected]
 

Definition at line 201 of file Queued_Message.h.

Referenced by TAO_Synch_Queued_Message::clone, TAO_Asynch_Queued_Message::clone, TAO_Synch_Queued_Message::destroy, and TAO_Asynch_Queued_Message::destroy.

TAO_Queued_Message* TAO_Queued_Message::next_ [private]
 

Implement an intrusive double-linked list for the message queue.

Definition at line 205 of file Queued_Message.h.

Referenced by next, push_back, push_front, and remove_from_list.

TAO_Queued_Message* TAO_Queued_Message::prev_ [private]
 

Definition at line 206 of file Queued_Message.h.

Referenced by prev, push_back, push_front, and remove_from_list.


The documentation for this class was generated from the following files:
Generated on Mon Jun 16 15:38:01 2003 for TAO by doxygen1.2.14 written by Dimitri van Heesch, © 1997-2002