Public Member Functions
|TAO_Queued_Message (TAO_ORB_Core *oc, ACE_Allocator *alloc=0, bool is_heap_allocated=false)|
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.
|TAO_Queued_Message *||next (void) const|
|Set/get the next element in the list. |
|TAO_Queued_Message *||prev (void) const|
|Set/get the previous element in the list. |
|void||remove_from_list (TAO_Queued_Message *&head, TAO_Queued_Message *&tail)|
|Remove this element from the list. |
|void||push_back (TAO_Queued_Message *&head, TAO_Queued_Message *&tail)|
|Insert the current element at the tail of the queue. |
|void||push_front (TAO_Queued_Message *&head, TAO_Queued_Message *&tail)|
|Insert the current element at the head of the queue. |
|virtual size_t||message_length (void) const =0|
|Return the length of the message. |
|virtual int||all_data_sent (void) const =0|
|Return 1 if all the data has been sent. |
|virtual void||fill_iov (int iovcnt_max, int &iovcnt, iovec iov) const =0|
|Fill up an io vector using the connects of the message. |
|virtual void||bytes_transferred (size_t &byte_count)=0|
|Update the internal state, data has been sent. |
|virtual TAO_Queued_Message *||clone (ACE_Allocator *allocator)=0|
|Clone this element. |
|virtual void||destroy (void)=0|
|Reclaim resources. |
|virtual bool||is_expired (const ACE_Time_Value &now) const|
|Check for timeout. |
|virtual void||copy_if_necessary (const ACE_Message_Block *chain)=0|
|Provide a hook for copying the underlying data. |
|Cached copy of ORB_Core pointer. |
|Implement an intrusive double-linked list for the message queue. |
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 be 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 importantly, 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'
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.
|ACE_Allocator *|| alloc =
|bool|| is_heap_allocated = |
|virtual int TAO_Queued_Message::all_data_sent||(||void||)|| const
|virtual void TAO_Queued_Message::bytes_transferred||(||size_t &||byte_count||)||
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.
|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.|
|virtual void TAO_Queued_Message::copy_if_necessary||(||const ACE_Message_Block *||chain||)||
|virtual void TAO_Queued_Message::destroy||(||void||)||
|virtual void TAO_Queued_Message::fill_iov||(||int||iovcnt_max,|
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.
|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|
|bool TAO_Queued_Message::is_expired||(||const ACE_Time_Value &||now||)|| const
Check for timeout.
|now||Pass in the current time using ACE_High_Res_Timer::gettimeofday_hr(). This is a parameter in order to avoid calling gettimeofday_hr() inside of this method (which will be called in a tight loop).|
Reimplemented in TAO_Asynch_Queued_Message.
|virtual size_t TAO_Queued_Message::message_length||(||void||)|| const
|TAO_Queued_Message * TAO_Queued_Message::next||(||void||)||const|
Set/get the next element in the list.
|TAO_Queued_Message * TAO_Queued_Message::prev||(||void||)||const|
Set/get the previous element in the list.
Insert the current element at the tail of the queue.
Insert the current element at the head of the queue.
|void TAO_Queued_Message::remove_from_list||(||TAO_Queued_Message *&||head,|
Remove this element from the list.
|bool const TAO_Queued_Message::is_heap_created_
Implement an intrusive double-linked list for the message queue.