ACE Tutorial 015
Building a protocol stream
And now the implementation of the Protocol_Stream. There are more
lines of code here than we've seen so far but it still isn't
complicated. The basic idea is to construct the ACE_Stream with our
set of protocol objects that will manipulate the data. Our primary
concern in this file is to get everything in the correct order!
// $Id: page12.html,v 1.4 1998/10/27 19:05:55 jcej Exp $
#ifndef PROTOCOL_TASK_H
#define PROTOCOL_TASK_H
#include "ace/Task.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
/* A typical ACE_Task<> derivative that adds a few things appropriate
to protocol stacks.
*/
class Protocol_Task : public ACE_Task<ACE_MT_SYNCH>
{
public:
typedef ACE_Task<ACE_MT_SYNCH> inherited;
// A choice of concurrency strategies is offered by the
// constructor. In most cases it makes sense to set this to
// zero and let things proceed serially. You might have a
// need, however, for some of your tasks to have their own thread.
Protocol_Task( int _thr_count );
~Protocol_Task(void);
// open() is invoked when the task is inserted into the stream.
virtual int open(void *arg);
// close() is invoked when the stream is closed (flags will be
// set to '1') and when the svc() method exits (flags will be
// '0').
virtual int close(u_long flags);
// As data travels through the stream, the put() method of
// each task is invoked to keep the data moving along.
virtual int put(ACE_Message_Block *message,
ACE_Time_Value *timeout);
// If you choose to activate the task then this method will be
// doing all of the work.
virtual int svc(void);
protected:
// Called by put() or svc() as necessary to process a block of
// data.
int process(ACE_Message_Block * message, ACE_Time_Value *timeout);
// Just let us know if we're active or not.
int is_active(void)
{
return this->thr_count() != 0;
}
// Tasks on the writter (downstream) side of the stream
// are called upon to send() data that will ultimately go to
// the peer.
virtual int send(ACE_Message_Block *message,
ACE_Time_Value *timeout);
// Tasks on the reader (upstream) side will be receiving data
// that came from the peer.
virtual int recv(ACE_Message_Block * message,
ACE_Time_Value *timeout);
private:
int desired_thr_count_;
};
#endif // PROTOCOL_TASK_H
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