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/*
Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
This file is part of 0MQ.
0MQ is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
0MQ is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ZMQ_ENCODER_HPP_INCLUDED__
#define __ZMQ_ENCODER_HPP_INCLUDED__
#if defined(_MSC_VER)
#ifndef NOMINMAX
#define NOMINMAX
#endif
#endif
#include <stddef.h>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include "err.hpp"
#include "msg.hpp"
#include "i_encoder.hpp"
namespace zmq
{
// Helper base class for encoders. It implements the state machine that
// fills the outgoing buffer. Derived classes should implement individual
// state machine actions.
template <typename T> class encoder_base_t : public i_encoder
{
public:
inline encoder_base_t (size_t bufsize_) :
bufsize (bufsize_),
in_progress (NULL)
{
buf = (unsigned char*) malloc (bufsize_);
alloc_assert (buf);
}
// The destructor doesn't have to be virtual. It is made virtual
// just to keep ICC and code checking tools from complaining.
inline virtual ~encoder_base_t ()
{
free (buf);
}
// The function returns a batch of binary data. The data
// are filled to a supplied buffer. If no buffer is supplied (data_
// points to NULL) decoder object will provide buffer of its own.
inline size_t encode (unsigned char **data_, size_t size_)
{
unsigned char *buffer = !*data_ ? buf : *data_;
size_t buffersize = !*data_ ? bufsize : size_;
if (in_progress == NULL)
return 0;
size_t pos = 0;
while (pos < buffersize) {
// If there are no more data to return, run the state machine.
// If there are still no data, return what we already have
// in the buffer.
if (!to_write) {
if (new_msg_flag) {
int rc = in_progress->close ();
errno_assert (rc == 0);
rc = in_progress->init ();
errno_assert (rc == 0);
in_progress = NULL;
break;
}
(static_cast <T*> (this)->*next) ();
}
// If there are no data in the buffer yet and we are able to
// fill whole buffer in a single go, let's use zero-copy.
// There's no disadvantage to it as we cannot stuck multiple
// messages into the buffer anyway. Note that subsequent
// write(s) are non-blocking, thus each single write writes
// at most SO_SNDBUF bytes at once not depending on how large
// is the chunk returned from here.
// As a consequence, large messages being sent won't block
// other engines running in the same I/O thread for excessive
// amounts of time.
if (!pos && !*data_ && to_write >= buffersize) {
*data_ = write_pos;
pos = to_write;
write_pos = NULL;
to_write = 0;
return pos;
}
// Copy data to the buffer. If the buffer is full, return.
size_t to_copy = std::min (to_write, buffersize - pos);
memcpy (buffer + pos, write_pos, to_copy);
pos += to_copy;
write_pos += to_copy;
to_write -= to_copy;
}
*data_ = buffer;
return pos;
}
void load_msg (msg_t *msg_)
{
zmq_assert (in_progress == NULL);
in_progress = msg_;
(static_cast <T*> (this)->*next) ();
}
protected:
// Prototype of state machine action.
typedef void (T::*step_t) ();
// This function should be called from derived class to write the data
// to the buffer and schedule next state machine action.
inline void next_step (void *write_pos_, size_t to_write_,
step_t next_, bool new_msg_flag_)
{
write_pos = (unsigned char*) write_pos_;
to_write = to_write_;
next = next_;
new_msg_flag = new_msg_flag_;
}
private:
// Where to get the data to write from.
unsigned char *write_pos;
// How much data to write before next step should be executed.
size_t to_write;
// Next step. If set to NULL, it means that associated data stream
// is dead.
step_t next;
bool new_msg_flag;
// The buffer for encoded data.
size_t bufsize;
unsigned char *buf;
encoder_base_t (const encoder_base_t&);
void operator = (const encoder_base_t&);
protected:
msg_t *in_progress;
};
}
#endif
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