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/*
Copyright (c) 2007-2011 iMatix Corporation
Copyright (c) 2007-2011 Other 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_SWAP_HPP_INCLUDED__
#define __ZMQ_SWAP_HPP_INCLUDED__
#include "../include/zmq.h"
#include <string>
#include "stdint.hpp"
namespace zmq
{
// This class implements a message swap. Messages are retrieved from
// the swap in the same order as they entered it.
class swap_t
{
public:
enum { default_block_size = 8192 };
// Creates the swap.
swap_t (int64_t filesize_);
~swap_t ();
int init ();
// Stores the message into the swap. The function
// returns false if the swap is full; true otherwise.
bool store (zmq_msg_t *msg_);
// Fetches the oldest message from the swap. It is an error
// to call this function when the swap is empty.
void fetch (zmq_msg_t *msg_);
void commit ();
void rollback ();
// Returns true if the swap is empty; false otherwise.
bool empty ();
// // Returns true if and only if the swap is full.
// bool full ();
// Returns true if the message fits into swap.
bool fits (zmq_msg_t *msg_);
private:
// Copies data from a memory buffer to the backing file.
// Wraps around when reaching maximum file size.
void copy_from_file (void *buffer_, size_t count_);
// Copies data from the backing file to the memory buffer.
// Wraps around when reaching end-of-file.
void copy_to_file (const void *buffer_, size_t count_);
// Returns the buffer space available.
int64_t buffer_space ();
void fill_buf (char *buf, int64_t pos);
void save_write_buf ();
// File descriptor to the backing file.
int fd;
// Name of the backing file.
std::string filename;
// Maximum size of the backing file.
int64_t filesize;
// File offset associated with the fd file descriptor.
int64_t file_pos;
// File offset the next message will be stored at.
int64_t write_pos;
// File offset the next message will be read from.
int64_t read_pos;
int64_t commit_pos;
size_t block_size;
char *buf1;
char *buf2;
char *read_buf;
char *write_buf;
int64_t write_buf_start_addr;
// Disable copying of the swap object.
swap_t (const swap_t&);
const swap_t &operator = (const swap_t&);
};
}
#endif
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