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/*
Copyright (c) 2007-2010 iMatix Corporation
This file is part of 0MQ.
0MQ is free software; you can redistribute it and/or modify it under
the terms of the Lesser GNU 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
Lesser GNU General Public License for more details.
You should have received a copy of the Lesser GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ZMQ_MSG_STORE_HPP_INCLUDED__
#define __ZMQ_MSG_STORE_HPP_INCLUDED__
#include "../include/zmq.h"
#include <string>
#include "stdint.hpp"
namespace zmq
{
// This class implements a message store. Messages are retrieved from
// the store in the same order as they entered it.
class msg_store_t
{
public:
enum { default_block_size = 8192 };
// Creates message store.
msg_store_t (int64_t filesize_, size_t block_size_ = default_block_size);
~msg_store_t ();
int init ();
// Stores the message into the message store. The function
// returns false if the message store is full; true otherwise.
bool store (zmq_msg_t *msg_);
// Fetches the oldest message from the message store. It is an error
// to call this function when the message store is empty.
void fetch (zmq_msg_t *msg_);
void commit ();
void rollback ();
// Returns true if the message store is empty; false otherwise.
bool empty ();
// Returns true if and only if the store is full.
bool full ();
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;
};
}
#endif
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