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/* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2008-2009 Sun Microsystems
* Copyright (c) 2010 Jay Pipes <jaypipes@gmail.com>
*
* Authors:
*
* Jay Pipes <jaypipes@gmail.com.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
*
* Defines the API of the transaction log file descriptor.
*
* @details
*
* Basically, the TransactionLog is a descriptor for a log
* file containing transaction messages that is written by
* the TransactionLogApplier plugin(s).
*/
#ifndef PLUGIN_TRANSACTION_LOG_TRANSACTION_LOG_H
#define PLUGIN_TRANSACTION_LOG_TRANSACTION_LOG_H
#include <drizzled/atomics.h>
#include <drizzled/replication_services.h>
#include "transaction_log_entry.h"
#include <vector>
#include <string>
class TransactionLog
{
public:
typedef std::vector<TransactionLogEntry> Entries;
typedef std::vector<TransactionLogTransactionEntry> TransactionEntries;
/**
* The state the log is in
*/
enum Status
{
CRASHED= 0,
OFFLINE, /* Default state, uninited. */
ONLINE,
WRITING
};
static const uint32_t FLUSH_FREQUENCY_OS= 0; ///< Rely on operating system to sync log file
static const uint32_t FLUSH_FREQUENCY_EVERY_WRITE= 1; //< Sync on every write to the log file
static const uint32_t FLUSH_FREQUENCY_EVERY_SECOND= 2; ///< Sync no more than once a second
public:
TransactionLog(const std::string in_log_file_path,
uint32_t in_flush_frequency,
bool in_do_checksum);
/** Destructor */
~TransactionLog();
/**
* Returns the current offset into the log
*/
inline off_t getLogOffset()
{
return log_offset;
}
/**
* Returns the filename of the transaction log
*/
const std::string &getLogFilename();
/**
* Returns the filename of the transaction log
*/
const std::string &getLogFilepath();
/**
* Returns the state that the log is in
*/
inline enum Status getState()
{
return state;
}
/**
* Static helper method which returns the transaction
* log entry size in bytes of a given transaction
* message.
*
* @param[in] Transaction message
*/
static size_t getLogEntrySize(const drizzled::message::Transaction &trx);
/**
* Method which packs into a raw byte buffer
* a transaction log entry. Supplied buffer should
* be of adequate size.
*
* Returns a pointer to the start of the original
* buffer.
*
* @param[in] Transaction message to pack
* @param[in] Raw byte buffer
* @param[out] Pointer to storage for checksum of message
*/
uint8_t *packTransactionIntoLogEntry(const drizzled::message::Transaction &trx,
uint8_t *buffer,
uint32_t *checksum_out);
/**
* Writes a chunk of data to the log file of a specified
* length and returns the offset at which the chunk of
* data was written.
*
* @param[in] Bytes to write
* @param[in[ Length of bytes to write
*
* @retval
* Returns the write offset if the write succeeded, OFF_T_MAX otherwise.
*/
off_t writeEntry(const uint8_t *data, size_t data_length);
/**
* Truncates the existing log file
*
* @note
*
* This is only called currently during debugging and testing of the
* command log...when the global command_log_truncate variable is
* set to anything other than false, this is called.
*/
void truncate();
/**
* Takes a global transaction ID and a reference to a string to fill
* with the name of the log file which contains the command with the
* transaction ID. If the transaction ID is contained in a log file,
* the function returns true, false otherwise.
*
* @param[in] Global transaction ID to search on
* @param[inout] String to fill with name of logfile containing command with
* the needed transaction ID
*
* @retval
* true if found
* @retval
* false otherwise
*/
bool findLogFilenameContainingTransactionId(const drizzled::ReplicationServices::GlobalTransactionId &to_find,
std::string &out_filename) const;
/**
* Returns whether the log is currently in error.
*/
bool hasError() const;
/**
* Returns the log's current error message
*/
const std::string &getErrorMessage() const;
private:
static const uint32_t HEADER_TRAILER_BYTES= sizeof(uint32_t) + /* 4-byte msg type header */
sizeof(uint32_t) + /* 4-byte length header */
sizeof(uint32_t); /* 4 byte checksum trailer */
/* Don't allows these */
TransactionLog();
TransactionLog(const TransactionLog &other);
TransactionLog &operator=(const TransactionLog &other);
/**
* Clears the current error message
*/
void clearError();
/**
* Helper method which synchronizes/flushes the transaction log file
* according to the transaction_log_flush_frequency system variable
*
* @retval
* 0 == Success
* @retval
* >0 == Failure. Error code.
*/
int syncLogFile();
int log_file; ///< Handle for our log file
Status state; ///< The state the log is in
const std::string log_file_path; ///< Full path to the log file
std::string log_file_name; ///< Name of the log file
drizzled::atomic<off_t> log_offset; ///< Offset in log file where log will write next command
bool has_error; ///< Is the log in error?
std::string error_message; ///< Current error message
uint32_t flush_frequency; ///< Determines behaviour of syncing log file
time_t last_sync_time; ///< Last time the log file was synced (only set in FLUSH_FREQUENCY_EVERY_SECOND)
bool do_checksum; ///< Do a CRC32 checksum when writing Transaction message to log?
};
#endif /* PLUGIN_TRANSACTION_LOG_TRANSACTION_LOG_H */
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