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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
*
* 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 default command log.
*
* @see drizzled/plugin/replicator.h
* @see drizzled/plugin/applier.h
*
* @details
*
* The CommandLog applies events it receives from the TransactionServices
* server component to a simple log file on disk.
*
* Events are received in no guaranteed order and the command log
* is in charge of writing these events to the log as they are received.
*/
#ifndef DRIZZLE_PLUGIN_command_log_H
#define DRIZZLE_PLUGIN_command_log_H
#include <drizzled/server_includes.h>
#include <drizzled/atomics.h>
#include <drizzled/plugin/replicator.h>
#include <drizzled/plugin/applier.h>
#include <vector>
#include <string>
class CommandLog: public drizzled::plugin::Applier
{
public:
enum status
{
CRASHED= 0,
OFFLINE, /* Default state, uninited. */
ONLINE,
WRITING
};
private:
int log_file; /**< Handle for our log file */
enum status state; /**< The state the log is in */
drizzled::atomic<bool> is_enabled; /**< Internal toggle. Atomic to support online toggling of command log... */
drizzled::atomic<bool> is_active; /**< Internal toggle. If true, log was initialized properly... */
const char *log_file_path; /**< Full path to the log file */
drizzled::atomic<off_t> log_offset; /**< Offset in log file where log will write next command */
public:
CommandLog(const char *in_log_file_path);
/** Destructor */
~CommandLog();
/**
* Applies a Command to the serial log
*
* @note
*
* It is important to note that memory allocation for the
* supplied pointer is not guaranteed after the completion
* of this function -- meaning the caller can dispose of the
* supplied message. Therefore, appliers which are
* implementing an asynchronous replication system must copy
* the supplied message to their own controlled memory storage
* area.
*
* @param Command message to be replicated
*/
void apply(drizzled::message::Command *to_apply);
/**
* Returns whether the command log is active.
*/
bool isActive();
/**
* Disables the plugin.
* Disabled just means that the user has done an online set @command_log_enable= false
*/
inline void disable()
{
is_enabled= false;
}
/**
* Enables the plugin. Enabling is a bit different from isActive().
* Enabled just means that the user has done an online set global command_log_enable= true
* or has manually started up the server with --command-log-enable
*/
inline void enable()
{
is_enabled= true;
}
/**
* Returns the state that the log is in
*/
inline enum status getState()
{
return state;
}
/**
* 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();
};
#endif /* DRIZZLE_PLUGIN_command_log_H */
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