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/* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2009 Sun Microsystems
*
* Authors:
*
* Jay Pipes <joinfu@sun.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 implementation of the background worker thread
* which maintains summary information about transaction log.
*
* @details
*
* The general process that the background worker (collector) thread goes through
* is the following:
*
* a) At thread start, we first check to see if there is an index
* file for the transaction log that has previously been written
* by the collector thread. If there is, we read in the index and
* use that information to construct our in-memory index.
*
* b) If no index is around, we read the transaction log and create
* an in-memory index. This in-memory index is sync'd to disk
* every once in a while. We don't care about crashes and the state
* of the index written to disk, since the transaction log file is
* the main stable state of the transaction log, not the index.
*
* c) Periodically, the collector thread queries the transaction
* log's current offset. If this offset is greater than the last
* offset in the collector's index, it reads a segment of the transaction
* log, building the index for the transactions it finds.
*
* d) When querying the INFORMATION_SCHEMA, or the replication system
* needs an exact read of the index, the collector thread is signalled
* via a pthread_cond_broadcast() call and the collector thread reads
* the transaction log up until the last log offset of the transaction log,
* building the index as it reads the log file.
*/
#include "config.h"
#include <drizzled/gettext.h>
#include <drizzled/errmsg_print.h>
#include <drizzled/definitions.h>
#include <errno.h>
#include "transaction_log.h"
#include "background_worker.h"
bool initTransactionLogBackgroundWorker()
{
pthread_t thread;
int error;
if ((error= pthread_create(&thread, NULL, collectTransactionLogStats, 0)))
{
char errmsg[STRERROR_MAX];
strerror_r(errno, errmsg, sizeof(errmsg));
drizzled::errmsg_printf(ERRMSG_LVL_ERROR,
_("Unable to create background worker thread. "
"Got error %s.\n"),
errmsg);
return true;
}
return false;
}
void *collectTransactionLogStats(void *)
{
/* Check to see if there is an index file on disk */
/* No index file. Create one on disk and in memory. */
/* Read in the index file. */
/* Enter collection loop */
/* Ask for the transaction log's latest written timestamp */
/* Does our index have a smaller timestamp? */
pthread_exit(0);
return NULL;
}
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