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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
*
* 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
*
* Implementation of a transaction reader for the transaction log.
*
* @details
*
* This is currently an extremely simple implementation which
* reads through the transaction log file one message at a time, using the
* length-coded bytes to skip through the log. Once it finds the message
* which corresponds to the transaction id the caller to read() is looking
* for, it copies the message into the supplied pointer and returns true.
*
* @todo
*
* Cache offsets so that readers don't have to continually scan through
* the log file(s)
*/
#include "config.h"
#include <fcntl.h>
#include <climits>
#include <cerrno>
#include <cstdio>
#include "transaction_log_reader.h"
#include "transaction_log.h"
#include <drizzled/gettext.h>
#include <drizzled/message/transaction.pb.h>
#include <google/protobuf/io/zero_copy_stream_impl.h>
#include <google/protobuf/io/coded_stream.h>
#include <drizzled/algorithm/crc32.h>
#include <drizzled/errmsg_print.h>
#include "drizzled/definitions.h"
using namespace std;
using namespace drizzled;
using namespace google;
bool TransactionLogReader::read(const ReplicationServices::GlobalTransactionId &to_read_trx_id,
message::Transaction *to_fill)
{
/*
* We ask the log to give us the log file containing the
* transaction message with the needed transaction id, then
* we read into the log file to obtain the message, and
* fill the supplied pointer to Transaction message from the
* raw data in the log file.
*/
string log_filename_to_read;
bool log_file_found= log.findLogFilenameContainingTransactionId(to_read_trx_id, log_filename_to_read);
bool result= true;
bool do_checksum= false;
if (unlikely(! log_file_found))
{
return false;
}
else
{
/* Open the log file and read through the log until the transaction ID is found */
int log_file= open(log_filename_to_read.c_str(), O_RDONLY | O_NONBLOCK);
if (log_file == -1)
{
char errmsg[STRERROR_MAX];
strerror_r(errno, errmsg, sizeof(errmsg));
errmsg_printf(ERRMSG_LVL_ERROR,
_("Failed to open transaction log file %s. Got error: %s\n"),
log_filename_to_read.c_str(),
errmsg);
return false;
}
protobuf::io::ZeroCopyInputStream *raw_input= new protobuf::io::FileInputStream(log_file);
protobuf::io::CodedInputStream *coded_input= new protobuf::io::CodedInputStream(raw_input);
char *buffer= NULL;
char *temp_buffer= NULL;
uint32_t length= 0;
uint32_t previous_length= 0;
uint32_t checksum= 0;
message::Transaction transaction;
/* Read in the length of the command */
while (result == true && coded_input->ReadLittleEndian32(&length) == true)
{
if (length > INT_MAX)
{
fprintf(stderr, _("Attempted to read record bigger than INT_MAX\n"));
exit(1);
}
if (buffer == NULL)
{
/*
* First time around...just malloc the length. This block gets rid
* of a GCC warning about uninitialized temp_buffer.
*/
temp_buffer= (char *) malloc(static_cast<size_t>(length));
}
/* No need to allocate if we have a buffer big enough... */
else if (length > previous_length)
{
temp_buffer= (char *) realloc(buffer, static_cast<size_t>(length));
}
if (temp_buffer == NULL)
{
fprintf(stderr, _("Memory allocation failure trying to allocate %" PRIu64 " bytes.\n"),
static_cast<uint64_t>(length));
break;
}
else
buffer= temp_buffer;
/* Read the Command */
result= coded_input->ReadRaw(buffer, length);
if (result == false)
{
char errmsg[STRERROR_MAX];
strerror_r(errno, errmsg, sizeof(errmsg));
fprintf(stderr, _("Could not read transaction message.\n"));
fprintf(stderr, _("GPB ERROR: %s.\n"), errmsg);
fprintf(stderr, _("Raw buffer read: %s.\n"), buffer);
break;
}
result= transaction.ParseFromArray(buffer, static_cast<int32_t>(length));
if (result == false)
{
fprintf(stderr, _("Unable to parse transaction. Got error: %s.\n"), transaction.InitializationErrorString().c_str());
if (buffer != NULL)
fprintf(stderr, _("BUFFER: %s\n"), buffer);
break;
}
/* Skip 4 byte checksum */
coded_input->ReadLittleEndian32(&checksum);
if (do_checksum)
{
if (checksum != drizzled::algorithm::crc32(buffer, static_cast<size_t>(length)))
{
fprintf(stderr, _("Checksum failed. Wanted %" PRIu32 " got %" PRIu32 "\n"), checksum, drizzled::algorithm::crc32(buffer, static_cast<size_t>(length)));
}
}
/* Cool, message was read. Check the trx id */
if (transaction.transaction_context().transaction_id() == to_read_trx_id)
{
/* Found what we were looking for...copy to the pointer we should fill */
to_fill->CopyFrom(transaction);
break;
}
previous_length= length;
}
if (buffer)
free(buffer);
delete coded_input;
delete raw_input;
return result;
}
}
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