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/*************************************************************************************************
* Example of restoration with update logs
*
* Copyright 2020 Google LLC
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of the License at
* https://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
*************************************************************************************************/
#include "tkrzw_dbm_tree.h"
#include "tkrzw_dbm_ulog.h"
#include "tkrzw_file_util.h"
#include "tkrzw_message_queue.h"
using namespace tkrzw;
int main(int argc, char** argv) {
// Makes the initial content and the first full backup.
{
TreeDBM dbm;
dbm.Open("casket.tkt", true, File::OPEN_TRUNCATE).OrDie();
dbm.Set("one", "hop");
dbm.CopyFileData("casket-backup.tkt").OrDie();
dbm.Close().OrDie();
}
// Updates the database with the update logging enabled.
{
MessageQueue mq;
mq.Open("casket-ulog", 512 << 20, MessageQueue::OPEN_TRUNCATE).OrDie();
DBMUpdateLoggerMQ ulog(&mq);
TreeDBM dbm;
dbm.SetUpdateLogger(&ulog);
dbm.Open("casket.tkt", true).OrDie();
dbm.Set("two", "step");
dbm.Close().OrDie();
mq.Close().OrDie();
}
// The database is lost somehow.
RemoveFile("casket.tkt").OrDie();
// Applies the update log to the backup file.
{
CopyFileData("casket-backup.tkt", "casket-restored.tkt").OrDie();
TreeDBM dbm;
dbm.Open("casket-restored.tkt", true).OrDie();
DBMUpdateLoggerMQ::ApplyUpdateLogFromFiles(&dbm, "casket-ulog");
dbm.Close().OrDie();
}
// Checks the recovered content.
{
TreeDBM dbm;
dbm.Open("casket-restored.tkt", false).OrDie();
auto iter = dbm.MakeIterator();
iter->First();
std::string key, value;
while (iter->Get(&key, &value).IsOK()) {
std::cout << key << ":" << value << std::endl;
iter->Next();
}
dbm.Close().OrDie();
}
return 0;
}
// END OF FILE
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