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/*************************************************************************************************
* Example for serious use cases of the on-memory hash database
*
* 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_cmd_util.h"
#include "tkrzw_dbm_tiny.h"
// Main routine.
int main(int argc, char** argv) {
// All symbols of Tkrzw are under the namespace "tkrzw".
using namespace tkrzw;
// Creates the database manager.
// The number of buckets can be set by the constructor.
TinyDBM dbm(11);
// Opens a database by associating it with a file.
// The result is returned as a Status object.
Status status = dbm.Open("casket.flat", true, File::OPEN_TRUNCATE);
if (status != Status::SUCCESS) {
// Failure of the Open operation is critical so we stop.
Die("Open failed: ", status);
}
// Stores records.
// On-memory databases don't cause errors except for logical ones:
// NOT_FOUND_ERROR and DUPLICATION_ERROR.
dbm.Set("foo", "hop");
dbm.Set("bar", "step");
dbm.Set("baz", "jump");
// Closes the database.
status = dbm.Close();
if (status != Status::SUCCESS) {
// The Close operation shouldn't fail. So we stop if it happens.
Die("Close failed: ", status);
}
// Opens the existing database as a reader mode.
status = dbm.Open("casket.flat", false);
if (status != Status::SUCCESS) {
// Failure of the Open operation is critical so we stop.
Die("Open failed: ", status);
}
// Lands all records whose status is "jump".
auto iter = dbm.MakeIterator();
iter->First();
std::string key;
while (iter->Get(&key) == Status::SUCCESS) {
if (dbm.CompareExchange(key, "jump", "land") == Status::SUCCESS) {
std::cout << key << " landed" << std::endl;
}
std::cout << key << " is now " << dbm.GetSimple(key) << std::endl;
iter->Next();
}
// Closes the database.
// In the reader mode, the file is not updated and no error occurs.
dbm.Close();
return 0;
}
// END OF FILE
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