io.journalkeeper.examples.kv.KvState Maven / Gradle / Ivy
/**
* 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
*
* http://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.
*/
package io.journalkeeper.examples.kv;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import io.journalkeeper.core.serialize.WrappedState;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
/**
* 基于HashMap，使用JSON序列化存储的简易KV存储。
* @author LiYue
* Date: 2019-04-03
*/
public class KvState implements WrappedState {
private static final Logger logger = LoggerFactory.getLogger(KvState.class);
private final static String FILENAME = "map";
private static final String CMD_GET = "GET";
private static final String CMD_SET = "SET";
private static final String CMD_DEL = "DEL";
private static final String CMD_LIST = "KEYS";
private final Gson gson = new Gson();
private Map stateMap = new HashMap<>();
private Path statePath;
@Override
public void recover(Path statePath, Properties properties) {
this.statePath = statePath;
try {
stateMap = gson.fromJson(new String(Files.readAllBytes(statePath.resolve(FILENAME)), StandardCharsets.UTF_8),
new TypeToken>() {
}.getType());
int keys = stateMap == null ? -1 : stateMap.size();
logger.info("State map recovered from {}, keys {} ", statePath.toString(), keys);
} catch (NoSuchFileException e) {
stateMap = new HashMap<>();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
private void checkInput(String[] input, int count) {
if (input.length < count) {
throw new IllegalArgumentException("Bad request: " + String.join(" ", input) + "!");
}
}
@Override
public String execute(String cmd) {
String[] splt = cmd.split("\\s");
try {
checkInput(splt, 1);
if (CMD_SET.equals(splt[0])) {
checkInput(splt, 3);
stateMap.put(splt[1], splt[2]);
Files.write(statePath.resolve(FILENAME), gson.toJson(stateMap).getBytes(StandardCharsets.UTF_8));
return null;
}
if (CMD_DEL.equals(splt[0])) {
checkInput(splt, 2);
stateMap.remove(splt[1]);
Files.write(statePath.resolve(FILENAME), gson.toJson(stateMap).getBytes(StandardCharsets.UTF_8));
return null;
}
throw new IllegalArgumentException("Unknown command: " + cmd + "!");
} catch (Exception e) {
return e.getMessage();
}
}
@Override
public String query(String query) {
String[] splt = query.split("\\s");
try {
checkInput(splt, 1);
if (CMD_GET.equals(splt[0])) {
checkInput(splt, 2);
return stateMap.get(splt[1]);
}
if (CMD_LIST.equals(splt[0])) {
return String.join(", ", stateMap.keySet());
}
throw new IllegalArgumentException("Unknown command: " + query + "!");
} catch (Exception e) {
return e.getMessage();
}
}
}