org.sonar.server.util.cache.MemoryCache Maven / Gradle / Ivy
/*
* SonarQube
* Copyright (C) 2009-2018 SonarSource SA
* mailto:info AT sonarsource DOT com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.sonar.server.util.cache;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.CheckForNull;
import org.sonar.server.exceptions.NotFoundException;
/**
* This in-memory cache relies on {@link org.sonar.server.util.cache.CacheLoader} to
* load missing elements.
* Warning - all searches are kept in memory, even when elements are not found.
*/
public class MemoryCache {
private final CacheLoader loader;
private final Map map = new HashMap<>();
public MemoryCache(CacheLoader loader) {
this.loader = loader;
}
@CheckForNull
public V getNullable(K key) {
V value = map.get(key);
if (value == null && !map.containsKey(key)) {
value = loader.load(key);
map.put(key, value);
}
return value;
}
public V get(K key) {
V value = getNullable(key);
if (value == null) {
throw new NotFoundException("Not found: " + key);
}
return value;
}
/**
* Get values associated with keys. All the requested keys are included
* in the Map result. Value is null if the key is not found in cache.
*/
public Map getAll(Iterable keys) {
List missingKeys = new ArrayList<>();
Map result = new HashMap<>();
for (K key : keys) {
V value = map.get(key);
if (value == null && !map.containsKey(key)) {
missingKeys.add(key);
} else {
result.put(key, value);
}
}
if (!missingKeys.isEmpty()) {
Map missingValues = loader.loadAll(missingKeys);
map.putAll(missingValues);
result.putAll(missingValues);
for (K missingKey : missingKeys) {
if (!map.containsKey(missingKey)) {
map.put(missingKey, null);
result.put(missingKey, null);
}
}
}
return result;
}
public void clear() {
map.clear();
}
}