/*
* Copyright 2000-2016 JetBrains s.r.o.
*
* 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 com.intellij.util.indexing;
import org.jetbrains.annotations.NotNull;
@SuppressWarnings({"WhileLoopSpinsOnField", "SynchronizeOnThis"})
class StorageGuard {
private int myHolds;
private int myWaiters;
public interface StorageModeExitHandler {
void leave();
}
private final StorageModeExitHandler myTrueStorageModeExitHandler = new StorageModeExitHandler() {
@Override
public void leave() {
StorageGuard.this.leave(true);
}
};
private final StorageModeExitHandler myFalseStorageModeExitHandler = new StorageModeExitHandler() {
@Override
public void leave() {
StorageGuard.this.leave(false);
}
};
@NotNull
synchronized StorageModeExitHandler enter(boolean mode) {
if (mode) {
while (myHolds < 0) {
doWait();
}
myHolds++;
return myTrueStorageModeExitHandler;
}
else {
while (myHolds > 0) {
doWait();
}
myHolds--;
return myFalseStorageModeExitHandler;
}
}
private void doWait() {
try {
++myWaiters;
wait();
}
catch (InterruptedException ignored) {
}
finally {
--myWaiters;
}
}
private synchronized void leave(boolean mode) {
myHolds += mode ? -1 : 1;
if (myHolds == 0 && myWaiters > 0) {
notifyAll();
}
}
}