com.absmartly.sdk.internal.Concurrency Maven / Gradle / Ivy

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package com.absmartly.sdk.internal;

import java.util.List;
import java.util.Map;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java8.util.function.Function;

public class Concurrency {
	static public  V computeIfAbsentRW(ReentrantReadWriteLock lock, Map map, K key,
			Function computer) {
		final ReentrantReadWriteLock.ReadLock readLock = lock.readLock();
		try {
			readLock.lock();
			final V value = map.get(key);
			if (value != null) {
				return value;
			}
		} finally {
			readLock.unlock();
		}

		final ReentrantReadWriteLock.WriteLock writeLock = lock.writeLock();
		try {
			writeLock.lock();
			final V value = map.get(key); // double check
			if (value != null) {
				return value;
			}

			final V newValue = computer.apply(key);
			map.put(key, newValue);
			return newValue;
		} finally {
			writeLock.unlock();
		}
	}

	static public  V getRW(ReentrantReadWriteLock lock, Map map, K key) {
		final ReentrantReadWriteLock.ReadLock readLock = lock.readLock();
		try {
			readLock.lock();
			return map.get(key);
		} finally {
			readLock.unlock();
		}
	}

	static public  V putRW(ReentrantReadWriteLock lock, Map map, K key, V value) {
		final ReentrantReadWriteLock.WriteLock writeLock = lock.writeLock();
		try {
			writeLock.lock();
			return map.put(key, value);
		} finally {
			writeLock.unlock();
		}
	}

	static public  void addRW(ReentrantReadWriteLock lock, List list, V value) {
		final ReentrantReadWriteLock.WriteLock writeLock = lock.writeLock();
		try {
			writeLock.lock();
			list.add(value);
		} finally {
			writeLock.unlock();
		}
	}
}