CODESAMPLE

Object Pool - Java

Object Pool Java

The Object Pool pattern manages a pool of reusable objects to avoid the expensive operation of repeatedly creating and destroying them. This is particularly useful for objects that are resource-intensive to initialize. The code demonstrates a simple generic Object Pool using a java.util.concurrent.ArrayBlockingQueue to store available objects. acquireObject() blocks if no object is available, and releaseObject() returns an object to the pool. The PooledObjectFactory interface allows for custom object creation. This implementation leverages Java’s generics for type safety and uses a blocking queue for thread-safe access, fitting idiomatic Java concurrency practices.

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

interface PooledObjectFactory<T> {
    T createObject();
}

public class ObjectPool<T> {

    private final BlockingQueue<T> pool;
    private final PooledObjectFactory<T> factory;
    private final int poolSize;

    public ObjectPool(int poolSize, PooledObjectFactory<T> factory) {
        this.poolSize = poolSize;
        this.factory = factory;
        this.pool = new ArrayBlockingQueue<>(poolSize);

        // Pre-populate the pool
        for (int i = 0; i < poolSize; i++) {
            pool.add(factory.createObject());
        }
    }

    public T acquireObject() throws InterruptedException {
        return pool.take(); // Blocks until an object is available
    }

    public void releaseObject(T obj) {
        if (pool.offer(obj)) {
            // Object added back to the pool successfully
        } else {
            // Pool is full, potentially log or handle the situation
            System.err.println("Pool is full. Object discarded.");
        }
    }

    public int getPoolSize() {
        return poolSize;
    }

    public int getAvailableObjects() {
        return pool.size();
    }

    public static void main(String[] args) throws InterruptedException {
        // Example Usage with a simple object
        ObjectPool<String> stringPool = new ObjectPool<>(5, String::new);

        System.out.println("Available objects: " + stringPool.getAvailableObjects());

        String obj1 = stringPool.acquireObject();
        obj1 = "Hello";
        System.out.println("Acquired object: " + obj1);
        System.out.println("Available objects: " + stringPool.getAvailableObjects());

        stringPool.releaseObject(obj1);
        System.out.println("Released object. Available objects: " + stringPool.getAvailableObjects());
    }
}