package com.wsx;


import lombok.Data;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.atomic.AtomicIntegerArray;

@Data
public class ConcurrentPool {
    private final Logger logger = (Logger) LoggerFactory.getLogger(Connection.class);
    private final int poolSize;
    private Connection[] connections;
    private AtomicIntegerArray states;

    public ConcurrentPool(int poolSize) {
        this.poolSize = poolSize;
        this.connections = new Connection[poolSize];
        this.states = new AtomicIntegerArray(new int[poolSize]);
        for (int i = 0; i < poolSize; i++) {
            connections[i] = new Connection();
        }
    }

    public Connection borrow() {
        while (true) {
            for (int i = 0; i < poolSize; i++) {
                if (states.get(i) == 0) {
                    if (states.compareAndSet(i, 0, 1)) {
                        logger.debug("return {}",i);
                        return connections[i];
                    }
                }
            }
            synchronized (this) {
                try {
                    logger.debug("wait...");
                    this.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public void free(Connection conn) {
        for (int i = 0; i < poolSize; i++) {
            if (conn == connections[i]) {
                states.set(i, 0);
                synchronized (this) {
                    logger.debug("notifyAll...");
                    this.notifyAll();
                }
                break;
            }
        }
    }
}