<?php

abstract class CoPool
{
    private $mMaxClient;
    private $mFreeClients;
    private $mUsingCount;
    private $mSuspendCIDS;
    private $mStop;

    public function __construct($max_clients)
    {
        $this->mMaxClient = $max_clients;
        $this->mUsingCount = 0;
        $this->mFreeClients = [];
        $this->mSuspendCIDS = [];
        $this->mStop = false;
    }

    public function get($args)
    {
        if(!empty($this->mFreeClients)) {
            $client = array_shift($this->mFreeClients);
        }
        elseif($this->mUsingCount < $this->mMaxClient) {
            $client = $this->create_client($args);
        }
        else {
            $this->mSuspendCIDS[] = Co::getCid();
            Co::suspend();
            $client = array_shift($this->mFreeClients);
        }
        $this->mUsingCount++;

        return $client;
    }

    public function put($client) {

        $this->mFreeClients[] = $client;
        $this->mUsingCount--;
        $cid = $this->getSuspend();
        if($cid > 0) {
            Co::resume($cid);
        }
    }

    private function getSuspend()
    {
        if(empty($this->mSuspendCIDS)) {
            return 0;
        }
        else {
            $cid = array_shift($this->mSuspendCIDS);
            return $cid;
        }
    }
    public function stoped() {
        return $this->mStop;
    }
    public function stop() {
        $this->mStop = true;
    }

    abstract public function create_client($args);
}