Donkeyid.php

<?php

/**
 * Created by PhpStorm.
 * User: ClownFish
 * Email: 187231450#qq.com
 * Date: 16-8-5
 * Time: 下午2:14
 */
class Donkeyid
{
    private $node_id;
    private $epoch;
    private $table;

    const snowflake = 0;

    const TIMESTAMP_BITS = 42;
    const NODE_ID_BITS=12;
    const SEQUENCE_BITS = 9;

    const TIMESTAMP_LEFT_SHIFT = 21;
    const NODE_ID_LEFT_SHIFT=9;


    public function __construct($node_id=false,$epoch=false)
    {
        if ($node_id === false){
            $node_id = ini_get("donkeyid.node_id");
        }
        if ($epoch === false){
            $epoch = ini_get("donkeyid.epoch");
        }
        $this->node_id = ($node_id == false || $node_id < 0)?0:$node_id;
        $this->epoch = ($epoch == false || $epoch < 0)?0:$epoch;
        $this->create_table();
    }

    /**
     * 创建共享内存
     */
    private function create_table()
    {
        $this->table = new swoole_table(3);
        $this->table->column("last_timestamp",swoole_table::TYPE_INT, 8);
        $this->table->column("sequence",swoole_table::TYPE_INT, 4);
        $this->table->create();
    }

    /**
     * 获取当前毫秒
     * @return int
     */
    private function get_curr_timestamp_ms()
    {
        return (int)(microtime(true)*1000);
    }

    /**
     * 暂停一毫秒
     * @return int
     */
    private function wait_next_ms()
    {
        usleep(1000);
        return $this->get_curr_timestamp_ms();
    }

    /**
     * 获取id
     * @return int
     */
    public function dk_get_next_id()
    {
        $now = $this->get_curr_timestamp_ms();
        $this->table->lock();
        $col = $this->table->get(self::snowflake);
        if ($col == false || $col["last_timestamp"] > $now){
            $last_timestamp = $now;
            $sequence =  rand(0,10) % 2;
        }else{
            $last_timestamp = $col["last_timestamp"];
            $sequence = $col["sequence"];
        }
        if ($now == $last_timestamp){
            $sequence = ($sequence+1)&((-1^(-1<<self::SEQUENCE_BITS)));
            if ($sequence == 0){
                $now = $this->wait_next_ms();
            }
        }
        $this->table->set(self::snowflake,array("last_timestamp"=>$now,"sequence"=>$sequence));
        $id = (($now-($this->epoch*1000)&(-1^(-1<<self::TIMESTAMP_BITS)))<<self::TIMESTAMP_LEFT_SHIFT)
            |(($this->node_id&(-1^(-1<<self::NODE_ID_BITS)))<<self::NODE_ID_LEFT_SHIFT)
            |($sequence);

        $this->table->unlock();
        return $id;
    }

    public function dk_parse_id($id)
    {
        $ret["time"] =  ($id>>self::TIMESTAMP_LEFT_SHIFT)+($this->epoch*1000);
        $ret["node_id"] = ($id>>self::NODE_ID_LEFT_SHIFT)&(-1^(-1<<self::NODE_ID_BITS));
        $ret["sequence"] = $id&(-1^(-1<<self::SEQUENCE_BITS));
        return $ret;
    }
}