<?php
/**
 * PHP memcache 环形队列类
 * 原作者 LKK/lianq.net
 * 修改 FoxHunter
 * 因业务需要只保留的队列中的Pop和Push,修改过期时间为0即永久
 */
class MQueue
{
 public static $client;
 private $expire; //过期时间,秒,1~2592000,即30天内
 private $sleepTime; //等待解锁时间,微秒
 private $queueName; //队列名称,唯一值
 private $retryNum; //尝试次数
 private $MAXNUM; //最大队列容量
 private $canRewrite; //是否可以覆写开关，满出来的内容从头部开始覆盖重写原来的数据
 private $HEAD; //下一步要进入的指针位置
 private $TAIL; //下一步要进入的指针位置
 private $LEN; //队列现有长度
 const LOCK_KEY = '_Fox_MQ_LOCK_'; //锁存储标示
 const LENGTH_KEY = '_Fox_MQ_LENGTH_'; //队列现长度存储标示
 const VALU_KEY = '_Fox_MQ_VAL_'; //队列键值存储标示
 const HEAD_KEY = '_Fox_MQ_HEAD_'; //队列HEAD指针位置标示
 const TAIL_KEY = '_Fox_MQ_TAIL_'; //队列TAIL指针位置标示
 /*
 * 构造函数
 * 对于同一个$queueName，实例化时必须保障构造函数的参数值一致，否则pop和push会导队列顺序混乱
 */
 public function __construct($queueName = '', $maxqueue = 1, $canRewrite = false, $expire = 0, $config = '')
 {
 if (empty($config)) {
  self::$client = memcache_pconnect('127.0.0.1', 11211);
 } elseif (is_array($config)) { //array('host'=>'127.0.0.1','port'=>'11211')
  self::$client = memcache_pconnect($config['host'], $config['port']);
 } elseif (is_string($config)) { //"127.0.0.1:11211"
  $tmp  = explode(':', $config);
  $conf['host'] = isset($tmp[0]) ? $tmp[0] : '127.0.0.1';
  $conf['port'] = isset($tmp[1]) ? $tmp[1] : '11211';
  self::$client = memcache_pconnect($conf['host'], $conf['port']);
 }
 if (!self::$client)
  return false;
 ignore_user_abort(true); //当客户断开连接,允许继续执行
 set_time_limit(0); //取消脚本执行延时上限
 $this->access = false;
 $this->sleepTime = 1000;
 $expire  = (empty($expire)) ? 0 : (int) $expire + 1;
 $this->expire = $expire;
 $this->queueName = $queueName;
 $this->retryNum = 20000;
 $this->MAXNUM = $maxqueue != null ? $maxqueue : 1;
 $this->canRewrite = $canRewrite;
 $this->getHeadAndTail();
 if (!isset($this->HEAD) || empty($this->HEAD))
  $this->HEAD = 0;
 if (!isset($this->TAIL) || empty($this->TAIL))
  $this->TAIL = 0;
 if (!isset($this->LEN) || empty($this->LEN))
  $this->LEN = 0;
 }
 //获取队列首尾指针信息和长度
 private function getHeadAndTail()
 {
 $this->HEAD = (int) memcache_get(self::$client, $this->queueName . self::HEAD_KEY);
 $this->TAIL = (int) memcache_get(self::$client, $this->queueName . self::TAIL_KEY);
 $this->LEN = (int) memcache_get(self::$client, $this->queueName . self::LENGTH_KEY);
 }
 // 利用memcache_add原子性加锁
 private function lock()
 {
 if ($this->access === false) {
  $i = 0;
  while (!memcache_add(self::$client, $this->queueName . self::LOCK_KEY, 1, false, $this->expire)) {
  usleep($this->sleepTime);
  @$i++;
  if ($i > $this->retryNum) { //尝试等待N次
   return false;
   break;
  }
  }
  return $this->access = true;
 }
 return false;
 }
 //更新头部指针指向,指向下一个位置
 private function incrHead()
 {
 //$this->getHeadAndTail(); //获取最新指针信息 ,由于本方法体均在锁内调用，其锁内已调用了此方法，本行注释
 $this->HEAD++; //头部指针下移
 if ($this->HEAD >= $this->MAXNUM) {
  $this->HEAD = 0; //边界值修正
 }
 ;
 $this->LEN--; //Head的移动由Pop触发，所以相当于数量减少
 if ($this->LEN < 0) {
  $this->LEN = 0; //边界值修正
 }
 ;
 memcache_set(self::$client, $this->queueName . self::HEAD_KEY, $this->HEAD, false, $this->expire); //更新
 memcache_set(self::$client, $this->queueName . self::LENGTH_KEY, $this->LEN, false, $this->expire); //更新
 }
 //更新尾部指针指向，指向下一个位置
 private function incrTail()
 {
 //$this->getHeadAndTail(); //获取最新指针信息，由于本方法体均在锁内调用，其锁内已调用了此方法，本行注释
 $this->TAIL++; //尾部指针下移
 if ($this->TAIL >= $this->MAXNUM) {
  $this->TAIL = 0; //边界值修正
 }
 ;
 $this->LEN++; //Head的移动由Push触发，所以相当于数量增加
 if ($this->LEN >= $this->MAXNUM) {
  $this->LEN = $this->MAXNUM; //边界值长度修正
 }
 ;
 memcache_set(self::$client, $this->queueName . self::TAIL_KEY, $this->TAIL, false, $this->expire); //更新
 memcache_set(self::$client, $this->queueName . self::LENGTH_KEY, $this->LEN, false, $this->expire); //更新
 }
 // 解锁
 private function unLock()
 {
 memcache_delete(self::$client, $this->queueName . self::LOCK_KEY);
 $this->access = false;
 }
 //判断是否满队列
 public function isFull()
 {
 //外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有lock，所以可信
 if ($this->canRewrite)
  return false;
 return $this->LEN == $this->MAXNUM ? true : false;
 }
 //判断是否为空
 public function isEmpty()
 {
 //外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有lock，所以可信
 return $this->LEN == 0 ? true : false;
 }
 public function getLen()
 {
 //外部直接调用的时候由于没有锁所以此处的值是个大概值，并不很准确，但是内部调用由于在前面有lock，所以可信
 return $this->LEN;
 }
 /*
 * push值
 * @param mixed 值
 * @return bool
 */
 public function push($data = '')
 {
 $result = false;
 if (empty($data))
  return $result;
 if (!$this->lock()) {
  return $result;
 }
 $this->getHeadAndTail(); //获取最新指针信息
 if ($this->isFull()) { //只有在非覆写下才有Full概念
  $this->unLock();
  return false;
 }
 if (memcache_set(self::$client, $this->queueName . self::VALU_KEY . $this->TAIL, $data, MEMCACHE_COMPRESSED, $this->expire)) {
  //当推送后，发现尾部和头部重合（此时指针还未移动），且右边仍有未由Head读取的数据，那么移动Head指针，避免尾部指针跨越Head
  if ($this->TAIL == $this->HEAD && $this->LEN >= 1) {
  $this->incrHead();
  }
  $this->incrTail(); //移动尾部指针
  $result = true;
 }
 $this->unLock();
 return $result;
 }
 /*
 * Pop一个值
 * @param [length] int 队列长度
 * @return array
 */
 public function pop($length = 0)
 {
 if (!is_numeric($length))
  return false;
 if (!$this->lock())
  return false;
 $this->getHeadAndTail();
 if (empty($length))
  $length = $this->LEN; //默认读取所有
 if ($this->isEmpty()) {
  $this->unLock();
  return false;
 }
 //获取长度超出队列长度后进行修正
 if ($length > $this->LEN)
  $length = $this->LEN;
 $data = $this->popKeyArray($length);
 $this->unLock();
 return $data;
 }
 /*
 * pop某段长度的值
 * @param [length] int 队列长度
 * @return array
 */
 private function popKeyArray($length)
 {
 $result = array();
 if (empty($length))
  return $result;
 for ($k = 0; $k < $length; $k++) {
  $result[] = @memcache_get(self::$client, $this->queueName . self::VALU_KEY . $this->HEAD);
  @memcache_delete(self::$client, $this->queueName . self::VALU_KEY . $this->HEAD, 0);
  //当提取值后，发现头部和尾部重合（此时指针还未移动），且右边没有数据，即队列中最后一个数据被完全掏空，此时指针停留在本地不移动，队列长度变为0
  if ($this->TAIL == $this->HEAD && $this->LEN <= 1) {
  $this->LEN = 0;
  memcache_set(self::$client, $this->queueName . self::LENGTH_KEY, $this->LEN, false, $this->expire); //更新
  break;
  } else {
  $this->incrHead(); //首尾未重合，或者重合但是仍有未读取出的数据，均移动HEAD指针到下一处待读取位置
  }
 }
 return $result;
 }
 /*
 * 重置队列
 * * @return NULL
 */
 private function reset($all = false)
 {
 if ($all) {
  memcache_delete(self::$client, $this->queueName . self::HEAD_KEY, 0);
  memcache_delete(self::$client, $this->queueName . self::TAIL_KEY, 0);
  memcache_delete(self::$client, $this->queueName . self::LENGTH_KEY, 0);
 } else {
  $this->HEAD = $this->TAIL = $this->LEN = 0;
  memcache_set(self::$client, $this->queueName . self::HEAD_KEY, 0, false, $this->expire);
  memcache_set(self::$client, $this->queueName . self::TAIL_KEY, 0, false, $this->expire);
  memcache_set(self::$client, $this->queueName . self::LENGTH_KEY, 0, false, $this->expire);
 }
 }
 /*
 * 清除所有memcache缓存数据
 * @return NULL
 */
 public function memFlush()
 {
 memcache_flush(self::$client);
 }
 public function clear($all = false)
 {
 if (!$this->lock())
  return false;
 $this->getHeadAndTail();
 $Head = $this->HEAD;
 $Length = $this->LEN;
 $curr = 0;
 for ($i = 0; $i < $Length; $i++) {
  $curr = $this->$Head + $i;
  if ($curr >= $this->MAXNUM) {
  $this->HEAD = $curr = 0;
  }
  @memcache_delete(self::$client, $this->queueName . self::VALU_KEY . $curr, 0);
 }
 $this->unLock();
 $this->reset($all);
 return true;
 }
}