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标题: PHP实现的memcache环形队列类实例 [打印本页]

作者: 新格网络 时间: 2018-2-14 05:43

本文实例讲述了PHP实现的memcache环形队列类。分享给大家供大家参考。具体如下：
这里介绍了PHP实现的memcache环形队列类。没咋学过数据结构，因为业务需要，所以只是硬着头皮模拟的！参考PHP memcache 队列代码。为使队列随时可入可出，且不受int长度越界危险（单链采取Head自增的话不作处理有越界可能），所以索性改写成环形队列。可能还有BUG，忘见谅！
'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:

ENGTH_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:

OCK_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 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:

ENGTH_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:

ENGTH_KEY, $this->LEN, false, $this->expire); //更新
}
// 解锁
private function unLock()
{
memcache_delete(self::$client, $this->queueName . self:

OCK_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 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 && $this->LEN LEN = 0;
memcache_set(self::$client, $this->queueName . self:

ENGTH_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:

ENGTH_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:

ENGTH_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 $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;
}
}
希望本文所述对大家的php程序设计有所帮助。


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