http://blog.s135.com/httpsqs/
例如:郵件隊列、任務隊列、消息隊列、Feed隊列
用戶註冊成功,而不是直接給用戶發送email,而是把新註冊的用戶的email插入到郵件任務隊列中。由服務器給用戶發送郵件。發送成功或發送N次失敗的將從隊列中清除。
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如果是普通的網站,如平均每秒產生的隊列消息不超過上百,則用低成本數據庫+輪詢程序,完全可行.
具體思路如下:
1. 當產生消息時,使用MySQL的表保存產生的新隊列消息,並記錄一些運行參數
2. 服務器上開啓cron(Linux),或開啓自動刷新的瀏覽器窗口(Windows),比如按半分鐘運行一次輪詢程序
3. 這些輪詢程序每次取出一些隊列消息,進行處理,處理成功或是處理失敗N次後,刪除MySQL隊列表中的相關記錄
如此反覆,即可實現.我覺得這個方式的優點是:
1. 實現最爲容易,可行性最好
2. 低成本的開發或是平臺部署成本
在我們的生產環境中,這種方式得到了大量實踐,表現良好.
當然,如果確實是"高性能",那麼這個問題更不問題,既然需要高性能,說明網站的規模不一般,既然規模不一般,還會缺錢嗎? 不缺錢,就可以找這方面的專家去解決.
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/**
* 使用共享內存的PHP循環內存隊列實現
* 支持多進程, 支持各種數據類型的存儲,需要pcntl擴展的支持。
* 注: 完成入隊或出隊操作,儘快使用unset(), 以釋放臨界區
*
* @author [email protected]
* @created 2009-12-23
*/
class SHMQueue
{
private $maxQSize = 0; // 隊列最大長度
private $front = 0; // 隊頭指針
private $rear = 0; // 隊尾指針
private $blockSize = 256; // 塊的大小(byte)
private $memSize = 25600; // 最大共享內存(byte)
private $shmId = 0;
private $filePtr = './shmq.ptr';
private $semId = 0;
public function __construct()
{
$shmkey = ftok(__FILE__, 't');
$this->shmId = shmop_open($shmkey, "c", 0644, $this->memSize );
$this->maxQSize = $this->memSize / $this->blockSize;
// 申請一個信號量
$this->semId = sem_get($shmkey, 1);
sem_acquire($this->semId); // 申請進入臨界區
$this->init();
}
private function init()
{
if ( file_exists($this->filePtr) ){
$contents = file_get_contents($this->filePtr);
$data = explode( '|', $contents );
if ( isset($data[0]) && isset($data[1])){
$this->front = (int)$data[0];
$this->rear = (int)$data[1];
}
}
}
public function getLength()
{
return (($this->rear - $this->front + $this->memSize) % ($this->memSize) )/$this->blockSize;
}
public function enQueue( $value )
{
if ( $this->ptrInc($this->rear) == $this->front ){ // 隊滿
return false;
}
$data = $this->encode($value);
shmop_write($this->shmId, $data, $this->rear );
$this->rear = $this->ptrInc($this->rear);
return true;
}
public function deQueue()
{
if ( $this->front == $this->rear ){ // 隊空
return false;
}
$value = shmop_read($this->shmId, $this->front, $this->blockSize-1);
$this->front = $this->ptrInc($this->front);
return $this->decode($value);
}
private function ptrInc( $ptr )
{
return ($ptr + $this->blockSize) % ($this->memSize);
}
private function encode( $value )
{
$data = serialize($value) . "__eof";
if ( strlen($data) > $this->blockSize -1 ){
throw new Exception(strlen($data)." is overload block size!");
}
return $data;
}
private function decode( $value )
{
$data = explode("__eof", $value);
return unserialize($data[0]);
}
public function __destruct()
{
$data = $this->front . '|' . $this->rear;
file_put_contents($this->filePtr, $data);
sem_release($this->semId); // 出臨界區, 釋放信號量
}
}
使用的樣例代碼如下:
// 進隊操作
$shmq = new SHMQueue();
$data = 'test data';
$shmq->enQueue($data);
unset($shmq);
// 出隊操作
$shmq = new SHMQueue();
$data = $shmq->deQueue();
unset($shmq);
PHP下用Memcache 實現消息隊列
Memcache 一般用於緩存服務。但是很多時候,比如一個消息廣播系統,需要一個消息隊列。直接從數據庫取消息,負載往往不行。如果將整個消息隊列用一個key緩存到memcache裏面,
對於一個很大的消息隊列,頻繁進行進行大數據庫的序列化 和 反序列化,有太耗費。下面是我用PHP 實現的一個消息隊列,只需要在尾部插入一個數據,就操作尾部,不用操作整個消息隊列進行讀取,與操作。但是,這個消息隊列不是線程安全的,我只是儘量的避免了衝突的可能性。如果消息不是非常的密集,比如幾秒鐘才一個,還是可以考慮這樣使用的。
如果你要實現線程安全的,一個建議是通過文件進行鎖定,然後進行操作。下面是代碼:
{
private $memcache;
private $name;
private $prefix;
function __construct($maxSize, $name, $memcache, $prefix = "__memcache_queue__")
{
if ($memcache == null) {
throw new Exception("memcache object is null, new the object first.");
}
$this->memcache = $memcache;
$this->name = $name;
$this->prefix = $prefix;
$this->maxSize = $maxSize;
$this->front = 0;
$this->real = 0;
$this->size = 0;
}
function __get($name)
{
return $this->get($name);
}
function __set($name, $value)
{
$this->add($name, $value);
return $this;
}
function isEmpty()
{
return $this->size == 0;
}
function isFull()
{
return $this->size == $this->maxSize;
}
function enQueue($data)
{
if ($this->isFull()) {
throw new Exception("Queue is Full");
}
$this->increment("size");
$this->set($this->real, $data);
$this->set("real", ($this->real + 1) % $this->maxSize);
return $this;
}
function deQueue()
{
if ($this->isEmpty()) {
throw new Exception("Queue is Empty");
}
$this->decrement("size");
$this->delete($this->front);
$this->set("front", ($this->front + 1) % $this->maxSize);
return $this;
}
function getTop()
{
return $this->get($this->front);
}
function getAll()
{
return $this->getPage();
}
function getPage($offset = 0, $limit = 0)
{
if ($this->isEmpty() || $this->size < $offset) {
return null;
}
$keys[] = $this->getKeyByPos(($this->front + $offset) % $this->maxSize);
$num = 1;
for ($pos = ($this->front + $offset + 1) % $this->maxSize; $pos != $this->real; $pos = ($pos + 1) % $this->maxSize)
{
$keys[] = $this->getKeyByPos($pos);
$num++;
if ($limit > 0 && $limit == $num) {
break;
}
}
return array_values($this->memcache->get($keys));
}
function makeEmpty()
{
$keys = $this->getAllKeys();
foreach ($keys as $value) {
$this->delete($value);
}
$this->delete("real");
$this->delete("front");
$this->delete("size");
$this->delete("maxSize");
}
private function getAllKeys()
{
if ($this->isEmpty())
{
return array();
}
$keys[] = $this->getKeyByPos($this->front);
for ($pos = ($this->front + 1) % $this->maxSize; $pos != $this->real; $pos = ($pos + 1) % $this->maxSize)
{
$keys[] = $this->getKeyByPos($pos);
}
return $keys;
}
private function add($pos, $data)
{
$this->memcache->add($this->getKeyByPos($pos), $data);
return $this;
}
private function increment($pos)
{
return $this->memcache->increment($this->getKeyByPos($pos));
}
private function decrement($pos)
{
$this->memcache->decrement($this->getKeyByPos($pos));
}
private function set($pos, $data)
{
$this->memcache->set($this->getKeyByPos($pos), $data);
return $this;
}
private function get($pos)
{
return $this->memcache->get($this->getKeyByPos($pos));
}
private function delete($pos)
{
return $this->memcache->delete($this->getKeyByPos($pos));
}
private function getKeyByPos($pos)
{
return $this->prefix . $this->name . $pos;
}
}