$shm_key = ftok(__FILE__, 't');
/**
 開辟一塊共享內(nèi)存
int $key , string $flags , int $mode , int $size 
$flags: a:訪問只讀內(nèi)存段
    c:創(chuàng)建一個(gè)新內(nèi)存段，或者如果該內(nèi)存段已存在，嘗試打開它進(jìn)行讀寫
    w:可讀寫的內(nèi)存段
    n:創(chuàng)建一個(gè)新內(nèi)存段，如果該內(nèi)存段已存在，則會失敗
$mode: 八進(jìn)制格式 0655
$size: 開辟的數(shù)據(jù)大小 字節(jié)
 */
$shm_id = shmop_open($shm_key, "c", 0644, 1024);
/**
 * 寫入數(shù)據(jù) 數(shù)據(jù)必須是字符串格式 , 最后一個(gè)指偏移量
 * 注意：偏移量必須在指定的范圍之內(nèi)，否則寫入不了
 * 
 */
$size = shmop_write($shm_id, 'songjiankang', 0);
echo "write into {$size}";
#讀取的范圍也必須在申請的內(nèi)存范圍之內(nèi),否則失敗
$data = shmop_read($shm_id, 0, 100);
var_dump($data);
#刪除 只是做一個(gè)刪除標(biāo)志位，同時(shí)不在允許新的進(jìn)程進(jìn)程讀取，當(dāng)在沒有任何進(jìn)程讀取時(shí)系統(tǒng)會自動刪除
shmop_delete($shm_id);
#關(guān)閉該內(nèi)存段
shmop_close($shm_id);

// Get the file token key
$key = ftok(__DIR__, 'a');
// 創(chuàng)建一個(gè)共享內(nèi)存
$shm_id = shm_attach($key, 1024, 777); // resource type
if ($shm_id === false) {
  die('Unable to create the shared memory segment');
}
#設(shè)置一個(gè)值
shm_put_var($shm_id, 111, 'value');
#刪除一個(gè)key
//shm_remove_var($shm_id, 111);
#獲取一個(gè)值
$value = shm_get_var($shm_id, 111);
var_dump($value);
#檢測一個(gè)key是否存在
// var_dump(shm_has_var($shm_id, 111));
#從系統(tǒng)中移除
shm_remove($shm_id);
#關(guān)閉和共享內(nèi)存的連接
shm_detach($shm_id);

/**
* 使用共享內(nèi)存和信號量實(shí)現(xiàn)
* 
* 支持多進(jìn)程, 支持各種數(shù)據(jù)類型的存儲
* 注: 完成入隊(duì)或出隊(duì)操作,盡快使用unset(), 以釋放臨界區(qū)
*
*/
class ShmQueue
{
  private $maxQSize = 0; // 隊(duì)列最大長度
  private $front = 0; // 隊(duì)頭指針
  private $rear = 0; // 隊(duì)尾指針
  private $blockSize = 256; // 塊的大小(byte)
  private $memSize = 25600; // 最大共享內(nèi)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(gè)信號量
    $this->semId = sem_get($shmkey, 1);
    sem_acquire($this->semId); // 申請進(jìn)入臨界區(qū)
    $this->init();
  }
  private function init ()
  {
    if (file_exists($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(duì)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(duì)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";
    echo '';
    echo strlen($data);
    echo '';
    echo $this->blockSize - 1;
    echo '';
    if (strlen($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(qū), 釋放信號量
  }
}
/*
 * // 進(jìn)隊(duì)操作 $shmq = new ShmQueue(); $data = 'test data'; $shmq->enQueue($data);
 * unset($shmq); // 出隊(duì)操作 $shmq = new ShmQueue(); $data = $shmq->deQueue();
 * unset($shmq);
 */