Detailed explanation of beanstalkd message queue in php and sharing of classes

<?php
namespace Common\Business;
/**
 * beanstalk: A minimalistic PHP beanstalk client.
 *
 * Copyright (c) 2009-2015 David Persson
 *
 * Distributed under the terms of the MIT License.
 * Redistributions of files must retain the above copyright notice.
 */
 
use RuntimeException;
 
/**
 * An interface to the beanstalk queue service. Implements the beanstalk
 * protocol spec 1.9. Where appropriate the documentation from the protocol
 * has been added to the docblocks in this class.
 *
 * @link https://github.com/kr/beanstalkd/blob/master/doc/protocol.txt
 */
class BeanStalk {
 
  /**
   * Minimum priority value which can be assigned to a job. The minimum
   * priority value is also the _highest priority_ a job can have.
   *
   * @var integer
   */
  const MIN_PRIORITY = 0;
 
  /**
   * Maximum priority value which can be assigned to a job. The maximum
   * priority value is also the _lowest priority_ a job can have.
   *
   * @var integer
   */
  const MAX_PRIORITY = 4294967295;
 
  /**
   * Holds a boolean indicating whether a connection to the server is
   * currently established or not.
   *
   * @var boolean
   */
  public $connected = false;
 
  /**
   * Holds configuration values.
   *
   * @var array
   */
  protected $_config = [];
 
  /**
   * The current connection resource handle (if any).
   *
   * @var resource
   */
  protected $_connection;
 
  /**
   * Constructor.
   *
   * @param array $config An array of configuration values:
   *    - `&#39;persistent&#39;` Whether to make the connection persistent or
   *             not, defaults to `true` as the FAQ recommends
   *             persistent connections.
   *    - `&#39;host&#39;`    The beanstalk server hostname or IP address to
   *             connect to, defaults to `127.0.0.1`.
   *    - `&#39;port&#39;`    The port of the server to connect to, defaults
   *             to `11300`.
   *    - `&#39;timeout&#39;`   Timeout in seconds when establishing the
   *             connection, defaults to `1`.
   *    - `&#39;logger&#39;`   An instance of a PSR-3 compatible logger.
   *
   * @link https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-3-logger-interface.md
   * @return void
   */
  public function __construct(array $config = []) {
    $defaults = [
      &#39;persistent&#39; => true,
      &#39;host&#39; => &#39;127.0.0.1&#39;,
      &#39;port&#39; => 11300,
      &#39;timeout&#39; => 1,
      &#39;logger&#39; => null
    ];
    $this->_config = $config + $defaults;
  }
 
  /**
   * Destructor, disconnects from the server.
   *
   * @return void
   */
  public function __destruct() {
    $this->disconnect();
  }
 
  /**
   * Initiates a socket connection to the beanstalk server. The resulting
   * stream will not have any timeout set on it. Which means it can wait
   * an unlimited amount of time until a packet becomes available. This
   * is required for doing blocking reads.
   *
   * @see \Beanstalk\Client::$_connection
   * @see \Beanstalk\Client::reserve()
   * @return boolean `true` if the connection was established, `false` otherwise.
   */
  public function connect() {
    if (isset($this->_connection)) {
      $this->disconnect();
    }
    $errNum = &#39;&#39;;
    $errStr = &#39;&#39;;
    $function = $this->_config[&#39;persistent&#39;] ? &#39;pfsockopen&#39; : &#39;fsockopen&#39;;
    $params = [$this->_config[&#39;host&#39;], $this->_config[&#39;port&#39;], &$errNum, &$errStr];
 
    if ($this->_config[&#39;timeout&#39;]) {
      $params[] = $this->_config[&#39;timeout&#39;];
    }
    $this->_connection = @call_user_func_array($function, $params);
 
    if (!empty($errNum) || !empty($errStr)) {
      $this->_error("{$errNum}: {$errStr}");
    }
 
    $this->connected = is_resource($this->_connection);
 
    if ($this->connected) {
      stream_set_timeout($this->_connection, -1);
    }
    return $this->connected;
  }
 
  /**
   * Closes the connection to the beanstalk server by first signaling
   * that we want to quit then actually closing the socket connection.
   *
   * @return boolean `true` if diconnecting was successful.
   */
  public function disconnect() {
    if (!is_resource($this->_connection)) {
      $this->connected = false;
    } else {
      $this->_write(&#39;quit&#39;);
      $this->connected = !fclose($this->_connection);
 
      if (!$this->connected) {
        $this->_connection = null;
      }
    }
    return !$this->connected;
  }
 
  /**
   * Pushes an error message to the logger, when one is configured.
   *
   * @param string $message The error message.
   * @return void
   */
  protected function _error($message) {
    if ($this->_config[&#39;logger&#39;]) {
      $this->_config[&#39;logger&#39;]->error($message);
    }
  }
 
  public function errors()
  {
    return $this->_config[&#39;logger&#39;];
  }
  /**
   * Writes a packet to the socket. Prior to writing to the socket will
   * check for availability of the connection.
   *
   * @param string $data
   * @return integer|boolean number of written bytes or `false` on error.
   */
  protected function _write($data) {
    if (!$this->connected) {
      $message = &#39;No connecting found while writing data to socket.&#39;;
      throw new RuntimeException($message);
    }
 
    $data .= "\r\n";
    return fwrite($this->_connection, $data, strlen($data));
  }
 
  /**
   * Reads a packet from the socket. Prior to reading from the socket
   * will check for availability of the connection.
   *
   * @param integer $length Number of bytes to read.
   * @return string|boolean Data or `false` on error.
   */
  protected function _read($length = null) {
    if (!$this->connected) {
      $message = &#39;No connection found while reading data from socket.&#39;;
      throw new RuntimeException($message);
    }
    if ($length) {
      if (feof($this->_connection)) {
        return false;
      }
      $data = stream_get_contents($this->_connection, $length + 2);
      $meta = stream_get_meta_data($this->_connection);
 
      if ($meta[&#39;timed_out&#39;]) {
        $message = &#39;Connection timed out while reading data from socket.&#39;;
        throw new RuntimeException($message);
      }
      $packet = rtrim($data, "\r\n");
    } else {
      $packet = stream_get_line($this->_connection, 16384, "\r\n");
    }
    return $packet;
  }
 
  /* Producer Commands */
 
  /**
   * The `put` command is for any process that wants to insert a job into the queue.
   *
   * @param integer $pri Jobs with smaller priority values will be scheduled
   *    before jobs with larger priorities. The most urgent priority is
   *    0; the least urgent priority is 4294967295.
   * @param integer $delay Seconds to wait before putting the job in the
   *    ready queue. The job will be in the "delayed" state during this time.
   * @param integer $ttr Time to run - Number of seconds to allow a worker to
   *    run this job. The minimum ttr is 1.
   * @param string $data The job body.
   * @return integer|boolean `false` on error otherwise an integer indicating
   *     the job id.
   */
  public function put($pri, $delay, $ttr, $data) {
    $this->_write(sprintf("put %d %d %d %d\r\n%s", $pri, $delay, $ttr, strlen($data), $data));
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;INSERTED&#39;:
      case &#39;BURIED&#39;:
        return (integer) strtok(&#39; &#39;); // job id
      case &#39;EXPECTED_CRLF&#39;:
      case &#39;JOB_TOO_BIG&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * The `use` command is for producers. Subsequent put commands will put
   * jobs into the tube specified by this command. If no use command has
   * been issued, jobs will be put into the tube named `default`.
   *
   * @param string $tube A name at most 200 bytes. It specifies the tube to
   *    use. If the tube does not exist, it will be created.
   * @return string|boolean `false` on error otherwise the name of the tube.
   */
  public function useTube($tube) {
    $this->_write(sprintf(&#39;use %s&#39;, $tube));
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;USING&#39;:
        return strtok(&#39; &#39;);
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Pause a tube delaying any new job in it being reserved for a given time.
   *
   * @param string $tube The name of the tube to pause.
   * @param integer $delay Number of seconds to wait before reserving any more
   *    jobs from the queue.
   * @return boolean `false` on error otherwise `true`.
   */
  public function pauseTube($tube, $delay) {
    $this->_write(sprintf(&#39;pause-tube %s %d&#39;, $tube, $delay));
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;PAUSED&#39;:
        return true;
      case &#39;NOT_FOUND&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /* Worker Commands */
 
  /**
   * Reserve a job (with a timeout).
   *
   * @param integer $timeout If given specifies number of seconds to wait for
   *    a job. `0` returns immediately.
   * @return array|false `false` on error otherwise an array holding job id
   *     and body.
   */
  public function reserve($timeout = null) {
    if (isset($timeout)) {
      $this->_write(sprintf(&#39;reserve-with-timeout %d&#39;, $timeout));
    } else {
      $this->_write(&#39;reserve&#39;);
    }
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;RESERVED&#39;:
        return [
          &#39;id&#39; => (integer) strtok(&#39; &#39;),
          &#39;body&#39; => $this->_read((integer) strtok(&#39; &#39;))
        ];
      case &#39;DEADLINE_SOON&#39;:
      case &#39;TIMED_OUT&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Removes a job from the server entirely.
   *
   * @param integer $id The id of the job.
   * @return boolean `false` on error, `true` on success.
   */
  public function delete($id) {
    $this->_write(sprintf(&#39;delete %d&#39;, $id));
    $status = $this->_read();
 
    switch ($status) {
      case &#39;DELETED&#39;:
        return true;
      case &#39;NOT_FOUND&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Puts a reserved job back into the ready queue.
   *
   * @param integer $id The id of the job.
   * @param integer $pri Priority to assign to the job.
   * @param integer $delay Number of seconds to wait before putting the job in the ready queue.
   * @return boolean `false` on error, `true` on success.
   */
  public function release($id, $pri, $delay) {
    $this->_write(sprintf(&#39;release %d %d %d&#39;, $id, $pri, $delay));
    $status = $this->_read();
 
    switch ($status) {
      case &#39;RELEASED&#39;:
      case &#39;BURIED&#39;:
        return true;
      case &#39;NOT_FOUND&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Puts a job into the `buried` state Buried jobs are put into a FIFO
   * linked list and will not be touched until a client kicks them.
   *
   * @param integer $id The id of the job.
   * @param integer $pri *New* priority to assign to the job.
   * @return boolean `false` on error, `true` on success.
   */
  public function bury($id, $pri) {
    $this->_write(sprintf(&#39;bury %d %d&#39;, $id, $pri));
    $status = $this->_read();
 
    switch ($status) {
      case &#39;BURIED&#39;:
        return true;
      case &#39;NOT_FOUND&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Allows a worker to request more time to work on a job.
   *
   * @param integer $id The id of the job.
   * @return boolean `false` on error, `true` on success.
   */
  public function touch($id) {
    $this->_write(sprintf(&#39;touch %d&#39;, $id));
    $status = $this->_read();
 
    switch ($status) {
      case &#39;TOUCHED&#39;:
        return true;
      case &#39;NOT_TOUCHED&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Adds the named tube to the watch list for the current connection.
   *
   * @param string $tube Name of tube to watch.
   * @return integer|boolean `false` on error otherwise number of tubes in watch list.
   */
  public function watch($tube) {
    $this->_write(sprintf(&#39;watch %s&#39;, $tube));
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;WATCHING&#39;:
        return (integer) strtok(&#39; &#39;);
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Remove the named tube from the watch list.
   *
   * @param string $tube Name of tube to ignore.
   * @return integer|boolean `false` on error otherwise number of tubes in watch list.
   */
  public function ignore($tube) {
    $this->_write(sprintf(&#39;ignore %s&#39;, $tube));
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;WATCHING&#39;:
        return (integer) strtok(&#39; &#39;);
      case &#39;NOT_IGNORED&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /* Other Commands */
 
  /**
   * Inspect a job by its id.
   *
   * @param integer $id The id of the job.
   * @return string|boolean `false` on error otherwise the body of the job.
   */
  public function peek($id) {
    $this->_write(sprintf(&#39;peek %d&#39;, $id));
    return $this->_peekRead();
  }
 
  /**
   * Inspect the next ready job.
   *
   * @return string|boolean `false` on error otherwise the body of the job.
   */
  public function peekReady() {
    $this->_write(&#39;peek-ready&#39;);
    return $this->_peekRead();
  }
 
  /**
   * Inspect the job with the shortest delay left.
   *
   * @return string|boolean `false` on error otherwise the body of the job.
   */
  public function peekDelayed() {
    $this->_write(&#39;peek-delayed&#39;);
    return $this->_peekRead();
  }
 
  /**
   * Inspect the next job in the list of buried jobs.
   *
   * @return string|boolean `false` on error otherwise the body of the job.
   */
  public function peekBuried() {
    $this->_write(&#39;peek-buried&#39;);
    return $this->_peekRead();
  }
 
  /**
   * Handles response for all peek methods.
   *
   * @return string|boolean `false` on error otherwise the body of the job.
   */
  protected function _peekRead() {
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;FOUND&#39;:
        return [
          &#39;id&#39; => (integer) strtok(&#39; &#39;),
          &#39;body&#39; => $this->_read((integer) strtok(&#39; &#39;))
        ];
      case &#39;NOT_FOUND&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Moves jobs into the ready queue (applies to the current tube).
   *
   * If there are buried jobs those get kicked only otherwise delayed
   * jobs get kicked.
   *
   * @param integer $bound Upper bound on the number of jobs to kick.
   * @return integer|boolean False on error otherwise number of jobs kicked.
   */
  public function kick($bound) {
    $this->_write(sprintf(&#39;kick %d&#39;, $bound));
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;KICKED&#39;:
        return (integer) strtok(&#39; &#39;);
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * This is a variant of the kick command that operates with a single
   * job identified by its job id. If the given job id exists and is in a
   * buried or delayed state, it will be moved to the ready queue of the
   * the same tube where it currently belongs.
   *
   * @param integer $id The job id.
   * @return boolean `false` on error `true` otherwise.
   */
  public function kickJob($id) {
    $this->_write(sprintf(&#39;kick-job %d&#39;, $id));
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;KICKED&#39;:
        return true;
      case &#39;NOT_FOUND&#39;:
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /* Stats Commands */
 
  /**
   * Gives statistical information about the specified job if it exists.
   *
   * @param integer $id The job id.
   * @return string|boolean `false` on error otherwise a string with a yaml formatted dictionary.
   */
  public function statsJob($id) {
    $this->_write(sprintf(&#39;stats-job %d&#39;, $id));
    return $this->_statsRead();
  }
 
  /**
   * Gives statistical information about the specified tube if it exists.
   *
   * @param string $tube Name of the tube.
   * @return string|boolean `false` on error otherwise a string with a yaml formatted dictionary.
   */
  public function statsTube($tube) {
    $this->_write(sprintf(&#39;stats-tube %s&#39;, $tube));
    return $this->_statsRead();
  }
 
  /**
   * Gives statistical information about the system as a whole.
   *
   * @return string|boolean `false` on error otherwise a string with a yaml formatted dictionary.
   */
  public function stats() {
    $this->_write(&#39;stats&#39;);
    return $this->_statsRead();
  }
 
  /**
   * Returns a list of all existing tubes.
   *
   * @return string|boolean `false` on error otherwise a string with a yaml formatted list.
   */
  public function listTubes() {
    $this->_write(&#39;list-tubes&#39;);
    return $this->_statsRead();
  }
 
  /**
   * Returns the tube currently being used by the producer.
   *
   * @return string|boolean `false` on error otherwise a string with the name of the tube.
   */
  public function listTubeUsed() {
    $this->_write(&#39;list-tube-used&#39;);
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;USING&#39;:
        return strtok(&#39; &#39;);
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Returns a list of tubes currently being watched by the worker.
   *
   * @return string|boolean `false` on error otherwise a string with a yaml formatted list.
   */
  public function listTubesWatched() {
    $this->_write(&#39;list-tubes-watched&#39;);
    return $this->_statsRead();
  }
 
  /**
   * Handles responses for all stat methods.
   *
   * @param boolean $decode Whether to decode data before returning it or not. Default is `true`.
   * @return array|string|boolean `false` on error otherwise statistical data.
   */
  protected function _statsRead($decode = true) {
    $status = strtok($this->_read(), &#39; &#39;);
 
    switch ($status) {
      case &#39;OK&#39;:
        $data = $this->_read((integer) strtok(&#39; &#39;));
        return $decode ? $this->_decode($data) : $data;
      default:
        $this->_error($status);
        return false;
    }
  }
 
  /**
   * Decodes YAML data. This is a super naive decoder which just works on
   * a subset of YAML which is commonly returned by beanstalk.
   *
   * @param string $data The data in YAML format, can be either a list or a dictionary.
   * @return array An (associative) array of the converted data.
   */
  protected function _decode($data) {
    $data = array_slice(explode("\n", $data), 1);
    $result = [];
 
    foreach ($data as $key => $value) {
      if ($value[0] === &#39;-&#39;) {
        $value = ltrim($value, &#39;- &#39;);
      } elseif (strpos($value, &#39;:&#39;) !== false) {
        list($key, $value) = explode(&#39;:&#39;, $value);
        $value = ltrim($value, &#39; &#39;);
      }
      if (is_numeric($value)) {
        $value = (integer) $value == $value ? (integer) $value : (float) $value;
      }
      $result[$key] = $value;
    }
    return $result;
  }
}
 
?>