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<?php |
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/** |
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* This file is part of graze/dog-statsd |
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* |
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* Copyright (c) 2017 Nature Delivered Ltd. <https://www.graze.com> |
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* |
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* For the full copyright and license information, please view the LICENSE |
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* file that was distributed with this source code. |
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* |
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* @license https://github.com/graze/dog-statsd/blob/master/LICENSE.md |
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* @link https://github.com/graze/dog-statsd |
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*/ |
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namespace Graze\DogStatsD\Stream; |
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use Graze\DogStatsD\Exception\ConnectionException; |
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/** |
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* StreamWriter will attempt to write a message to a udp socket. |
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* |
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* If the connection fails, it will never try and reconnect to prevent application blocking |
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*/ |
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class StreamWriter implements WriterInterface |
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{ |
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/** |
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* Seconds to wait (as a base) for exponential back-off on connection |
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* |
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* minDelay = RETRY_INTERVAL * (2 ^ num_failed_attempts) |
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* |
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* e.g. |
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* 0, 0.1 0.2 0.4 0.8 1.6 3.2 6.4 12.8 25.6 51.2 102.4 etc... |
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*/ |
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const RETRY_INTERVAL = 0.1; |
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/** |
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* Maximum length of a string to send |
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*/ |
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const MAX_SEND_LENGTH = 1024; |
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const ON_ERROR_ERROR = 'error'; |
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const ON_ERROR_EXCEPTION = 'exception'; |
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const ON_ERROR_IGNORE = 'ignore'; |
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/** @var resource|null */ |
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protected $socket; |
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/** @var string */ |
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private $host; |
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/** @var int */ |
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private $port; |
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/** @var string */ |
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private $onError; |
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/** @var float|null */ |
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private $timeout; |
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/** @var string */ |
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private $instance; |
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/** @var int */ |
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private $numFails = 0; |
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/** @var float */ |
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private $waitTill = 0.0; |
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/** |
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* @param string $instance |
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* @param string $host |
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* @param int $port |
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* @param string $onError What to do on connection error |
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* @param float|null $timeout |
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*/ |
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public function __construct( |
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$instance = 'writer', |
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$host = '127.0.0.1', |
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$port = 8125, |
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$onError = self::ON_ERROR_EXCEPTION, |
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$timeout = null |
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) { |
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$this->instance = $instance; |
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$this->host = $host; |
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$this->port = $port; |
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$this->onError = $onError; |
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$this->timeout = $timeout; |
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} |
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public function __destruct() |
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{ |
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if ($this->socket) { |
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// the reason for this failing is that it is already closed, so ignore the result and not messing with |
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// parent classes |
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@fclose($this->socket); |
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} |
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} |
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/** |
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* @param string $message |
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* |
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* @return bool |
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*/ |
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public function write($message) |
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{ |
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$this->ensureConnection(); |
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if ($this->socket) { |
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$totalLength = strlen($message); |
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$retries = 1; |
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for ($written = 0; $written < $totalLength; $written += $response) { |
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$response = @fwrite($this->socket, substr($message, $written), static::MAX_SEND_LENGTH); |
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if ($response === false) { |
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if ($retries-- > 0) { |
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$this->socket = $this->connect(); |
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$response = 0; |
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} else { |
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return false; |
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} |
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} |
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} |
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return ($written === $totalLength); |
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} |
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return false; |
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} |
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/** |
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* Ensure that we are currently connected to the socket |
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*/ |
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protected function ensureConnection() |
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{ |
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if ((!$this->socket) && ($this->canConnect())) { |
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$this->socket = $this->connect(); |
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} |
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} |
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/** |
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* @return bool |
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*/ |
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protected function canConnect() |
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{ |
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return (microtime(true) > $this->waitTill); |
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} |
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/** |
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* Attempt to connect to a stream |
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* |
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* @return null|resource |
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*/ |
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protected function connect() |
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{ |
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$socket = @fsockopen('udp://' . $this->host, $this->port, $errno, $errstr, $this->timeout); |
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if ($socket === false) { |
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$this->waitTill = microtime(true) + (static::RETRY_INTERVAL * (pow(2, $this->numFails++))); |
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switch ($this->onError) { |
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case static::ON_ERROR_ERROR: |
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trigger_error( |
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sprintf('StatsD server connection failed (udp://%s:%d)', $this->host, $this->port), |
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E_USER_WARNING |
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); |
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break; |
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case static::ON_ERROR_EXCEPTION: |
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throw new ConnectionException($this->instance, '(' . $errno . ') ' . $errstr); |
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} |
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} else { |
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$this->numFails = 0; |
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$this->waitTill = 0.0; |
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$sec = (int) $this->timeout; |
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$ms = (int) (($this->timeout - $sec) * 1000); |
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stream_set_timeout($socket, $sec, $ms); |
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} |
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return $socket; |
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} |
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} |
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If you suppress an error, we recommend checking for the error condition explicitly: