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libphutil/src/channel/PhutilJSONProtocolChannel.php
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PhutilJSONProtocolChannel.php
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<?php
/**
* Channel that transmits dictionaries of primitives using JSON serialization.
* This channel is not binary safe.
*
* This protocol is implemented by the Phabricator Aphlict realtime notification
* server.
*
* @task protocol Protocol Implementation
*/
final class PhutilJSONProtocolChannel extends PhutilProtocolChannel {
const MODE_LENGTH = 'length';
const MODE_OBJECT = 'object';
/**
* Size of the "length" frame of the protocol in bytes.
*/
const SIZE_LENGTH = 8;
private $mode = self::MODE_LENGTH;
private $byteLengthOfNextChunk = self::SIZE_LENGTH;
private $buf = '';
/* -( Protocol Implementation )-------------------------------------------- */
/**
* Encode a message for transmission over the channel. The message should
* be any serializable as JSON.
*
* Objects are transmitted as:
*
* <len><json>
*
* ...where <len> is an 8-character, zero-padded integer written as a string.
* For example, this is a valid message:
*
* 00000015{"key":"value"}
*
* @task protocol
*/
protected function encodeMessage($message) {
$message = json_encode($message);
$len = sprintf(
'%0'.self::SIZE_LENGTH.'.'.self::SIZE_LENGTH.'d',
strlen($message));
return "{$len}{$message}";
}
/**
* Decode a message received from the other end of the channel. Messages are
* decoded as associative arrays.
*
* @task protocol
*/
protected function decodeStream($data) {
$this->buf .= $data;
$objects = array();
while (strlen($this->buf) >= $this->byteLengthOfNextChunk) {
switch ($this->mode) {
case self::MODE_LENGTH:
$len = substr($this->buf, 0, self::SIZE_LENGTH);
$this->buf = substr($this->buf, self::SIZE_LENGTH);
$this->mode = self::MODE_OBJECT;
$this->byteLengthOfNextChunk = (int)$len;
break;
case self::MODE_OBJECT:
$data = substr($this->buf, 0, $this->byteLengthOfNextChunk);
$this->buf = substr($this->buf, $this->byteLengthOfNextChunk);
$obj = json_decode($data, true);
if (!is_array($obj)) {
throw new Exception("Failed to decode JSON object: {$data}");
} else {
$objects[] = $obj;
}
$this->mode = self::MODE_LENGTH;
$this->byteLengthOfNextChunk = self::SIZE_LENGTH;
break;
}
}
return $objects;
}
}
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