147 lines
2.5 KiB
PHP
147 lines
2.5 KiB
PHP
<?php
|
|
|
|
namespace Joop\Asynchronous;
|
|
|
|
class Promise
|
|
{
|
|
/*
|
|
* Define some default responses that will make it easy for us
|
|
* to check if the promise resulted in an error or if the promise
|
|
* was fulfilled by a void function.
|
|
* The '_' characters are arbitrary but ensure a higher entropy to
|
|
* minimize the chances of result collision.
|
|
*/
|
|
public const RESPONSE_NONE = '__PROMISE_RESPONSE_NONE__';
|
|
public const RESPONSE_ERROR = '__PROMISE_RESPONSE_ERROR__';
|
|
|
|
/** @var int */
|
|
private static $shmKey;
|
|
|
|
|
|
/** @var resource */
|
|
private $shm;
|
|
|
|
/** @var int */
|
|
private $key;
|
|
|
|
/** @var mixed|null */
|
|
private $value;
|
|
|
|
|
|
/**
|
|
* @param int $shmKey
|
|
*/
|
|
public static function __setShmKey(int $shmKey)
|
|
{
|
|
/*
|
|
* Should be done only once: when the Asynchronous class
|
|
* has created a key that will be used for IPC.
|
|
*/
|
|
self::$shmKey = $shmKey;
|
|
}
|
|
|
|
|
|
/**
|
|
* Promise constructor.
|
|
* @param int $key
|
|
*/
|
|
public function __construct(int $key)
|
|
{
|
|
$this->key = $key;
|
|
$this->value = null;
|
|
$this->shm = shm_attach(self::$shmKey);
|
|
}
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
public function shmValid()
|
|
{
|
|
return is_resource($this->shm);
|
|
}
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
public function isResolved()
|
|
{
|
|
if ($this->shmValid())
|
|
return shm_has_var($this->shm, $this->key);
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
public function isEmpty()
|
|
{
|
|
$value = $this->getValue();
|
|
|
|
return $value === self::RESPONSE_NONE || $value === null;
|
|
}
|
|
|
|
|
|
/**
|
|
* @return bool
|
|
*/
|
|
public function isError()
|
|
{
|
|
return $this->getValue() === self::RESPONSE_ERROR;
|
|
}
|
|
|
|
|
|
/**
|
|
* @return mixed|null
|
|
*/
|
|
public function getValue()
|
|
{
|
|
if ($this->shmValid())
|
|
return $this->isResolved() ? $this->resolve()->value : null;
|
|
|
|
$this->value = self::RESPONSE_ERROR;
|
|
|
|
return $this->value;
|
|
}
|
|
|
|
|
|
/**
|
|
* @return $this
|
|
*/
|
|
public function resolve()
|
|
{
|
|
/*
|
|
* Actually block execution until a value is written to
|
|
* the expected location of this Promise.
|
|
*/
|
|
while (!$this->isResolved())
|
|
usleep(1000);
|
|
|
|
if (is_null($this->value) && $this->shmValid())
|
|
$this->value = shm_get_var($this->shm, $this->key);
|
|
|
|
return $this;
|
|
}
|
|
|
|
|
|
/**
|
|
*
|
|
*/
|
|
public function __destruct()
|
|
{
|
|
/*
|
|
* Clean up our mess - the variable that we stored in the
|
|
* shared memory block - and detach from the block.
|
|
* Note: this destructor is only called after the
|
|
* garbage collector has noticed that there are no more
|
|
* references to this Promise instance.
|
|
*/
|
|
if ($this->shmValid()) {
|
|
if (shm_has_var($this->shm, $this->key))
|
|
shm_remove_var($this->shm, $this->key);
|
|
|
|
shm_detach($this->shm);
|
|
}
|
|
}
|
|
} |