joopschilder/php-async
joopschilder/php-async
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Updated README and fixed responsibility mixup. Also, added stability by cleaning the memory block on startup.

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Joop Schilder 2019-01-22 17:44:32 +01:00
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74
README.md
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@ -1,12 +1,23 @@
# joopschilder/php-async
Asynchronous PHP callable processing with return values via SysV shared memory.<br/>
Requires the `php-sysvshm` extension.<br/>
Works with PHP >= 5.3 due to `shm_attach(...)` returning a resource instead of an int.<br/><br/>
<b>Note:</b> This package should not be used in a CGI environment, as each PHP runtime that makes a call on the async functions WILL
create an 8MB shared memory block in RAM. If you run out of memory: you have been warned.
<br/>
<b>Note:</b> This project is an experiment. It is, however, available on packagist.
If you think your project lacks witchcraft and black magic, just add this package to your `composer.json`:
## Introduction
This package provides functions to run callables asynchronously in PHP. Return values are shared via System-V shared memory.<br/>
To use this package, you'll need PHP >= 7.0.0 with `ext-sysvshm` and `ext-pcntl`.<br/>
You should consider the state of this package to be <i>experimental</i>.<br/><br/>
<b>Note:</b> This package should not be used in a CGI environment.
The key that is used to access the block of shared memory is created based on the inode information of one of the source files.
This means that, whenever multiple instances (processes) from the same project source are created, they will try to use the same block of memory and collisions will occur.
I might swap the `ftok()` call for a random string generator somewhere down the road.<br/><br/>
<b>Note:</b> It is possible (but discouraged) to change the amount of available shared memory.
If you wish to do so, it's as simple as calling either `Runtime::_setSharedMemorySizeMB(<amount of MB>);` or `Runtime::_setSharedMemorySizeB(<amount of bytes>);`.<br/>
If you want to use 32MB for example, call `Runtime::_setSharedMemorySizeMB(32);`.<br/>
Be sure to make this call before using any of the asynchronous functionalities.
## Installation
This package is available on <a href="https://packagist.org/packages/joopschilder/php-async">Packagist</a>
and can be installed using <a href="https://getcomposer.org/">Composer</a>:<br/>
```bash
$ composer require joopschilder/async-php
```
It's also possible to manually add it to your `composer.json`:
```json
{
"require": {
@ -15,10 +26,18 @@ If you think your project lacks witchcraft and black magic, just add this packag
}
```
## Usage
#### Functions
The library exposes three functions in the global namespace that provide indirect access to the class `Asynchronous`:
* `async(callable $function, ...$parameters)` to run something asynchronously, giving back a `Promise`;
* `async_wait_all()` to wait for all currently running jobs to finish;
* `async_reap_zombies()` to clean up any zombie processes during runtime if any exist;
## Examples
### Promises
#### Promises
Whenever you call `async(...)`, a `Promise` instance is returned.<br/>
A `Promise` is considered to be resolved when the function it belongs to returned a value or finished execution.
To block execution until a promise is resolved, simply call the `resolve()` method on the promise.
It's possible to check whether the promise has been resolved in a non-blocking way by calling the `isResolved()` method.<br/>
You can actually return anything that is serializable in PHP: objects, arrays, strings, you name it.
```php
<?php
@ -29,24 +48,20 @@ $promise = async(function() {
return getmypid();
});
// ... some other work
// ... do some other work
$promise->resolve();
$pid = $promise->getValue();
printf("Me (%d) and %d have worked very hard!\n", getmypid(), $pid);
```
The shutdown handler and destructors should take care of the rest.
### Asynchronous curl requests
... though you should probably look into curl multi handles for this: <a href="http://php.net/manual/en/function.curl-multi-init.php">curl_multi_init() on PHP.net</a>.
The shutdown handler and destructors should take care of the cleanup.<br/>
#### Asynchronous curl requests
... though you should probably look into curl multi handles for this: <a href="http://php.net/manual/en/function.curl-multi-init.php">curl_multi_init()</a>.
```php
<?php
require_once __DIR__ . '/vendor/autoload.php';
// Create the body for the process
// Create the body for the process...
$process = function(string $url) {
$handle = curl_init($url);
curl_setopt($handle, CURLOPT_FOLLOWLOCATION, 1);
@ -56,21 +71,30 @@ $process = function(string $url) {
file_put_contents(uniqid('download_'), $response);
};
// Define some urls we want to download
// Define some urls we want to download...
$urls = [
'example.com',
'example2.com',
'some.other.domain'
];
// And away we go!
// And there we go.
foreach($urls as $url)
async($process, $url);
```
That's all there is to it.
## Tips
If you're on a UNIX system, you can make use of the tools `ipcs` and `ipcrm` to monitor and manage the shared memory blocks.<br/>
To track what's happening in real time, I like to use:<br/>
```bash
$ watch -n 1 "ipcs -m --human && ipcs -m -p && ipcs -m -t && ipcs -m -u"
```
<br/>To clean all 'unused' shared memory blocks (they might remain resident in RAM if your program terminated unexpectedly):<br/>
```bash
$ ipcrm -a
```
## What's next?
- Refactoring
- More functionality (maybe)
- Improving stability
- Add a diagram that explains this witchcraft
- Add an explaining diagram

3
composer.json
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@ -14,7 +14,6 @@
},
"require": {
"ext-pcntl": "*",
"ext-sysvshm": "*",
"ext-posix": "*"
"ext-sysvshm": "*"
}
}

56
src/Asynchronous.php
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@ -8,25 +8,15 @@ namespace JoopSchilder\Asynchronous;
*/
class Asynchronous
{
public const BLOCK_SIZE_MB = 8;
private const BLOCK_SIZE_BYTES = self::BLOCK_SIZE_MB * (1024 ** 2);
/** @var Asynchronous|null */
private static $instance;
/** @var int */
private static $key = 0;
/** @var int[] */
private $children = [];
/** @var resource */
private $shm;
/** @var int */
private $shmKey;
/**
* @param callable $function
@ -39,7 +29,7 @@ class Asynchronous
* Prepare for fork
*/
$instance = self::getInstance();
$key = self::generatePromiseKey();
$promiseKey = Promise::generatePromiseKey();
/*
* Fork the parent
@ -61,7 +51,7 @@ class Asynchronous
if ($pid > 0) {
$instance->children[] = $pid;
return new Promise($key);
return new Promise($promiseKey);
}
/*
@ -75,17 +65,17 @@ class Asynchronous
* On failure, write a default response to the block in order for
* the Promise to be able to resolve.
*/
Runtime::markChild();
Runtime::markAsChild();
$instance->_attachToShm();
try {
$response = call_user_func($function, ...$parameters);
shm_put_var($instance->shm, $key, $response ?? Promise::RESPONSE_NONE);
shm_put_var($instance->shm, $promiseKey, $response ?? Promise::RESPONSE_NONE);
exit(0);
} catch (\Throwable $throwable) {
shm_put_var($instance->shm, $key, Promise::RESPONSE_ERROR);
shm_put_var($instance->shm, $promiseKey, Promise::RESPONSE_ERROR);
exit(1);
}
@ -144,14 +134,11 @@ class Asynchronous
private function __construct()
{
/*
* Use the filename as an identifier to create the
* System V IPC key.
* The reason we do this is for when the shm block
* already exists. We attach, remove, detach and reattach
* to ensure a clean state.
*/
if ($this->shmKey == null)
$this->shmKey = ftok(__FILE__, 't');
Promise::__setShmKey($this->shmKey);
$this->_attachToShm();
$this->_attachToShm(); // Attach
}
/**
@ -192,7 +179,7 @@ class Asynchronous
*/
private function _attachToShm()
{
$this->shm = shm_attach($this->shmKey, self::BLOCK_SIZE_BYTES);
$this->shm = shm_attach(Runtime::getSharedMemoryKey(), Runtime::getSharedMemorySize());
return $this;
}
@ -217,29 +204,6 @@ class Asynchronous
}
/**
* @return int
*/
private static function generatePromiseKey()
{
/*
* Get the current key.
*/
$promiseKey = self::$key;
/*
* Reset the key to 0 if the upper bound of
* 9.999.999 is reached (Windows limit for
* shm keys).
*/
self::$key++;
if (self::$key > 99999999)
self::$key = 0;
return $promiseKey;
}
/**
*
*/

47
src/Promise.php
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@ -15,8 +15,7 @@ class Promise
public const RESPONSE_ERROR = '__PROMISE_RESPONSE_ERROR__';
/** @var int */
private static $shmKey;
private static $generatedKey = 0;
/** @var resource */
private $shm;
@ -27,16 +26,27 @@ class Promise
/** @var mixed|null */
private $value;
/**
* @param int $shmKey
* @return int
*/
public static function __setShmKey(int $shmKey)
public static function generatePromiseKey()
{
/*
* Should be done only once: when the Asynchronous class
* has created a key that will be used for IPC.
* Get the current key.
*/
self::$shmKey = $shmKey;
$promiseKey = self::$generatedKey;
/*
* Reset the key to 0 if the upper bound of
* 9.999.999 is reached (Windows limit for
* shm keys).
*/
self::$generatedKey++;
if (self::$generatedKey > 99999999)
self::$generatedKey = 0;
return $promiseKey;
}
@ -48,19 +58,9 @@ class Promise
{
$this->key = $key;
$this->value = null;
$this->shm = shm_attach(self::$shmKey);
$this->shm = shm_attach(Runtime::getSharedMemoryKey());
}
/**
* @return $this
*/
private function attempt()
{
if (shm_has_var($this->shm, $this->key))
$this->value = shm_get_var($this->shm, $this->key);
return $this;
}
/**
* @return bool
@ -137,4 +137,15 @@ class Promise
shm_detach($this->shm);
}
/**
* @return $this
*/
private function attempt()
{
if (shm_has_var($this->shm, $this->key))
$this->value = shm_get_var($this->shm, $this->key);
return $this;
}
}

76
src/Runtime.php
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@ -13,16 +13,54 @@ namespace JoopSchilder\Asynchronous;
*/
class Runtime
{
/** @var int */
public const INITIAL_SHM_SIZE_MB = 16;
/** @var int */
private static $sharedMemKey = null;
/** @var int */
private static $sharedMemSize = self::INITIAL_SHM_SIZE_MB * (1024 ** 2);
/** @var bool */
private static $inParentRuntime = true;
/**
*
* Runtime constructor.
*/
public static function markChild()
private function __construct()
{
self::$inParentRuntime = false;
}
/*
* Public
*/
/**
* @return int
*/
public static function getSharedMemorySize()
{
return self::$sharedMemSize;
}
/**
* @return int
*/
public static function getSharedMemoryKey()
{
/*
* Use the filename as an identifier to create the
* System V IPC key.
*/
if (is_null(self::$sharedMemKey))
self::$sharedMemKey = ftok(__FILE__, 't');
return self::$sharedMemKey;
}
@ -34,4 +72,36 @@ class Runtime
return !self::$inParentRuntime;
}
/*
* 'Semi' private.
* To be used by internal classes.
*/
/**
* @param int $size_mb
*/
public static function _setSharedMemorySizeMB(int $size_mb)
{
self::$sharedMemSize = abs($size_mb) * (1024 ** 2);
}
/**
* @param int $size_b
*/
public static function _setSharedMemorySizeB(int $size_b)
{
self::$sharedMemSize = $size_b;
}
/**
*
*/
public static function markAsChild()
{
self::$inParentRuntime = false;
}
}