Updated README and fixed responsibility mixup. Also, added stability by cleaning the memory block on startup.

README.md

@@ -1,12 +1,23 @@
 # joopschilder/php-async
-Asynchronous PHP callable processing with return values via SysV shared memory.<br/>
+## Introduction
-Requires the `php-sysvshm` extension.<br/>
+This package provides functions to run callables asynchronously in PHP. Return values are shared via System-V shared memory.<br/>
-Works with PHP >= 5.3 due to `shm_attach(...)` returning a resource instead of an int.<br/><br/>
+To use this package, you'll need PHP >= 7.0.0 with `ext-sysvshm` and `ext-pcntl`.<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
+You should consider the state of this package to be <i>experimental</i>.<br/><br/>
-create an 8MB shared memory block in RAM. If you run out of memory: you have been warned.
+<b>Note:</b> This package should not be used in a CGI environment. 
-<br/>
+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.
-<b>Note:</b> This project is an experiment. It is, however, available on packagist.
+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.
-If you think your project lacks witchcraft and black magic, just add this package to your `composer.json`:
+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": {
@@ -15,38 +26,42 @@ 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
-
+Whenever you call `async(...)`, a `Promise` instance is returned.<br/>
-### Promises
+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
 require_once __DIR__ . '/vendor/autoload.php';
 
 $promise = async(function() {
-	sleep(random_int(1, 5));
+    sleep(random_int(1, 5));
-	return getmypid();
+    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.
+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>.
-
-### 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>.
 
 ```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

composer.json

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

src/Asynchronous.php

@@ -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
+		 * The reason we do this is for when the shm block
-		 * System V IPC key.
+		 * already exists. We attach, remove, detach and reattach
+		 * to ensure a clean state.
 		 */
-		if ($this->shmKey == null)
+		$this->_attachToShm(); // Attach
-			$this->shmKey = ftok(__FILE__, 't');
-
-		Promise::__setShmKey($this->shmKey);
-		$this->_attachToShm();
 	}
 
 	/**
@@ -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;
-	}
-
-
 	/**
 	 *
 	 */

src/Promise.php

@@ -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 $shmKey)
+	public static function generatePromiseKey()
 	{
 		/*
-		 * Should be done only once: when the Asynchronous class
+		 * Get the current key.
-		 * has created a key that will be used for IPC.
 		 */
-		self::$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;
+	}
 }

src/Runtime.php

@@ -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;
+	}
 }