<?php
/**
* Provides access to information about the operating environment.
*
* @copyright 2011 Perforce Software. All rights reserved.
* @license Please see LICENSE.txt in top-level folder of this distribution.
* @version <release>/<patch>
*/
namespace P4\Environment;
class Environment
{
protected static $shutdownRegistered = false;
protected static $shutdownCallbacks = array();
/**
* Private constructor to prevent instances from being created.
*
* @codeCoverageIgnore
*/
final private function __construct()
{
}
/**
* Determines whether or not we are running on a windows system
* by checking for the PHP_WINDOWS_VERSION_MAJOR constant.
*
* @return boolean whether or not we are running on a windows OS
*/
public static function isWindows()
{
return defined("PHP_WINDOWS_VERSION_MAJOR");
}
/**
* Returns the maximum number of bytes that can be used for arguments
* when launching an application.
*
* @return int bytes available for arguments
*/
public static function getArgMax()
{
// if we are on windows early exit with 32k
if (static::isWindows()) {
return 32768;
}
// try getting a value via getconf;
$argMax = `getconf ARG_MAX`;
// if we didn't get a plain number back return 32k as a default
if ($argMax !== (string)(int)$argMax) {
return 32768;
}
return $argMax;
}
/**
* Register a function to execute at shutdown.
*
* This provides useful abstraction of PHP's built-in
* register_shutdown_function facility. This allows registered callbacks
* to be inspected or executed arbitrarily (especially useful during
* testing).
*
* @param callable $callback the function to execute at shutdown.
* @return void
*/
public static function addShutdownCallback($callback)
{
if (!is_callable($callback)) {
throw new \InvalidArgumentException(
"Cannot add shutdown callback. Given callback is not callable."
);
}
// if we haven't already done so, register
// runShutdownCallbacks as a shutdown function.
if (!static::$shutdownRegistered) {
register_shutdown_function(
get_called_class() . "::runShutdownCallbacks"
);
static::$shutdownRegistered = true;
}
static::$shutdownCallbacks[] = $callback;
}
/**
* Get all of the registered shutdown callbacks.
*
* @return array the list of registered shutdown functions.
*/
public static function getShutdownCallbacks()
{
return static::$shutdownCallbacks;
}
/**
* Set all of the registered shutdown callbacks at once.
*
* This could be useful for clearing, re-ordering or otherwise
* manipulating the list of registered shutdown callbacks.
*
* @param array|null $callbacks functions to execute at shutdown.
* @return void
*/
public static function setShutdownCallbacks(array $callbacks = null)
{
// start by clearing existing callbacks if present
static::$shutdownCallbacks = array();
// use add method to ensure callback is validated and our
// runShutdownCallbacks method has an opportunity to register.
foreach ($callbacks ?: array() as $callback) {
static::addShutdownCallback($callback);
}
}
/**
* Execute all of the registered shutdown callbacks.
*
* Callbacks are run in the same order that they were registered.
* Once a callback has been executed, it is removed from the shutdown
* callbacks list.
*
* @return void
*/
public static function runShutdownCallbacks()
{
foreach (static::$shutdownCallbacks as $key => $callback) {
// if callback is still callable, execute it.
// as we run at shutdown it is possible, though unlikely,
// a callback could go away between add and now.
if (is_callable($callback)) {
call_user_func($callback);
}
unset(static::$shutdownCallbacks[$key]);
}
}
}