<?php
/**
* PHP_Fork class usage examples
* ==================================================================================
* NOTE: In real world you surely want to keep each class into
* a separate file, then include() it into your application.
* For this examples is more useful to keep all_code_into_one_file,
* so that each example shows a unique feature of the PHP_Fork framework.
* ==================================================================================
* simple_controller.php
*
* This example shows how to attach a controller to started pseudo-threads
* Forked processes can sometime die or defunct for many reasons...
* Without a controller process that periodically check thread status we
* can not ensure that started threads are still alive into system
* Here we have n executeThreads and a controllerThread that check all them
* when the controller detect that a thread is died it try to respawn it.
*
* ATTENTION: this example fails on Cygwin platform, probably due to some bugs
* into ipc implementations that prevent the shared memory to be totally released
* when a process die.
*
* ==================================================================================
*
*/
// Import of base class
require_once ("PHP/Fork.php");
// number of executeThreads we want
define ("NUM_THREAD", 2);
// max delay (seconds) that controller can accept from child's ping
define ("CTRL_MAX_IDLE", 3);
// controller will check threads status every CTRL_POLLING_INTERVAL secs.
define ("CTRL_POLLING_INTERVAL", 5);
// The same as previos examples, with the add of the controller ping...
class executeThread extends PHP_Fork {
var $counter;
function executeThread($name)
{
$this->PHP_Fork($name);
$this->counter = 0;
}
function run()
{
while (true) {
// setVariable is a method inherited from PHP_Fork super class
// it sets a variable that can be accessed thru its name
// by parent process
$this->setVariable('counter', $this->counter++);
/**
* While using the controller, every child must notify to controller that it's alive
* The frequency of this notify must be set according to the parameter $maxIdleTime
* (controllerThread constructor, default is 60 sec.)
* Typically executeThreads runs an infinite loop making something useful; you should
* calculate a reasonable time for one loop, then set the controller's $maxIdleTime
* to a superior value.
* Into the while(true) { } loop of the thread insert a call to the "setAlive" method
* so that controller can detect properly the status of child processes.
*/
$this->setAlive();
sleep(1);
}
}
function getCounter()
{
// parent process can call this facility method
// in order to get back the actual value of the counter
return $this->getVariable('counter');
}
}
class controllerThread extends PHP_Fork {
var $_sleepInt;
var $_executeThreadPool;
var $_maxIdleTime;
var $_respawnThread;
/**
* controllerThread::controllerThread()
*
* @param $name
* @param $executeThreadPool
* @param $maxIdleTime
* @param $interval
* @return
*/
function controllerThread($name, &$executeThreadPool, $maxIdleTime = 60, $interval = 60)
{
$this->PHP_Fork($name);
$this->_sleepInt = $interval;
$this->_executeThreadPool = &$executeThreadPool;
$this->_maxIdleTime = $maxIdleTime;
$this->_respawnThread = array();
$this->setVariable('_executeThreadPool', $this->_executeThreadPool);
}
function run()
{
while (true) {
$this->_detectDeadChilds();
$this->_respawnDeadChilds();
sleep($this->_sleepInt);
}
}
function stopAllThreads()
{
$this->_executeThreadPool = $this->getThreadPool();
foreach($this->_executeThreadPool as $thread) {
$thread->stop();
echo "Stopped " . $thread->getName() . "\n";
}
unset($this->_executeThreadPool);
$this->_executeThreadPool = array();
$this->setVariable('_executeThreadPool', $this->_executeThreadPool);
}
function getThreadPool()
{
return $this->getVariable('_executeThreadPool');
}
function _detectDeadChilds()
{
// check every executethread to see if it is alive...
foreach ($this->_executeThreadPool as $idx => $executeThread) {
if ($executeThread->getLastAlive() > $this->_maxIdleTime) {
// this thread is not responding, probably [defunct]
$threadName = $executeThread->getName();
print time() . "-" . $this->getName() . "-" . $threadName . " seems to be died...\n";
// so let's kill it...
$executeThread->stop();
unset($executeThread);
// remove this thread from the pool
array_splice($this->_executeThreadPool, $idx, 1);
// and add them to the "to be respawned" thread list...
$this->_respawnThread[] = $threadName;
// stop this foreach
break;
}
}
}
function _respawnDeadChilds()
{
foreach ($this->_respawnThread as $idx => $threadName) {
$n = &new executeThread ($threadName);
// usually we try to start a Thread without this check
// if Shared Memory Area is not ready, the start() method
// die, so the process is destroyed. When respawing a dead child
// this is not useful, because die() will cause the controller itself
// to die!
// So let's check if IPC is ok before call the start() method.
if ($n->_ipc_is_ok) {
$n->start();
$this->_executeThreadPool[] = &$n;
print time() . "-" . $this->getName() . "- New instance of " . $threadName . " successfully spawned (PID=" . $n->getPid() . ")\n";
array_splice($this->_respawnThread, $idx, 1);
$this->setVariable('_executeThreadPool', $this->_executeThreadPool);
} else {
print "Unable to create IPC segment...\n";
}
}
}
}
/**
* Functions used by the console
*/
function _getInputCLI()
{
$opt = _read();
$opt = strtoupper (trim($opt));
return $opt;
}
function _read()
{
$fp = fopen("php://stdin", "r");
$input = fgets($fp, 255);
fclose($fp);
return $input;
}
/**
* Main program. Bring up two instances of the executeThread class that
* runs concurrently. It's a multi-thread app with a few lines of code!!!
* executeThread does nothing interesting, it simply has a counter and increment
* this counter each second... (see class definition at top of this file)
*/
for ($i = 0;$i < NUM_THREAD;$i++) {
$executeThread[$i] = &new executeThread ("executeThread-" . $i);
$executeThread[$i]->start();
echo "Started " . $executeThread[$i]->getName() . " with PID " . $executeThread[$i]->getPid() . "...\n";
}
$ctrl = new controllerThread("controllerThread", $executeThread, CTRL_MAX_IDLE, CTRL_POLLING_INTERVAL);
$ctrl->start();
print "Started " . $ctrl->getName() . " with PID " . $ctrl->getPid() . "...\n\n";
echo "This is the main process.\nPress [X] to terminate, [G] to read thread's counter, [T] to obtain the actual executeThreads dump.\nTo test the controller respawn functionality, simply kill one (or more) executeThread...\n";
/**
* Console simple listener
*/
while (true) {
echo ">";
$opt = _getInputCLI();
echo "\n";
switch ($opt) {
case "X":
// when using the controller we cannot traverse the $executeThread array
// because it only contains the original pool of thread.
// if a thread dies, the controller respawn it and updates it's own
// thread pool. The method stopAllThreads() stops all running threads.
$ctrl->stopAllThreads();
// stop the controller itself
$ctrl->stop();
print "Stopped " . $ctrl->getName() . "\n";
exit;
break;
case "G":
for ($i = 0;$i < NUM_THREAD;$i++) {
echo $executeThread[$i]->getName() . " returns " . $executeThread[$i]->getCounter() . "\n";
}
break;
case "T":
$thPool = &$ctrl->getThreadPool();
print_r($thPool);
foreach ($thPool as $th)
{
print ($th->getCounter()."\n");
}
break;
}
}
?>
