class Worker extends Zookeeper
{
const CONTAINER
= ‘/cluster‘ ;
protected $acl = array(
array (
‘perms‘ =>
Zookeeper:: PERM_ALL,
‘scheme‘ => ‘world‘ ,
‘id‘ => ‘anyone‘ )
);
private $isLeader = false;
private $znode ;
public function __construct(
$host = ‘‘, $watcher_cb = null ,
$recv_timeout = 10000 ) {
parent:: __construct(
$host, $watcher_cb, $recv_timeout );
}
public function register()
{
if(
! $this->exists( self ::CONTAINER )
) {
$this->create( self ::CONTAINER , null,
$this-> acl );
}
$this->znode = $this->create( self ::CONTAINER
. ‘/w-‘ ,
null ,
$this->acl,
Zookeeper::EPHEMERAL
| Zookeeper::SEQUENCE );
$this-> znode =
str_replace( self ::CONTAINER .‘/‘ , ‘‘ ,
$this-> znode );
printf( "I‘m registred
as: %s\n", $this-> znode );
$watching = $this->watchPrevious();
if(
$watching == $this-> znode )
{
printf( "Nobody
here, I‘m the leader\n" );
$this->setLeader( true );
}
else {
printf( "I‘m watching
%s\n" , $watching );
}
}
public function watchPrevious()
{
$workers = $this->getChildren( self ::CONTAINER );
sort( $workers );
$size = sizeof( $workers );
for(
$i = 0 ; $i < $size ; $i++ ) {
if(
$this-> znode == $workers[
$i ] ) {
if (
$i > 0 ) {
$this->get( self ::CONTAINER . ‘/‘ .
$workers[ $i - 1 ], array (
$this, ‘watchNode‘ )
);
return $workers[
$i - 1 ];
}
return $workers[
$i ];
}
}
throw new Exception(
sprintf( "Something went very wrong! I can‘t find myself: %s/%s",
self ::CONTAINER ,
$this-> znode )
);
}
public function watchNode(
$i, $type, $name ) {
$watching = $this->watchPrevious();
if(
$watching == $this-> znode )
{
printf( "I‘m the
new leader!\n" );
$this->setLeader( true );
}
else {
printf( "Now I‘m
watching %s\n" , $watching );
}
}
public function isLeader()
{
return $this-> isLeader ;
}
public function setLeader($flag)
{
$this-> isLeader =
$flag;
}
public function run()
{
$this->register();
while( true )
{
if(
$this->isLeader() ) {
$this->doLeaderJob();
}
else {
$this->doWorkerJob();
}
sleep( 2 );
}
}
public function doLeaderJob()
{
echo "Leading\n" ;
}
public function doWorkerJob()
{
echo "Working\n" ;
}
}
$worker = new Worker( ‘127.0.0.1:2181‘ );
$worker->run();
