利用PHP如何实现Socket服务器

// set time limit to indefinite execution 
set_time_limit (0); 
 
// set the ip and port we will listen on 
$address = 'localhost'; 
$port = 10000; 
$max_clients = 10; 
 
// array that will hold client information 
$client = array(); 
 
// create a tcp stream socket 
$sock = socket_create(af_inet, sock_stream, 0); 
// bind the socket to an address/port 
socket_bind($sock, $address, $port) or die('could not bind to address'); 
// start listening for connections 
socket_listen($sock); 
 
echo "waiting for connections...rn"; 
 
// loop continuously 
while (true) { 
// setup clients listen socket for reading 
$read[0] = $sock; 
for ($i = 0; $i < $max_clients; $i++) { 
 if (isset($client[$i]['sock'])) 
  $read[$i + 1] = $client[$i]['sock']; 
} 
// set up a blocking call to socket_select() 
if (socket_select($read, $write = null, $except = null, $tv_sec = 5) < 1) 
 continue; 
/* if a new connection is being made add it to the client array */ 
if (in_array($sock, $read)) { 
 for ($i = 0; $i < $max_clients; $i++) { 
  if (empty($client[$i]['sock'])) { 
  $client[$i]['sock'] = socket_accept($sock); 
  echo "new client connected $irn"; 
  break; 
  } 
  elseif ($i == $max_clients - 1) 
  echo "too many clients...rn"; 
 } 
} // end if in_array 
 
// if a client is trying to write - handle it now 
for ($i = 0; $i < $max_clients; $i++) { // for each client 
 if (isset($client[$i]['sock'])) { 
  if (in_array($client[$i]['sock'], $read)) { 
  $input = socket_read($client[$i]['sock'], 1024); 
  if ($input == null) { 
   echo "client disconnecting $irn"; 
   // zero length string meaning disconnected 
   unset($client[$i]); 
  } else { 
   echo "new input received $irn"; 
   // send it to the other clients 
   for ($j = 0; $j < $max_clients; $j++) { 
   if (isset($client[$j]['sock']) && $j != $i) { 
    echo "writing '$input' to client $jrn"; 
    socket_write($client[$j]['sock'], $input, strlen($input)); 
   } 
   } 
   if ($input == 'exit') { 
   // requested disconnect 
   socket_close($client[$i]['sock']); 
   } 
  } 
  } else { 
  echo "client disconnected $irn"; 
  // close the socket 
  socket_close($client[$i]['sock']); 
  unset($client[$i]); 
  } 
 } 
} 
} // end while 
// close the master sockets 
socket_close($sock);