dcledd

#!/usr/bin/php -q
<?php
/*
 * DCLED - state tracker
 * repeatedly calls dcled to display what's in the memory
 * see: https://github.com/misel228/dcled-state-tracker
 */

require 'config.php';
declare(ticks = 1); #necessary to catch ctrl-c

// Catch Ctrl+C, kill and SIGTERM (Rollback)
pcntl_signal(SIGTERM, 'sigintShutdown');
pcntl_signal(SIGINT,  'sigintShutdown');

define('COMMAND_STRING', 'echo %MESSAGE% | dcled -p %PRE%  ');
$placeholders = array('%PRE%', '%MESSAGE%');
define('SHORT_INTERVAL',5);
define('LONG_INTERVAL',15);


# Init: create a shared memory place and write an empty message into each of the MAX_MESSAGE slots

$shm_id = shmop_open(SHM_IDENTIFIER, "c", 0666, MAX_MESSAGE*MESSAGE_SIZE);
if($shm_id !== false){
  for($i=1;$i<=MAX_MESSAGE;$i++) {
    $shm_bytes_written = shmop_write($shm_id, EMPTY_MESSAGE, ($i-1)*MESSAGE_SIZE);
  }
  #close write access - is reopened read-only later 
  shmop_close($shm_id);
} else {
  die('Failed at creating shared memory area');
}



# Loop: reopen area read-only and loop through the slots

$shm_id = shmop_open(SHM_IDENTIFIER, "a", 0666, MAX_MESSAGE*MESSAGE_SIZE);

if($shm_id !== false){

  while(true){
    for($i = 1; $i <= MAX_MESSAGE; $i++) {
      $message = shmop_read($shm_id, ($i-1)*MESSAGE_SIZE, MESSAGE_SIZE);
      if($message != EMPTY_MESSAGE) {
        $time_stamp = substr($message,0,TIME_STAMP_SIZE);
        if((time()-MAX_TIME) < $time_stamp ) {
          $replacements = array($i, escapeshellarg(substr($message,TIME_STAMP_SIZE,MESSAGE_SIZE-TIME_STAMP_SIZE)));
          $command = str_replace($placeholders,$replacements, COMMAND_STRING);
          system($command);
          #echo $command."\n";
          sleep(SHORT_INTERVAL);
        }
      }
    }
    sleep(LONG_INTERVAL);
  }
}


// remove memory area at end of program
function shutdown() {
  global $shm_id;
  shmop_delete($shm_id);
  shmop_close($shm_id);
  die('END OF PROGRAM'."\n");
}


/**
 * Function, that is executed, if script has been killed by
 * SIGINT: Ctrl+C
 * SIGTERM: kill
 *
 * @param int $signal
 *
 * shamelessly plugged from. http://www.phpdevblog.net/2009/05/cli-catching-ctrlc-kill-commands-and-fatal-errors.html
 */  
function sigintShutdown($signal) {
    if ($signal === SIGINT || $signal === SIGTERM) {
        shutdown();
    }
}