To be able to converting hash into array in Ruby is easy but how do we convert an array into a hash? This tutorial did the ruby array to hash trick.

class Array
  def to_hash(other)
    Hash[ *(0...self.size()).inject([]) { |arr, ix| arr.push(self[ix], other[ix]) } ]
  end
end
%W{ a b c }.to_hash( %W{ 1 2 3 } )
 
#=> {"a"=>"1", "b"=>"2", "c"=>"3"}

If you are looking to wonder what hash map is, check out this Ruby Hash.

Challenge with Drupal 6 Cron

Drupal cron getting stucked is quite a common problem with Drupal 6 and I found out an interesting way to figure out the reason why it is getting stuck.

Logging as always

As always, the solution is to log at the correct place. Drupal cron is invoked at includes/common.inc in the function drupal_cron_run (around line 2727), so we begin here logging into watchdog. We have to start logging when the cron starts for a particular module and when it finishes as follows:

   foreach (module_implements('cron') as $module) {                    

  watchdog('cron', t('Cron processing initiated for module: @module.', array('@module' => $module)));

    $function = $module .'_cron';                                     

      if ($log_timing) {                                                

        timer_start($function);                                         

        if ($log_timing == 'debug') {                                   

          watchdog('cron', t('Cron processing initiated for module: @module.', array('@module' => $module)));

        }                                                                                                    

      }                                                                                                      

      $function();                                                                                           

      if ($log_timing) {                                                                                     

        $timer = timer_stop($function);                                                                      

        watchdog('cron', t('Cron time elapsed for @module is @millisecs ms.', array('@module' => $module, '@millisecs' => $timer['time'])));

      }                                                                                                                                     

Cron has been running for more than an hour and is most likely stuck.

Also, notice it is quite common that your are getting this message:

"Cron has been running for more than an hour and is most likely stuck."

This means the cron is locked and therefore, we  would need to delete the semaphore variable to get the cron to work again.

function drupal_cron_run() {       

  // If not in 'safe mode', increase the maximum execution time:

     variable_del('cron_semaphore');

Now, run http://www.example.com/cron.php and watch your logs.

IMPORTANT NOTE: Don't forget to comment this line from this function after your cron runs successfully.

I had issues with cron run on search module. I skipped search module as follows as everything went well after that.

/**

 * Executes a cron run when called

 * @return                        

 * Returns TRUE if ran successfully

 */                                

function drupal_cron_run() {       

  // If not in 'safe mode', increase the maximum execution time:

     variable_del('cron_semaphore');

  if (!ini_get('safe_mode')) {                                  

    set_time_limit(240);                                        

  }                                                             

  // Fetch the cron semaphore

  $semaphore = variable_get('cron_semaphore', FALSE);

  if ($semaphore) {

    if (time() - $semaphore > 3600) {

      // Either cron has been running for more than an hour or the semaphore

      // was not reset due to a database error.                             

      watchdog('cron', t('Cron has been running for more than an hour and is most likely stuck.'), WATCHDOG_ERROR);

      // Release cron semaphore

      variable_del('cron_semaphore');

    }                                

    else {                           

      // Cron is still running normally.

      watchdog('cron', t('Attempting to re-run cron while it is already running.'), WATCHDOG_WARNING);

    }                                                                                                 

  }                                                                                                   

  else {                                                                                              

    // Register shutdown callback                                                                     

    register_shutdown_function('drupal_cron_cleanup');                                                

    // Lock cron semaphore

    variable_set('cron_semaphore', time());

    // Iterate through the modules calling their cron handlers (if any):

    // module_invoke_all('cron');    

    $log_timing = variable_get('cron_log_times', '1');                  

    foreach (module_implements('cron') as $module) {                    

          watchdog('cron', t('Cron processing initiated for module: @module.', array('@module' => $module)));

 if ($module == "search") continue; 

    $function = $module .'_cron';                                     

      if ($log_timing) {                                                

        timer_start($function);                                         

        if ($log_timing == 'debug') {                                   

          watchdog('cron', t('Cron processing initiated for module: @module.', array('@module' => $module)));

        }                                                                                                    

      }                                                                                                      

      $function();                                                                                           

      if ($log_timing) {                                                                                     

        $timer = timer_stop($function);                                                                      

        watchdog('cron', t('Cron time elapsed for @module is @millisecs ms.', array('@module' => $module, '@millisecs' => $timer['time'])));

      }                                                                                                                                     

    }                                                                                                                                       

    // Record cron time

    variable_set('cron_last', time());

    watchdog('cron', t('Cron run completed.'), WATCHDOG_NOTICE);

    // Release cron semaphore

    variable_del('cron_semaphore');

    // Return TRUE so other functions can check if it did run successfully

    return TRUE;                                                          

  }                                                                       

} 

Search Cron Handled Separately

In order to run search cron, I wrote another hook_menu function to update search indexes and that worked well. This hook menu was called on cron from linux shell.

<?php
  register_shutdown_function('search_update_totals');

  // Update word index
  foreach (module_list() as $module) {
    module_invoke($module, 'update_index');
  }
?>

Did you ever try to install an application on CentOS using powerful "yum" and had following errors showing up:

--> Finished Dependency Resolution

rrdtool-1.3.8-2.el5.rf.x86_64 from rpmforge has depsolving problems

  --> Missing Dependency: ruby is needed by package rrdtool-1.3.8-2.el5.rf.x86_64 (rpmforge)

Error: Missing Dependency: ruby is needed by package rrdtool-1.3.8-2.el5.rf.x86_64 (rpmforge)

 You could try using --skip-broken to work around the problem

 You could try running: package-cleanup --problems

                        package-cleanup --dupes

                        rpm -Va --nofiles --nodigest

The program package-cleanup is found in the yum-utils package.

The above error implies that yum was trying to install ruby or perl dependency and could not install it because that was excluded in the global exclude in /etc/yum.conf.

The solution is to exclude "perl" or "ruby" or whatever dependecy the system is trying to install in /etc/yum.conf. I simply renamed perl and ruby to something else in the first line of /etc/yum.conf and my "yum install XXXX" wen smooth thereafter.