library/ajax/execute_background_services.php

   1 <?php
   2
   3 /**
   4  * Manage background operations that should be executed at intervals.
   5  *
   6  * This script may be executed by a suitable Ajax request, by a cron job, or both.
   7  *
   8  * When called from cron, optinal args are [site] [service] [force]
   9  * @param site to specify a specific site, 'default' used if omitted
  10  * @param service to specify a specific service, 'all' used if omitted
  11  * @param force '1' to ignore specified wait interval, '0' to honor wait interval
  12  *
  13  * The same parameters can be accessed via Ajax using the $_POST variables
  14  * 'site', 'background_service', and 'background_force', respectively.
  15  *
  16  * For both calling methods, this script guarantees that each active
  17  * background service function: (1) will not be called again before it has completed,
  18  * and (2) will not be called any more frequently than at the specified interval
  19  * (unless the force execution flag is used).  A service function that is already running
  20  * will not be called a second time even if the force execution flag is used.
  21  *
  22  * Notes for the default background behavior:
  23  * 1. If the Ajax method is used, services will only be checked while
  24  * Ajax requests are being received, which is currently only when users are
  25  * logged in.
  26  * 2. All services are checked and called sequentially in the order specified
  27  * by the sort_order field in the background_services table. Service calls that are "slow"
  28  * should be given a higher sort_order value.
  29  * 3. The actual interval between two calls to a given background service may be
  30  * as long as the time to complete that service plus the interval between
  31  * n+1 calls to this script where n is the number of other services preceding it
  32  * in the array, even if the specified minimum interval is shorter, so plan
  33  * accordingly. Example: with a 5 min cron interval, the 4th service on the list
  34  * may not be started again for up to 20 minutes after it has completed if
  35  * services 1, 2, and 3 take more than 15, 10, and 5 minutes to complete,
  36  * respectively.
  37  *
  38  * Returns a count of due messages for current user.
  39  *
  40  * @package   OpenEMR
  41  * @link      https://www.open-emr.org
  42  * @author    EMR Direct <https://www.emrdirect.com/>
  43  * @author    Brady Miller <brady.g.miller@gmail.com>
  44  * @copyright Copyright (c) 2013 EMR Direct <https://www.emrdirect.com/>
  45  * @copyright Copyright (c) 2018 Brady Miller <brady.g.miller@gmail.com>
  46  * @license   https://github.com/openemr/openemr/blob/master/LICENSE GNU General Public License 3
  47  */
  48
  49 use OpenEMR\Common\Csrf\CsrfUtils;
  50
  51 //ajax param should be set by calling ajax scripts
  52 $isAjaxCall = isset($_POST['ajax']);
  53
  54 //if false ajax and this is a called from command line, this is a cron job and set up accordingly
  55 if (!$isAjaxCall && (php_sapi_name() === 'cli')) {
  56     $ignoreAuth = 1;
  57     //process optional arguments when called from cron
  58     $_GET['site'] = $argv[1] ?? 'default';
  59     if (isset($argv[2]) && $argv[2] != 'all') {
  60         $_GET['background_service'] = $argv[2];
  61     }
  62
  63     if (isset($argv[3]) && $argv[3] == '1') {
  64         $_GET['background_force'] = 1;
  65     }
  66
  67     //an additional require file can be specified for each service in the background_services table
  68     // Since from command line, set $sessionAllowWrite since need to set site_id session and no benefit to set to false
  69     $sessionAllowWrite = true;
  70     require_once(__DIR__ . "/../../interface/globals.php");
  71 } else {
  72     //an additional require file can be specified for each service in the background_services table
  73     require_once(__DIR__ . "/../../interface/globals.php");
  74
  75     // not calling from cron job so ensure passes csrf check
  76     if (!CsrfUtils::verifyCsrfToken($_POST["csrf_token_form"])) {
  77         CsrfUtils::csrfNotVerified();
  78     }
  79 }
  80
  81 //Remove time limit so script doesn't time out
  82 set_time_limit(0);
  83
  84 //Safety in case one of the background functions tries to output data
  85 ignore_user_abort(1);
  86
  87 /**
  88  * Execute background services
  89  * This function reads a list of available services from the background_services table
  90  * For each service that is not already running and is due for execution, the associated
  91  * background function is run.
  92  *
  93  * Note: Each service must do its own logging, as appropriate, and should disable itself
  94  * to prevent continued service calls if an error condition occurs which requires
  95  * administrator intervention. Any service function return values and output are ignored.
  96  */
  97
  98 function execute_background_service_calls()
  99 {
 100   /**
 101    * Note: The global $service_name below is set to the name of the service currently being
 102    * processed before the actual service function call, and is unset after normal
 103    * completion of the loop. If the script exits abnormally, the shutdown_function
 104    * uses the value of $service_name to do any required clean up.
 105    */
 106     global $service_name;
 107
 108     $single_service = isset($_REQUEST['background_service']) ? $_REQUEST['background_service'] : '';
 109     $force = (isset($_REQUEST['background_force']) && $_REQUEST['background_force']);
 110
 111     $sql = 'SELECT * FROM background_services WHERE ' . ($force ? '1' : 'execute_interval > 0');
 112     if ($single_service != "") {
 113         $services = sqlStatementNoLog($sql . ' AND name=?', array($single_service));
 114     } else {
 115         $services = sqlStatementNoLog($sql . ' ORDER BY sort_order');
 116     }
 117
 118     while ($service = sqlFetchArray($services)) {
 119         $service_name = $service['name'];
 120         if (!$service['active'] || $service['running'] == 1) {
 121             continue;
 122         }
 123
 124         $interval = (int)$service['execute_interval'];
 125
 126         //leverage locking built-in to UPDATE to prevent race conditions
 127         //will need to assess performance in high concurrency setting at some point
 128         $sql = 'UPDATE background_services SET running = 1, next_run = NOW()+ INTERVAL ?'
 129         . ' MINUTE WHERE running < 1 ' . ($force ? '' : 'AND NOW() > next_run ') . 'AND name = ?';
 130         if (sqlStatementNoLog($sql, array($interval,$service_name)) === false) {
 131             continue;
 132         }
 133
 134         $acquiredLock =  generic_sql_affected_rows();
 135         if ($acquiredLock < 1) {
 136             continue; //service is already running or not due yet
 137         }
 138
 139         if ($service['require_once']) {
 140             require_once($GLOBALS['fileroot'] . $service['require_once']);
 141         }
 142
 143         if (!function_exists($service['function'])) {
 144             continue;
 145         }
 146
 147         //use try/catch in case service functions throw an unexpected Exception
 148         try {
 149             $service['function']();
 150         } catch (Exception $e) {
 151           //do nothing
 152         }
 153
 154         $sql = 'UPDATE background_services SET running = 0 WHERE name = ?';
 155         $res = sqlStatementNoLog($sql, array($service_name));
 156     }
 157 }
 158
 159 /**
 160  * Catch unexpected failures.
 161  *
 162  * if the global $service_name is still set, then a die() or exit() occurred during the execution
 163  * of that service's function call, and we did not complete the foreach loop properly,
 164  * so we need to reset the is_running flag for that service before quitting
 165  */
 166
 167 function background_shutdown()
 168 {
 169     global $service_name;
 170     if (isset($service_name)) {
 171         $sql = 'UPDATE background_services SET running = 0 WHERE name = ?';
 172         $res = sqlStatementNoLog($sql, array($service_name));
 173     }
 174 }
 175
 176 register_shutdown_function('background_shutdown');
 177 execute_background_service_calls();
 178 unset($service_name);