added fork on linux as well as implimented pid file to check for other running crons

--HG--
branch : rc-botanic-webdev

code/ryzom/tools/server/ryzom_ams/ams_lib/autoload/sync.php

@@ -15,6 +15,20 @@ class Sync{
      */
     static public function syncdata ($display = true) {
     
+    if (function_exists('pcntl_fork')) {
+        $pid = pcntl_fork();
+    }
+    $pidfile = '/tmp/ams_cron_pid';
+    if(isset($pid)) {
+    // We're the main process.
+    } else {
+        if(!file_exists($pidfile)) {
+            $pid = getmypid();
+            $file = fopen($pidfile, 'w');
+                
+            fwrite($file, $pid);
+            fclose($file);
+
             try {
                 $dbl = new DBLayer("lib");
                 $statement = $dbl->executeWithoutParams("SELECT * FROM ams_querycache");
@@ -66,6 +80,9 @@ class Sync{
                     print_r($e);
                 }
             }
+            unlink($pidfile);
+        }
 
     }
+    }
 }