DB lock v0.2 #685

front/php/server/db.php

@@ -5,45 +5,54 @@
 //
 //  db.php - Front module. Server side. DB common file
 //------------------------------------------------------------------------------
-#  Puche 2021 / 2022+ jokob             jokob@duck.com                GNU GPLv3
+#   2022 jokob             jokob@duck.com                GNU GPLv3
 //------------------------------------------------------------------------------
 
 //------------------------------------------------------------------------------
 // DB File Path
 $DBFILE = dirname(__FILE__).'/../../../db/app.db';
+$DBFILE_LOCKED_FILE = dirname(__FILE__).'/../../../logs/db_is_locked.log';
 
 $db_locked = false;
 
 //------------------------------------------------------------------------------
 // Connect DB
 //------------------------------------------------------------------------------
-function SQLite3_connect ($trytoreconnect) {
-  global $DBFILE;
-  try
-  {
-    // connect to database
+function SQLite3_connect ($trytoreconnect, $retryCount = 0) {
+  global $DBFILE, $DBFILE_LOCKED_FILE;
+  $maxRetries = 5; // Maximum number of retries
+  $baseDelay = 1; // Base delay in seconds
 
+
+  try {
+    // Connect to database
     global $db_locked;
-
     $db_locked = false;
 
-    // return new SQLite3($DBFILE, SQLITE3_OPEN_READONLY);
+    // Write unlock status to the locked file
+    file_put_contents($DBFILE_LOCKED_FILE, '0');
+
     return new SQLite3($DBFILE, SQLITE3_OPEN_READWRITE);
-  }
-  catch (Exception $exception)
-  {
+  } catch (Exception $exception) {
     // sqlite3 throws an exception when it is unable to connect
     global $db_locked;
-
     $db_locked = true;
 
-    // try to reconnect one time after 3 seconds
+    // Write lock status to the locked file
+    file_put_contents($DBFILE_LOCKED_FILE, '1');
 
-    if($trytoreconnect)
-    {
-      echo '<script>alert("Error connecting to database, will try in 3s")</script>';
-      sleep(3);      
-      return SQLite3_connect(false);
+    // Connection failed, check if we should retry
+    if ($trytoreconnect && $retryCount < $maxRetries) {
+      // Calculate exponential backoff delay
+      $delay = $baseDelay * pow(2, $retryCount);
+      sleep($delay);
+
+      // Retry the connection with an increased retry count
+      return SQLite3_connect(true, $retryCount + 1);
+    } else {
+      // Maximum retries reached, hide loading spinner and show failure alert
+      echo '<script>alert("Failed to connect to database after ' . $retryCount . ' retries.")</script>';
+      return false; // Or handle the failure appropriately
     }
   }
 }

front/php/server/dbHelper.php

@@ -72,7 +72,7 @@
       case 'read'  :    read($rawSql);    break;
       case 'update':    update($columnName, $id, $defaultValue, $expireMinutes, $dbtable, $columns, $values);  break;
       case 'delete':    delete($columnName, $id, $dbtable);  break;
-      case 'checkLock': checkLock();  break;
+      case 'checkLock':     checkLock();  break;
       default:     logServerConsole ('Action: '. $action);  break;
     }
   }
@@ -269,26 +269,44 @@ function delete($columnName, $id, $dbtable)
 //  check if the database is locked
 //------------------------------------------------------------------------------
 function checkLock() {
+
+  return checkLock_file() or checkLock_db(); 
+
+}
+
+function checkLock_db() {
   global $DBFILE, $db_locked;
 
   $file = fopen($DBFILE, 'r+');
 
   if (!$file or $db_locked) {
-      echo 1; // Could not open the file
-      return;
+      // Could not open the file
+      return 1;
   }
 
   if (flock($file, LOCK_EX | LOCK_NB)) {
       // Lock acquired, meaning the database is not locked by another process
       flock($file, LOCK_UN); // Release the lock
-      echo 0; // Not locked
+      return 0; // Not locked
   } else {
       // Could not acquire lock, meaning the database is locked
-      echo 1; // Locked
+      fclose($file);
+      return 1; // Locked
   }
 
-  fclose($file);
+  
 }
 
+function checkLock_file() {
+    $DBFILE_LOCKED_FILE = dirname(__FILE__).'/../../../logs/db_is_locked.log';
+
+        if (file_exists($DBFILE_LOCKED_FILE)) {
+            $status = file_get_contents($DBFILE_LOCKED_FILE);
+            return $status; // Output the content of the lock file (0 or 1)
+        } else {
+            return '0'; // If the file doesn't exist, consider it as unlocked
+        }
+        exit;
+}
 
 ?>