NetAlertX/front/php/server/db.php

<?php
//------------------------------------------------------------------------------
//  NetAlertX
//  Open Source Network Guard / WIFI & LAN intrusion detector 
//
//  db.php - Front module. Server side. DB common file
//------------------------------------------------------------------------------
#   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, $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;

    // Write unlock status to the locked file
    file_put_contents($DBFILE_LOCKED_FILE, '0');

    return new SQLite3($DBFILE, SQLITE3_OPEN_READWRITE);
  } catch (Exception $exception) {
    // sqlite3 throws an exception when it is unable to connect
    global $db_locked;
    $db_locked = true;

    // Write lock status to the locked file
    file_put_contents($DBFILE_LOCKED_FILE, '1');

    // 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
    }
  }
}


//------------------------------------------------------------------------------
// Open DB
//------------------------------------------------------------------------------

function OpenDB (...$DBPath) {
  global $DBFILE;
  global $db;

  // use custom path if supplied
  foreach ($DBPath as $path) {  
    $DBFILE = $path;  
  }  
  
  if(strlen($DBFILE) == 0)
  {
    echo '<script>alert("Database not available")</script>';
    die ('<div style="padding-left:150px">Database not available</div>');
  }

  $db = SQLite3_connect(true);
  
  if(!$db)
  {
    echo '<script>alert("Error connecting to the database")</script>';
    die ('<div style="padding-left:150px">Error connecting to the database</div>');
  }

  $db->exec('PRAGMA journal_mode = wal;');  
}


// # Open DB once and keep open
// # Opening / closing DB frequently actually casues more issues
OpenDB (); // main