Fix #5 serviceWorker DB access

serviceWorker openes DB only when needed and closes it directly

service-worker.js.php

@@ -109,30 +109,41 @@ workbox.routing.registerRoute(
 
 // DB
 
-var db = null;
+function openDb() {
+	return new Promise(function(resolve) {
 		if (indexedDB) {
 			var request = indexedDB.open('regatten_app_db_<?php echo BOATCLASS; ?>');
 			request.onerror = function (e) {
-		console.log('[sW] Cannot open DB:', e.target.errorCode);
+				console.log('[sW] Cannot open DB:', e.targer.errorCode);
+				resolve(null);
 			};
 			request.onupgradeneeded = function (e) {
 				console.log('[sW] DB does not exist');
 				e.target.transaction.abort();
+				resolve(null);
 			};
 			request.onsuccess = function (e) {
 				console.log('[sW] DB loaded');
-		db = e.target.result;
+				var db = e.target.result;
 				db.onerror = function (e) {
-			console.log('[sW] DB Error:', e)
-		}
+					console.log('[sW] DB Error:', e);
 				};
+				resolve(db);
+			}
+		} else {
+			resolve(null);
+		}
+	});
 }
 
 function dbSettingsGet(key) {
-	return new Promise(function(resolve) {
-		if (db != null) {
+	return new Promise(async function(resolve) {
+		var db = await openDb();
+		if (db !== null) {
 			var request = db.transaction('settings').objectStore('settings').get(key);
 			request.onsuccess = function (event) {
+				db.close();
+				console.log('[sW] DB closed');
 				resolve(typeof request.result != 'undefined' ? request.result.value : null);
 			}
 		} else {
@@ -141,10 +152,20 @@ function dbSettingsGet(key) {
 	});
 }
 
-function dbSettingsSet(key, value) {
+async function dbSettingsSet(key, value) {
+	var db = await openDb();
 	if (db != null) {
 		var os = db.transaction('settings', 'readwrite').objectStore('settings');
-		os.put({ key: key, value: value});
+		var request = os.put({ key: key, value: value});
+		request.onerror = function (event) {
+			console.log('[sW] Error while saving data to DB:', e);
+			db.close();
+			console.log('[sW] DB closed');
+		}
+		request.onsuccess = function (event) {
+			db.close();
+			console.log('[sW] DB closed');
+		}
 	}
 }
 
@@ -227,13 +248,50 @@ self.addEventListener('push', async function(event) {
 				}
 
 				// Force refresh on next app open
+				var db = await openDb();
+				if (db != null) {
 					var os = db.transaction('update_times', 'readwrite').objectStore('update_times');
-				os.put({ table: 'last_sync', time: 0 });
+					var request = os.put({ table: 'last_sync', time: 0 });
+					request.onerror = function (event) {
+						console.log('[sW] Error while saving data to DB:', e);
+						db.close();
+						console.log('[sW] DB closed');
+					}
+					request.onsuccess = function (event) {
+						db.close();
+						console.log('[sW] DB closed');
+					}
+				}
 
 				console.log('Showing notification');
 				self.registration.showNotification(data.title, options);
 				break;
+
+			case 'forcesync':
+				// Force refresh on next app open
+				var db = await openDb();
+				if (db != null) {
+					var os = db.transaction('update_times', 'readwrite').objectStore('update_times');
+					var request = os.put({ table: 'last_sync', time: 0 });
+					request.onerror = function (event) {
+						console.log('[sW] Error while saving data to DB:', e);
+						db.close();
+						console.log('[sW] DB closed');
 					}
+					request.onsuccess = function (event) {
+						console.log('[sW] Data successfully saved');
+						db.close();
+						console.log('[sW] DB closed');
+					}
+				}
+				break;
+
+			default:
+				console.log('[sW] Push type unknown:', data.type);
+				break;
+		}
+	} else {
+		console.log('[sW] No push type given!');
 	}
 });