Fix webhook application hang on exit

* Import d9fee18b28 manually

src/itemdb.d

@@ -680,6 +680,7 @@ final class ItemDatabase {
 		try {
 			auto stmt = db.prepare("VACUUM;");
 			stmt.exec();
+			log.vdebug("Database vacuum is complete");
 		} catch (SqliteException e) {
 			writeln();
 			log.error("ERROR: Unable to perform a database vacuum: " ~ e.msg);

src/main.d

@@ -898,28 +898,33 @@ int main(string[] cliArgs) {
 void performStandardExitProcess(string scopeCaller) {
 	// Who called this function
 	log.vdebug("Running performStandardExitProcess due to: ", scopeCaller);
-
-	// Shutdown the database
-	if (itemDB !is null) {
-		// Make sure the .wal file is incorporated into the main db before we exit
-		itemDB.performVacuum();
-		object.destroy(itemDB);
-	}
-
+	
+	// Wait for all parallel jobs that depend on the database to complete
+	log.vdebug("Wait for all parallel jobs that depend on the database to complete");
+	taskPool.finish(true);
+	
 	// Shutdown the OneDrive API instance
 	if (oneDriveApiInstance !is null) {
+		log.vdebug("Shutdown OneDrive API instance");
 		oneDriveApiInstance.shutdown();
 		object.destroy(oneDriveApiInstance);
 	}
 	
 	// Shutdown the sync engine
-	if (syncEngineInstance !is null) object.destroy(syncEngineInstance);
+	if (syncEngineInstance !is null) {
+		log.vdebug("Shutdown Sync Engine instance");
+		object.destroy(syncEngineInstance);
+	}
 	
 	// Shutdown the client side filtering objects
-	if (selectiveSync !is null) object.destroy(selectiveSync);
+	if (selectiveSync !is null) {
+		log.vdebug("Shutdown Client Side Filtering instance");
+		object.destroy(selectiveSync);
+	}
 	
 	// Shutdown the application configuration objects
 	if (appConfig !is null) {
+		log.vdebug("Shutdown Application Configuration instance");
 		// Cleanup any existing dry-run elements ... these should never be left hanging around
 		cleanupDryRunDatabaseFiles(appConfig.databaseFilePathDryRun);
 		object.destroy(appConfig);
@@ -927,10 +932,22 @@ void performStandardExitProcess(string scopeCaller) {
 	
 	// Shutdown any local filesystem monitoring
 	if (filesystemMonitor !is null) {
+		log.vdebug("Shutdown Filesystem Monitoring instance");
 		filesystemMonitor.shutdown();
 		object.destroy(filesystemMonitor);
 	}
 	
+	// Shutdown the database
+	if (itemDB !is null) {
+		log.vdebug("Shutdown Database instance");
+		// Make sure the .wal file is incorporated into the main db before we exit
+		if (itemDB.isDatabaseInitialised()) {
+			itemDB.performVacuum();
+		}
+		object.destroy(itemDB);
+	}
+	
+	// Set all objects to null
 	if (scopeCaller == "failureScope") {
 		// Set these to be null due to failure scope - prevent 'ERROR: Unable to perform a database vacuum: out of memory' when the exit scope is then called
 		log.vdebug("Setting Class Objects to null due to failure scope");

src/onedrive.d

@@ -76,6 +76,7 @@ class OneDriveWebhook {
 	private ushort port;
 	private Tid parentTid;
 	private shared uint count;
+	private bool started;
 
 	static OneDriveWebhook getOrCreate(string host, ushort port, Tid parentTid) {
 		if (!instantiated_) {
@@ -97,9 +98,23 @@ class OneDriveWebhook {
 		this.parentTid = parentTid;
 		this.count = 0;
 	}
+	
+	void serve() {
+		spawn(&serveStatic);
+		this.started = true;
+		log.log("Started webhook server");
+	}
+
+	void stop() {
+		if (this.started) {
+			RequestServer.stop();
+			this.started = false;
+		}
+		log.log("Stopped webhook server");
+	}
 
 	// The static serve() is necessary because spawn() does not like instance methods
-	static serve() {
+	private static void serveStatic() {
 		// we won't create the singleton instance if it hasn't been created already
 		// such case is a bug which should crash the program and gets fixed
 		instance_.serveImpl();
@@ -458,9 +473,20 @@ class OneDriveApi {
 	
 	// Shutdown OneDrive API Curl Engine
 	void shutdown() {
+		
 		// Delete subscription if there exists any
-		deleteSubscription();
-
+		try {
+			deleteSubscription();
+		} catch (OneDriveException e) {
+			logSubscriptionError(e);
+		}
+		
+		// Shutdown webhook server if it is running
+		if (webhook !is null) {
+			webhook.stop();
+			object.destroy(webhook);
+		}
+		
 		// Reset any values to defaults, freeing any set objects
 		curlEngine.http.clearRequestHeaders();
 		curlEngine.http.onSend = null;
@@ -858,7 +884,7 @@ class OneDriveApi {
 				to!ushort(appConfig.getValueLong("webhook_listening_port")),
 				thisTid
 			);
-			spawn(&OneDriveWebhook.serve);
+			webhook.serve();
 		}
 
 		auto elapsed = Clock.currTime(UTC()) - subscriptionLastErrorAt;
@@ -999,13 +1025,14 @@ class OneDriveApi {
 	
 	private void deleteSubscription() {
 		if (!hasValidSubscription()) {
+			log.vdebug("No valid Microsoft OneDrive webhook subscription to delete");
 			return;
 		}
 
 		string url;
 		url = subscriptionUrl ~ "/" ~ subscriptionId;
-		del(url);
-		log.log("Deleted subscription");
+		performDelete(url);
+		log.vdebug("Deleted Microsoft OneDrive webhook subscription");
 	}
 	
 	private void logSubscriptionError(OneDriveException e) {