It's not necessary to acquire all locks before closing the database,

since Database.close() prevents new transactions from starting anyway.

components/net/sf/briar/db/Database.java

@@ -48,9 +48,8 @@ interface Database<T> {
 	void open(boolean resume) throws DbException;
 
 	/**
-	 * Waits for all open transactions to finish and closes the database.
-	 * <p>
-	 * Locking: all locks write.
+	 * Prevents new transactions from starting, waits for all current
+	 * transactions to finish, and closes the database.
 	 */
 	void close() throws DbException;
 

components/net/sf/briar/db/ReadWriteLockDatabaseComponent.java

@@ -97,37 +97,7 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 
 	public void close() throws DbException {
 		cleaner.stopCleaning();
-		contactLock.writeLock().lock();
-		try {
-			messageLock.writeLock().lock();
-			try {
-				messageStatusLock.writeLock().lock();
-				try {
-					ratingLock.writeLock().lock();
-					try {
-						subscriptionLock.writeLock().lock();
-						try {
-							transportLock.writeLock().lock();
-							try {
-								db.close();
-							} finally {
-								transportLock.writeLock().unlock();
-							}
-						} finally {
-							subscriptionLock.writeLock().unlock();
-						}
-					} finally {
-						ratingLock.writeLock().unlock();
-					}
-				} finally {
-					messageStatusLock.writeLock().unlock();
-				}
-			} finally {
-				messageLock.writeLock().unlock();
-			}
-		} finally {
-			contactLock.writeLock().unlock();
-		}
+		db.close();
 	}
 
 	public ContactId addContact(Map<String, Map<String, String>> transports)

components/net/sf/briar/db/SynchronizedDatabaseComponent.java

@@ -81,19 +81,7 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 
 	public void close() throws DbException {
 		cleaner.stopCleaning();
-		synchronized(contactLock) {
-			synchronized(messageLock) {
-				synchronized(messageStatusLock) {
-					synchronized(ratingLock) {
-						synchronized(subscriptionLock) {
-							synchronized(transportLock) {
-								db.close();
-							}
-						}
-					}
-				}
-			}
-		}
+		db.close();
 	}
 
 	public ContactId addContact(Map<String, Map<String, String>> transports)