Locks lockable. If it is already locked by another thread, the current thread will block until it is unlocked by the other thread.
Tries to lock lockable. If it is already locked by another thread, then it immediately returns FALSE, otherwise it locks lockable.
Unlocks lockable. This method should not be called if the current does not already holds a lock on lockable (having used gda.lockable.Lockable.lock or gda.lockable.Lockable.trylock).