Locks this.
If it is already locked by another thread, the current thread will block until it is unlocked by the other thread.
This function can be used even if g_thread_init has not yet been called, and, in that case, will do nothing.
Note: unlike @lock, this method recursive, which means a thread can lock this several times (and has to unlock it as many times to actually unlock it).
| this |
a Lockable object. |