@lock

Obtains an exclusive lock on this and starts a transaction.

This should be called if you need to access this multiple times while ensuring an atomic transaction. End this transaction with @unlock.

If cancellable is specified, then this will retain a reference to it until @unlock is called. Any accesses to this with the lock held are expected to have the same cancellable specified, or null.

<note><para>Aside from ensuring atomicity of transactions, this function will hold a mutex which will cause further calls to @lock to block. If you are accessing this from multiple threads, then any interactions with this should be nested in calls to @lock and @unlock.</para></note>

Parameters:

this	An BookSqlite
lock_type	The bSqlLockType to acquire
cancellable	A Cancellable

Returns:

true on success, otherwise false is returned and throws is set appropriately.