3. gdbm

A gdbm class is a wrapper around the GDBM library. The GDBM library implements a simple key/value database in a flat file. The gdbm class provides the following methods:

A gdbm does not open the GDBM file immediately, upon instantiation. The GDBM file gets opened automatically the first time it's accessed by any method. Additionally, a method is provided to close the GDBM file (if another method is called afterwards the file gets reopened).

The gdbm class also creates a lock file in parallel with the GDBM file. The type of the lock parallels the access method. Instantiating a read-only gdbm object creates a read-only lock. Instantiating a read-write gdbm object creates a read-write lock.