Persistent Storage with gob
This lesson explains how to build persistent storage for the application.
We'll cover the following...
When the goto process (the web-server on a port) ends, and this has to happen sooner or later, the map with the shortened URLs in memory will be lost. To preserve our map data, we need to save them to a disk file. We will modify URLStore so that it writes its data to a file, and restores that data on goto start-up. For this, we will use Go’s encoding/gob package, which is a serialization and deserialization package that turns data structures into arrays (or more accurately slices) of bytes and vice versa (see Chapter 3).
With the gob package’s NewEncoder and NewDecoder functions, you can decide where you write the data to or read it from. The resulting Encoder and Decoder objects provide Encode and Decode methods for writing and reading Go data structures to and from files. Encoder also implements the Writer interface, and so does Decoder for the Reader interface.
We will add a new file field (of type *os.File) to URLStore that will be a handle to an open file that can be used for writing and reading.