fn mmapfile_datapool()

in src/storage/datapool/src/lib.rs [697:743]
36 lines of code
3 McCabe index (conditional complexity)

    fn mmapfile_datapool() {
        let tempdir = TempDir::new().expect("failed to generate tempdir");
        let mut path = tempdir.into_path();
        path.push("mmap_test.data");

        let magic_a = [0xDE, 0xCA, 0xFB, 0xAD];
        let magic_b = [0xBA, 0xDC, 0x0F, 0xFE, 0xEB, 0xAD, 0xCA, 0xFE];

        // create a datapool, write some content to it, and close it
        {
            let mut datapool =
                MmapFile::create(&path, 2 * PAGE_SIZE, 0).expect("failed to create pool");
            assert_eq!(datapool.len(), 2 * PAGE_SIZE);
            datapool.flush().expect("failed to flush");

            for (i, byte) in magic_a.iter().enumerate() {
                datapool.as_mut_slice()[i] = *byte;
            }
            datapool.flush().expect("failed to flush");
        }

        // open the datapool and check the content, then update it
        {
            let mut datapool =
                MmapFile::open(&path, 2 * PAGE_SIZE, 0).expect("failed to create pool");
            assert_eq!(datapool.len(), 2 * PAGE_SIZE);
            assert_eq!(datapool.as_slice()[0..4], magic_a[0..4]);
            assert_eq!(datapool.as_slice()[4..8], [0; 4]);

            for (i, byte) in magic_b.iter().enumerate() {
                datapool.as_mut_slice()[i] = *byte;
            }
            datapool.flush().expect("failed to flush");
        }

        // open the datapool again, and check that it has the new data
        {
            let datapool = MmapFile::open(&path, 2 * PAGE_SIZE, 0).expect("failed to create pool");
            assert_eq!(datapool.len(), 2 * PAGE_SIZE);
            assert_eq!(datapool.as_slice()[0..8], magic_b[0..8]);
        }

        // check that the datapool does not open if the user version is incorrect
        {
            assert!(MmapFile::open(&path, 2 * PAGE_SIZE, 1).is_err());
        }
    }