Perl, Binary and Memcached
The last few days I’ve been working on updating the binary protocol test in the latest memcached development branch to comply with the latest binary protocol specification. Prior to this update, the test client was sending an invalid request to the server, which as a consequence made the test hang and never finish.
In brief, this is the big difference:
Previously, CAS (compare and swap) value was treated as part of the extra header that is appended/serialized behind the request/response header. In the latest specification, CAS value is a required 8 byte field in the 24 byte request/response header (header size in the previous version was 16 bytes). Other than that, the rest were minor differences in the packet format of extra fields in certain commands. Easy work :)
Here is the actual diff:
http://github.com/tmaesaka/memcached/commit/67b4da9eb855ebe7695a197320232b8d25692f84
As you can see, the test suite currently used by memcached is Perl based. This was fortunate for me since Perl is the second language to C that I like. I also made the code style to be more “perl-like” by fixing the indents. Although heh, I can see a Perl programmer arguing that the use of if/else blocks in the test is not best practice.
You know, fixing the test was pretty meaningful to me since it had forced me to study the binary protocol specification, which I knew almost nothing about at the hackathon in Santa Clara, CA back in april. Hopefully I can make productive suggestions at the upcoming hackathon in Menlo Park, CA in october.
