[tahoe-dev] update on 1.9

[Brian Warner]

Just a quick update:

 * MDMF cleanup continues. I found and fixed a few significant problems
   over the weekend (#1510, and an unsafe dependency upon the ordering
   of dict.values()). I also added 'tahoe debug' support for MDMF
   (dump-cap, dump-share, catalog-shares), and fixed some documentation
   inaccuracies in layout.py

 * David-Sarah provided tests (currently failing) of zero-byte reads
   (they return more than zero bytes). We're still investigating the
   failure, and will block beta1 until we have a fix. #1512

 * I'm hoping to build a test harness that modifies and reads random
   spans of a mutable file nonstop and run it overnight. This might give
   us more confidence in MDMF's (intricate and tricky)
   which-segment-should-we-touch logic.

 * We've resurrected the memory-footprint -testing buildslaves. We don't
   yet have a way to graph the results over time: our old munin-based
   system bitrotted long ago. If I get some free time next weekend, I'm
   considering a Google-App-Engine DB service and some d3.js code: other
   tool suggestions are welcome (ideally we'd HTTP POST the numbers
   somewhere after each test). Also we need to add SDMF/MDMF operations
   into the test, to help make progress on #1513 and #1514.

 * I'm planning to resurrect the speedtest buildslaves too, using the
   hosted servers kindly donated by Atlas Networks. I'm looking for
   someone who can host a buildslave at home, behind a not-so-fast DSL
   line, so we can get graphs of upload/download performance when the
   client-to-server connection is the bottleneck (i.e. WAN use-cases
   instead of LAN ones). Your buildslave would upload and download about
   100MB each time the code changes and also once each night.

 * running unit tests is a bit painful because test_mutable.Update takes
   upwards of 7 minutes all by itself (#1500). We hope to fix it.

 * apart from testing MDMF, the most significant remaining work for 1.9
   is documentation. I plan to build a first draft of the NEWS entry (by
   walking revision history and summarizing the patches therein) this
   week. We also need some basic docs on how (and why not) to use MDMF.

If we're lucky, we can tag beta1 next weekend.

Test Test Test!
 -Brian