Development

• Packs bugs

• Benchmarks repositories TODO:
  • small pack without new patches
  • small pack with a few new patches
  • small pack with many new patches
  • big pack without new patches
  • big pack with a few new patches
  • big pack with many new patches Then compare times of get --no-packs --lazy, get --packs --lazy, get --no-packs --complete, get --packs --complete.

Benchmarks with existing big repositories

• Xmonad: ~ 1200 patches http://code.haskell.org/xmonad
• DDC: ~ 4500 patches http://code.ouroborus.net/ddc/ddc-head
• Agda: ~ 4600 patches http://code.haskell.org/Agda
• Darcs: ~ 11000 patches http://darcs.net
• Nikki and the robots: ~ 2000 patches http://code.joyridelabs.de/nikki
• : ~ 7500 patches http://darcs.net/darcs-wiki

Optimizing a repository for HTTP transfer

To reduce number of files needed to transfer over network, the optimize --http command packs a repository into two tarballs, basic.tar.gz and patches.tar.gz, with the following content:

basic.tar.gz

1. _darcs/hashed_inventory
2. _darcs/meta-filelist-pristine
3. _darcs/meta-filelist-inventories
4. _darcs/meta-*
5. _darcs/hashed.pristine/*
6. _darcs/inventories/*

meta-filelist-* files contain directory listings for hashed.pristine and inventories dirs, in reverse order wrt tarball itself. While getting, files from this listings are downloaded using cache in parallel with tarball.

meta-* files in general contain additional files and information that could extend the tarballs functionality in some way. They are expected to have a small size, so that negative effect on performance would be minimal.

patches.tar.gz

1. _darcs/patches/*

Getting an optimized repository

1. Download and unpack basic.tar.gz. Result: lazy repository from time when optimize --http has been done.
2. Pull from parent repository. Result: lazy repository from current time.
3. Download and unpack patches.tar.gz. Result: full repository.

Benchmarks from 2011

How does optimize --http improve the user experience?

• Jérémie’s repo (~900 patches): from 10s (get --no-packs) to 1s (get)
• http://darcs.net/ (~9300 patches): darcs optimize --http takes 14s to run. _darcs goes from 54 MBytes to 64 MBytes (indeed _darcs/packs/ is 11 MBytes) Complete get: from 37 to 2 minutes, lazy get from 27 seconds to 7 seconds.

screened + 12 patches:

.      packs    no-packs
lazy   30s      1m30
full   2m30s    31m