streamclone: also stream caches to the client
When stream clone is used over bundle2, relevant cache files are also streamed.
This is expected to be a massive performance win for clone since no important
cache will have to be recomputed.
Some performance numbers:
(All times are wall-clock times in seconds, 2 attempts per case.)
# Mozilla-Central
## Clone over ssh over lan
V1 streaming: 234.3 239.6
V2 streaming: 248.4 243.7
## Clone over ssh over Internet
V1 streaming: 175.5 110.9
V2 streaming: 109.1 111.0
## Clone over HTTP over lan
V1 streaming: 105.3 105.6
V2 streaming: 112.7 111.4
## Clone over HTTP over internet
V1 streaming: 105.6 114.6
V2 streaming: 226.7 225.9
## Hg tags
V1 streaming (no cache): 1.084 1.071
V2 streaming (cache): 0.312 0.325
## Hg branches
V1 streaming (no cache): 14.047 14.148
V2 streaming (with cache): 0.312 0.333
# Pypy
## Clone over ssh over internet
V1 streaming: 29.4 30.1
V2 streaming: 31.2 30.1
## Clone over http over internet
V1 streaming: 29.7 29.7
V2 streaming: 75.2 72.9
(since ssh and lan are not affected, there seems to be an issue with how we
read/write the http stream on connection with latency, unrelated to the format)
## Hg tags
V1 streaming (no cache): 1.752 1.664
V2 streaming (with cache): 0.274 0.260
## Hg branches
V1 streaming (no cache): 4.469 4.728
V2 streaming (with cache): 0.318 0.321
# Private repository:
* 500K revision revisions
* 11K topological heads
* 28K branch heads
## hg tags
no cache: 1543.332
with cache: 4.900
## hg branches
no cache: 91.828
with cache: 2.955
# invalid filenames
test-add.t
test-init.t
test-clone.t
test-contrib.t
test-hgweb-raw.t
test-walk.t
# no sockets or fifos
test-hup.t
# no hardlinks
test-hardlinks.t
test-relink.t
# exec bit problems
test-convert-bzr-114.t
test-convert-bzr-directories.t
test-convert-bzr-merges.t
test-convert-bzr-treeroot.t
test-convert-darcs.t
test-merge-tools.t
# debugstate exec bit false positives
test-dirstate.t
test-filebranch.t
test-merge-remove.t