diff tests/test-bundle-phases.t @ 36971:b89a7ef29013

bundle: include advisory rev branch cache part in bundle2 bundle

`hg bundle` command producing bundle2 will now include an optional part
containing the revision-branch cache data.

The data sent are mostly nodes so it is quite compact.  The goal of the
rev-branch-cache is to speed up branch map computation, especially when the
branchmap gets invalidated so we send data for all exchanged changesets. In
addition, computing the relevant heads to send in case of partial pulling would
be challenging.

As a reminder, the rev branch cache data significantly speed up branch
computation. Having it around provides a small speedup to pull/clone and much
higher tolerance to branch map cache invalidation that might happens from later
commands.

On the Mercurial repository, computing the visible branchmap from scratch move
from 2.00 seconds to 0.34s (a -83% speedup).

Using this new part, Unbundling the full Mercurial repository moves from 25.736
seconds to 24.030 seconds (around -7% speedup). The bundle size increase is
around 3% (from 22.43 MB to 23.13MB)


On an half a million revision repository with twenty thousand
branches, computing the branchmap moves from 75 seconds to 45 second (-40%) if
the caches is used.

A bundle containing 50 000 changesets in such repository get a 0.5% size
increase from such part for a -3% unbundling time speedup.

--- a/tests/test-bundle-phases.t	Wed Feb 21 17:26:22 2018 +0100
+++ b/tests/test-bundle-phases.t	Wed Feb 21 17:33:00 2018 +0100
@@ -42,6 +42,7 @@
       26805aba1e600a82e93661149f2313866a221a7b
       f585351a92f85104bff7c284233c338b10eb1df7
       9bc730a19041f9ec7cb33c626e811aa233efb18c
+  cache:rev-branch-cache -- {}
   phase-heads -- {}
       26805aba1e600a82e93661149f2313866a221a7b draft
   $ hg strip --no-backup C
@@ -233,6 +234,7 @@
       dc0947a82db884575bb76ea10ac97b08536bfa03
       4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
       03ca77807e919db8807c3749086dc36fb478cac0
+  cache:rev-branch-cache -- {}
   phase-heads -- {}
       dc0947a82db884575bb76ea10ac97b08536bfa03 public
       03ca77807e919db8807c3749086dc36fb478cac0 draft
@@ -258,6 +260,7 @@
   changegroup -- {nbchanges: 2, targetphase: 2, version: 02}
       112478962961147124edd43549aedd1a335e44bf
       4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
+  cache:rev-branch-cache -- {}
   phase-heads -- {}
   $ rm bundle
 
@@ -269,6 +272,7 @@
       112478962961147124edd43549aedd1a335e44bf
       dc0947a82db884575bb76ea10ac97b08536bfa03
       4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
+  cache:rev-branch-cache -- {}
   phase-heads -- {}
       dc0947a82db884575bb76ea10ac97b08536bfa03 public
   $ rm bundle
@@ -280,6 +284,7 @@
   changegroup -- {nbchanges: 2, targetphase: 2, version: 02}
       4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
       03ca77807e919db8807c3749086dc36fb478cac0
+  cache:rev-branch-cache -- {}
   phase-heads -- {}
       03ca77807e919db8807c3749086dc36fb478cac0 draft
   $ rm bundle