[PATCH 2 of 4] revbranchcache: add a bundle2 handler for a rbc part

[Boris Feld]

# HG changeset patch
# User Boris Feld <boris.feld at octobus.net>
# Date 1516282142 -3600
#      Thu Jan 18 14:29:02 2018 +0100
# Node ID 9c1ad82226a2e1fc7ca69550a46a7f7329c6b579
# Parent  4ad1a1054450063cc9aa19ab2037722c64877eb7
# EXP-Topic wire-rbc
# Available At https://bitbucket.org/octobus/mercurial-devel/
#              hg pull https://bitbucket.org/octobus/mercurial-devel/ -r 9c1ad82226a2
revbranchcache: add a bundle2 handler for a rbc part

We add the necessary bit to process a part containing rev-branch-cache
information. The local rev branch cache is then updated with the received
information.

Computing branch cache can become a signifiant part of the time spent pulling so
this is expected to provide worthwhile speedup.

diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -2101,6 +2101,40 @@ def handlehgtagsfnodes(op, inpart):
     cache.write()
     op.ui.debug('applied %i hgtags fnodes cache entries\n' % count)
 
+rbcstruct = struct.Struct('>III')
+
+ at parthandler('cache:rev-branch-cache')
+def handlerbc(op, inpart):
+    """receive a rev-branch-cache payload and update the local cache
+
+    The payload is a series of data related to each branch
+
+    1) branch name length
+    2) number of open heads
+    3) number of closed heads
+    4) open heads nodes
+    5) closed heads nodes
+    """
+    total = 0
+    rawheader = inpart.read(rbcstruct.size)
+    cache = op.repo.revbranchcache()
+    cl = op.repo.unfiltered().changelog
+    while rawheader:
+        header = rbcstruct.unpack(rawheader)
+        total += header[1] + header[2]
+        branch = inpart.read(header[0])
+        for x in xrange(header[1]):
+            node = inpart.read(20)
+            rev = cl.rev(node)
+            cache.setdata(branch, rev, node, False)
+        for x in xrange(header[2]):
+            node = inpart.read(20)
+            rev = cl.rev(node)
+            cache.setdata(branch, rev, node, True)
+        rawheader = inpart.read(rbcstruct.size)
+    if total and 'branchinfo' in vars(cache):
+        del cache.branchinfo
+
 @parthandler('pushvars')
 def bundle2getvars(op, part):
     '''unbundle a bundle2 containing shellvars on the server'''