diff mercurial/bundle2.py @ 46713:bc2519513ae0

sidedata-exchange: add `wanted_sidedata` and `sidedata_computers` to repos

Each repo will advertise the sidedata categories it requires (categories being
unique and canonical), and have a set of "computers", functions to generate
sidedata from `(repo, revlog, rev, previous_sidedata)`, for a given category.
The set of computers can be a superset of the set of the wanted categories, but
not smaller: repos are expected to be coherent in their handling of sidedata.

Differential Revision: https://phab.mercurial-scm.org/D10028

--- a/mercurial/bundle2.py	Thu Feb 18 18:18:35 2021 +0100
+++ b/mercurial/bundle2.py	Fri Feb 19 10:53:27 2021 +0100
@@ -1812,6 +1812,28 @@
     return params
 
 
+def format_remote_wanted_sidedata(repo):
+    """Formats a repo's wanted sidedata categories into a bytestring for
+    capabilities exchange."""
+    wanted = b""
+    if repo._wanted_sidedata:
+        wanted = b','.join(
+            pycompat.bytestr(c) for c in sorted(repo._wanted_sidedata)
+        )
+    return wanted
+
+
+def read_remote_wanted_sidedata(remote):
+    sidedata_categories = remote.capable(b'exp-wanted-sidedata')
+    return read_wanted_sidedata(sidedata_categories)
+
+
+def read_wanted_sidedata(formatted):
+    if formatted:
+        return set(formatted.split(b','))
+    return set()
+
+
 def addpartbundlestream2(bundler, repo, **kwargs):
     if not kwargs.get('stream', False):
         return
@@ -1957,6 +1979,7 @@
         b'version',
         b'nbchanges',
         b'exp-sidedata',
+        b'exp-wanted-sidedata',
         b'treemanifest',
         b'targetphase',
     ),
@@ -1999,6 +2022,10 @@
     targetphase = inpart.params.get(b'targetphase')
     if targetphase is not None:
         extrakwargs['targetphase'] = int(targetphase)
+
+    remote_sidedata = inpart.params.get(b'exp-wanted-sidedata')
+    extrakwargs['sidedata_categories'] = read_wanted_sidedata(remote_sidedata)
+
     ret = _processchangegroup(
         op,
         cg,
@@ -2559,5 +2586,7 @@
             part.addparam(b'treemanifest', b'1')
         if b'exp-sidedata-flag' in repo.requirements:
             part.addparam(b'exp-sidedata', b'1')
+            wanted = format_remote_wanted_sidedata(repo)
+            part.addparam(b'exp-wanted-sidedata', wanted)
 
     return bundler