diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -702,6 +702,13 @@ coreconfigitem(
b'debug.peer-request',
default=False,
)
+# If discovery.exchange-heads is False, the discovery will not start with
+# remote head fetching and local head querying.
+coreconfigitem(
+ b'devel',
+ b'discovery.exchange-heads',
+ default=True,
+)
# If discovery.grow-sample is False, the sample size used in set discovery will
# not be increased through the process
coreconfigitem(
diff --git a/mercurial/setdiscovery.py b/mercurial/setdiscovery.py
--- a/mercurial/setdiscovery.py
+++ b/mercurial/setdiscovery.py
@@ -314,6 +314,8 @@ def findcommonheads(
else:
ownheads = [rev for rev in cl.headrevs() if rev != nullrev]
+ initial_head_exchange = ui.configbool(b'devel', b'discovery.exchange-heads')
+
# We also ask remote about all the local heads. That set can be arbitrarily
# large, so we used to limit it size to `initialsamplesize`. We no longer
# do as it proved counter productive. The skipped heads could lead to a
@@ -365,33 +367,39 @@ def findcommonheads(
# graph (with many heads) attached to, but very independant to a the
# "simple" graph on the server. This is a fairly usual case and have
# not been met in the wild so far.
- if remote.limitedarguments:
- sample = _limitsample(ownheads, initialsamplesize)
- # indices between sample and externalized version must match
- sample = list(sample)
- else:
- sample = ownheads
+ if initial_head_exchange:
+ if remote.limitedarguments:
+ sample = _limitsample(ownheads, initialsamplesize)
+ # indices between sample and externalized version must match
+ sample = list(sample)
+ else:
+ sample = ownheads
- ui.debug(b"query 1; heads\n")
- roundtrips += 1
- with remote.commandexecutor() as e:
- fheads = e.callcommand(b'heads', {})
- fknown = e.callcommand(
- b'known',
- {
- b'nodes': [clnode(r) for r in sample],
- },
- )
+ ui.debug(b"query 1; heads\n")
+ roundtrips += 1
+ with remote.commandexecutor() as e:
+ fheads = e.callcommand(b'heads', {})
+ fknown = e.callcommand(
+ b'known',
+ {
+ b'nodes': [clnode(r) for r in sample],
+ },
+ )
+
+ srvheadhashes, yesno = fheads.result(), fknown.result()
- srvheadhashes, yesno = fheads.result(), fknown.result()
-
- if audit is not None:
- audit[b'total-roundtrips'] = 1
+ if audit is not None:
+ audit[b'total-roundtrips'] = 1
- if cl.tip() == nullid:
- if srvheadhashes != [nullid]:
- return [nullid], True, srvheadhashes
- return [nullid], False, []
+ if cl.tip() == nullid:
+ if srvheadhashes != [nullid]:
+ return [nullid], True, srvheadhashes
+ return [nullid], False, []
+ else:
+ # we still need the remote head for the function return
+ with remote.commandexecutor() as e:
+ fheads = e.callcommand(b'heads', {})
+ srvheadhashes = fheads.result()
# start actual discovery (we note this before the next "if" for
# compatibility reasons)
@@ -408,15 +416,16 @@ def findcommonheads(
except error.LookupError:
continue
- # early exit if we know all the specified remote heads already
- if len(knownsrvheads) == len(srvheadhashes):
- ui.debug(b"all remote heads known locally\n")
- return srvheadhashes, False, srvheadhashes
+ if initial_head_exchange:
+ # early exit if we know all the specified remote heads already
+ if len(knownsrvheads) == len(srvheadhashes):
+ ui.debug(b"all remote heads known locally\n")
+ return srvheadhashes, False, srvheadhashes
- if len(sample) == len(ownheads) and all(yesno):
- ui.note(_(b"all local changesets known remotely\n"))
- ownheadhashes = [clnode(r) for r in ownheads]
- return ownheadhashes, True, srvheadhashes
+ if len(sample) == len(ownheads) and all(yesno):
+ ui.note(_(b"all local changesets known remotely\n"))
+ ownheadhashes = [clnode(r) for r in ownheads]
+ return ownheadhashes, True, srvheadhashes
# full blown discovery
@@ -429,12 +438,13 @@ def findcommonheads(
disco = partialdiscovery(
local, ownheads, hard_limit_sample, randomize=randomize
)
- # treat remote heads (and maybe own heads) as a first implicit sample
- # response
- disco.addcommons(knownsrvheads)
- disco.addinfo(zip(sample, yesno))
+ if initial_head_exchange:
+ # treat remote heads (and maybe own heads) as a first implicit sample
+ # response
+ disco.addcommons(knownsrvheads)
+ disco.addinfo(zip(sample, yesno))
- full = False
+ full = not initial_head_exchange
progress = ui.makeprogress(_(b'searching'), unit=_(b'queries'))
while not disco.iscomplete():
diff --git a/tests/test-setdiscovery.t b/tests/test-setdiscovery.t
--- a/tests/test-setdiscovery.t
+++ b/tests/test-setdiscovery.t
@@ -1412,23 +1412,22 @@ One with >200 heads. We now switch to se
missing: 1040
common heads: 3ee37d65064a
- $ hg -R a debugdiscovery b --debug --config devel.discovery.randomize=false --config devel.discovery.grow-sample.rate=1.01
+ $ hg -R a debugdiscovery b --debug --config devel.discovery.exchange-heads=false --config devel.discovery.randomize=false --config devel.discovery.grow-sample.rate=1.01
comparing with b
- query 1; heads
searching for changes
- taking quick initial sample
- query 2; still undecided: 1080, sample size is: 100
sampling from both directions
- query 3; still undecided: 980, sample size is: 200
+ query 1; still undecided: 1340, sample size is: 200
+ sampling from both directions
+ query 2; still undecided: 795, sample size is: 202
sampling from both directions
- query 4; still undecided: 497, sample size is: 202
+ query 3; still undecided: 525, sample size is: 204
sampling from both directions
- query 5; still undecided: 294, sample size is: 204
+ query 4; still undecided: 252, sample size is: 206
sampling from both directions
- query 6; still undecided: 90, sample size is: 90
- 6 total queries in *s (glob)
+ query 5; still undecided: 44, sample size is: 44
+ 5 total queries in *s (glob)
elapsed time: * seconds (glob)
- round-trips: 6
+ round-trips: 5
heads summary:
total common heads: 1
also local heads: 0