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Differential D4667

setdiscovery: access future.result() inside command executor
ClosedPublic

Authored by martinvonz on Sep 20 2018, 12:32 AM.

Details

Reviewers
indygreg
Group Reviewers
hg-reviewers
Commits
rHG63c2b44bbe60: setdiscovery: access future.result() inside command executor
Summary

peer.commandexecutor()'s context manager waits for all responses to
arrive in its exit() method. When batching requests, one often
wants to process the requests as they arrive. That means one has to
call future.result() before exiting the command executor's context
manager. It doesn't matter in practice here (where we batch only
"heads" and "known" and don't care to process either until both
responses have arrived), but let's make this code a good example for
others who may want to copy the pattern.

Diff Detail

Repository
rHG Mercurial
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Automatic diff as part of commit; lint not applicable.
Unit
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Event Timeline

martinvonz created this revision.Sep 20 2018, 12:32 AM
Closed by commit rHG63c2b44bbe60: setdiscovery: access future.result() inside command executor (authored by martinvonz). · Explain WhySep 20 2018, 8:26 AM
This revision was automatically updated to reflect the committed changes.
indygreg added a comment.Sep 20 2018, 12:46 PM

I'm going to drop this from hg-committed because it introduces deadlock in test-http-bad-server.t.

The deadlock is due to buggy future handling in (at least) httppeer. I'll keep this patch in my local queue and will try to hack on a fix for the peer.

Revision Contents
Changeset List

PathPackages
Mmercurial/setdiscovery.py (3 lines)

Diff 11205

mercurial/setdiscovery.py

# indices between sample and externalized version must match # indices between sample and externalized version must match
sample = list(sample) sample = list(sample)
with remote.commandexecutor() as e: with remote.commandexecutor() as e:
fheads = e.callcommand('heads', {}) fheads = e.callcommand('heads', {})
fknown = e.callcommand('known', { fknown = e.callcommand('known', {
'nodes': [clnode(r) for r in sample], 'nodes': [clnode(r) for r in sample],
}) })
srvheadhashes, yesno = fheads.result(), fknown.result() srvheadhashes, yesno = fheads.result(), fknown.result()
if cl.tip() == nullid: if cl.tip() == nullid:
if srvheadhashes != [nullid]: if srvheadhashes != [nullid]:
return [nullid], True, srvheadhashes return [nullid], True, srvheadhashes
return [nullid], False, [] return [nullid], False, []
# start actual discovery (we note this before the next "if" for # start actual discovery (we note this before the next "if" for
# compatibility reasons) # compatibility reasons)