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Differential D9151

test: add test-transaction-rollback-on-sigpipe.t demonstrating py3 regression
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Authored by mplamann on Oct 5 2020, 6:37 PM.

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pulkit
Group Reviewers
hg-reviewers
Commits
rHG2c6b054e22d0: test: add test-transaction-rollback-on-sigpipe.t demonstrating py3 regression
Summary

When an hg push is interrupted with C-c, the remote [hg serve] command
receives SIGPIPE.

If a pretxnchangegroup hook fails, the remote hg then tries to
rollback the transaction. It begins by printing "transaction
abort!\n". This returns EPIPE, but ui.py ignores that error.

In python3 (but not python2), this "transaction abort!\n" message
stays in a buffer, so future flushes of stderr will try to print the
message again, and so those flushes will also hit EPIPE.

This test demonstrates such a case where this EPIPE causes the
transaction rollback to fail, leaving behind an abandoned transaction.

Diff Detail

Repository
rHG Mercurial
Branch
stable
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Event Timeline

mplamann created this revision.Oct 5 2020, 6:37 PM
pulkit added a subscriber: pulkit.Oct 9 2020, 5:18 AM
pulkit added inline comments.
tests/test-transaction-rollback-on-sigpipe.t
4

We use the hg build by run-tests.py in test suite.

9

I thought hg summary prints about abandoned transaction but I am not sure.

mplamann updated this revision to Diff 23206.Oct 14 2020, 12:33 PM
pulkit accepted this revision.Oct 16 2020, 3:31 AM
This revision is now accepted and ready to land.Oct 16 2020, 3:31 AM

Revision Contents
Changeset List

Diff 23039

tests/test-transaction-rollback-on-sigpipe.t

  • This file was added.
Test that, when an hg push is interrupted and the remote side recieves SIGPIPE,
the remote hg is able to successfully roll back the transaction.
$ hg=$(which hg)
pulkitUnsubmitted
Not Done

We use the hg build by run-tests.py in test suite.

pulkit: We use the `hg` build by `run-tests.py` in test suite.
$ $hg init -q remote
$ $hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" -q ssh://user@dummy/`pwd`/remote local
$ check_for_abandoned_transaction() {
pulkitUnsubmitted
Not Done

I thought hg summary prints about abandoned transaction but I am not sure.

pulkit: I thought `hg summary` prints about abandoned transaction but I am not sure.
> [[ -f $TESTTMP/remote/.hg/store/journal ]] && echo "Abandoned transaction!"
> }
$ pidfile=`pwd`/pidfile
$ >$pidfile
$ script() {
> cat >"$1"
> chmod +x "$1"
> }
On the remote end, run hg, piping stdout and stderr through processes that we
know the PIDs of. We will later kill these to simulate an ssh client
disconnecting.
$ killable_pipe=`pwd`/killable_pipe.sh
$ script $killable_pipe <<EOF
> #!/bin/bash
> echo \$\$ >> $pidfile
> exec cat
> EOF
$ remotecmd=`pwd`/remotecmd.sh
$ script $remotecmd <<EOF
> #!/bin/bash
> $hg "\$@" 1> >($killable_pipe) 2> >($killable_pipe >&2)
> EOF
In the pretxnchangegroup hook, kill the PIDs recorded above to simulate ssh
disconnecting. Then exit nonzero, to force a transaction rollback.
$ hook_script=`pwd`/pretxnchangegroup.sh
$ script $hook_script <<EOF
> #!/bin/bash
> for pid in \$(cat $pidfile) ; do
> kill \$pid
> while kill -0 \$pid 2>/dev/null ; do
> sleep 0.1
> done
> done
> exit 1
> EOF
$ cat >remote/.hg/hgrc <<EOF
> [hooks]
> pretxnchangegroup.break-things=$hook_script
> EOF
$ cd local
$ echo foo > foo ; $hg commit -qAm "commit"
$ $hg push -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" --remotecmd $remotecmd 2>&1 | grep -v $killable_pipe
pushing to ssh://user@dummy/$TESTTMP/remote
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
abort: stream ended unexpectedly (got 0 bytes, expected 4)
$ check_for_abandoned_transaction
Abandoned transaction!