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When running Git commands quickly -- such as in a shell script or the
test suite -- the Git commands frequently complete and start again
during the same second. The example fsmonitor hooks to integrate with
Watchman truncate the nanosecond times to seconds. In principle, this is
fine, as Watchman claims to use inclusive comparisons [1]. The result
should only be an over-representation of the changed paths since the
last Git command.
However, Watchman's own documentation claims "Using a timestamp is prone
to race conditions in understanding the complete state of the file tree"
[2]. All of their documented examples use a "clockspec" that looks like
'c:123:234'. Git should eventually learn how to store this type of
string to provide a stronger integration, but that will be a more
invasive change.
When using GIT_TEST_FSMONITOR="$(pwd)/t7519/fsmonitor-watchman", scripts
such as t7519-wtstatus.sh fail due to these race conditions. In fact,
running any test script with GIT_TEST_FSMONITOR pointing at
t/t7519/fsmonitor-wathcman will cause failures in the test_commit
function. The 'git add "$indir$file"' command fails due to not enough
time between the creation of '$file' and the 'git add' command.
For now, subtract one second from the timestamp we pass to Watchman.
This will make our window large enough to avoid these race conditions.
Increasing the window causes tests like t7519-wtstatus.sh to pass.
When the integration was introduced in def437671 (fsmonitor: add a
sample integration script for Watchman, 2018-09-22), the query included
an expression that would ignore files created and deleted in that
window. The performance reason for this change was to ignore temporary
files created by a build between Git commands. However, this causes
failures in script scenarios where Git is creating or deleting files
quickly.
When using GIT_TEST_FSMONITOR as before, t2203-add-intent.sh fails
due to this add-and-delete race condition.
By removing the "expression" from the Watchman query, we remove this
race condition. It will lead to some performance degradation in the case
of users creating and deleting temporary files inside their working
directory between Git commands. However, that is a cost we need to pay
to be correct.
[1] https://github.com/facebook/watchman/blob/master/query/since.cpp#L35-L39
[2] https://facebook.github.io/watchman/docs/clockspec.html
Helped-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Kevin Willford <Kevin.Willford@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Simplify and speed up the process of finding the git worktree when
running on Windows by keeping it in perl and avoiding spawning helper
processes.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Though the process has chdir'd to the root of the working tree, the
PWD environment variable is only guaranteed to be updated accordingly
if a shell is involved -- which is not guaranteed to be the case.
That is, if `/usr/bin/perl` is a binary, $ENV{PWD} is unchanged from
whatever spawned `git` -- if `/usr/bin/perl` is a trivial shell
wrapper to the real `perl`, `$ENV{PWD}` will have been updated to the
root of the working copy.
Update to read from the Cwd module using the `getcwd` syscall, not the
PWD environment variable. The Cygwin case is left unchanged, as it
necessarily _does_ go through a shell.
Signed-off-by: Alex Vandiver <alexmv@dropbox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Update the test fsmonitor-watchman integration script to properly
preserve utf8 filenames when outputting the .git/watchman-output.out log
file.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In Perl, setting $/ sets the string that is used as the "record
separator," which sets the boundary that the `<>` construct reads to.
Setting `local $/ = 0666;` evaluates the octal, getting 438, and
stringifies it. Thus, the later read from `<CHLD_OUT>` stops as soon
as it encounters the string "438" in the watchman output, yielding
invalid JSON; repositories containing filenames with SHA1 hashes are
able to trip this easily.
Set `$/` to undefined, thus slurping all output from watchman. Also
close STDIN which is provided to watchman, to better guarantee that we
cannot deadlock with watchman while both attempting to read.
Signed-off-by: Alex Vandiver <alexmv@dropbox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Instead of just taking $ENV{'PWD'}, use the same logic that converts
PWD to $git_work_tree on MSYS_NT in the watchman integration hook
script also on MINGW.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Test the ability to add/remove the fsmonitor index extension via
update-index.
Test that dirty files returned from the integration script are properly
represented in the index extension and verify that ls-files correctly
reports their state.
Test that ensure status results are correct when using the new fsmonitor
extension. Test untracked, modified, and new files by ensuring the
results are identical to when not using the extension.
Test that if the fsmonitor extension doesn't tell git about a change, it
doesn't discover it on its own. This ensures git is honoring the
extension and that we get the performance benefits desired.
Three test integration scripts are provided:
fsmonitor-all - marks all files as dirty
fsmonitor-none - marks no files as dirty
fsmonitor-watchman - integrates with Watchman with debug logging
To run tests in the test suite while utilizing fsmonitor:
First copy t/t7519/fsmonitor-all to a location in your path and then set
GIT_FORCE_PRELOAD_TEST=true and GIT_FSMONITOR_TEST=fsmonitor-all and run
your tests.
Note: currently when using the test script fsmonitor-watchman on
Windows, many tests fail due to a reported but not yet fixed bug in
Watchman where it holds on to handles for directories and files which
prevents the test directory from being cleaned up properly.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Kevin Willford
Ben Peart
Alex Vandiver