On 5/26/2017 5:47 AM, Ævar Arnfjörð Bjarmason wrote:
On Wed, May 24, 2017 at 3:12 PM, Christian Couder
<christian.couder@xxxxxxxxx> wrote:
On Thu, May 18, 2017 at 10:13 PM, Ben Peart <peartben@xxxxxxxxx> wrote:
This hook script integrates the new fsmonitor capabilities of git with
the cross platform Watchman file watching service. To use the script:
Download and install Watchman from https://facebook.github.io/watchman/
and instruct Watchman to watch your working directory for changes
('watchman watch-project /usr/src/git').
Rename the sample integration hook from query-fsmonitor.sample to
query-fsmonitor.
Configure git to use the extension ('git config core.fsmonitor true')
and optionally turn on the untracked cache for optimal performance
('git config core.untrackedcache true').
Ok, it looks like the untracked cache can be used, but it could work without it.
Signed-off-by: Ben Peart <benpeart@xxxxxxxxxxxxx>
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
templates/hooks--query-fsmonitor.sample | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
create mode 100644 templates/hooks--query-fsmonitor.sample
diff --git a/templates/hooks--query-fsmonitor.sample b/templates/hooks--query-fsmonitor.sample
new file mode 100644
index 0000000000..4bd22f21d8
--- /dev/null
+++ b/templates/hooks--query-fsmonitor.sample
@@ -0,0 +1,27 @@
+#!/bin/sh
+#
+# An example hook script to integrate Watchman
+# (https://facebook.github.io/watchman/) with git to provide fast
+# git status.
+#
+# The hook is passed a time_t formatted as a string and outputs to
+# stdout all files that have been modified since the given time.
+# Paths must be relative to the root of the working tree and
+# separated by a single NUL.
+#
+# To enable this hook, rename this file to "query-fsmonitor"
+
+# Convert unix style paths to escaped Windows style paths
+case "$(uname -s)" in
+MINGW*|MSYS_NT*)
+ GIT_WORK_TREE="$(cygpath -aw "$PWD" | sed 's,\\,\\\\,g')"
+ ;;
+*)
+ GIT_WORK_TREE="$PWD"
+ ;;
+esac
+
+# Query Watchman for all the changes since the requested time
+echo "[\"query\", \"$GIT_WORK_TREE\", {\"since\": $1, \"fields\":[\"name\"]}]" | \
+watchman -j | \
+perl -e 'use JSON::PP; my $o = JSON::PP->new->utf8->decode(join("", <>)); die "Watchman: $o->{'error'}.\nFalling back to scanning...\n" if defined($o->{"error"}); print(join("\0", @{$o->{"files"}}));'
Maybe put the above small perl script on multiple lines for improved
readability.
I'll pick up the suggestions from Ævar on the perl script. I believe
that fixes all the issues you have raised.
I've also tested the various error cases of watchman not installed and
when watchman returns an error and they are all properly handled by 1)
giving an error message and 2) falling back to the git codepath without
fsmonitor so that the git command succeeds.
Is JSON::PP always available in Perl >= 5.8?
No, it's shipped with perl as of 5.14.0, which came out in May 2011.
I think depending on that is fine. FWIW we bumped the required core
dependency (but you might still need to install modules) in 2010 in my
d48b284183 ("perl: bump the required Perl version to 5.8 from
5.6.[21]", 2010-09-24). Maybe we should be bumping that again...
What happens if watchman is not installed or not in the PATH?
It seems to me that the git process will not die, and will just work
as if the hook does not exist, except that it will call the hook which
will probably output error messages.
I think a good solution to this is to just add "set -euo pipefail" to
that script.
Then we'll print out on stderr that we couldn't find the watchman
command. Right now (with my patch) it'll make its way to the perl
program and get empty input.
With or without "set -euo pipefail" the output if watchman is not
installed is:
.git/hooks/query-fsmonitor: line 37: watchman: command not found
Watchman: command returned no output.
Falling back to scanning...
On branch fsmonitor
Your branch is up-to-date with 'benpeart/fsmonitor'.
To try this out on Mac, you can install the package maintained by
MacPorts by running "sudo port install watchman"
https://facebook.github.io/watchman/docs/install.html