Maintenance IV: Platform-specific background maintenance

This is based on ds/maintenance-part-3.

After sitting with the background maintenance as it has been cooking, I wanted to come back around and implement the background maintenance for Windows. However, I noticed that there were some things bothering me with background maintenance on my macOS machine. These are detailed in PATCH 3, but the tl;dr is that 'cron' is not recommended by Apple and instead 'launchd' satisfies our needs.

This series implements the background scheduling so git maintenance (start|stop) works on those platforms. I've been operating with these schedules for a while now without the problems described in the patches.

There is a particularly annoying case about console windows popping up on Windows, but PATCH 4 describes a plan to get around that.

Update in V7
============

* I had included an "encoding" string in the XML file for schtasks based on an example using UTF-8. The cross-platform tests then complained (in xmllint) because they wrote in ASCII instead. However, actually testing the situation on Windows (see [1]) against the real schtasks finds that it doesn't like that encoding string. I removed it entirely, and everything seems happier.

* I squashed Eric's two commits making the tests better. He remains a co-author and I kept his Helped-by. I had to rearrange the commit message a bit to point out the care he took for the cross-platform tests without referring to the test doing the wrong thing.

[1] https://github.com/microsoft/git/pull/304

Thanks, -Stolee

cc: [email protected] cc: [email protected] cc: [email protected]
cc: Đoàn Trần Công Danh [email protected] cc: Martin Ågren [email protected] cc: Eric Sunshine [email protected] cc: Derrick Stolee [email protected]

Derrick Stolee (4):
maintenance: extract platform-specific scheduling
maintenance: include 'cron' details in docs
maintenance: use launchctl on macOS
maintenance: use Windows scheduled tasks

 Documentation/git-maintenance.txt | 116 ++++++++
 builtin/gc.c                      | 422 ++++++++++++++++++++++++++++--
 t/t7900-maintenance.sh            | 104 +++++++-
 t/test-lib.sh                     |   7 +-
 4 files changed, 615 insertions(+), 34 deletions(-)

base-commit: 0016b618182f642771dc589cf0090289f9fe1b4f
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-776%2Fderrickstolee%2Fmaintenance%2FmacOS-v7
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-776/derrickstolee/maintenance/macOS-v7
Pull-Request: https://github.com/gitgitgadget/git/pull/776

Range-diff vs v6:

 1:  4807342b001 = 1:  4807342b001 maintenance: extract platform-specific scheduling
 2:  7cc70a8fe7b = 2:  7cc70a8fe7b maintenance: include 'cron' details in docs
 3:  cd015a5cbd7 ! 3:  3576c7aa54e maintenance: use launchctl on macOS
     @@ Commit message
          the XML format. This is useful for any system that might contain
          the tool, so use it whenever it is available.
      
     +    We strive to make these tests work on all platforms, but Windows caused
     +    some headaches. In particular, the value of getuid() called by the C
     +    code is not guaranteed to be the same as `$(id -u)` invoked by a test.
     +    This is because `git.exe` is a native Windows program, whereas the
     +    utility programs run by the test script mostly utilize the MSYS2 runtime,
     +    which emulates a POSIX-like environment. Since the purpose of the test
     +    is to check that the input to the hook is well-formed, the actual user
     +    ID is immaterial, thus we can work around the problem by making the the
     +    test UID-agnostic. Another subtle issue is the $HOME environment
     +    variable being a Windows-style path instead of a Unix-style path. We can
     +    be more flexible here instead of expecting exact path matches.
     +
     +    Helped-by: Ævar Arnfjörð Bjarmason <[email protected]>
          Co-authored-by: Eric Sunshine <[email protected]>
          Signed-off-by: Eric Sunshine <[email protected]>
          Signed-off-by: Derrick Stolee <[email protected]>
     @@ t/t7900-maintenance.sh: test_expect_success 'start preserves existing schedule'
       	grep "Important information!" cron.txt
       '
       
     -+test_expect_success !MINGW 'start and stop macOS maintenance' '
     -+	uid=$(id -u) &&
     ++test_expect_success 'start and stop macOS maintenance' '
     ++	# ensure $HOME can be compared against hook arguments on all platforms
     ++	pfx=$(cd "$HOME" && pwd) &&
      +
      +	write_script print-args <<-\EOF &&
     -+	echo $* >>args
     ++	echo $* | sed "s:gui/[0-9][0-9]*:gui/[UID]:" >>args
      +	EOF
      +
      +	rm -f args &&
     @@ t/t7900-maintenance.sh: test_expect_success 'start preserves existing schedule'
      +	EOF
      +	test_cmp expect actual &&
      +
     -+	rm expect &&
     ++	rm -f expect &&
      +	for frequency in hourly daily weekly
      +	do
     -+		PLIST="$HOME/Library/LaunchAgents/org.git-scm.git.$frequency.plist" &&
     ++		PLIST="$pfx/Library/LaunchAgents/org.git-scm.git.$frequency.plist" &&
      +		test_xmllint "$PLIST" &&
      +		grep schedule=$frequency "$PLIST" &&
     -+		echo "bootout gui/$uid $PLIST" >>expect &&
     -+		echo "bootstrap gui/$uid $PLIST" >>expect || return 1
     ++		echo "bootout gui/[UID] $PLIST" >>expect &&
     ++		echo "bootstrap gui/[UID] $PLIST" >>expect || return 1
      +	done &&
      +	test_cmp expect args &&
      +
     @@ t/t7900-maintenance.sh: test_expect_success 'start preserves existing schedule'
      +	# stop does not unregister the repo
      +	git config --get --global maintenance.repo "$(pwd)" &&
      +
     -+	printf "bootout gui/$uid $HOME/Library/LaunchAgents/org.git-scm.git.%s.plist\n" \
     ++	printf "bootout gui/[UID] $pfx/Library/LaunchAgents/org.git-scm.git.%s.plist\n" \
      +		hourly daily weekly >expect &&
      +	test_cmp expect args &&
      +	ls "$HOME/Library/LaunchAgents" >actual &&
 4:  6ad4a6b98c6 ! 4:  68f5013dee3 maintenance: use Windows scheduled tasks
     @@ Documentation/git-maintenance.txt: To create more advanced customizations to you
       Part of the linkgit:git[1] suite
      
       ## builtin/gc.c ##
     +@@ builtin/gc.c: static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit
     + 		die(_("failed to create directories for '%s'"), filename);
     + 	plist = xfopen(filename, "w");
     + 
     +-	preamble = "<?xml version=\"1.0\" encoding=\"US-ASCII\"?>\n"
     ++	preamble = "<?xml version=\"1.0\"?>\n"
     + 		   "<!DOCTYPE plist PUBLIC \"-//Apple//DTD PLIST 1.0//EN\" \"http://www.apple.com/DTDs/PropertyList-1.0.dtd\">\n"
     + 		   "<plist version=\"1.0\">"
     + 		   "<dict>\n"
      @@ builtin/gc.c: static int launchctl_update_schedule(int run_maintenance, int fd, const char *cm
       		return launchctl_remove_plists(cmd);
       }
     @@ builtin/gc.c: static int launchctl_update_schedule(int run_maintenance, int fd,
      +	char *name = schtasks_task_name(frequency);
      +	struct strbuf tfilename = STRBUF_INIT;
      +
     -+	strbuf_addf(&tfilename, "schedule_%s_XXXXXX", frequency);
     ++	strbuf_addf(&tfilename, "%s/schedule_%s_XXXXXX",
     ++		    get_git_common_dir(), frequency);
      +	tfile = xmks_tempfile(tfilename.buf);
      +	strbuf_release(&tfilename);
      +
      +	if (!fdopen_tempfile(tfile, "w"))
      +		die(_("failed to create temp xml file"));
      +
     -+	xml = "<?xml version=\"1.0\" encoding=\"US-ASCII\"?>\n"
     ++	xml = "<?xml version=\"1.0\" ?>\n"
      +	      "<Task version=\"1.4\" xmlns=\"http://schemas.microsoft.com/windows/2004/02/mit/task\">\n"
      +	      "<Triggers>\n"
      +	      "<CalendarTrigger>\n";
     @@ builtin/gc.c: static int update_background_schedule(int enable)
       	else
      
       ## t/t7900-maintenance.sh ##
     -@@ t/t7900-maintenance.sh: test_expect_success !MINGW 'start and stop macOS maintenance' '
     +@@ t/t7900-maintenance.sh: test_expect_success 'start and stop macOS maintenance' '
       	test_line_count = 0 actual
       '
       
     @@ t/t7900-maintenance.sh: test_expect_success !MINGW 'start and stop macOS mainten
      +	EOF
      +
      +	rm -f args &&
     -+	GIT_TEST_MAINT_SCHEDULER="schtasks:./print-args" GIT_TRACE2_PERF=1 git maintenance start &&
     ++	GIT_TEST_MAINT_SCHEDULER="schtasks:./print-args" git maintenance start &&
      +
      +	# start registers the repo
      +	git config --get --global maintenance.repo "$(pwd)" &&
     @@ t/t7900-maintenance.sh: test_expect_success !MINGW 'start and stop macOS mainten
      +	for frequency in hourly daily weekly
      +	do
      +		grep "/create /tn Git Maintenance ($frequency) /f /xml" args &&
     -+		file=$(ls schedule_$frequency*.xml) &&
     -+		test_xmllint "$file" &&
     -+		grep "encoding=.US-ASCII." "$file" || return 1
     ++		file=$(ls .git/schedule_${frequency}*.xml) &&
     ++		test_xmllint "$file" || return 1
      +	done &&
      +
      +	rm -f args &&
     @@ t/t7900-maintenance.sh: test_expect_success !MINGW 'start and stop macOS mainten
      +	# stop does not unregister the repo
      +	git config --get --global maintenance.repo "$(pwd)" &&
      +
     -+	rm expect &&
      +	printf "/delete /tn Git Maintenance (%s) /f\n" \
      +		hourly daily weekly >expect &&
      +	test_cmp expect args

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