@matheusbsbs / matheus-bagliano / commits / 3797a0a7b7

maintenance: use Windows scheduled tasks

Git's background maintenance uses cron by default, but this is not available on Windows. Instead, integrate with Task Scheduler. Tasks can be scheduled using the 'schtasks' command. There are several command-line options that can allow for some advanced scheduling, but unfortunately these seem to all require authenticating using a password. Instead, use the "/xml" option to pass an XML file that contains the configuration for the necessary schedule. These XML files are based on some that I exported after constructing a schedule in the Task Scheduler GUI. These options only run background maintenance when the user is logged in, and more fields are populated with the current username and SID at run-time by 'schtasks'. Since the GIT_TEST_MAINT_SCHEDULER environment variable allows us to specify 'schtasks' as the scheduler, we can test the Windows-specific logic on other platforms. Thus, add a check that the XML file written by Git is valid when xmllint exists on the system. Since we use a temporary file for the XML files sent to 'schtasks', we prefix the random characters with the frequency so it is easier to examine the proper file during tests. Instead of an exact match on the 'args' file, we 'grep' for the arguments other than the filename. There is a deficiency in the current design. Windows has two kinds of applications: GUI applications that start by "winmain()" and console applications that start by "main()". Console applications are attached to a new Console window if they are not already associated with a GUI application. This means that every hour the scheudled task launches a command window for the scheduled tasks. Not only is this visually obtrusive, but it also takes focus from whatever else the user is doing! A simple fix would be to insert a GUI application that acts as a shim between the scheduled task and Git. This is currently possible in Git for Windows by setting the <Command> tag equal to C:\Program Files\Git\git-bash.exe with options "--hide --no-needs-console --command=cmd\git.exe" followed by the arguments currently used. Since git-bash.exe is not included in Windows builds of core Git, I chose to leave out this feature. My plan is to submit a small patch to Git for Windows that converts the use of git.exe with this use of git-bash.exe in the short term. In the long term, we can consider creating this GUI shim application within core Git, perhaps in contrib/. Co-authored-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Derrick Stolee committed Jan 5, 2021 at 13:08 UTC 3797a0a7b7aa8d0abd1b7ff7b95a40a9739d9278

3 files changed +226 -1

Documentation/git-maintenance.txt

+22

@@ -313,6 +313,28 @@ To create more advanced customizations to your background tasks, see

313 launchctl.plist(5) for more information.

314

315

316 +BACKGROUND MAINTENANCE ON WINDOWS SYSTEMS

317 +-----------------------------------------

318 +

319 +Windows does not support `cron` and instead has its own system for

320 +scheduling background tasks. The `git maintenance start` command uses

321 +the `schtasks` command to submit tasks to this system. You can inspect

322 +all background tasks using the Task Scheduler application. The tasks

323 +added by Git have names of the form `Git Maintenance (<frequency>)`.

324 +The Task Scheduler GUI has ways to inspect these tasks, but you can also

325 +export the tasks to XML files and view the details there.

326 +

327 +Note that since Git is a console application, these background tasks

328 +create a console window visible to the current user. This can be changed

329 +manually by selecting the "Run whether user is logged in or not" option

330 +in Task Scheduler. This change requires a password input, which is why

331 +`git maintenance start` does not select it by default.

332 +

333 +If you want to customize the background tasks, please rename the tasks

334 +so future calls to `git maintenance (start|stop)` do not overwrite your

335 +custom tasks.

336 +

337 +

338 GIT

339 ---

340 Part of the linkgit:git[1] suite

builtin/gc.c

+167 -1

@@ -1589,7 +1589,7 @@ static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit

1589 die(_("failed to create directories for '%s'"), filename);

1590 plist = xfopen(filename, "w");

1591

1592 - preamble = "<?xml version=\"1.0\" encoding=\"US-ASCII\"?>\n"

1592 + preamble = "<?xml version=\"1.0\"?>\n"

1593 "<!DOCTYPE plist PUBLIC \"-//Apple//DTD PLIST 1.0//EN\" \"http://www.apple.com/DTDs/PropertyList-1.0.dtd\">\n"

1594 "<plist version=\"1.0\">"

1595 "<dict>\n"

@@ -1671,6 +1671,168 @@ static int launchctl_update_schedule(int run_maintenance, int fd, const char *cm

1671 return launchctl_remove_plists(cmd);

1672 }

1673

1674 +static char *schtasks_task_name(const char *frequency)

1675 +{

1676 + struct strbuf label = STRBUF_INIT;

1677 + strbuf_addf(&label, "Git Maintenance (%s)", frequency);

1678 + return strbuf_detach(&label, NULL);

1679 +}

1680 +

1681 +static int schtasks_remove_task(enum schedule_priority schedule, const char *cmd)

1682 +{

1683 + int result;

1684 + struct strvec args = STRVEC_INIT;

1685 + const char *frequency = get_frequency(schedule);

1686 + char *name = schtasks_task_name(frequency);

1687 +

1688 + strvec_split(&args, cmd);

1689 + strvec_pushl(&args, "/delete", "/tn", name, "/f", NULL);

1690 +

1691 + result = run_command_v_opt(args.v, 0);

1692 +

1693 + strvec_clear(&args);

1694 + free(name);

1695 + return result;

1696 +}

1697 +

1698 +static int schtasks_remove_tasks(const char *cmd)

1699 +{

1700 + return schtasks_remove_task(SCHEDULE_HOURLY, cmd) ||

1701 + schtasks_remove_task(SCHEDULE_DAILY, cmd) ||

1702 + schtasks_remove_task(SCHEDULE_WEEKLY, cmd);

1703 +}

1704 +

1705 +static int schtasks_schedule_task(const char *exec_path, enum schedule_priority schedule, const char *cmd)

1706 +{

1707 + int result;

1708 + struct child_process child = CHILD_PROCESS_INIT;

1709 + const char *xml;

1710 + struct tempfile *tfile;

1711 + const char *frequency = get_frequency(schedule);

1712 + char *name = schtasks_task_name(frequency);

1713 + struct strbuf tfilename = STRBUF_INIT;

1714 +

1715 + strbuf_addf(&tfilename, "%s/schedule_%s_XXXXXX",

1716 + get_git_common_dir(), frequency);

1717 + tfile = xmks_tempfile(tfilename.buf);

1718 + strbuf_release(&tfilename);

1719 +

1720 + if (!fdopen_tempfile(tfile, "w"))

1721 + die(_("failed to create temp xml file"));

1722 +

1723 + xml = "<?xml version=\"1.0\" ?>\n"

1724 + "<Task version=\"1.4\" xmlns=\"http://schemas.microsoft.com/windows/2004/02/mit/task\">\n"

1725 + "<Triggers>\n"

1726 + "<CalendarTrigger>\n";

1727 + fputs(xml, tfile->fp);

1728 +

1729 + switch (schedule) {

1730 + case SCHEDULE_HOURLY:

1731 + fprintf(tfile->fp,

1732 + "<StartBoundary>2020-01-01T01:00:00</StartBoundary>\n"

1733 + "<Enabled>true</Enabled>\n"

1734 + "<ScheduleByDay>\n"

1735 + "<DaysInterval>1</DaysInterval>\n"

1736 + "</ScheduleByDay>\n"

1737 + "<Repetition>\n"

1738 + "<Interval>PT1H</Interval>\n"

1739 + "<Duration>PT23H</Duration>\n"

1740 + "<StopAtDurationEnd>false</StopAtDurationEnd>\n"

1741 + "</Repetition>\n");

1742 + break;

1743 +

1744 + case SCHEDULE_DAILY:

1745 + fprintf(tfile->fp,

1746 + "<StartBoundary>2020-01-01T00:00:00</StartBoundary>\n"

1747 + "<Enabled>true</Enabled>\n"

1748 + "<ScheduleByWeek>\n"

1749 + "<DaysOfWeek>\n"

1750 + "<Monday />\n"

1751 + "<Tuesday />\n"

1752 + "<Wednesday />\n"

1753 + "<Thursday />\n"

1754 + "<Friday />\n"

1755 + "<Saturday />\n"

1756 + "</DaysOfWeek>\n"

1757 + "<WeeksInterval>1</WeeksInterval>\n"

1758 + "</ScheduleByWeek>\n");

1759 + break;

1760 +

1761 + case SCHEDULE_WEEKLY:

1762 + fprintf(tfile->fp,

1763 + "<StartBoundary>2020-01-01T00:00:00</StartBoundary>\n"

1764 + "<Enabled>true</Enabled>\n"

1765 + "<ScheduleByWeek>\n"

1766 + "<DaysOfWeek>\n"

1767 + "<Sunday />\n"

1768 + "</DaysOfWeek>\n"

1769 + "<WeeksInterval>1</WeeksInterval>\n"

1770 + "</ScheduleByWeek>\n");

1771 + break;

1772 +

1773 + default:

1774 + break;

1775 + }

1776 +

1777 + xml = "</CalendarTrigger>\n"

1778 + "</Triggers>\n"

1779 + "<Principals>\n"

1780 + "<Principal id=\"Author\">\n"

1781 + "<LogonType>InteractiveToken</LogonType>\n"

1782 + "<RunLevel>LeastPrivilege</RunLevel>\n"

1783 + "</Principal>\n"

1784 + "</Principals>\n"

1785 + "<Settings>\n"

1786 + "<MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>\n"

1787 + "<Enabled>true</Enabled>\n"

1788 + "<Hidden>true</Hidden>\n"

1789 + "<UseUnifiedSchedulingEngine>true</UseUnifiedSchedulingEngine>\n"

1790 + "<WakeToRun>false</WakeToRun>\n"

1791 + "<ExecutionTimeLimit>PT72H</ExecutionTimeLimit>\n"

1792 + "<Priority>7</Priority>\n"

1793 + "</Settings>\n"

1794 + "<Actions Context=\"Author\">\n"

1795 + "<Exec>\n"

1796 + "<Command>\"%s\\git.exe\"</Command>\n"

1797 + "<Arguments>--exec-path=\"%s\" for-each-repo --config=maintenance.repo maintenance run --schedule=%s</Arguments>\n"

1798 + "</Exec>\n"

1799 + "</Actions>\n"

1800 + "</Task>\n";

1801 + fprintf(tfile->fp, xml, exec_path, exec_path, frequency);

1802 + strvec_split(&child.args, cmd);

1803 + strvec_pushl(&child.args, "/create", "/tn", name, "/f", "/xml",

1804 + get_tempfile_path(tfile), NULL);

1805 + close_tempfile_gently(tfile);

1806 +

1807 + child.no_stdout = 1;

1808 + child.no_stderr = 1;

1809 +

1810 + if (start_command(&child))

1811 + die(_("failed to start schtasks"));

1812 + result = finish_command(&child);

1813 +

1814 + delete_tempfile(&tfile);

1815 + free(name);

1816 + return result;

1817 +}

1818 +

1819 +static int schtasks_schedule_tasks(const char *cmd)

1820 +{

1821 + const char *exec_path = git_exec_path();

1822 +

1823 + return schtasks_schedule_task(exec_path, SCHEDULE_HOURLY, cmd) ||

1824 + schtasks_schedule_task(exec_path, SCHEDULE_DAILY, cmd) ||

1825 + schtasks_schedule_task(exec_path, SCHEDULE_WEEKLY, cmd);

1826 +}

1827 +

1828 +static int schtasks_update_schedule(int run_maintenance, int fd, const char *cmd)

1829 +{

1830 + if (run_maintenance)

1831 + return schtasks_schedule_tasks(cmd);

1832 + else

1833 + return schtasks_remove_tasks(cmd);

1834 +}

1835 +

1836 #define BEGIN_LINE "# BEGIN GIT MAINTENANCE SCHEDULE"

1837 #define END_LINE "# END GIT MAINTENANCE SCHEDULE"

1838

@@ -1761,6 +1923,8 @@ done_editing:

1923

1924 #if defined(__APPLE__)

1925 static const char platform_scheduler[] = "launchctl";

1926 +#elif defined(GIT_WINDOWS_NATIVE)

1927 +static const char platform_scheduler[] = "schtasks";

1928 #else

1929 static const char platform_scheduler[] = "crontab";

1930 #endif

@@ -1789,6 +1953,8 @@ static int update_background_schedule(int enable)

1953

1954 if (!strcmp(scheduler, "launchctl"))

1955 result = launchctl_update_schedule(enable, lk.tempfile->fd, cmd);

1956 + else if (!strcmp(scheduler, "schtasks"))

1957 + result = schtasks_update_schedule(enable, lk.tempfile->fd, cmd);

1958 else if (!strcmp(scheduler, "crontab"))

1959 result = crontab_update_schedule(enable, lk.tempfile->fd, cmd);

1960 else

t/t7900-maintenance.sh

+37

@@ -454,6 +454,43 @@ test_expect_success 'start and stop macOS maintenance' '

454 test_line_count = 0 actual

455 '

456

457 +test_expect_success 'start and stop Windows maintenance' '

458 + write_script print-args <<-\EOF &&

459 + echo $* >>args

460 + while test $# -gt 0

461 + do

462 + case "$1" in

463 + /xml) shift; xmlfile=$1; break ;;

464 + *) shift ;;

465 + esac

466 + done

467 + test -z "$xmlfile" || cp "$xmlfile" "$xmlfile.xml"

468 + EOF

469 +

470 + rm -f args &&

471 + GIT_TEST_MAINT_SCHEDULER="schtasks:./print-args" git maintenance start &&

472 +

473 + # start registers the repo

474 + git config --get --global maintenance.repo "$(pwd)" &&

475 +

476 + for frequency in hourly daily weekly

477 + do

478 + grep "/create /tn Git Maintenance ($frequency) /f /xml" args &&

479 + file=$(ls .git/schedule_${frequency}*.xml) &&

480 + test_xmllint "$file" || return 1

481 + done &&

482 +

483 + rm -f args &&

484 + GIT_TEST_MAINT_SCHEDULER="schtasks:./print-args" git maintenance stop &&

485 +

486 + # stop does not unregister the repo

487 + git config --get --global maintenance.repo "$(pwd)" &&

488 +

489 + printf "/delete /tn Git Maintenance (%s) /f\n" \

490 + hourly daily weekly >expect &&

491 + test_cmp expect args

492 +'

493 +

494 test_expect_success 'register preserves existing strategy' '

495 git config maintenance.strategy none &&

496 git maintenance register &&