[PATCH 2 of 8 v4] ui: provide a mechanism to track and log blocked time

[Gregory Szorc]

> On Feb 13, 2017, at 10:29, Simon Farnsworth <simonfar at fb.com> wrote:
> 
> # HG changeset patch
> # User Simon Farnsworth <simonfar at fb.com>
> # Date 1486994849 28800
> #      Mon Feb 13 06:07:29 2017 -0800
> # Node ID 00f01e9a24bc050ab5cbbfc5a8dc99e992e31d2b
> # Parent  88b51cd7e8e3764af542c25d79a33f5cbda37ac6
> ui: provide a mechanism to track and log blocked time
> 
> We want to log the time Mercurial spends trapped in things outside
> programmatic control. Provide a mechanism to give us both command runtime
> and as many different sources of blocking as we deem useful
> 
> diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
> --- a/mercurial/dispatch.py
> +++ b/mercurial/dispatch.py
> @@ -137,6 +137,9 @@
>     finally:
>         duration = util.timer() - starttime
>         req.ui.flush()
> +        if req.ui.logblockedtimes:
> +            req.ui._blockedtimes['command_duration'] = duration * 1000
> +            req.ui.log('uiblocked', 'ui blocked ms', **req.ui._blockedtimes)
>         req.ui.log("commandfinish", "%s exited %s after %0.2f seconds\n",
>                    msg, ret or 0, duration)
>     return ret
> diff --git a/mercurial/ui.py b/mercurial/ui.py
> --- a/mercurial/ui.py
> +++ b/mercurial/ui.py
> @@ -7,6 +7,7 @@
> 
> from __future__ import absolute_import
> 
> +import collections
> import contextlib
> import errno
> import getpass
> @@ -120,6 +121,8 @@
>         self.callhooks = True
>         # Insecure server connections requested.
>         self.insecureconnections = False
> +        # Blocked time
> +        self.logblockedtimes = False
> 
>         if src:
>             self.fout = src.fout
> @@ -137,6 +140,7 @@
>             self.fixconfig()
> 
>             self.httppasswordmgrdb = src.httppasswordmgrdb
> +            self._blockedtimes = src._blockedtimes
>         else:
>             self.fout = util.stdout
>             self.ferr = util.stderr
> @@ -146,6 +150,7 @@
>             self.environ = encoding.environ
> 
>             self.httppasswordmgrdb = urlreq.httppasswordmgrwithdefaultrealm()
> +            self._blockedtimes = collections.defaultdict(lambda: 0)
> 
>         allowed = self.configlist('experimental', 'exportableenviron')
>         if '*' in allowed:
> @@ -174,6 +179,14 @@
>             self._progbar.resetstate()  # reset last-print time of progress bar
>         self.httppasswordmgrdb = urlreq.httppasswordmgrwithdefaultrealm()
> 
> +    @contextlib.contextmanager
> +    def timeblockedsection(self, key):
> +        starttime = util.timer()
> +        yield
> +        duration = (util.timer() - starttime) * 1000
> +        key += '_blocked'
> +        self._blockedtimes[key] += duration
> +

If the code inside the activated context manager raises, then the code here after the "yield" won't get executed.

Typically, @contextmanager functions have the following structure to avoid this pitfall:

try:
    yield
finally:
    #cleanup

>     def formatter(self, topic, opts):
>         return formatter.formatter(self, topic, opts)
> 
> @@ -277,6 +290,7 @@
>             self._reportuntrusted = self.debugflag or self.configbool("ui",
>                 "report_untrusted", True)
>             self.tracebackflag = self.configbool('ui', 'traceback', False)
> +            self.logblockedtimes = self.configbool('ui', 'logblockedtimes')
> 
>         if section in (None, 'trusted'):
>             # update trust information
> diff --git a/tests/test-logtoprocess.t b/tests/test-logtoprocess.t
> --- a/tests/test-logtoprocess.t
> +++ b/tests/test-logtoprocess.t
> @@ -10,6 +10,7 @@
>> def foo(ui, repo):
>>    ui.log('foo', 'a message: %(bar)s\n', bar='spam')
>> EOF
> +  $ cp $HGRCPATH $HGRCPATH.bak
>   $ cat >> $HGRCPATH << EOF
>> [extensions]
>> logtoprocess=
> @@ -52,3 +53,18 @@
>   logtoprocess commandfinish output:
>   logtoprocess foo output:
>   spam
> +
> +Confirm that logging blocked time catches stdio properly:
> +  $ cp $HGRCPATH.bak $HGRCPATH
> +  $ cat >> $HGRCPATH << EOF
> +  > [extensions]
> +  > logtoprocess=
> +  > pager=
> +  > [logtoprocess]
> +  > uiblocked=echo "\$EVENT stdio \$OPT_STDIO_BLOCKED ms command \$OPT_COMMAND_DURATION ms"
> +  > [ui]
> +  > logblockedtimes=True
> +  > EOF
> +
> +  $ hg log
> +  uiblocked stdio [0-9]+.[0-9]* ms command [0-9]+.[0-9]* ms (re)
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