[PATCH 2 of 8 v3] ui: provide a mechanism to track and log blocked time

[Simon Farnsworth]

# HG changeset patch
# User Simon Farnsworth <simonfar at fb.com>
# Date 1486757727 28800
#      Fri Feb 10 12:15:27 2017 -0800
# Node ID 25b4512a095b2f3788b255274a15d68dbc10f7b4
# Parent  bd40abfb4e5dbaf6e373636c8e7bab7a6bf34e17
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
@@ -138,6 +138,9 @@
     finally:
         duration = timeit.default_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
@@ -16,6 +17,7 @@
 import socket
 import sys
 import tempfile
+import timeit
 import traceback
 
 from .i18n import _
@@ -120,6 +122,8 @@
         self.callhooks = True
         # Insecure server connections requested.
         self.insecureconnections = False
+        # Blocked time
+        self.logblockedtimes = False
 
         if src:
             self.fout = src.fout
@@ -137,6 +141,7 @@
             self.fixconfig()
 
             self.httppasswordmgrdb = src.httppasswordmgrdb
+            self._blockedtimes = src._blockedtimes
         else:
             self.fout = util.stdout
             self.ferr = util.stderr
@@ -146,6 +151,7 @@
             self.environ = encoding.environ
 
             self.httppasswordmgrdb = urlreq.httppasswordmgrwithdefaultrealm()
+            self._blockedtimes = collections.defaultdict(lambda: 0)
 
         allowed = self.configlist('experimental', 'exportableenviron')
         if '*' in allowed:
@@ -174,6 +180,14 @@
             self._progbar.resetstate()  # reset last-print time of progress bar
         self.httppasswordmgrdb = urlreq.httppasswordmgrwithdefaultrealm()
 
+    @contextlib.contextmanager
+    def timeblockedsection(self, key):
+        starttime = timeit.default_timer()
+        yield
+        duration = (timeit.default_timer() - starttime) * 1000
+        key += '_blocked'
+        self._blockedtimes[key] += duration
+
     def formatter(self, topic, opts):
         return formatter.formatter(self, topic, opts)
 
@@ -277,6 +291,7 @@
             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 * ms command * ms (glob)