changeset 32783:4483696dacee

profile: upgrade the "profile" context manager to a full class So far we have been able to use a simple decorator for this. However using the current context manager makes the scope of the profiling in dispatch constrainted and the time frame to decide to enable profiling quite limited (using "maybeprofile") This is the first step toward the ability to enable the profiling from within the profiling scope. eg:: with maybeprofiling(ui) as profiler: ... bar.foo(): ... if options['profile']: profiler.start() ... fooz() ... My target usecase is adding support for "--profile" to alias definitions with effect. These are to be used with "profiling.output=blackbox" to gather data about operation that get slow from time to time (eg: pull being minutes instead of seconds from time to time). Of course, in such case, the scope of the profiling would be smaller since profiler would be started after running extensions 'reposetup' (and other potentially costly logic), but these are not relevant for my target usecase (multiple second commits, multiple tens of seconds pull). Currently adding '--profile' to a command through alias requires to re-spin a Mercurial binary (using "!$HG" in alias), which as a significant performance impact, especially in context where startup performance is being worked on... An alternative approach would be to stop using the context manager in dispatch and move back to a try/finally setup.
author Pierre-Yves David <pierre-yves.david@octobus.net>
date Thu, 08 Jun 2017 01:38:48 +0100
parents 9a4adc76c88a
children 086c1ef0f666
files mercurial/profiling.py
diffstat 1 files changed, 38 insertions(+), 29 deletions(-) [+]
line wrap: on
line diff
--- a/mercurial/profiling.py	Fri Jun 09 22:15:53 2017 -0400
+++ b/mercurial/profiling.py	Thu Jun 08 01:38:48 2017 +0100
@@ -141,35 +141,41 @@
 
         statprof.display(fp, data=data, format=displayformat, **kwargs)
 
-@contextlib.contextmanager
-def profile(ui):
+class profile(object):
     """Start profiling.
 
     Profiling is active when the context manager is active. When the context
     manager exits, profiling results will be written to the configured output.
     """
-    profiler = encoding.environ.get('HGPROF')
-    proffn = None
-    if profiler is None:
-        profiler = ui.config('profiling', 'type', default='stat')
-    if profiler not in ('ls', 'stat', 'flame'):
-        # try load profiler from extension with the same name
-        proffn = _loadprofiler(ui, profiler)
-        if proffn is None:
-            ui.warn(_("unrecognized profiler '%s' - ignored\n") % profiler)
-            profiler = 'stat'
+    def __init__(self, ui):
+        self._ui = ui
+        self._output = None
+        self._fp = None
+        self._profiler = None
 
-    output = ui.config('profiling', 'output')
+    def __enter__(self):
+        profiler = encoding.environ.get('HGPROF')
+        proffn = None
+        if profiler is None:
+            profiler = self._ui.config('profiling', 'type', default='stat')
+        if profiler not in ('ls', 'stat', 'flame'):
+            # try load profiler from extension with the same name
+            proffn = _loadprofiler(self._ui, profiler)
+            if proffn is None:
+                self._ui.warn(_("unrecognized profiler '%s' - ignored\n")
+                              % profiler)
+                profiler = 'stat'
 
-    if output == 'blackbox':
-        fp = util.stringio()
-    elif output:
-        path = ui.expandpath(output)
-        fp = open(path, 'wb')
-    else:
-        fp = ui.ferr
+        self._output = self._ui.config('profiling', 'output')
 
-    try:
+        if self._output == 'blackbox':
+            self._fp = util.stringio()
+        elif self._output:
+            path = self._ui.expandpath(self._output)
+            self._fp = open(path, 'wb')
+        else:
+            self._fp = self._ui.ferr
+
         if proffn is not None:
             pass
         elif profiler == 'ls':
@@ -179,18 +185,21 @@
         else:
             proffn = statprofile
 
-        with proffn(ui, fp):
-            yield
+        self._profiler = proffn(self._ui, self._fp)
+        self._profiler.__enter__()
 
-    finally:
-        if output:
-            if output == 'blackbox':
-                val = 'Profile:\n%s' % fp.getvalue()
+    def __exit__(self, exception_type, exception_value, traceback):
+        if self._profiler is None:
+            return
+        self._profiler.__exit__(exception_type, exception_value, traceback)
+        if self._output:
+            if self._output == 'blackbox':
+                val = 'Profile:\n%s' % self._fp.getvalue()
                 # ui.log treats the input as a format string,
                 # so we need to escape any % signs.
                 val = val.replace('%', '%%')
-                ui.log('profile', val)
-            fp.close()
+                self._ui.log('profile', val)
+            self._fp.close()
 
 @contextlib.contextmanager
 def maybeprofile(ui):