profiling: allow logging profile to the blackbox

This allows specifying '--config profiling.output=blackbox' which will log the
profile output to the blackbox (if enabled). This is useful for doing profiling
on the server since it allows us to record the command, it's result, any
exceptions, and it's profile, all in one spot.  And we get log rotation for
free.

mercurial/dispatch.py

@@ -1023,7 +1023,10 b' def _runcommand(ui, options, cmd, cmdfun'
 
         output = ui.config('profiling', 'output')
 
-        if output:
+        if output == 'blackbox':
+            import StringIO
+            fp = StringIO.StringIO()
+        elif output:
             path = ui.expandpath(output)
             fp = open(path, 'wb')
         else:
@@ -1038,6 +1041,12 b' def _runcommand(ui, options, cmd, cmdfun'
                 return statprofile(ui, checkargs, fp)
         finally:
             if output:
+                if output == 'blackbox':
+                    val = "Profile:\n%s" % 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()
     else:
         return checkargs()

tests/test-profile.t

@@ -14,6 +14,9 b' test --profile'
   $ hg --profile --config profiling.output=../out st
   $ grep CallCount ../out > /dev/null || cat ../out
 
+  $ hg --profile --config profiling.output=blackbox --config extensions.blackbox= st
+  $ grep CallCount .hg/blackbox.log > /dev/null || cat .hg/blackbox.log
+
   $ hg --profile --config profiling.format=text st 2>../out
   $ grep CallCount ../out > /dev/null || cat ../out