revsetbenchmarks: parse perfrevset output into actual number

We cannot just ask perfrevset to provide debug output because we usually want
to compare output from old version of Mercurial that do not support it. So, we
are using a regular expression.

(/we now have \d problems/).

contrib/revsetbenchmarks.py

@@ -15,6 +15,7 b''
 
 import sys
 import os
+import re
 from subprocess import check_call, Popen, CalledProcessError, STDOUT, PIPE
 # cannot use argparse, python 2.7 only
 from optparse import OptionParser
@@ -54,8 +55,7 b' def perf(revset, target=None):'
     """run benchmark for this very revset"""
     try:
         output = hg(['perfrevset', revset], repo=target)
-        output = output.lstrip('!') # remove useless ! in this context
-        return output.strip()
+        return parseoutput(output)
     except CalledProcessError, exc:
         print >> sys.stderr, 'abort: cannot run revset benchmark: %s' % exc.cmd
         if exc.output is None:
@@ -64,6 +64,27 b' def perf(revset, target=None):'
             print >> sys.stderr, exc.output
         sys.exit(exc.returncode)
 
+outputre = re.compile(r'! wall (\d+.\d+) comb (\d+.\d+) user (\d+.\d+) '
+                      'sys (\d+.\d+) \(best of (\d+)\)')
+
+def parseoutput(output):
+    """parse a textual output into a dict
+
+    We cannot just use json because we want to compare with old
+    versions of Mercurial that may not support json output.
+    """
+    match = outputre.search(output)
+    if not match:
+        print >> sys.stderr, 'abort: invalid output:'
+        print >> sys.stderr, output
+        sys.exit(1)
+    return {'comb': float(match.group(2)),
+            'count': int(match.group(5)),
+            'sys': float(match.group(3)),
+            'user': float(match.group(4)),
+            'wall': float(match.group(1)),
+            }
+
 def printrevision(rev):
     """print data about a revision"""
     sys.stdout.write("Revision: ")
@@ -71,6 +92,13 b' def printrevision(rev):'
     check_call(['hg', 'log', '--rev', str(rev), '--template',
                '{desc|firstline}\n'])
 
+def formatresult(data):
+    """format the data dict into a line of text for humans"""
+    return ("wall %f comb %f user %f sys %f (best of %d)"
+            % (data['wall'], data['comb'], data['user'],
+               data['sys'], data['count']))
+
+
 def getrevs(spec):
     """get the list of rev matched by a revset"""
     try:
@@ -128,7 +156,7 b' for r in revs:'
     for idx, rset in enumerate(revsets):
         data = perf(rset, target=options.repo)
         res.append(data)
-        print "%i)" % idx, data
+        print "%i)" % idx, formatresult(data)
         sys.stdout.flush()
     print "----------------------------"
 
@@ -152,5 +180,5 b' for ridx, rset in enumerate(revsets):'
 
     print "revset #%i: %s" % (ridx, rset)
     for idx, data in enumerate(results):
-        print '%i) %s' % (idx, data[ridx])
+        print '%i) %s' % (idx, formatresult(data[ridx]))
     print