revsetbenchmarks: allow running multiple variants per revset

The current benchmarks were only testing the whole iteration. This is suboptimal
because some changes are meaningful for things like first result, minimum or
sorting.

We introduce a "variants" feature that let you systematically add some variants
to all revsets tested.

A typical variants value would be 'plain,min,last,sort'. When testing 'all()' it
will also provide testing for:
- all()
- min(all())
- last(all())
- sort(sort)

and output:

   plain         min            last           sort
0) 0.034568      0.037857       0.000074       0.034238
1) 0.011358  32% 0.020181  53%  0.000080 108%  0.011405  33%

Using revsets (who hit the API) instead of the internal API add some overhead,
but the overhead should be the same everywhere so it still allow comparison.
This is is more simple to implement and allows comparison with older versions
who do not have the same API.

contrib/revsetbenchmarks.py

@@ -16,6 +16,8 b' from subprocess import check_call, Popen'
 # cannot use argparse, python 2.7 only
 from optparse import OptionParser
 
+DEFAULTVARIANTS = ['plain']
+
 def check_output(*args, **kwargs):
     kwargs.setdefault('stderr', PIPE)
     kwargs.setdefault('stdout', PIPE)
@@ -144,25 +146,30 b' def formatfactor(factor):'
         return 'x%ix%i' % (factor, order)
 
 _marker = object()
-def printresult(idx, data, maxidx, verbose=False, reference=_marker):
+def printresult(variants, idx, data, maxidx, verbose=False, reference=_marker):
     """print a line of result to stdout"""
     mask = '%%0%ii) %%s' % idxwidth(maxidx)
-    out = ['%10.6f' % data['wall']]
+    out = []
+    for var in variants:
+        out.append('%10.6f' % data[var]['wall'])
     if reference is not _marker:
         factor = None
         if reference is not None:
-            factor = getfactor(reference, data, 'wall')
+                factor = getfactor(reference[var], data[var], 'wall')
         out.append(formatfactor(factor))
     if verbose:
-        out.append('%10.6f' % data['comb'])
-        out.append('%10.6f' % data['user'])
-        out.append('%10.6f' % data['sys'])
-        out.append('%6d'    % data['count'])
+            out.append('%10.6f' % data[var]['comb'])
+            out.append('%10.6f' % data[var]['user'])
+            out.append('%10.6f' % data[var]['sys'])
+            out.append('%6d'    % data[var]['count'])
     print mask % (idx, ' '.join(out))
 
-def printheader(maxidx, verbose=False, relative=False):
-    header = [' ' * (idxwidth(maxidx) + 1),
-              '  %-8s' % 'time']
+def printheader(variants, maxidx, verbose=False, relative=False):
+    header = [' ' * (idxwidth(maxidx) + 1)]
+    for var in variants:
+        if not var:
+            var = 'iter'
+        header.append('  %-8s' % var)
     if relative:
         header.append('    ')
     if verbose:
@@ -182,6 +189,12 b' def getrevs(spec):'
     return [r for r in out.split() if r]
 
 
+def applyvariants(revset, variant):
+    if variant == 'plain':
+        return revset
+    return '%s(%s)' % (variant, revset)
+
+
 parser = OptionParser(usage="usage: %prog [options] <revs>")
 parser.add_option("-f", "--file",
                   help="read revset from FILE (stdin if omitted)",
@@ -193,6 +206,11 b' parser.add_option("-v", "--verbose",'
                   action='store_true',
                   help="display all timing data (not just best total time)")
 
+parser.add_option("", "--variants",
+                  default=','.join(DEFAULTVARIANTS),
+                  help="comma separated list of variant to test "
+                       "(eg: plain,min,sorted) (plain = no modification)")
+
 (options, args) = parser.parse_args()
 
 if not args:
@@ -221,6 +239,8 b' revs = []'
 for a in args:
     revs.extend(getrevs(a))
 
+variants = options.variants.split(',')
+
 results = []
 for r in revs:
     print "----------------------------"
@@ -229,11 +249,16 b' for r in revs:'
     update(r)
     res = []
     results.append(res)
-    printheader(len(revsets), verbose=options.verbose)
+    printheader(variants, len(revsets), verbose=options.verbose)
     for idx, rset in enumerate(revsets):
-        data = perf(rset, target=options.repo)
-        res.append(data)
-        printresult(idx, data, len(revsets), verbose=options.verbose)
+        varres = {}
+        for var in variants:
+            varrset = applyvariants(rset, var)
+            data = perf(varrset, target=options.repo)
+            varres[var] = data
+        res.append(varres)
+        printresult(variants, idx, varres, len(revsets),
+                    verbose=options.verbose)
         sys.stdout.flush()
     print "----------------------------"
 
@@ -256,10 +281,10 b' print'
 for ridx, rset in enumerate(revsets):
 
     print "revset #%i: %s" % (ridx, rset)
-    printheader(len(results), verbose=options.verbose, relative=True)
+    printheader(variants, len(results), verbose=options.verbose, relative=True)
     ref = None
     for idx, data in enumerate(results):
-        printresult(idx, data[ridx], len(results), verbose=options.verbose,
-                    reference=ref)
+        printresult(variants, idx, data[ridx], len(results),
+                    verbose=options.verbose, reference=ref)
         ref = data[ridx]
     print