revsetbenchmarks: add main documention for the script

This allow us to document the fact we can use comment in the file listing revsets.

contrib/revsetbenchmarks.py

@@ -1,305 +1,311 b''
 #!/usr/bin/env python
 
 # Measure the performance of a list of revsets against multiple revisions
 # defined by parameter. Checkout one by one and run perfrevset with every
 # revset in the list to benchmark its performance.
 #
 # You should run this from the root of your mercurial repository.
 #
 # call with --help for details
 
 import sys
 import os
 import re
 import math
 from subprocess import check_call, Popen, CalledProcessError, STDOUT, PIPE
 # cannot use argparse, python 2.7 only
 from optparse import OptionParser
 
 DEFAULTVARIANTS = ['plain', 'min', 'max', 'first', 'last',
                    'reverse', 'reverse+first', 'reverse+last',
                    'sort', 'sort+first', 'sort+last']
 
 def check_output(*args, **kwargs):
     kwargs.setdefault('stderr', PIPE)
     kwargs.setdefault('stdout', PIPE)
     proc = Popen(*args, **kwargs)
     output, error = proc.communicate()
     if proc.returncode != 0:
         raise CalledProcessError(proc.returncode, ' '.join(args[0]))
     return output
 
 def update(rev):
     """update the repo to a revision"""
     try:
         check_call(['hg', 'update', '--quiet', '--check', str(rev)])
     except CalledProcessError, exc:
         print >> sys.stderr, 'update to revision %s failed, aborting' % rev
         sys.exit(exc.returncode)
 
 
 def hg(cmd, repo=None):
     """run a mercurial command
 
     <cmd> is the list of command + argument,
     <repo> is an optional repository path to run this command in."""
     fullcmd = ['./hg']
     if repo is not None:
         fullcmd += ['-R', repo]
     fullcmd += ['--config',
                 'extensions.perf=' + os.path.join(contribdir, 'perf.py')]
     fullcmd += cmd
     return check_output(fullcmd, stderr=STDOUT)
 
 def perf(revset, target=None):
     """run benchmark for this very revset"""
     try:
         output = hg(['perfrevset', revset], repo=target)
         return parseoutput(output)
     except CalledProcessError, exc:
         print >> sys.stderr, 'abort: cannot run revset benchmark: %s' % exc.cmd
         if exc.output is None:
             print >> sys.stderr, '(no ouput)'
         else:
             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 ")
     sys.stdout.flush()
     check_call(['hg', 'log', '--rev', str(rev), '--template',
                 '{if(tags, " ({tags})")} '
                 '{rev}:{node|short}: {desc|firstline}\n'])
 
 def idxwidth(nbidx):
     """return the max width of number used for index
 
     This is similar to log10(nbidx), but we use custom code here
     because we start with zero and we'd rather not deal with all the
     extra rounding business that log10 would imply.
     """
     nbidx -= 1 # starts at 0
     idxwidth = 0
     while nbidx:
         idxwidth += 1
         nbidx //= 10
     if not idxwidth:
         idxwidth = 1
     return idxwidth
 
 def getfactor(main, other, field, sensitivity=0.05):
     """return the relative factor between values for 'field' in main and other
 
     Return None if the factor is insignicant (less than <sensitivity>
     variation)."""
     factor = 1
     if main is not None:
         factor = other[field] / main[field]
     low, high = 1 - sensitivity, 1 + sensitivity
     if (low < factor < high):
         return None
     return factor
 
 def formatfactor(factor):
     """format a factor into a 4 char string
 
      22%
     156%
     x2.4
      x23
     x789
     x1e4
     x5x7
 
     """
     if factor is None:
         return '    '
     elif factor < 2:
         return '%3i%%' % (factor * 100)
     elif factor < 10:
         return 'x%3.1f' % factor
     elif factor < 1000:
         return '%4s' % ('x%i' % factor)
     else:
         order = int(math.log(factor)) + 1
         while 1 < math.log(factor):
             factor //= 0
         return 'x%ix%i' % (factor, order)
 
 def formattiming(value):
     """format a value to strictly 8 char, dropping some precision if needed"""
     if value < 10**7:
         return ('%.6f' % value)[:8]
     else:
         # value is HUGE very unlikely to happen (4+ month run)
         return '%i' % value
 
 _marker = object()
 def printresult(variants, idx, data, maxidx, verbose=False, reference=_marker):
     """print a line of result to stdout"""
     mask = '%%0%ii) %%s' % idxwidth(maxidx)
     out = []
     for var in variants:
         out.append(formattiming(data[var]['wall']))
         if reference is not _marker:
             factor = None
             if reference is not None:
                 factor = getfactor(reference[var], data[var], 'wall')
             out.append(formatfactor(factor))
         if verbose:
             out.append(formattiming(data[var]['comb']))
             out.append(formattiming(data[var]['user']))
             out.append(formattiming(data[var]['sys']))
             out.append('%6d'    % data[var]['count'])
     print mask % (idx, ' '.join(out))
 
 def printheader(variants, maxidx, verbose=False, relative=False):
     header = [' ' * (idxwidth(maxidx) + 1)]
     for var in variants:
         if not var:
             var = 'iter'
         if 8 < len(var):
             var = var[:3] + '..' + var[-3:]
         header.append('%-8s' % var)
         if relative:
             header.append('    ')
         if verbose:
             header.append('%-8s' % 'comb')
             header.append('%-8s' % 'user')
             header.append('%-8s' % 'sys')
             header.append('%6s' % 'count')
     print ' '.join(header)
 
 def getrevs(spec):
     """get the list of rev matched by a revset"""
     try:
         out = check_output(['hg', 'log', '--template={rev}\n', '--rev', spec])
     except CalledProcessError, exc:
         print >> sys.stderr, "abort, can't get revision from %s" % spec
         sys.exit(exc.returncode)
     return [r for r in out.split() if r]
 
 
 def applyvariants(revset, variant):
     if variant == 'plain':
         return revset
     for var in variant.split('+'):
         revset = '%s(%s)' % (var, revset)
     return revset
 
-
-parser = OptionParser(usage="usage: %prog [options] <revs>")
+helptext="""This script will run multiple variants of provided revsets using
+different revisions in your mercurial repository. After the benchmark are run
+summary output is provided. Use itto demonstrate speed improvements or pin
+point regressions. Revsets to run are specified in a file (or from stdin), one
+revsets per line. Line starting with '#' will be ignored, allowing insertion of
+comments."""
+parser = OptionParser(usage="usage: %prog [options] <revs>",
+                      description=helptext)
 parser.add_option("-f", "--file",
                   help="read revset from FILE (stdin if omitted)",
                   metavar="FILE")
 parser.add_option("-R", "--repo",
                   help="run benchmark on REPO", metavar="REPO")
 
 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:
     parser.print_help()
     sys.exit(255)
 
 # the directory where both this script and the perf.py extension live.
 contribdir = os.path.dirname(__file__)
 
 revsetsfile = sys.stdin
 if options.file:
     revsetsfile = open(options.file)
 
 revsets = [l.strip() for l in revsetsfile if not l.startswith('#')]
 
 print "Revsets to benchmark"
 print "----------------------------"
 
 for idx, rset in enumerate(revsets):
     print "%i) %s" % (idx, rset)
 
 print "----------------------------"
 print
 
 revs = []
 for a in args:
     revs.extend(getrevs(a))
 
 variants = options.variants.split(',')
 
 results = []
 for r in revs:
     print "----------------------------"
     printrevision(r)
     print "----------------------------"
     update(r)
     res = []
     results.append(res)
     printheader(variants, len(revsets), verbose=options.verbose)
     for idx, rset in enumerate(revsets):
         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 "----------------------------"
 
 
 print """
 
 Result by revset
 ================
 """
 
 print 'Revision:'
 for idx, rev in enumerate(revs):
     sys.stdout.write('%i) ' % idx)
     sys.stdout.flush()
     printrevision(rev)
 
 print
 print
 
 for ridx, rset in enumerate(revsets):
 
     print "revset #%i: %s" % (ridx, rset)
     printheader(variants, len(results), verbose=options.verbose, relative=True)
     ref = None
     for idx, data in enumerate(results):
         printresult(variants, idx, data[ridx], len(results),
                     verbose=options.verbose, reference=ref)
         ref = data[ridx]
     print