revsetbenchmark: remove python 2.7 dependency

revsetbenchmark.py used check_output which only exists in python 2.7. This
fixes it.

contrib/revsetbenchmarks.py

@@ -1,117 +1,125
 #!/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.
 #
 # - First argument is a revset of mercurial own repo to runs against.
 # - Second argument is the file from which the revset array will be taken
 #   If second argument is omitted read it from standard input
 #
 # You should run this from the root of your mercurial repository.
 #
 # This script also does one run of the current version of mercurial installed
 # to compare performance.
 
 import sys
-from subprocess import check_call, check_output, CalledProcessError, STDOUT
+from subprocess import check_call, Popen, CalledProcessError, STDOUT, PIPE
 
+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))
+    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 perf(revset):
     """run benchmark for this very revset"""
     try:
         output = check_output(['./hg',
                                '--config',
                                'extensions.perf=contrib/perf.py',
                                'perfrevset',
                                revset],
                                stderr=STDOUT)
         output = output.lstrip('!') # remove useless ! in this context
         return output.strip()
     except CalledProcessError, exc:
         print >> sys.stderr, 'abort: cannot run revset benchmark'
         sys.exit(exc.returncode)
 
 def printrevision(rev):
     """print data about a revision"""
     sys.stdout.write("Revision: ")
     sys.stdout.flush()
     check_call(['hg', 'log', '--rev', str(rev), '--template',
                '{desc|firstline}\n'])
 
 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]
 
 
 
 target_rev = sys.argv[1]
 
 revsetsfile = sys.stdin
 if len(sys.argv) > 2:
     revsetsfile = open(sys.argv[2])
 
 revsets = [l.strip() for l in revsetsfile]
 
 print "Revsets to benchmark"
 print "----------------------------"
 
 for idx, rset in enumerate(revsets):
     print "%i) %s" % (idx, rset)
 
 print "----------------------------"
 print
 
 
 revs = getrevs(target_rev)
 
 results = []
 for r in revs:
     print "----------------------------"
     printrevision(r)
     print "----------------------------"
     update(r)
     res = []
     results.append(res)
     for idx, rset in enumerate(revsets):
         data = perf(rset)
         res.append(data)
         print "%i)" % idx, data
         sys.stdout.flush()
     print "----------------------------"
 
 
 print """
 
 Result by revset
 ================
 """
 
 print 'Revision:', revs
 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)
     for idx, data in enumerate(results):
         print '%i) %s' % (idx, data[ridx])
     print