[tools] Add ranking to GC NVP eval script

tools/eval_gc_nvp.py

 #!/usr/bin/env python
 #
 # Copyright 2015 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """This script is used to analyze GCTracer's NVP output."""
 
 
 from argparse import ArgumentParser
@@ skipping 67 matching lines @@
     self.key = key
     self.values = []
     self.histogram = histogram
 
   def process_entry(self, entry):
     if self.key in entry:
       self.values.append(float(entry[self.key]))
       if self.histogram:
         self.histogram.add(float(entry[self.key]))
 
+  def min(self):
+    return min(self.values)
+
+  def max(self):
+    return max(self.values)
+
+  def avg(self):
+    return sum(self.values) / len(self.values)
+
   def __str__(self):
     ret = [self.key]
     ret.append("  len: {0}".format(len(self.values)))
     if len(self.values) > 0:
       ret.append("  min: {0}".format(min(self.values)))
       ret.append("  max: {0}".format(max(self.values)))
       ret.append("  avg: {0}".format(sum(self.values) / len(self.values)))
       if self.histogram:
         ret.append(str(self.histogram))
     return "\n".join(ret)
 
+  def __repr__(self):
+    return "<Category: {0}>".format(self.key)
+
+
+def make_key_func(cmp_metric):
+  def key_func(a):
+    return getattr(a, cmp_metric)()
+  return key_func
+
 
 def main():
   parser = ArgumentParser(description="Process GCTracer's NVP output")
   parser.add_argument('keys', metavar='KEY', type=str, nargs='+',
                       help='the keys of NVPs to process')
   parser.add_argument('--histogram-type', metavar='<linear|log2>',
                       type=str, nargs='?', default="linear",
                       help='histogram type to use (default: linear)')
   linear_group = parser.add_argument_group('linear histogram specific')
   linear_group.add_argument('--linear-histogram-granularity',
                             metavar='GRANULARITY', type=int, nargs='?',
                             default=5,
                             help='histogram granularity (default: 5)')
   log2_group = parser.add_argument_group('log2 histogram specific')
   log2_group.add_argument('--log2-histogram-init-bucket', metavar='START',
                           type=int, nargs='?', default=64,
                           help='initial buck size (default: 64)')
   parser.add_argument('--histogram-omit-empty-buckets',
                       dest='histogram_omit_empty',
                       action='store_true',
                       help='omit empty histogram buckets')
   parser.add_argument('--no-histogram', dest='histogram',
                       action='store_false', help='do not print histogram')
   parser.set_defaults(histogram=True)
   parser.set_defaults(histogram_omit_empty=False)
+  parser.add_argument('--rank', metavar='<no|min|max|avg>',
+                      type=str, nargs='?',
+                      default="no",
+                      help="rank keys by metric (default: no)")
   args = parser.parse_args()
 
   histogram = None
   if args.histogram:
     bucket_trait = None
     if args.histogram_type == "log2":
       bucket_trait = Log2Bucket(args.log2_histogram_init_bucket)
     else:
       bucket_trait = LinearBucket(args.linear_histogram_granularity)
     histogram = Histogram(bucket_trait, not args.histogram_omit_empty)
 
   categories = [ Category(key, deepcopy(histogram))
                  for key in args.keys ]
 
   while True:
     line = stdin.readline()
     if not line:
       break
     obj = split_nvp(line)
     for category in categories:
       category.process_entry(obj)
 
+  if args.rank != "no":
+    categories = sorted(categories, key=make_key_func(args.rank), reverse=True)
+
   for category in categories:
     print(category)
 
 
 if __name__ == '__main__':
   main()