stats-viewer.py: support passing test_shell pid.

tools/stats-viewer.py

 #!/usr/bin/env python
 #
 # Copyright 2008 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
@@ skipping 19 matching lines @@
 
 """A cross-platform execution counter viewer.
 
 The stats viewer reads counters from a binary file and displays them
 in a window, re-reading and re-displaying with regular intervals.
 """
 
 
 import mmap
 import os
+import re
 import struct
 import sys
 import time
 import Tkinter
 
 
 # The interval, in milliseconds, between ui updates
 UPDATE_INTERVAL_MS = 100
 
 
@@ skipping 38 matching lines @@
       # OpenWindow blocks until the main window is closed
       self.OpenWindow()
     finally:
       self.CleanUp()
 
   def MountSharedData(self):
     """Mount the binary counters file as a memory-mapped file.  If
     something goes wrong print an informative message and exit the
     program."""
     if not os.path.exists(self.data_name):
-      print "File %s doesn't exist." % self.data_name
-      sys.exit(1)
+      maps_name = "/proc/%s/maps" % self.data_name
+      if not os.path.exists(maps_name):
+        print "\"%s\" is neither a counter file nor a PID." % self.data_name
+        sys.exit(1)
+      maps_file = open(maps_name, "r")
+      try:
+        m = re.search(r"/dev/shm/\S*", maps_file.read())
+        if m is not None and os.path.exists(m.group(0)):
+          self.data_name = m.group(0)
+        else:
+          print "Can't find counter file in maps for PID %s." % self.data_name
+          sys.exit(1)
+      finally:
+        maps_file.close()
     data_file = open(self.data_name, "r")
     size = os.fstat(data_file.fileno()).st_size
     fileno = data_file.fileno()
     self.shared_mmap = mmap.mmap(fileno, size, access=mmap.ACCESS_READ)
     data_access = SharedDataAccess(self.shared_mmap)
     if data_access.IntAt(0) == COUNTERS_FILE_MAGIC_NUMBER:
       return CounterCollection(data_access)
     elif data_access.IntAt(0) == CHROME_COUNTERS_FILE_MAGIC_NUMBER:
       return ChromeCounterCollection(data_access)
     print "File %s is not stats data." % self.data_name
@@ skipping 321 matching lines @@
   """Run the stats counter.
 
   Args:
     data_file: The counters file to monitor.
   """
   StatsViewer(data_file).Run()
 
 
 if __name__ == "__main__":
   if len(sys.argv) != 2:
-    print "Usage: stats-viewer.py <stats data>"
+    print "Usage: stats-viewer.py <stats data>|<test_shell pid>"
     sys.exit(1)
   Main(sys.argv[1])