Refactor the symbolize step of the orderfile generation.

tools/cygprofile/cyglog_to_orderfile.py

+#!/usr/bin/python
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Symbolize log file produced by cyprofile instrumentation.
+
+Given a log file and the binary being profiled, create an order file.
+"""
+
+import logging
+import multiprocessing
+import optparse
+import os
+import tempfile
+import string
+import sys
+
+import symbol_extractor
+
+
+def _ParseLogLines(log_file_lines):
+  """Parse a merge cyglog produced by mergetraces.py.

[pasko, 2015/01/30 19:31:33]

s/Parse/Parses/ (and similarly below)
(sorry forgot to mention this in previous CLs) We try to follow the same
practices in python as suggested in the C++ style:

These comments should be descriptive ("Opens the file") rather than imperative
("Open the file"); the comment describes the function, it does not tell the
function what to do.
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Function_Comm...

Similarly, the top-level description of the file should probably be:
s/Symbolize/Symbolizes/
s/create/creates/

And finally here:
s/merge/merged/

[Benoit L, 2015/02/02 09:28:14]

Ah, I was consistently doing the wrong thing.
Done.

+
+  Args:
+    log_file_lines: array of lines in log file produced by profiled run
+    lib_name: library or executable containing symbols
+
+    Below is an example of a small log file:
+    5086e000-52e92000 r-xp 00000000 b3:02 51276      libchromeview.so
+    secs       usecs      pid:threadid    func
+    START
+    1314897086 795828     3587:1074648168 0x509e105c
+    1314897086 795874     3587:1074648168 0x509e0eb4
+    1314897086 796326     3587:1074648168 0x509e0e3c
+    1314897086 796552     3587:1074648168 0x509e07bc
+    END
+
+  Returns:
+    A list of tuples of the format (sec, usec, call id, function address called)
+  """
+  call_lines = []
+  vm_start = 0
+  line = log_file_lines[0]
+  assert 'r-xp' in line
+  end_index = line.find('-')
+  vm_start = int(line[:end_index], 16)
+  for line in log_file_lines[2:]:
+    fields = line.split()
+    if len(fields) == 4:
+      call_lines.append(fields)

[pasko, 2015/01/30 19:31:33]

else:
  assert fields[0] == 'END'

wdyt?

[Benoit L, 2015/02/02 09:28:14]

There are lines at the start that don't follow this pattern.

[pasko-google - do not use, 2015/02/02 10:35:49]

But but .. you can replace the '2' with '3' in the 'log_file_lines[2:]', no?

+
+  # Convert strings to int in fields.
+  call_info = []
+  for call_line in call_lines:
+    (sec_timestamp, usec_timestamp) = map(int, call_line[0:2])

[pasko, 2015/01/30 19:31:33]

Why are we doing all this? We only use the ordered offsets later.

[Benoit L, 2015/02/02 09:28:14]

Carried over from the previous version of the code...
Done.

+    callee_id = call_line[2]
+    addr = int(call_line[3], 16)
+    if vm_start < addr:
+      addr -= vm_start
+      call_info.append((sec_timestamp, usec_timestamp, callee_id, addr))
+
+  return call_info
+
+
+def _GroupLibrarySymbolInfosByOffset(lib_filename):
+  """Return a dict {offset: [SymbolInfo]} from a library."""
+  symbol_infos = symbol_extractor.SymbolInfosFromBinary(lib_filename)
+  return symbol_extractor.GroupSymbolInfosByOffset(symbol_infos)
+
+
+class SymbolNotFoundException(Exception):
+  def __init__(self, value):
+    super(SymbolNotFoundException, self).__init__(value)
+    self.value = value
+
+  def __str__(self):
+    return repr(self.value)
+
+
+def _FindSymbolInfosAtOffset(offset_to_symbol_infos, offset):

[pasko, 2015/01/30 19:31:33]

not sure how strongly I feel about this. Usually the first argument would be
'what to find', and the second 'where to find'. Not sure why.

Feel free to disregard.

[Benoit L, 2015/02/02 09:28:14]

Acknowledged.

+  """Find all SymbolInfo at a given offset.
+
+  Args:
+    offset_to_symbol_infos: {offset: [SymbolInfo]}
+    offset: offset to look the symbols at
+
+  Returns:
+    The list of SymbolInfo at the given offset
+
+  Raises:
+    SymbolNotFoundException if the offset doesn't match any symbol.
+  """
+  if offset in offset_to_symbol_infos:
+    return offset_to_symbol_infos[offset]
+  elif offset % 2 and (offset - 1) in offset_to_symbol_infos:
+    # On ARM, odd addresses are used to signal thumb instruction. They are
+    # generated by setting the LSB to 1 (see
+    # http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0471e/Babfjhia.html).
+    # TODO(lizeb): Make sure this hack doesn't propagate to other archs.
+    return offset_to_symbol_infos[offset - 1]
+  else:
+    raise SymbolNotFoundException(offset)
+
+
+class WarningCollector(object):
+  """Collect warnings, but limit the number printed to a set value."""
+  def __init__(self, max_warnings):
+    self._warnings = 0
+    self._max_warnings = max_warnings
+
+  def Write(self, message):
+    if self._warnings < self._max_warnings:
+      logging.warning(message)
+    self._warnings += 1
+
+  def WriteEnd(self, message):
+    if self._warnings > self._max_warnings:
+      logging.warning('%d more warnings for %s' % (
+          self._warnings - self._max_warnings, message))
+
+
+def _GetObjectFileNames(obj_dir):
+  """Return the list of object files in a directory."""
+  obj_files = []
+  for (dirpath, _, filenames) in os.walk(obj_dir):
+    for file_name in filenames:
+      if file_name.endswith('.o'):
+        obj_files.append(os.path.join(dirpath, file_name))
+  return obj_files
+
+
+def _AllSymbolInfos(object_filenames):
+  """Return a list of SymbolInfo from an iterable of filenames."""
+  pool = multiprocessing.Pool()
+  symbol_infos_nested = pool.map(
+      symbol_extractor.SymbolInfosFromBinary, object_filenames)

[pasko, 2015/01/30 19:31:32]

maybe just write a comment saying that we expect everything to be in the page
cache after linking, so I/O is _probably_ not a problem?

[Benoit L, 2015/02/02 09:28:14]

Done.

+  result = []
+  for symbol_infos in symbol_infos_nested:
+    result += symbol_infos
+  return result
+
+
+def _GetSymbolToSectionMapFromObjectFiles(obj_dir):
+  """ Create a mapping from symbol to linker section name by scanning all
+      the object files.
+  """
+  object_files = _GetObjectFileNames(obj_dir)
+  symbol_to_section_map = {}
+  symbol_warnings = WarningCollector(300)
+  symbol_infos = _AllSymbolInfos(object_files)
+  symbol_infos = [s for s in symbol_infos if not s.name.startswith('.LTHUNK')]

[pasko, 2015/01/30 19:31:33]

I think it would be more readable if it lives in the loop:

for symbol_info in symbol_infos:
  symbol = symbol_info.name
  if symbol.name.startswith('.LTHUNK'):
    continue;

Higher order functions and lambda expressions are nice when they help making
things clear, this line just made it a little more complex without clear reason.
Also copied all of the array without a need, and provided an extra kick for GC.

[Benoit L, 2015/02/02 09:28:14]

Done.

+  for symbol_info in symbol_infos:
+    symbol = symbol_info.name
+    section = symbol_info.section
+    if ((symbol in symbol_to_section_map) and
+        (symbol_to_section_map[symbol] != symbol_info.section)):
+      symbol_warnings.Write('Symbol ' + symbol +
+                            ' in conflicting sections ' + section +
+                            ' and ' + symbol_to_section_map[symbol])
+    elif not section.startswith('.text'):
+      symbol_warnings.Write('Symbol ' + symbol +
+                            ' in incorrect section ' + section)

[pasko, 2015/01/30 19:31:32]

I forgot why it would be incorrect for a symbol to be in a section
".text.Something", because .text is suppowed to be stripped?

[Benoit L, 2015/02/02 09:28:15]

It is the contrary, print a warning if the section names doesn't start with
'.text'.

[pasko-google - do not use, 2015/02/02 10:35:49]

ah, sorry, did not spot the 'not' in the condition, dumb.

curious, cannotwait: how many warnings are printed in your experiments?

+    else:
+      symbol_to_section_map[symbol] = section
+  symbol_warnings.WriteEnd('bad sections')
+  return symbol_to_section_map
+
+
+def _WarnAboutDuplicates(offsets):
+  """Warn about duplicate offsets.
+
+  Args:
+    offsets: list of offsets to check for duplicates
+
+  Returns:
+    True if there are no duplicates, False otherwise.
+  """
+  seen_offsets = set()
+  ok = True
+  for offset in offsets:
+    if offset not in seen_offsets:
+      seen_offsets.add(offset)
+    else:
+      ok = False
+      logging.warning('Duplicate offset: ' + hex(offset))
+  return ok
+
+
+def _OutputOrderfile(offsets, offset_to_symbol_infos, symbol_to_section_map,
+                     output_file):
+  """Output the order file to output_file.

[pasko, 2015/01/30 19:31:33]

s/order file/orderfile/

[Benoit L, 2015/02/02 09:28:14]

Done.

+
+  Args:
+    offsets: Iterable of offsets to match to section names
+    offset_to_symbol_infos: {offset: [SymbolInfo]}
+    symbol_to_section_map: {name: section}
+    output_file: file-like object to write the results to
+  """
+  success = True
+  unknown_symbol_warnings = WarningCollector(300)
+  symbol_not_found_warnings = WarningCollector(300)
+  for offset in offsets:
+    try:
+      symbol_infos = _FindSymbolInfosAtOffset(offset_to_symbol_infos, offset)
+      for symbol_info in symbol_infos:
+        if symbol_info.name in symbol_to_section_map:
+          output_file.write(symbol_to_section_map[symbol_info.name] + '\n')
+        else:
+          unknown_symbol_warnings.Write(
+              'No known section for symbol ' + symbol_info.name)
+    except SymbolNotFoundException:
+      symbol_not_found_warnings.Write(
+          'Did not find function in binary. offset: ' + hex(offset))
+      success = False
+  unknown_symbol_warnings.WriteEnd('no known section for symbol')
+  symbol_not_found_warnings.WriteEnd('did not find function')

[pasko, 2015/01/30 19:31:32]

"X more warnings for did not find function" sounds awkward, maybe:
"X more warnings for: function not found in the binary"
(and also: symbol_not_found_warnings.Write('function not found in the binary'))

[Benoit L, 2015/02/02 09:28:14]

Done.

+  return success
+
+
+def main():
+  if len(sys.argv) != 4:
+    logging.error('Usage: cyglog_to_orderfile.py <merged_cyglog> '
+                  '<library> <output_filename>')
+    return 1
+  (log_file, lib_file, output_filename) = sys.argv[1:]

[pasko, 2015/01/30 19:31:33]

nit: they are all file names, but two of them are _file, while one is _filename.

log_filename and lib_filename would be more pleasing to my eye, but up to you

[Benoit L, 2015/02/02 09:28:15]

Done.

+
+  obj_dir = os.path.abspath(os.path.join(os.path.dirname(lib_file), '../obj'))
+
+  log_file_lines = map(string.rstrip, open(log_file).readlines())
+  call_info = _ParseLogLines(log_file_lines)

[pasko, 2015/01/30 19:31:33]

s/call_info/call_infos/

[Benoit L, 2015/02/02 09:28:15]

Done.

+  offsets = [call[3] for call in call_info]
+  offset_to_symbol_infos = _GroupLibrarySymbolInfosByOffset(lib_file)
+
+  _WarnAboutDuplicates(offsets)
+
+  symbol_to_section_map = _GetSymbolToSectionMapFromObjectFiles(obj_dir)
+  success = False
+  temp_filename = None
+  output_file = None
+  try:
+    (fd, temp_filename) = tempfile.mkstemp(dir=os.path.dirname(output_filename))
+    output_file = os.fdopen(fd, 'w')
+    ok = _OutputOrderfile(offsets, offset_to_symbol_infos,
+                               symbol_to_section_map, output_file)

[pasko, 2015/01/30 19:31:33]

nit: less whitespace

[Benoit L, 2015/02/02 09:28:14]

Done.

+    output_file.close()
+    os.rename(temp_filename, output_filename)
+    temp_filename = None
+    success = ok
+  finally:
+    if output_file:
+      output_file.close()
+    if temp_filename:
+      os.remove(temp_filename)
+
+  return 0 if success else 1
+
+
+if __name__ == '__main__':
+  logging.basicConfig(level=logging.INFO)
+  sys.exit(main())

[pasko, 2015/01/30 19:31:32]

so, symbol_extractor.CreateNameToSymbolInfo() is never used in this CL, is it
going to be used in following CLs? If not, please delete it here with the
corresponding unittest.

[Benoit L, 2015/02/02 09:28:15]

Used later on. :-)