webrtc_m130/webrtc/tools/barcode_tools/helper_functions.py
phoglund be81fa538d Rewrote perform_action_on_all_files to be parallell.
This speeds up decode for a 720p workload from 25s to 5s on my machine.
I did some benchmarking and it appears we spend the vast majority of
the time on zxing decoding, so now we will bring all processors on the
the machine to bear.

BUG=webrtc:4986

Review URL: https://codereview.webrtc.org/1428433002

Cr-Commit-Position: refs/heads/master@{#10443}
2015-10-29 09:22:51 +00:00

106 lines
3.6 KiB
Python

#!/usr/bin/env python
# Copyright (c) 2012 The WebRTC 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 in the root of the source
# tree. An additional intellectual property rights grant can be found
# in the file PATENTS. All contributing project authors may
# be found in the AUTHORS file in the root of the source tree.
import multiprocessing
import os
import subprocess
import sys
_DEFAULT_PADDING = 4
class HelperError(Exception):
"""Exception raised for errors in the helper."""
pass
def zero_pad(number, padding=_DEFAULT_PADDING):
"""Converts an int into a zero padded string.
Args:
number(int): The number to convert.
padding(int): The number of chars in the output. Note that if you pass for
example number=23456 and padding=4, the output will still be '23456',
i.e. it will not be cropped. If you pass number=2 and padding=4, the
return value will be '0002'.
Return:
(string): The zero padded number converted to string.
"""
return str(number).zfill(padding)
def run_shell_command(cmd_list, fail_msg=None):
"""Executes a command.
Args:
cmd_list(list): Command list to execute.
fail_msg(string): Message describing the error in case the command fails.
Return:
(string): The standard output from running the command.
Raise:
HelperError: If command fails.
"""
process = subprocess.Popen(cmd_list, stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
output, error = process.communicate()
if process.returncode != 0:
if fail_msg:
print >> sys.stderr, fail_msg
raise HelperError('Failed to run %s: command returned %d and printed '
'%s and %s' % (' '.join(cmd_list), process.returncode,
output, error))
return output.strip()
def perform_action_on_all_files(directory, file_pattern, file_extension,
start_number, action, **kwargs):
"""Function that performs a given action on all files matching a pattern.
It is assumed that the files are named file_patternxxxx.file_extension, where
xxxx are digits starting from start_number.
Args:
directory(string): The directory where the files live.
file_pattern(string): The name pattern of the files.
file_extension(string): The files' extension.
start_number(int): From where to start to count frames.
action(function): The action to be performed over the files. Must return
False if the action failed, True otherwise. It should take a file name
as the first argument and **kwargs as arguments. The function must be
possible to pickle, so it cannot be a bound function (for instance).
Return:
(bool): Whether performing the action over all files was successful or not.
"""
file_prefix = os.path.join(directory, file_pattern)
file_number = start_number
process_pool = multiprocessing.Pool(processes=multiprocessing.cpu_count())
results = []
while True:
zero_padded_file_number = zero_pad(file_number)
file_name = file_prefix + zero_padded_file_number + '.' + file_extension
if not os.path.isfile(file_name):
break
future = process_pool.apply_async(action, args=(file_name,), kwds=kwargs)
results.append(future)
file_number += 1
successful = True
for result in results:
if not result.get():
print "At least one action %s failed for files %sxxxx.%s." % (
action, file_pattern, file_extension)
successful = False
process_pool.close()
return successful