Update checked in version of gsutil to version 4.6

gslib/thread_pool.py

-# Copyright 2011 Google Inc. All Rights Reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""Basic thread pool with exception handler."""
-
-import logging
-import Queue
-import threading
-
-
-# Magic values used to cleanly bring down threads.
-_THREAD_EXIT_MAGIC = ('Clean', 'Thread', 'Exit')
-
-
-def _DefaultExceptionHandler(e):
-  logging.exception(e)
-
-
-class Worker(threading.Thread):
-  """Thread executing tasks from a given task's queue."""
-
-  def __init__(self, tasks, exception_handler):
-    threading.Thread.__init__(self)
-    self.tasks = tasks
-    self.daemon = True
-    self.exception_handler = exception_handler
-    self.results = []
-    self.start()
-
-  def run(self):
-    while True:
-      func, args, kargs = self.tasks.get()
-
-      # Listen for magic value indicating thread exit.
-      if (func, args, kargs) == _THREAD_EXIT_MAGIC:
-        break
-
-      try:
-        result = func(*args, **kargs)
-        if result is not None:
-          self.results.append(result)
-      except Exception, e:
-        self.exception_handler(e)
-      finally:
-        self.tasks.task_done()
-
-
-class ThreadPool(object):
-  """Pool of threads consuming tasks from a queue."""
-
-  def __init__(self, num_threads, exception_handler=_DefaultExceptionHandler):
-    self.tasks = Queue.Queue(num_threads)
-    self.threads = []
-    for _ in range(num_threads):
-      self.threads.append(Worker(self.tasks, exception_handler))
-
-  def AddTask(self, func, *args, **kargs):
-    """Add a task to the queue."""
-    self.tasks.put((func, args, kargs))
-
-  def Shutdown(self, should_return_results=False):
-    """Shutdown the thread pool."""
-    self.tasks.join()
-    for thread in self.threads:
-      self.tasks.put(_THREAD_EXIT_MAGIC)
-
-    results = []
-    for thread in self.threads:
-      thread.join()
-      if should_return_results:
-        results += thread.results
-    return results