Add local results details pages.

build/android/pylib/base/output_manager.py

+# Copyright 2017 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.
+
+import contextlib
+import logging
+import os
+import tempfile
+
+from devil.utils import reraiser_thread
+
+
+class Datatype(object):
+  HTML = 'html'
+  IMAGE = 'image'
+  TEXT = 'text'
+
+
+class OutputManager(object):
+
+  def __init__(self):
+    """OutputManager Constructor.
+
+    This class provides a simple interface to save test output. Subclasses
+    of this will allow users to save test results in the cloud or locally.
+    """
+    self._allow_upload = False
+    self._thread_group = None
+
+  @contextlib.contextmanager
+  def ArchivedTempfile(
+      self, out_filename, out_subdir, datatype=Datatype.TEXT):
+    """Archive file contents asynchonously and then deletes file.
+
+    Args:
+      out_filename: Name for saved file.
+      out_subdir: Directory to save |out_filename| to.
+      datatype: Datatype of file.
+
+    Returns:
+      An ArchivedFile file. This file will be uploaded async when the context
+      manager exits. AFTER the context manager exits, you can get the link to
+      where the file will be stored using the Link() API. You can use typical
+      file APIs to write and flish the ArchivedFile. You can also use file.name
+      to get the local filepath to where the underlying file exists. If you do
+      this, you are responsible of flushing the file before exiting the context
+      manager.
+    """
+    if not self._allow_upload:
+      raise Exception('Must run |SetUp| before attempting to upload!')
+
+    f = self._CreateArchivedFile(out_filename, out_subdir, datatype)
+    yield f
+    f.PrepareArchive()

[jbudorick, 2017/08/23 16:16:19]

The remainder of this function won't execute if an Exception is raised inside
the context. I'm not sure that's what we want, so this should probably be:

  try:
    yield f
  finally:
    f.PrepareArchive()
    ...

[mikecase (-- gone --), 2017/08/24 05:29:07]

Done. GOod catch

+
+    def archive():
+      try:
+        f.Archive()
+      finally:
+        os.remove(f.name)
+
+    thread = reraiser_thread.ReraiserThread(func=archive)
+    thread.start()
+    self._thread_group.Add(thread)
+
+  def _CreateArchivedFile(self, out_filename, out_subdir, datatype):
+    """Returns an instance of ArchivedFile."""
+    raise NotImplementedError
+
+  def SetUp(self):
+    self._allow_upload = True
+    self._thread_group = reraiser_thread.ReraiserThreadGroup()
+
+  def TearDown(self):
+    self._allow_upload = False
+    logging.info('Finishing archiving output.')
+    self._thread_group.JoinAll()
+
+  def __enter__(self):
+    self.SetUp()
+    return self
+
+  def __exit__(self, _exc_type, _exc_val, _exc_tb):
+    self.TearDown()
+

[jbudorick, 2017/08/23 16:16:19]

super nit: +1 blank line

[mikecase (-- gone --), 2017/08/24 05:29:07]

Done

+class ArchivedFile(object):
+
+  def __init__(self, out_filename, out_subdir, datatype):
+    self._out_filename = out_filename
+    self._out_subdir = out_subdir
+    self._datatype = datatype
+
+    self._f = tempfile.NamedTemporaryFile(delete=False)

[jbudorick, 2017/08/23 16:16:19]

Does this ever get removed?

[mikecase (-- gone --), 2017/08/24 05:29:07]

Yes. so, I think Im doing it an alright way.

os.remove(f.name) is called by the thread spawned by ArchivedTempfile. 

[jbudorick, 2017/08/24 13:18:45]

ah, ok.

+    self.name = self._f.name

[jbudorick, 2017/08/23 16:16:19]

nit: @property for this?

[mikecase (-- gone --), 2017/08/24 05:29:07]

Good idea, for some reason I forgot about those....

+    self._ready_to_archive = False
+
+  def write(self, *args, **kwargs):
+    if self._ready_to_archive:
+      raise Exception('Cannot write to file after archiving has begun!')
+    self._f.write(*args, **kwargs)
+
+  def flush(self, *args, **kwargs):
+    if self._ready_to_archive:
+      raise Exception('Cannot flush file after archiving has begun!')
+    self._f.flush(*args, **kwargs)
+
+  def Link(self):
+    """Returns location of archived file."""
+    if not self._ready_to_archive:
+      raise Exception('Cannot get link to archived file before archiving'

[jbudorick, 2017/08/23 16:16:19]

super nit: +1 space after archiving, otherwise this will be

  "... before archivinghas begun"

[mikecase (-- gone --), 2017/08/24 05:29:07]

Done

+                      'has begun')
+    return self._Link()
+
+  def _Link(self):
+    """Note for when overriding this function.
+
+    This function will certainly be called before the file
+    has finished being archived. Therefore, this needs to be able to know the
+    exact location of the archived file before it is finished being archived.
+    """
+    raise NotImplementedError
+
+  def PrepareArchive(self):
+    """Meant to be called synchronously to prepare file for async archiving."""
+    self.flush()
+    self._ready_to_archive = True
+    self._PrepareArchive()
+
+  def _PrepareArchive(self):
+    """Note for when overriding this function.
+
+    This function is needed for things such as computing the location of
+    content addressed files. This is called after the file is written but
+    before archiving has begun.
+    """
+    pass
+
+  def Archive(self):
+    """Archives file."""
+    assert self._ready_to_archive

[jbudorick, 2017/08/23 16:16:20]

I think this should be an Exception, analogous to what you have above, rather
than an Assertion. All are cases of the client calling a function at the wrong
time.

[mikecase (-- gone --), 2017/08/24 05:29:07]

Well, this isnt well documented, but the only thing that should call Archive is
the ArchivedTempfile context manager. This shouldnt have to be altered by
anything/anyone. But changing to exception.

+    self._Archive()
+
+  def _Archive(self):
+    raise NotImplementedError