commit 1b2885dd0b4fa957e747cd0f19868f8505b049fe
author Marc-Antoine Ruel <maruel@chromium.org> Tue Dec 04 18:30:33 2018
committer Commit Bot <commit-bot@chromium.org> Tue Dec 04 18:30:33 2018
tree 0dc5b2a490b4fa68e04aadaa0f62473f1378f0a3
parent 13554fd6a0280b77cd3cdcf9c73ab890ae15fe92

[client] lazy hash and improve symlink processing

- Stop hashing in file_to_metadata(). The hashing must be delayed for
  tarballs, as only the hash of the whole tarball is needed, not the
  hash of each of its individual files.
- Small performance improvement for symlinks, to not call stat() twice
  on them. This is still the case for other files. :/
- Make isolate_storage.Item more 'immutable'. This is to help with data
  flow.
- Make isolate_storage.Item know how to calculate its own digest. This
  is needed for tarfiles, as they won't be written to disk, nor be fully
  kept in memory. This removes the need for prepare().
- As a small performance improvement, do not saves isolated files
  created for directory to disk anymore. This should be fine even on
  32-bit process, as the size and number of isolated files is generally
  small.

This code is the final (!) preparation for adding tarball support to
python isolated upload.

Bug: 825418
Change-Id: I9e68cb2b2b9cf7bd9c3d099c32168f0414b3c14a
Reviewed-on: https://chromium-review.googlesource.com/c/1358673
Commit-Queue: Marc-Antoine Ruel <maruel@chromium.org>
Reviewed-by: Quinten Yearsley <qyearsley@chromium.org>
Cr-Mirrored-From: https://chromium.googlesource.com/infra/luci/luci-py
Cr-Mirrored-Commit: 7560565e15538cfca0387172aeb4123110cc20a1