The current gsutil download code silently fails when the connection
drops mid-download, as read() returns an empty buffer instead of raising
an exception. This may lead to errors such as "zipfile.BadZipFile: File
is not a zip file" on Chromium sync with freshly-bootstrapped
depot_tools when downloading gcs deps.
This change solves this by hardening the process:
- Use retry mechanism with exponential backoff for gsutil download
- Switch to urlretrieve, which looks at Content-Length
- Compare MD5 of the downloaded file with the value from API
- Move exponential_backoff_retry from git_cache.py to gclient_utils.py
Change-Id: I25242948399e01373eb2afd9352e5c78a889051d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6485485
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>
Auto-Submit: Aleksei Khoroshilov <akhoroshilov@brave.com>
Reviewed-by: Scott Lee <ddoman@chromium.org>
998f7bfaf2