Add Google Cloud Storage Cache

[oittaa]

This is useful in cloud environments where shared disk cache doesn't exist, but the computation takes a lot of resources and the resulted data doesn't fit easily in Memcached or Redis.

I used an abandoned S3 pull request as a starting point. pallets-eco/cachelib#6

[coveralls]

Coverage increased (+0.4%) to 79.608% when pulling 2e492cd on oittaa:master into f1899bc on sh4nks:master.

[oittaa]

All tests passed with my test server.

GCS_BUCKET=my-test-bucket python3 -m pytest

tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_get_dict PASSED                                                                                                     [ 56%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_set_get PASSED                                                                                                      [ 56%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_get_set PASSED                                                                                                      [ 57%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_get_many PASSED                                                                                                     [ 57%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_set_many PASSED                                                                                                     [ 58%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_add PASSED                                                                                                          [ 58%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_delete PASSED                                                                                                       [ 59%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_delete_many PASSED                                                                                                  [ 59%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_inc_dec PASSED                                                                                                      [ 60%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_true_false PASSED                                                                                                   [ 60%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_timeout PASSED                                                                                                      [ 61%]
tests/test_backend_cache.py::TestGoogleCloudStorageCache::test_generic_has PASSED                                                                                                          [ 61%]

[oittaa]

For better code coverage you'll need to configure proper Cloud Storage support to your Travis instance.

[sh4nks]

Hi @oittaa, could you rebase your PR against current master and move your backend to flask_caching.contrib?

[oittaa]

Sure thing!

[oittaa]

Please, tell me if something needs to be changed, but this pull request should be rebased now.

[sh4nks]

I made some comments on your PR. Would be cool if you could address the issues I have with this PR.

[oittaa]

Removed. You still might want to add a test like I had before. For example JSON can't handle byte strings and they need to be handled as a special case.

    def test_generic_get_binary(self, c):
        assert c.set("foo", b"bar")
        assert c.get("foo") == b"bar"

[sh4nks]

Removed. You still might want to add a test like I had before. For example JSON can't handle byte strings and they need to be handled as a special case.

    def test_generic_get_binary(self, c):
        assert c.set("foo", b"bar")
        assert c.get("foo") == b"bar"

Feel free to open a new PR for this!