recipe_modules/cache/api.py

# Copyright 2020 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

from contextlib import contextmanager
from recipe_engine import recipe_api


class CacheApi(recipe_api.RecipeApi):
    @contextmanager
    def guard(self, cache):
        """Context wrapping Swarming named cache writes."""
        cache_path = self.m.path["cache"].join(cache)
        cache_guard_file = cache_path.join(".GUARD_FILE")
        if self.m.path.exists(cache_guard_file):
            self.m.file.rmcontents(
                name="%s cache corrupted; purging" % cache, source=cache_path
            )
        self.m.file.write_raw(name="write guard file", dest=cache_guard_file, data="")
        try:
            yield
        # This block is covered by git.cache_failure but recipe_engine says its not.
        except:  # pragma: no cover
            self.m.file.rmcontents(
                name="%s cache corrupted; purging" % cache, source=cache_path
            )
            raise
        finally:
            self.m.file.remove(name="remove guard file", source=cache_guard_file)