recipe_modules/builder_state/api.py

# Copyright 2021 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 PB.go.chromium.org.luci.buildbucket.proto import (
    builds_service as builds_service_pb2,
)
from PB.go.chromium.org.luci.buildbucket.proto import common as common_pb2
from recipe_engine import recipe_api


class BuilderStateApi(recipe_api.RecipeApi):
    """Provides common logic for passing generic "state" data between
    sequential builds of a single builder.

    `state` can be any JSON-serializable Python object.
    """

    def fetch_previous_state(self, limit=5):
        """Fetch the state of the previous build of the current builder.

        Looks at the last `limit` builds in case the immediately previous
        build did not save its state (for example, because it infra-failed
        before it was able to save its state).
        """
        state = {}
        previous_runs = self.m.buildbucket.search(
            builds_service_pb2.BuildPredicate(
                builder=self.m.buildbucket.build.builder,
                status=common_pb2.ENDED_MASK,  # Include only completed builds.
            ),
            fields=["output.properties"],
            limit=limit,
            step_name="fetch previous build state",
        )

        for run in previous_runs:
            try:
                previous_state = run.output.properties["state"]
            except ValueError:
                continue
            if previous_state:
                state = self.m.json.loads(previous_state)
                break
        return state

    def save(self, state):
        """Save the current build's state to an output property.

        So that it can be fetched by the next build.
        """
        step = self.m.step.empty("record state")
        step.presentation.properties["state"] = self.m.json.dumps(state)