src/buildstream/_scheduler/queues/fetchqueue.py

#
#  Copyright (C) 2016 Codethink Limited
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
#
#  Authors:
#        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
#        Jürg Billeter <juerg.billeter@codethink.co.uk>

# Local imports
from . import Queue, QueueStatus
from ..resources import ResourceType
from ..jobs import JobStatus


# A queue which fetches element sources
#
class FetchQueue(Queue):

    action_name = "Fetch"
    complete_name = "Sources Fetched"
    resources = [ResourceType.DOWNLOAD]

    def __init__(self, scheduler, skip_cached=False, fetch_original=False):
        super().__init__(scheduler)

        self._skip_cached = skip_cached
        self._should_fetch_original = fetch_original

    def get_process_func(self):
        if self._should_fetch_original:
            return FetchQueue._fetch_original
        else:
            return FetchQueue._fetch_not_original

    def status(self, element):
        # Optionally skip elements that are already in the artifact cache
        if self._skip_cached:
            if not element._can_query_cache():
                return QueueStatus.PENDING

            if element._cached_success():
                return QueueStatus.SKIP

        # This will automatically skip elements which
        # have no sources.

        if element._can_query_source_cache() and not element._should_fetch(self._should_fetch_original):
            return QueueStatus.SKIP

        return QueueStatus.READY

    def done(self, _, element, result, status):

        if status is JobStatus.FAIL:
            return

        element._fetch_done(self._should_fetch_original)

    def register_pending_element(self, element):
        # Set a "can_query_cache" callback for an element not yet ready
        # to be processed in the fetch queue.
        element._set_can_query_cache_callback(self._enqueue_element)

    @staticmethod
    def _fetch_not_original(element):
        element._fetch(fetch_original=False)

    @staticmethod
    def _fetch_original(element):
        element._fetch(fetch_original=True)