git_patrol_db.py

# Copyright 2018 Google LLC
#
# 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
#
#     https://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.

"""Database abstraction library for the Git Patrol service.

Provides a high level API to the database of persistent state.
"""

import json
import uuid


class GitPatrolDb:
  """Database abstraction class for commonly used operations.

  Rather than have client code depend on the database library directly, this
  class provides some insulation between the two. It also wraps the commonly
  used operations behind simple method calls to provide a clean layer between
  the callers and potentially complex database acrobatics.
  """

  def __init__(self, asyncpg_pool):
    self.db_pool = asyncpg_pool

  async def fetch_latest_refs_by_alias(self, alias):
    """Retrieve the most recent git refs for a given alias.

    Args:
      alias: The git alias to use when looking up git refs.
    Returns:
      A (UUID, dict) tuple. The first item is the UUID of the most recent poll
      attempt for the alias. The second item is a dictionary of git refs and
      commit hashes. Otherwise (None, {}).
    """
    async with self.db_pool.acquire() as conn:
      row = await conn.fetchrow(
          '''SELECT git_poll_uuid, refs
          FROM git_poll_journal
          WHERE alias = $1
          ORDER BY update_time DESC LIMIT 1;
          ''', alias)
      if row:
        return row['git_poll_uuid'], {ref[0]: ref[1] for ref in row['refs']}

    return None, {}

  async def record_git_poll(
      self, utc_datetime, url, alias, previous_uuid, refs, ref_filters):
    """Update the git poll journal with results from the latest poll.

    Args:
      utc_datetime: Timestamp of the poll operation in UTC time zone.
      url: Git URL of the polled repository.
      alias: Human readable alias for the repository.
      previous_uuid: When the current poll attempt records new git refs, this
        field will contain the UUID of the poll attempt from which the delta
        was calculated. None if there were no new refs in this attempt.
      refs: Dictionary of git reference names and commit hashes retrieved from
        the repository.
      ref_filters: Git ref filters used to prune the returned references.
    Returns:
      The unique identifier assigned to this entry if successful. None
      otherwise.
    """
    poll_journal_uuid = uuid.uuid4()

    async with self.db_pool.acquire() as conn:
      insert_status = await conn.execute(
          '''INSERT INTO git_poll_journal (
            git_poll_uuid, update_time, url, alias, previous_uuid, refs,
            ref_filters)
          VALUES ($1, $2, $3, $4, $5, $6, $7);
          ''', poll_journal_uuid, utc_datetime, url, alias, previous_uuid,
          [[refname, commit] for (refname, commit) in refs.items()],
          ref_filters)
      if insert_status == 'INSERT 0 1':
        return poll_journal_uuid

  async def record_cloud_build(
      self, parent_id, git_poll_uuid, utc_datetime, alias, ref,
      cloud_build_status):
    """Update the Cloud Build journal with the current build status.

    Args:
      parent_id: Reference to the previous update for this Cloud Build attempt.
        Zero if this is the first update.
      git_poll_uuid: Reference to the git poll entry that triggered this build.
      utc_datetime: Timestamp of the poll operation in UTC time zone.
      alias: Human readable alias for the repository.
      ref: Git reference name and commit hash that triggered this build.
      cloud_build_status: Cloud Build status JSON.
    Returns:
      The unique identifier assigned to this entry if successful. None
      otherwise.
    """
    async with self.db_pool.acquire() as conn:
      journal_id = await conn.fetchval(
          '''INSERT INTO cloud_build_journal (
            parent_id, git_poll_uuid, update_time, alias, ref,
            cloud_build_status)
          VALUES ($1, $2, $3, $4, $5, $6)
          RETURNING journal_id;
          ''', parent_id, git_poll_uuid, utc_datetime, alias, ref,
          json.dumps(cloud_build_status))
      return journal_id