9a239a0a2e
This commit makes a set of small adjustments to examples. - Rework some of the comments to be more clear. - Add links to the original source tree file. - Rename some of the examples to make it clear the concept the example is intented to show. - Move some common example functionality to the example utility file. Change-Id: I858e0dbf72fe8cb40a05bfdbb0857720ffb71c7f
112 lines
3.2 KiB
Python
112 lines
3.2 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import contextlib
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import logging
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import os
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import shutil
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import sys
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import tempfile
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from six.moves import urllib_parse
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from taskflow import exceptions
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from taskflow.persistence import backends
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LOG = logging.getLogger(__name__)
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try:
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import sqlalchemy as _sa # noqa
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SQLALCHEMY_AVAILABLE = True
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except ImportError:
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SQLALCHEMY_AVAILABLE = False
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def print_wrapped(text):
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print("-" * (len(text)))
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print(text)
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print("-" * (len(text)))
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def rm_path(persist_path):
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if not os.path.exists(persist_path):
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return
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if os.path.isdir(persist_path):
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rm_func = shutil.rmtree
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elif os.path.isfile(persist_path):
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rm_func = os.unlink
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else:
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raise ValueError("Unknown how to `rm` path: %s" % (persist_path))
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try:
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rm_func(persist_path)
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except (IOError, OSError):
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pass
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def _make_conf(backend_uri):
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parsed_url = urllib_parse.urlparse(backend_uri)
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backend_type = parsed_url.scheme.lower()
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if not backend_type:
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raise ValueError("Unknown backend type for uri: %s" % (backend_type))
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if backend_type in ('file', 'dir'):
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conf = {
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'path': parsed_url.path,
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'connection': backend_uri,
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}
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elif backend_type in ('zookeeper',):
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conf = {
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'path': parsed_url.path,
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'hosts': parsed_url.netloc,
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'connection': backend_uri,
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}
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else:
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conf = {
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'connection': backend_uri,
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}
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return conf
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@contextlib.contextmanager
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def get_backend(backend_uri=None):
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tmp_dir = None
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if not backend_uri:
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if len(sys.argv) > 1:
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backend_uri = str(sys.argv[1])
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if not backend_uri:
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tmp_dir = tempfile.mkdtemp()
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backend_uri = "file:///%s" % tmp_dir
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try:
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backend = backends.fetch(_make_conf(backend_uri))
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except exceptions.NotFound as e:
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# Fallback to one that will work if the provided backend is not found.
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if not tmp_dir:
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tmp_dir = tempfile.mkdtemp()
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backend_uri = "file:///%s" % tmp_dir
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LOG.exception("Falling back to file backend using temporary"
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" directory located at: %s", tmp_dir)
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backend = backends.fetch(_make_conf(backend_uri))
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else:
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raise e
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try:
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# Ensure schema upgraded before we continue working.
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with contextlib.closing(backend.get_connection()) as conn:
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conn.upgrade()
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yield backend
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finally:
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# Make sure to cleanup the temporary path if one was created for us.
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if tmp_dir:
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rm_path(tmp_dir)
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