101 lines
4.0 KiB
Python
101 lines
4.0 KiB
Python
# Copyright 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from typing import Dict
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from twisted.web.resource import NoResource, Resource
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logger = logging.getLogger(__name__)
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def create_resource_tree(
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desired_tree: Dict[str, Resource], root_resource: Resource
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) -> Resource:
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"""Create the resource tree for this homeserver.
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This in unduly complicated because Twisted does not support putting
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child resources more than 1 level deep at a time.
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Args:
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desired_tree: Dict from desired paths to desired resources.
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root_resource: The root resource to add the tree to.
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Returns:
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The ``root_resource`` with a tree of child resources added to it.
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"""
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# ideally we'd just use getChild and putChild but getChild doesn't work
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# unless you give it a Request object IN ADDITION to the name :/ So
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# instead, we'll store a copy of this mapping so we can actually add
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# extra resources to existing nodes. See self._resource_id for the key.
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resource_mappings: Dict[str, Resource] = {}
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for full_path_str, res in desired_tree.items():
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# twisted requires all resources to be bytes
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full_path = full_path_str.encode("utf-8")
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logger.info("Attaching %s to path %s", res, full_path)
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last_resource = root_resource
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for path_seg in full_path.split(b"/")[1:-1]:
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if path_seg not in last_resource.listNames():
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# resource doesn't exist, so make a "dummy resource"
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child_resource: Resource = NoResource()
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last_resource.putChild(path_seg, child_resource)
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res_id = _resource_id(last_resource, path_seg)
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resource_mappings[res_id] = child_resource
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last_resource = child_resource
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else:
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# we have an existing Resource, use that instead.
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res_id = _resource_id(last_resource, path_seg)
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last_resource = resource_mappings[res_id]
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# ===========================
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# now attach the actual desired resource
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last_path_seg = full_path.split(b"/")[-1]
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# if there is already a resource here, thieve its children and
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# replace it
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res_id = _resource_id(last_resource, last_path_seg)
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if res_id in resource_mappings:
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# there is a dummy resource at this path already, which needs
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# to be replaced with the desired resource.
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existing_dummy_resource = resource_mappings[res_id]
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for child_name in existing_dummy_resource.listNames():
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child_res_id = _resource_id(existing_dummy_resource, child_name)
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child_resource = resource_mappings[child_res_id]
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# steal the children
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res.putChild(child_name, child_resource)
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# finally, insert the desired resource in the right place
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last_resource.putChild(last_path_seg, res)
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res_id = _resource_id(last_resource, last_path_seg)
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resource_mappings[res_id] = res
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return root_resource
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def _resource_id(resource: Resource, path_seg: bytes) -> str:
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"""Construct an arbitrary resource ID so you can retrieve the mapping
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later.
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If you want to represent resource A putChild resource B with path C,
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the mapping should looks like _resource_id(A,C) = B.
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Args:
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resource (Resource): The *parent* Resourceb
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path_seg (str): The name of the child Resource to be attached.
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Returns:
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str: A unique string which can be a key to the child Resource.
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"""
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return "%s-%r" % (resource, path_seg)
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