Add an admin API for users' media statistics (#8700)

Add `GET /_synapse/admin/v1/statistics/users/media` to get statisics about local media usage by users.
Related to #6094
It is the first API for statistics.
Goal is to avoid/reduce usage of sql queries like [Wiki analyzing Synapse](https://github.com/matrix-org/synapse/wiki/SQL-for-analyzing-Synapse-PostgreSQL-database-stats)

Signed-off-by: Dirk Klimpel dirk@klimpel.org

synapse/rest/admin/statistics.py

@@ -0,0 +1,122 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Dirk Klimpel
+#
+# 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.
+
+import logging
+from typing import TYPE_CHECKING, Tuple
+
+from synapse.api.errors import Codes, SynapseError
+from synapse.http.servlet import RestServlet, parse_integer, parse_string
+from synapse.http.site import SynapseRequest
+from synapse.rest.admin._base import admin_patterns, assert_requester_is_admin
+from synapse.storage.databases.main.stats import UserSortOrder
+from synapse.types import JsonDict
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
+logger = logging.getLogger(__name__)
+
+
+class UserMediaStatisticsRestServlet(RestServlet):
+    """
+    Get statistics about uploaded media by users.
+    """
+
+    PATTERNS = admin_patterns("/statistics/users/media$")
+
+    def __init__(self, hs: "HomeServer"):
+        self.hs = hs
+        self.auth = hs.get_auth()
+        self.store = hs.get_datastore()
+
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
+        await assert_requester_is_admin(self.auth, request)
+
+        order_by = parse_string(
+            request, "order_by", default=UserSortOrder.USER_ID.value
+        )
+        if order_by not in (
+            UserSortOrder.MEDIA_LENGTH.value,
+            UserSortOrder.MEDIA_COUNT.value,
+            UserSortOrder.USER_ID.value,
+            UserSortOrder.DISPLAYNAME.value,
+        ):
+            raise SynapseError(
+                400,
+                "Unknown value for order_by: %s" % (order_by,),
+                errcode=Codes.INVALID_PARAM,
+            )
+
+        start = parse_integer(request, "from", default=0)
+        if start < 0:
+            raise SynapseError(
+                400,
+                "Query parameter from must be a string representing a positive integer.",
+                errcode=Codes.INVALID_PARAM,
+            )
+
+        limit = parse_integer(request, "limit", default=100)
+        if limit < 0:
+            raise SynapseError(
+                400,
+                "Query parameter limit must be a string representing a positive integer.",
+                errcode=Codes.INVALID_PARAM,
+            )
+
+        from_ts = parse_integer(request, "from_ts", default=0)
+        if from_ts < 0:
+            raise SynapseError(
+                400,
+                "Query parameter from_ts must be a string representing a positive integer.",
+                errcode=Codes.INVALID_PARAM,
+            )
+
+        until_ts = parse_integer(request, "until_ts")
+        if until_ts is not None:
+            if until_ts < 0:
+                raise SynapseError(
+                    400,
+                    "Query parameter until_ts must be a string representing a positive integer.",
+                    errcode=Codes.INVALID_PARAM,
+                )
+            if until_ts <= from_ts:
+                raise SynapseError(
+                    400,
+                    "Query parameter until_ts must be greater than from_ts.",
+                    errcode=Codes.INVALID_PARAM,
+                )
+
+        search_term = parse_string(request, "search_term")
+        if search_term == "":
+            raise SynapseError(
+                400,
+                "Query parameter search_term cannot be an empty string.",
+                errcode=Codes.INVALID_PARAM,
+            )
+
+        direction = parse_string(request, "dir", default="f")
+        if direction not in ("f", "b"):
+            raise SynapseError(
+                400, "Unknown direction: %s" % (direction,), errcode=Codes.INVALID_PARAM
+            )
+
+        users_media, total = await self.store.get_users_media_usage_paginate(
+            start, limit, from_ts, until_ts, order_by, direction, search_term
+        )
+        ret = {"users": users_media, "total": total}
+        if (start + limit) < total:
+            ret["next_token"] = start + len(users_media)
+
+        return 200, ret