Implement storage interfaces (#841)

* Implement interfaces for federationsender storage

* Implement interfaces for mediaapi storage

* Implement interfaces for publicroomsapi storage

* Implement interfaces for roomserver storage

* Implement interfaces for syncapi storage

* Implement interfaces for keydb storage

* common.PartitionStorer in publicroomsapi interface

* Update copyright notices

roomserver/storage/postgres/event_json_table.go

@@ -0,0 +1,106 @@
+// Copyright 2017-2018 New Vector Ltd
+// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
+//
+// 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.
+
+package postgres
+
+import (
+	"context"
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/roomserver/types"
+)
+
+const eventJSONSchema = `
+-- Stores the JSON for each event. This kept separate from the main events
+-- table to keep the rows in the main events table small.
+CREATE TABLE IF NOT EXISTS roomserver_event_json (
+    -- Local numeric ID for the event.
+    event_nid BIGINT NOT NULL PRIMARY KEY,
+    -- The JSON for the event.
+    -- Stored as TEXT because this should be valid UTF-8.
+    -- Not stored as a JSONB because we always just pull the entire event
+    -- so there is no point in postgres parsing it.
+    -- Not stored as JSON because we already validate the JSON in the server
+    -- so there is no point in postgres validating it.
+    -- TODO: Should we be compressing the events with Snappy or DEFLATE?
+    event_json TEXT NOT NULL
+);
+`
+
+const insertEventJSONSQL = "" +
+	"INSERT INTO roomserver_event_json (event_nid, event_json) VALUES ($1, $2)" +
+	" ON CONFLICT DO NOTHING"
+
+// Bulk event JSON lookup by numeric event ID.
+// Sort by the numeric event ID.
+// This means that we can use binary search to lookup by numeric event ID.
+const bulkSelectEventJSONSQL = "" +
+	"SELECT event_nid, event_json FROM roomserver_event_json" +
+	" WHERE event_nid = ANY($1)" +
+	" ORDER BY event_nid ASC"
+
+type eventJSONStatements struct {
+	insertEventJSONStmt     *sql.Stmt
+	bulkSelectEventJSONStmt *sql.Stmt
+}
+
+func (s *eventJSONStatements) prepare(db *sql.DB) (err error) {
+	_, err = db.Exec(eventJSONSchema)
+	if err != nil {
+		return
+	}
+	return statementList{
+		{&s.insertEventJSONStmt, insertEventJSONSQL},
+		{&s.bulkSelectEventJSONStmt, bulkSelectEventJSONSQL},
+	}.prepare(db)
+}
+
+func (s *eventJSONStatements) insertEventJSON(
+	ctx context.Context, eventNID types.EventNID, eventJSON []byte,
+) error {
+	_, err := s.insertEventJSONStmt.ExecContext(ctx, int64(eventNID), eventJSON)
+	return err
+}
+
+type eventJSONPair struct {
+	EventNID  types.EventNID
+	EventJSON []byte
+}
+
+func (s *eventJSONStatements) bulkSelectEventJSON(
+	ctx context.Context, eventNIDs []types.EventNID,
+) ([]eventJSONPair, error) {
+	rows, err := s.bulkSelectEventJSONStmt.QueryContext(ctx, eventNIDsAsArray(eventNIDs))
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close() // nolint: errcheck
+
+	// We know that we will only get as many results as event NIDs
+	// because of the unique constraint on event NIDs.
+	// So we can allocate an array of the correct size now.
+	// We might get fewer results than NIDs so we adjust the length of the slice before returning it.
+	results := make([]eventJSONPair, len(eventNIDs))
+	i := 0
+	for ; rows.Next(); i++ {
+		result := &results[i]
+		var eventNID int64
+		if err := rows.Scan(&eventNID, &result.EventJSON); err != nil {
+			return nil, err
+		}
+		result.EventNID = types.EventNID(eventNID)
+	}
+	return results[:i], nil
+}