113 lines
4.0 KiB
Go
113 lines
4.0 KiB
Go
// Copyright 2017 Vector Creations 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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package storage
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import (
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"database/sql"
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"fmt"
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"github.com/lib/pq"
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"github.com/matrix-org/dendrite/roomserver/types"
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)
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const stateSnapshotSchema = `
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-- The state of a room before an event.
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-- Stored as a list of state_block entries stored in a separate table.
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-- The actual state is constructed by combining all the state_block entries
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-- referenced by state_block_nids together. If the same state key tuple appears
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-- multiple times then the entry from the later state_block clobbers the earlier
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-- entries.
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-- This encoding format allows us to implement a delta encoding which is useful
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-- because room state tends to accumulate small changes over time. Although if
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-- the list of deltas becomes too long it becomes more efficient to encode
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-- the full state under single state_block_nid.
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CREATE SEQUENCE IF NOT EXISTS state_snapshot_nid_seq;
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CREATE TABLE IF NOT EXISTS state_snapshots (
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-- Local numeric ID for the state.
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state_snapshot_nid bigint PRIMARY KEY DEFAULT nextval('state_snapshot_nid_seq'),
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-- Local numeric ID of the room this state is for.
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-- Unused in normal operation, but useful for background work or ad-hoc debugging.
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room_nid bigint NOT NULL,
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-- List of state_block_nids, stored sorted by state_block_nid.
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state_block_nids bigint[] NOT NULL
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);
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`
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const insertStateSQL = "" +
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"INSERT INTO state_snapshots (room_nid, state_block_nids)" +
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" VALUES ($1, $2)" +
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" RETURNING state_snapshot_nid"
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// Bulk state data NID lookup.
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// Sorting by state_snapshot_nid means we can use binary search over the result
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// to lookup the state data NIDs for a state snapshot NID.
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const bulkSelectStateBlockNIDsSQL = "" +
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"SELECT state_snapshot_nid, state_block_nids FROM state_snapshots" +
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" WHERE state_snapshot_nid = ANY($1) ORDER BY state_snapshot_nid ASC"
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type stateSnapshotStatements struct {
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insertStateStmt *sql.Stmt
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bulkSelectStateBlockNIDsStmt *sql.Stmt
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}
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func (s *stateSnapshotStatements) prepare(db *sql.DB) (err error) {
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_, err = db.Exec(stateSnapshotSchema)
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if err != nil {
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return
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}
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return statementList{
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{&s.insertStateStmt, insertStateSQL},
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{&s.bulkSelectStateBlockNIDsStmt, bulkSelectStateBlockNIDsSQL},
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}.prepare(db)
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}
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func (s *stateSnapshotStatements) insertState(roomNID types.RoomNID, stateBlockNIDs []types.StateBlockNID) (stateNID types.StateSnapshotNID, err error) {
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nids := make([]int64, len(stateBlockNIDs))
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for i := range stateBlockNIDs {
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nids[i] = int64(stateBlockNIDs[i])
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}
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err = s.insertStateStmt.QueryRow(int64(roomNID), pq.Int64Array(nids)).Scan(&stateNID)
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return
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}
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func (s *stateSnapshotStatements) bulkSelectStateBlockNIDs(stateNIDs []types.StateSnapshotNID) ([]types.StateBlockNIDList, error) {
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nids := make([]int64, len(stateNIDs))
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for i := range stateNIDs {
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nids[i] = int64(stateNIDs[i])
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}
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rows, err := s.bulkSelectStateBlockNIDsStmt.Query(pq.Int64Array(nids))
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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results := make([]types.StateBlockNIDList, len(stateNIDs))
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i := 0
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for ; rows.Next(); i++ {
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result := &results[i]
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var stateBlockNIDs pq.Int64Array
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if err := rows.Scan(&result.StateSnapshotNID, &stateBlockNIDs); err != nil {
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return nil, err
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}
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result.StateBlockNIDs = make([]types.StateBlockNID, len(stateBlockNIDs))
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for k := range stateBlockNIDs {
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result.StateBlockNIDs[k] = types.StateBlockNID(stateBlockNIDs[k])
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}
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}
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if i != len(stateNIDs) {
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return nil, fmt.Errorf("storage: state NIDs missing from the database (%d != %d)", i, len(stateNIDs))
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}
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return results, nil
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}
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