188 lines
7.4 KiB
Go
188 lines
7.4 KiB
Go
// Copyright 2017-2018 New Vector Ltd
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// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
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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 postgres
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import (
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"context"
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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/util"
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"github.com/matrix-org/dendrite/internal/sqlutil"
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"github.com/matrix-org/dendrite/roomserver/storage/tables"
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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 roomserver_state_snapshot_nid_seq;
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CREATE TABLE IF NOT EXISTS roomserver_state_snapshots (
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-- The state snapshot NID that identifies this snapshot.
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state_snapshot_nid bigint PRIMARY KEY DEFAULT nextval('roomserver_state_snapshot_nid_seq'),
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-- The hash of the state snapshot, which is used to enforce uniqueness. The hash is
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-- generated in Dendrite and passed through to the database, as a btree index over
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-- this column is cheap and fits within the maximum index size.
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state_snapshot_hash BYTEA UNIQUE,
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-- The room NID that the snapshot belongs to.
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room_nid bigint NOT NULL,
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-- The state blocks contained within this snapshot.
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state_block_nids bigint[] NOT NULL
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);
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`
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// Insert a new state snapshot. If we conflict on the hash column then
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// we must perform an update so that the RETURNING statement returns the
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// ID of the row that we conflicted with, so that we can then refer to
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// the original snapshot.
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const insertStateSQL = "" +
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"INSERT INTO roomserver_state_snapshots (state_snapshot_hash, room_nid, state_block_nids)" +
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" VALUES ($1, $2, $3)" +
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" ON CONFLICT (state_snapshot_hash) DO UPDATE SET room_nid=$2" +
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// Performing an update, above, ensures that the RETURNING statement
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// below will always return a valid state snapshot ID
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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 roomserver_state_snapshots" +
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" WHERE state_snapshot_nid = ANY($1) ORDER BY state_snapshot_nid ASC"
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// Looks up both the history visibility event and relevant membership events from
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// a given domain name from a given state snapshot. This is used to optimise the
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// helpers.CheckServerAllowedToSeeEvent function.
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// TODO: There's a sequence scan here because of the hash join strategy, which is
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// probably O(n) on state key entries, so there must be a way to avoid that somehow.
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// Event type NIDs are:
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// - 5: m.room.member as per https://github.com/matrix-org/dendrite/blob/c7f7aec4d07d59120d37d5b16a900f6d608a75c4/roomserver/storage/postgres/event_types_table.go#L40
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// - 7: m.room.history_visibility as per https://github.com/matrix-org/dendrite/blob/c7f7aec4d07d59120d37d5b16a900f6d608a75c4/roomserver/storage/postgres/event_types_table.go#L42
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const bulkSelectStateForHistoryVisibilitySQL = `
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SELECT event_nid FROM (
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SELECT event_nid, event_type_nid, event_state_key_nid FROM roomserver_events
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WHERE (event_type_nid = 5 OR event_type_nid = 7)
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AND event_nid = ANY(
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SELECT UNNEST(event_nids) FROM roomserver_state_block
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WHERE state_block_nid = ANY(
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SELECT UNNEST(state_block_nids) FROM roomserver_state_snapshots
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WHERE state_snapshot_nid = $1
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)
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)
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ORDER BY depth ASC
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) AS roomserver_events
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INNER JOIN roomserver_event_state_keys
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ON roomserver_events.event_state_key_nid = roomserver_event_state_keys.event_state_key_nid
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AND (event_type_nid = 7 OR event_state_key LIKE '%:' || $2);
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`
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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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bulkSelectStateForHistoryVisibilityStmt *sql.Stmt
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}
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func CreateStateSnapshotTable(db *sql.DB) error {
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_, err := db.Exec(stateSnapshotSchema)
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return err
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}
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func PrepareStateSnapshotTable(db *sql.DB) (tables.StateSnapshot, error) {
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s := &stateSnapshotStatements{}
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return s, sqlutil.StatementList{
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{&s.insertStateStmt, insertStateSQL},
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{&s.bulkSelectStateBlockNIDsStmt, bulkSelectStateBlockNIDsSQL},
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{&s.bulkSelectStateForHistoryVisibilityStmt, bulkSelectStateForHistoryVisibilitySQL},
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}.Prepare(db)
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}
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func (s *stateSnapshotStatements) InsertState(
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ctx context.Context, txn *sql.Tx, roomNID types.RoomNID, nids types.StateBlockNIDs,
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) (stateNID types.StateSnapshotNID, err error) {
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nids = nids[:util.SortAndUnique(nids)]
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err = sqlutil.TxStmt(txn, s.insertStateStmt).QueryRowContext(ctx, nids.Hash(), int64(roomNID), stateBlockNIDsAsArray(nids)).Scan(&stateNID)
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if err != nil {
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return 0, err
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}
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return
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}
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func (s *stateSnapshotStatements) BulkSelectStateBlockNIDs(
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ctx context.Context, txn *sql.Tx, stateNIDs []types.StateSnapshotNID,
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) ([]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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stmt := sqlutil.TxStmt(txn, s.bulkSelectStateBlockNIDsStmt)
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rows, err := stmt.QueryContext(ctx, 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() // nolint: errcheck
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results := make([]types.StateBlockNIDList, len(stateNIDs))
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i := 0
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var stateBlockNIDs pq.Int64Array
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for ; rows.Next(); i++ {
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result := &results[i]
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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 err = rows.Err(); err != nil {
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return nil, err
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}
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if i != len(stateNIDs) {
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return nil, types.MissingStateError(fmt.Sprintf("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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func (s *stateSnapshotStatements) BulkSelectStateForHistoryVisibility(
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ctx context.Context, txn *sql.Tx, stateSnapshotNID types.StateSnapshotNID, domain string,
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) ([]types.EventNID, error) {
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stmt := sqlutil.TxStmt(txn, s.bulkSelectStateForHistoryVisibilityStmt)
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rows, err := stmt.QueryContext(ctx, stateSnapshotNID, domain)
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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() // nolint: errcheck
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results := make([]types.EventNID, 0, 16)
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for rows.Next() {
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var eventNID types.EventNID
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if err = rows.Scan(&eventNID); err != nil {
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return nil, err
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}
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results = append(results, eventNID)
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}
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return results, rows.Err()
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}
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