1 files changed, 281 insertions, 0 deletions
diff --git a/roomserver/storage/postgres/state_block_table.go b/roomserver/storage/postgres/state_block_table.go
new file mode 100644
index 00000000..15e69cc9
--- /dev/null
+++ b/roomserver/storage/postgres/state_block_table.go
@@ -0,0 +1,281 @@
+// 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"
+	"fmt"
+	"sort"
+
+	"github.com/lib/pq"
+	"github.com/matrix-org/dendrite/roomserver/types"
+	"github.com/matrix-org/util"
+)
+
+const stateDataSchema = `
+-- The state data map.
+-- Designed to give enough information to run the state resolution algorithm
+-- without hitting the database in the common case.
+-- TODO: Is it worth replacing the unique btree index with a covering index so
+-- that postgres could lookup the state using an index-only scan?
+-- The type and state_key are included in the index to make it easier to
+-- lookup a specific (type, state_key) pair for an event. It also makes it easy
+-- to read the state for a given state_block_nid ordered by (type, state_key)
+-- which in turn makes it easier to merge state data blocks.
+CREATE SEQUENCE IF NOT EXISTS roomserver_state_block_nid_seq;
+CREATE TABLE IF NOT EXISTS roomserver_state_block (
+    -- Local numeric ID for this state data.
+    state_block_nid bigint NOT NULL,
+    event_type_nid bigint NOT NULL,
+    event_state_key_nid bigint NOT NULL,
+    event_nid bigint NOT NULL,
+    UNIQUE (state_block_nid, event_type_nid, event_state_key_nid)
+);
+`
+
+const insertStateDataSQL = "" +
+	"INSERT INTO roomserver_state_block (state_block_nid, event_type_nid, event_state_key_nid, event_nid)" +
+	" VALUES ($1, $2, $3, $4)"
+
+const selectNextStateBlockNIDSQL = "" +
+	"SELECT nextval('roomserver_state_block_nid_seq')"
+
+// Bulk state lookup by numeric state block ID.
+// Sort by the state_block_nid, event_type_nid, event_state_key_nid
+// This means that all the entries for a given state_block_nid will appear
+// together in the list and those entries will sorted by event_type_nid
+// and event_state_key_nid. This property makes it easier to merge two
+// state data blocks together.
+const bulkSelectStateBlockEntriesSQL = "" +
+	"SELECT state_block_nid, event_type_nid, event_state_key_nid, event_nid" +
+	" FROM roomserver_state_block WHERE state_block_nid = ANY($1)" +
+	" ORDER BY state_block_nid, event_type_nid, event_state_key_nid"
+
+// Bulk state lookup by numeric state block ID.
+// Filters the rows in each block to the requested types and state keys.
+// We would like to restrict to particular type state key pairs but we are
+// restricted by the query language to pull the cross product of a list
+// of types and a list state_keys. So we have to filter the result in the
+// application to restrict it to the list of event types and state keys we
+// actually wanted.
+const bulkSelectFilteredStateBlockEntriesSQL = "" +
+	"SELECT state_block_nid, event_type_nid, event_state_key_nid, event_nid" +
+	" FROM roomserver_state_block WHERE state_block_nid = ANY($1)" +
+	" AND event_type_nid = ANY($2) AND event_state_key_nid = ANY($3)" +
+	" ORDER BY state_block_nid, event_type_nid, event_state_key_nid"
+
+type stateBlockStatements struct {
+	insertStateDataStmt                     *sql.Stmt
+	selectNextStateBlockNIDStmt             *sql.Stmt
+	bulkSelectStateBlockEntriesStmt         *sql.Stmt
+	bulkSelectFilteredStateBlockEntriesStmt *sql.Stmt
+}
+
+func (s *stateBlockStatements) prepare(db *sql.DB) (err error) {
+	_, err = db.Exec(stateDataSchema)
+	if err != nil {
+		return
+	}
+
+	return statementList{
+		{&s.insertStateDataStmt, insertStateDataSQL},
+		{&s.selectNextStateBlockNIDStmt, selectNextStateBlockNIDSQL},
+		{&s.bulkSelectStateBlockEntriesStmt, bulkSelectStateBlockEntriesSQL},
+		{&s.bulkSelectFilteredStateBlockEntriesStmt, bulkSelectFilteredStateBlockEntriesSQL},
+	}.prepare(db)
+}
+
+func (s *stateBlockStatements) bulkInsertStateData(
+	ctx context.Context,
+	stateBlockNID types.StateBlockNID,
+	entries []types.StateEntry,
+) error {
+	for _, entry := range entries {
+		_, err := s.insertStateDataStmt.ExecContext(
+			ctx,
+			int64(stateBlockNID),
+			int64(entry.EventTypeNID),
+			int64(entry.EventStateKeyNID),
+			int64(entry.EventNID),
+		)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (s *stateBlockStatements) selectNextStateBlockNID(
+	ctx context.Context,
+) (types.StateBlockNID, error) {
+	var stateBlockNID int64
+	err := s.selectNextStateBlockNIDStmt.QueryRowContext(ctx).Scan(&stateBlockNID)
+	return types.StateBlockNID(stateBlockNID), err
+}
+
+func (s *stateBlockStatements) bulkSelectStateBlockEntries(
+	ctx context.Context, stateBlockNIDs []types.StateBlockNID,
+) ([]types.StateEntryList, error) {
+	nids := make([]int64, len(stateBlockNIDs))
+	for i := range stateBlockNIDs {
+		nids[i] = int64(stateBlockNIDs[i])
+	}
+	rows, err := s.bulkSelectStateBlockEntriesStmt.QueryContext(ctx, pq.Int64Array(nids))
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close() // nolint: errcheck
+
+	results := make([]types.StateEntryList, len(stateBlockNIDs))
+	// current is a pointer to the StateEntryList to append the state entries to.
+	var current *types.StateEntryList
+	i := 0
+	for rows.Next() {
+		var (
+			stateBlockNID    int64
+			eventTypeNID     int64
+			eventStateKeyNID int64
+			eventNID         int64
+			entry            types.StateEntry
+		)
+		if err := rows.Scan(
+			&stateBlockNID, &eventTypeNID, &eventStateKeyNID, &eventNID,
+		); err != nil {
+			return nil, err
+		}
+		entry.EventTypeNID = types.EventTypeNID(eventTypeNID)
+		entry.EventStateKeyNID = types.EventStateKeyNID(eventStateKeyNID)
+		entry.EventNID = types.EventNID(eventNID)
+		if current == nil || types.StateBlockNID(stateBlockNID) != current.StateBlockNID {
+			// The state entry row is for a different state data block to the current one.
+			// So we start appending to the next entry in the list.
+			current = &results[i]
+			current.StateBlockNID = types.StateBlockNID(stateBlockNID)
+			i++
+		}
+		current.StateEntries = append(current.StateEntries, entry)
+	}
+	if i != len(stateBlockNIDs) {
+		return nil, fmt.Errorf("storage: state data NIDs missing from the database (%d != %d)", i, len(stateBlockNIDs))
+	}
+	return results, nil
+}
+
+func (s *stateBlockStatements) bulkSelectFilteredStateBlockEntries(
+	ctx context.Context,
+	stateBlockNIDs []types.StateBlockNID,
+	stateKeyTuples []types.StateKeyTuple,
+) ([]types.StateEntryList, error) {
+	tuples := stateKeyTupleSorter(stateKeyTuples)
+	// Sort the tuples so that we can run binary search against them as we filter the rows returned by the db.
+	sort.Sort(tuples)
+
+	eventTypeNIDArray, eventStateKeyNIDArray := tuples.typesAndStateKeysAsArrays()
+	rows, err := s.bulkSelectFilteredStateBlockEntriesStmt.QueryContext(
+		ctx,
+		stateBlockNIDsAsArray(stateBlockNIDs),
+		eventTypeNIDArray,
+		eventStateKeyNIDArray,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close() // nolint: errcheck
+
+	var results []types.StateEntryList
+	var current types.StateEntryList
+	for rows.Next() {
+		var (
+			stateBlockNID    int64
+			eventTypeNID     int64
+			eventStateKeyNID int64
+			eventNID         int64
+			entry            types.StateEntry
+		)
+		if err := rows.Scan(
+			&stateBlockNID, &eventTypeNID, &eventStateKeyNID, &eventNID,
+		); err != nil {
+			return nil, err
+		}
+		entry.EventTypeNID = types.EventTypeNID(eventTypeNID)
+		entry.EventStateKeyNID = types.EventStateKeyNID(eventStateKeyNID)
+		entry.EventNID = types.EventNID(eventNID)
+
+		// We can use binary search here because we sorted the tuples earlier
+		if !tuples.contains(entry.StateKeyTuple) {
+			// The select will return the cross product of types and state keys.
+			// So we need to check if type of the entry is in the list.
+			continue
+		}
+
+		if types.StateBlockNID(stateBlockNID) != current.StateBlockNID {
+			// The state entry row is for a different state data block to the current one.
+			// So we append the current entry to the results and start adding to a new one.
+			// The first time through the loop current will be empty.
+			if current.StateEntries != nil {
+				results = append(results, current)
+			}
+			current = types.StateEntryList{StateBlockNID: types.StateBlockNID(stateBlockNID)}
+		}
+		current.StateEntries = append(current.StateEntries, entry)
+	}
+	// Add the last entry to the list if it is not empty.
+	if current.StateEntries != nil {
+		results = append(results, current)
+	}
+	return results, nil
+}
+
+func stateBlockNIDsAsArray(stateBlockNIDs []types.StateBlockNID) pq.Int64Array {
+	nids := make([]int64, len(stateBlockNIDs))
+	for i := range stateBlockNIDs {
+		nids[i] = int64(stateBlockNIDs[i])
+	}
+	return pq.Int64Array(nids)
+}
+
+type stateKeyTupleSorter []types.StateKeyTuple
+
+func (s stateKeyTupleSorter) Len() int           { return len(s) }
+func (s stateKeyTupleSorter) Less(i, j int) bool { return s[i].LessThan(s[j]) }
+func (s stateKeyTupleSorter) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+
+// Check whether a tuple is in the list. Assumes that the list is sorted.
+func (s stateKeyTupleSorter) contains(value types.StateKeyTuple) bool {
+	i := sort.Search(len(s), func(i int) bool { return !s[i].LessThan(value) })
+	return i < len(s) && s[i] == value
+}
+
+// List the unique eventTypeNIDs and eventStateKeyNIDs.
+// Assumes that the list is sorted.
+func (s stateKeyTupleSorter) typesAndStateKeysAsArrays() (eventTypeNIDs pq.Int64Array, eventStateKeyNIDs pq.Int64Array) {
+	eventTypeNIDs = make(pq.Int64Array, len(s))
+	eventStateKeyNIDs = make(pq.Int64Array, len(s))
+	for i := range s {
+		eventTypeNIDs[i] = int64(s[i].EventTypeNID)
+		eventStateKeyNIDs[i] = int64(s[i].EventStateKeyNID)
+	}
+	eventTypeNIDs = eventTypeNIDs[:util.SortAndUnique(int64Sorter(eventTypeNIDs))]
+	eventStateKeyNIDs = eventStateKeyNIDs[:util.SortAndUnique(int64Sorter(eventStateKeyNIDs))]
+	return
+}
+
+type int64Sorter []int64
+
+func (s int64Sorter) Len() int           { return len(s) }
+func (s int64Sorter) Less(i, j int) bool { return s[i] < s[j] }
+func (s int64Sorter) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }