fix: events: sqlite db improvements (#12090)

* fix: events: sqlite db improvements

* fix unclosed multi-row query
* tune options to limit wal growth

Ref: #12089

* fix: events: use correct context for CollectEvents transaction

* fix: events: close prepared read statement

* fix: events: close initial query; handle lint failures

Author: rvagg

chain/events/filter/index.go

@@ -26,10 +26,11 @@ var pragmas = []string{
 	"PRAGMA temp_store = memory",
 	"PRAGMA mmap_size = 30000000000",
 	"PRAGMA page_size = 32768",
-	"PRAGMA auto_vacuum = NONE", // not useful until we implement GC
+	"PRAGMA auto_vacuum = NONE",
 	"PRAGMA automatic_index = OFF",
 	"PRAGMA journal_mode = WAL",
-	"PRAGMA read_uncommitted = ON",
+	"PRAGMA wal_autocheckpoint = 256", // checkpoint @ 256 pages
+	"PRAGMA journal_size_limit = 0",   // always reset journal and wal files
 }
 
 // Any changes to this schema should be matched for the `lotus-shed indexes backfill-events` command
@@ -438,6 +439,9 @@ func NewEventIndex(ctx context.Context, path string, chainStore *store.ChainStor
 	eventIndex := EventIndex{db: db}
 
 	q, err := db.QueryContext(ctx, "SELECT name FROM sqlite_master WHERE type='table' AND name='_meta';")
+	if q != nil {
+		defer func() { _ = q.Close() }()
+	}
 	if errors.Is(err, sql.ErrNoRows) || !q.Next() {
 		// empty database, create the schema
 		for _, ddl := range ddls {
@@ -521,7 +525,7 @@ func (ei *EventIndex) Close() error {
 }
 
 func (ei *EventIndex) CollectEvents(ctx context.Context, te *TipSetEvents, revert bool, resolver func(ctx context.Context, emitter abi.ActorID, ts *types.TipSet) (address.Address, bool)) error {
-	tx, err := ei.db.Begin()
+	tx, err := ei.db.BeginTx(ctx, nil)
 	if err != nil {
 		return xerrors.Errorf("begin transaction: %w", err)
 	}
@@ -743,6 +747,7 @@ func (ei *EventIndex) prefillFilter(ctx context.Context, f *eventFilter, exclude
 	if err != nil {
 		return xerrors.Errorf("prepare prefill query: %w", err)
 	}
+	defer func() { _ = stmt.Close() }()
 
 	q, err := stmt.QueryContext(ctx, values...)
 	if err != nil {
@@ -751,6 +756,7 @@ func (ei *EventIndex) prefillFilter(ctx context.Context, f *eventFilter, exclude
 		}
 		return xerrors.Errorf("exec prefill query: %w", err)
 	}
+	defer func() { _ = q.Close() }()
 
 	var ces []*CollectedEvent
 	var currentID int64 = -1
@@ -839,7 +845,6 @@ func (ei *EventIndex) prefillFilter(ctx context.Context, f *eventFilter, exclude
 			Codec: row.codec,
 			Value: row.value,
 		})
-
 	}
 
 	if ce != nil {