Consistent lock timeouts.

vfs/memdb/memdb.go

@@ -187,17 +187,11 @@ func (m *memFile) Lock(lock vfs.LockLevel) error {
 
 	m.lockMtx.Lock()
 	defer m.lockMtx.Unlock()
-	deadline := time.Now().Add(time.Millisecond)
 
 	switch lock {
 	case vfs.LOCK_SHARED:
-		for m.pending != nil {
-			if time.Now().After(deadline) {
-				return sqlite3.BUSY
-			}
-			m.lockMtx.Unlock()
-			runtime.Gosched()
-			m.lockMtx.Lock()
+		if m.pending != nil {
+			return sqlite3.BUSY
 		}
 		m.shared++
 
@@ -216,8 +210,8 @@ func (m *memFile) Lock(lock vfs.LockLevel) error {
 			m.pending = m
 		}
 
-		for m.shared > 1 {
-			if time.Now().After(deadline) {
+		for start := time.Now(); m.shared > 1; {
+			if time.Since(start) > time.Millisecond {
 				return sqlite3.BUSY
 			}
 			m.lockMtx.Unlock()

vfs/readervfs/api.go

@@ -28,7 +28,7 @@ var (
 )
 
 // Create creates an immutable database from reader.
-// The caller should insure that data from reader does not mutate,
+// The caller should ensure that data from reader does not mutate,
 // otherwise SQLite might return incorrect query results and/or [sqlite3.CORRUPT] errors.
 func Create(name string, reader SizeReaderAt) {
 	readerMtx.Lock()

vfs/readervfs/reader.go

@@ -37,7 +37,7 @@ func (readerVFS) FullPathname(name string) (string, error) {
 
 type readerFile struct{ SizeReaderAt }
 
-func (r readerFile) Close() error {
+func (readerFile) Close() error {
 	return nil
 }