Reduce mutex scope, use temp files.

vfs/memdb/api.go

@@ -34,9 +34,6 @@ var (
 // The new database takes ownership of data,
 // and the caller should not use data after this call.
 func Create(name string, data []byte) {
-	memoryMtx.Lock()
-	defer memoryMtx.Unlock()
-
 	db := &memDB{
 		refs: 1,
 		name: name,
@@ -63,14 +60,16 @@ func Create(name string, data []byte) {
 		}
 	}
 
+	memoryMtx.Lock()
 	memoryDBs[name] = db
+	memoryMtx.Unlock()
 }
 
 // Delete deletes a shared memory database.
 func Delete(name string) {
 	memoryMtx.Lock()
-	defer memoryMtx.Unlock()
 	delete(memoryDBs, name)
+	memoryMtx.Unlock()
 }
 
 // TestDB creates an empty shared memory database for the test to use.

vfs/memdb/memdb.go

@@ -92,10 +92,10 @@ type memDB struct {
 
 func (m *memDB) release() {
 	memoryMtx.Lock()
-	defer memoryMtx.Unlock()
 	if m.refs--; m.refs == 0 && m == memoryDBs[m.name] {
 		delete(memoryDBs, m.name)
 	}
+	memoryMtx.Unlock()
 }
 
 type memFile struct {

vfs/mvcc/api.go

@@ -35,13 +35,12 @@ var (
 // using a snapshot as its initial contents.
 func Create(name string, snapshot Snapshot) {
 	memoryMtx.Lock()
-	defer memoryMtx.Unlock()
-
 	memoryDBs[name] = &mvccDB{
 		refs: 1,
 		name: name,
 		data: snapshot.Tree,
 	}
+	memoryMtx.Unlock()
 }
 
 // Delete deletes a shared memory database.
@@ -49,8 +48,8 @@ func Delete(name string) {
 	name = getName(name)
 
 	memoryMtx.Lock()
-	defer memoryMtx.Unlock()
 	delete(memoryDBs, name)
+	memoryMtx.Unlock()
 }
 
 // Snapshot represents a database snapshot.
@@ -83,8 +82,9 @@ func TakeSnapshot(name string) Snapshot {
 	name = getName(name)
 
 	memoryMtx.Lock()
-	defer memoryMtx.Unlock()
 	db := memoryDBs[name]
+	memoryMtx.Unlock()
+
 	if db == nil {
 		return Snapshot{}
 	}

vfs/mvcc/mvcc.go

@@ -79,10 +79,10 @@ type mvccDB struct {
 
 func (m *mvccDB) release() {
 	memoryMtx.Lock()
-	defer memoryMtx.Unlock()
 	if m.refs--; m.refs == 0 && m == memoryDBs[m.name] {
 		delete(memoryDBs, m.name)
 	}
+	memoryMtx.Unlock()
 }
 
 type mvccFile struct {
@@ -105,10 +105,10 @@ func (m *mvccFile) Close() error {
 	m.data = nil
 	m.lock = vfs.LOCK_NONE
 	m.mtx.Lock()
-	defer m.mtx.Unlock()
 	if m.owner == m {
 		m.owner = nil
 	}
+	m.mtx.Unlock()
 	return nil
 }
 
@@ -313,10 +313,10 @@ func (m *mvccFile) CommitPhaseTwo() error {
 	// Modified without lock, commit changes.
 	if m.lock > vfs.LOCK_EXCLUSIVE {
 		m.mtx.Lock()
-		defer m.mtx.Unlock()
 		m.mvccDB.data = m.data
 		m.lock = vfs.LOCK_NONE
 		m.data = nil
+		m.mtx.Unlock()
 	}
 	return nil
 }

vfs/readervfs/api.go

@@ -30,13 +30,13 @@ var (
 // otherwise SQLite might return incorrect query results and/or [sqlite3.CORRUPT] errors.
 func Create(name string, reader ioutil.SizeReaderAt) {
 	readerMtx.Lock()
-	defer readerMtx.Unlock()
 	readerDBs[name] = reader
+	readerMtx.Unlock()
 }
 
 // Delete deletes a shared memory database.
 func Delete(name string) {
 	readerMtx.Lock()
-	defer readerMtx.Unlock()
 	delete(readerDBs, name)
+	readerMtx.Unlock()
 }

vfs/readervfs/reader.go

@@ -3,16 +3,15 @@ package readervfs
 import (
 	"github.com/ncruces/go-sqlite3"
 	"github.com/ncruces/go-sqlite3/util/ioutil"
-	"github.com/ncruces/go-sqlite3/util/vfsutil"
 	"github.com/ncruces/go-sqlite3/vfs"
 )
 
 type readerVFS struct{}
 
 func (readerVFS) Open(name string, flags vfs.OpenFlag) (vfs.File, vfs.OpenFlag, error) {
-	// Temp journals, as used by the sorter, use SliceFile.
+	// Temp journals, as used by the sorter, use a temporary file.
 	if flags&vfs.OPEN_TEMP_JOURNAL != 0 {
-		return &vfsutil.SliceFile{}, flags | vfs.OPEN_MEMORY, nil
+		return vfs.Find("").Open(name, flags)
 	}
 	// Refuse to open all other file types.
 	if flags&vfs.OPEN_MAIN_DB == 0 {

vfs/registry.go

@@ -10,13 +10,17 @@ var (
 
 // Find returns a VFS given its name.
 // If there is no match, nil is returned.
-// If name is empty, the default VFS is returned.
+// If name is empty or "os", the default VFS is returned.
 //
 // https://sqlite.org/c3ref/vfs_find.html
 func Find(name string) VFS {
 	if name == "" || name == "os" {
 		return vfsOS{}
 	}
+	return find(name)
+}
+
+func find(name string) VFS {
 	vfsRegistryMtx.RLock()
 	defer vfsRegistryMtx.RUnlock()
 	return vfsRegistry[name]
@@ -31,11 +35,11 @@ func Register(name string, vfs VFS) {
 		return
 	}
 	vfsRegistryMtx.Lock()
-	defer vfsRegistryMtx.Unlock()
 	if vfsRegistry == nil {
 		vfsRegistry = map[string]VFS{}
 	}
 	vfsRegistry[name] = vfs
+	vfsRegistryMtx.Unlock()
 }
 
 // Unregister unregisters a VFS.
@@ -43,6 +47,6 @@ func Register(name string, vfs VFS) {
 // https://sqlite.org/c3ref/vfs_find.html
 func Unregister(name string) {
 	vfsRegistryMtx.Lock()
-	defer vfsRegistryMtx.Unlock()
 	delete(vfsRegistry, name)
+	vfsRegistryMtx.Unlock()
 }

vfs/vfs.go

@@ -50,8 +50,7 @@ func ExportHostFunctions(env wazero.HostModuleBuilder) wazero.HostModuleBuilder
 }
 
 func vfsFind(ctx context.Context, mod api.Module, zVfsName ptr_t) uint32 {
-	name := util.ReadString(mod, zVfsName, _MAX_NAME)
-	if vfs := Find(name); vfs != nil && vfs != (vfsOS{}) {
+	if find(util.ReadString(mod, zVfsName, _MAX_NAME)) != nil {
 		return 1
 	}
 	return 0