SQLITE_FCNTL_BUSYHANDLER.

Author: ncruces

embed/exports.txt

@@ -77,6 +77,7 @@ sqlite3_get_autocommit
 sqlite3_get_auxdata
 sqlite3_hard_heap_limit64
 sqlite3_interrupt
+sqlite3_invoke_busy_handler_go
 sqlite3_last_insert_rowid
 sqlite3_limit
 sqlite3_malloc64

sqlite3/vfs.c

@@ -162,5 +162,10 @@ int sqlite3_os_init() {
   return SQLITE_OK;
 }
 
+int sqlite3_invoke_busy_handler_go(sqlite3_int64 token) {
+  void **ap = (void **)&token;
+  return ((int(*)(void *))(ap[0]))(ap[1]);
+}
+
 static_assert(offsetof(sqlite3_vfs, zName) == 16, "Unexpected offset");
 static_assert(offsetof(struct go_file, handle) == 4, "Unexpected offset");

util/vfsutil/wrap.go

@@ -46,8 +46,8 @@ func WrapPersistWAL(f vfs.File) bool {
 	return false
 }
 
-// WrapSetPersistentWAL helps wrap [vfs.FilePersistWAL].
-func WrapSetPersistentWAL(f vfs.File, keepWAL bool) {
+// WrapSetPersistWAL helps wrap [vfs.FilePersistWAL].
+func WrapSetPersistWAL(f vfs.File, keepWAL bool) {
 	if f, ok := f.(vfs.FilePersistWAL); ok {
 		f.SetPersistWAL(keepWAL)
 	}
@@ -99,6 +99,14 @@ func WrapOverwrite(f vfs.File) error {
 	return sqlite3.NOTFOUND
 }
 
+// WrapSyncSuper helps wrap [vfs.FileSync].
+func WrapSyncSuper(f vfs.File, super string) error {
+	if f, ok := f.(vfs.FileSync); ok {
+		return f.SyncSuper(super)
+	}
+	return sqlite3.NOTFOUND
+}
+
 // WrapCommitPhaseTwo helps wrap [vfs.FileCommitPhaseTwo].
 func WrapCommitPhaseTwo(f vfs.File) error {
 	if f, ok := f.(vfs.FileCommitPhaseTwo); ok {
@@ -153,6 +161,13 @@ func WrapPragma(f vfs.File, name, value string) (string, error) {
 	return "", sqlite3.NOTFOUND
 }
 
+// WrapBusyHandler helps wrap [vfs.FilePragma].
+func WrapBusyHandler(f vfs.File, handler func() bool) {
+	if f, ok := f.(vfs.FileBusyHandler); ok {
+		f.BusyHandler(handler)
+	}
+}
+
 // WrapSharedMemory helps wrap [vfs.FileSharedMemory].
 func WrapSharedMemory(f vfs.File) vfs.SharedMemory {
 	if f, ok := f.(vfs.FileSharedMemory); ok {

vfs/adiantum/hbsh.go

@@ -242,7 +242,7 @@ func (h *hbshFile) PersistentWAL() bool {
 }
 
 func (h *hbshFile) SetPersistentWAL(keepWAL bool) {
-	vfsutil.WrapSetPersistentWAL(h.File, keepWAL) // notest
+	vfsutil.WrapSetPersistWAL(h.File, keepWAL) // notest
 }
 
 func (h *hbshFile) HasMoved() (bool, error) {
@@ -253,6 +253,10 @@ func (h *hbshFile) Overwrite() error {
 	return vfsutil.WrapOverwrite(h.File) // notest
 }
 
+func (h *hbshFile) SyncSuper(super string) error {
+	return vfsutil.WrapSyncSuper(h.File, super) // notest
+}
+
 func (h *hbshFile) CommitPhaseTwo() error {
 	return vfsutil.WrapCommitPhaseTwo(h.File) // notest
 }
@@ -276,3 +280,7 @@ func (h *hbshFile) CheckpointStart() {
 func (h *hbshFile) CheckpointDone() {
 	vfsutil.WrapCheckpointDone(h.File) // notest
 }
+
+func (h *hbshFile) BusyHandler(handler func() bool) {
+	vfsutil.WrapBusyHandler(h.File, handler) // notest
+}

vfs/api.go

@@ -171,6 +171,15 @@ type FilePragma interface {
 	Pragma(name, value string) (string, error)
 }
 
+// FileBusyHandler extends File to implement the
+// SQLITE_FCNTL_BUSYHANDLER file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlbusyhandler
+type FileBusyHandler interface {
+	File
+	BusyHandler(func() bool)
+}
+
 // FileSharedMemory extends File to possibly implement
 // shared-memory for the WAL-index.
 // The same shared-memory instance must be returned

vfs/vfs.go

@@ -379,6 +379,20 @@ func vfsFileControlImpl(ctx context.Context, mod api.Module, file File, op _Fcnt
 			return ret
 		}
 
+	case _FCNTL_BUSYHANDLER:
+		if file, ok := file.(FileBusyHandler); ok {
+			arg := util.ReadUint64(mod, pArg)
+			fn := mod.ExportedFunction("sqlite3_invoke_busy_handler_go")
+			file.BusyHandler(func() bool {
+				stack := [...]uint64{arg}
+				if err := fn.CallWithStack(ctx, stack[:]); err != nil {
+					panic(err)
+				}
+				return uint32(stack[0]) != 0
+			})
+			return _OK
+		}
+
 	case _FCNTL_LOCK_TIMEOUT:
 		if file, ok := file.(FileSharedMemory); ok {
 			if shm, ok := file.SharedMemory().(blockingSharedMemory); ok {

vfs/xts/xts.go

@@ -238,7 +238,7 @@ func (x *xtsFile) PersistentWAL() bool {
 }
 
 func (x *xtsFile) SetPersistentWAL(keepWAL bool) {
-	vfsutil.WrapSetPersistentWAL(x.File, keepWAL) // notest
+	vfsutil.WrapSetPersistWAL(x.File, keepWAL) // notest
 }
 
 func (x *xtsFile) HasMoved() (bool, error) {
@@ -249,6 +249,10 @@ func (x *xtsFile) Overwrite() error {
 	return vfsutil.WrapOverwrite(x.File) // notest
 }
 
+func (x *xtsFile) SyncSuper(super string) error {
+	return vfsutil.WrapSyncSuper(x.File, super) // notest
+}
+
 func (x *xtsFile) CommitPhaseTwo() error {
 	return vfsutil.WrapCommitPhaseTwo(x.File) // notest
 }
@@ -272,3 +276,7 @@ func (x *xtsFile) CheckpointStart() {
 func (x *xtsFile) CheckpointDone() {
 	vfsutil.WrapCheckpointDone(x.File) // notest
 }
+
+func (x *xtsFile) BusyHandler(handler func() bool) {
+	vfsutil.WrapBusyHandler(x.File, handler) // notest
+}