cleanup images from deleted comments

Previously, images were deleted only from comments deleted
before EditDuration expiration. After this change, any deletion
of the comment deletes images if they are not used elsewhere
in comments under the same page.

backend/_example/memory_store/accessor/image.go

@@ -70,6 +70,17 @@ func (m *MemImage) Load(id string) ([]byte, error) {
 	return img, nil
 }
 
+// Delete image by ID
+func (m *MemImage) Delete(id string) error {
+	m.mu.Lock()
+	// delete key from permanent and staging storage
+	delete(m.images, id)
+	delete(m.insertTime, id)
+	delete(m.imagesStaging, id)
+	m.mu.Unlock()
+	return nil
+}
+
 // Commit moves image from staging to permanent
 func (m *MemImage) Commit(id string) error {
 	m.mu.RLock()

backend/_example/memory_store/accessor/image_test.go

@@ -18,7 +18,7 @@ import (
 )
 
 // gopher png for test, from https://golang.org/src/image/png/example_test.go
-const gopher = "iVBORw0KGgoAAAANSUhEUgAAAEsAAAA8CAAAAAALAhhPAAAFfUlEQVRYw62XeWwUVRzHf2" +
+const rawGopher = "iVBORw0KGgoAAAANSUhEUgAAAEsAAAA8CAAAAAALAhhPAAAFfUlEQVRYw62XeWwUVRzHf2" +
 	"+OPbo9d7tsWyiyaZti6eWGAhISoIGKECEKCAiJJkYTiUgTMYSIosYYBBIUIxoSPIINEBDi2VhwkQrVsj1ESgu9doHWdrul7ba" +
 	"73WNm3vOPtsseM9MdwvvrzTs+8/t95ze/33sI5BqiabU6m9En8oNjduLnAEDLUsQXFF8tQ5oxK3vmnNmDSMtrncks9Hhtt" +
 	"/qeWZapHb1ha3UqYSWVl2ZmpWgaXMXGohQAvmeop3bjTRtv6SgaK/Pb9/bFzUrYslbFAmHPp+3WhAYdr+7GN/YnpN46Opv55VDs" +
@@ -38,7 +38,9 @@ const gopher = "iVBORw0KGgoAAAANSUhEUgAAAEsAAAA8CAAAAAALAhhPAAAFfUlEQVRYw62XeWwU
 	"1y98c3D27eppUjsZ6fql3jcd5rUe7+ZIlLNQny3Rd+E5Tct3WVhTM5RBCEdiEK0b6B+/ca2gYU393nFj/n1AygRQxPIUA043M42u85+z2S" +
 	"nssKrPl8Mx76NL3E6eXc3be7OD+H4WHbJkKI8AU8irbITQjZ+0hQcPEgId/Fn/pl9crKH02+5o2b9T/eMx7pKoskYgAAAABJRU5ErkJggg=="
 
-func gopherPNG() io.Reader { return base64.NewDecoder(base64.StdEncoding, strings.NewReader(gopher)) }
+func gopherPNG() io.Reader {
+	return base64.NewDecoder(base64.StdEncoding, strings.NewReader(rawGopher))
+}
 
 func TestMemImage_LoadAfterSave(t *testing.T) {
 	svc := NewMemImageStore()
@@ -57,7 +59,8 @@ func TestMemImage_LoadAfterSave(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, gopher, img)
 
-	svc.ResetCleanupTimer(id)
+	err = svc.ResetCleanupTimer(id)
+	assert.NoError(t, err)
 
 	err = svc.Commit(id)
 	assert.NoError(t, err)
@@ -70,6 +73,26 @@ func TestMemImage_LoadAfterSave(t *testing.T) {
 	assert.Equal(t, gopher, img)
 }
 
+func TestMemImage_LoadAfterDelete(t *testing.T) {
+	svc := NewMemImageStore()
+	gopher, err := io.ReadAll(gopherPNG())
+	assert.NoError(t, err)
+
+	id := "test_img"
+	err = svc.Save(id, gopher)
+	assert.NoError(t, err)
+
+	err = svc.Delete(id)
+	assert.NoError(t, err)
+
+	img, err := svc.Load(id)
+	assert.EqualError(t, err, "image test_img not found")
+	assert.Empty(t, img)
+
+	err = svc.ResetCleanupTimer(id)
+	assert.EqualError(t, err, "image test_img not found")
+}
+
 func TestMemImage_CommitFail(t *testing.T) {
 	svc := NewMemImageStore()
 	err := svc.Commit("test_id")

backend/_example/memory_store/server/image.go

@@ -35,7 +35,6 @@ func (s *RPC) imgResetClnTimerHndl(id uint64, params json.RawMessage) (rr jrpc.R
 	}
 	err := s.img.ResetCleanupTimer(fileID)
 	return jrpc.EncodeResponse(id, nil, err)
-
 }
 
 func (s *RPC) imgLoadHndl(id uint64, params json.RawMessage) (rr jrpc.Response) {
@@ -47,6 +46,16 @@ func (s *RPC) imgLoadHndl(id uint64, params json.RawMessage) (rr jrpc.Response)
 	return jrpc.EncodeResponse(id, value, err)
 }
 
+func (s *RPC) imgDeleteHndl(id uint64, params json.RawMessage) (rr jrpc.Response) {
+	var fileID string
+	if err := json.Unmarshal(params, &fileID); err != nil {
+		return jrpc.Response{Error: err.Error()}
+	}
+	err := s.img.Delete(fileID)
+	return jrpc.EncodeResponse(id, nil, err)
+
+}
+
 func (s *RPC) imgCommitHndl(id uint64, params json.RawMessage) (rr jrpc.Response) {
 	var fileID string
 	if err := json.Unmarshal(params, &fileID); err != nil {

backend/_example/memory_store/server/image_test.go

@@ -158,4 +158,9 @@ func TestRPC_imgInfoHndl(t *testing.T) {
 	info, err = ri.Info()
 	assert.NoError(t, err)
 	assert.False(t, info.FirstStagingImageTS.IsZero())
+
+	err = ri.Delete("test_img")
+	assert.NoError(t, err)
+	_, err = ri.Load("test_img")
+	assert.EqualError(t, err, "image test_img not found")
 }

backend/_example/memory_store/server/rpc.go

@@ -60,6 +60,7 @@ func (s *RPC) addHandlers() {
 		"save_with_id":        s.imgSaveWithIDHndl,
 		"reset_cleanup_timer": s.imgResetClnTimerHndl,
 		"load":                s.imgLoadHndl,
+		"delete":              s.imgDeleteHndl,
 		"commit":              s.imgCommitHndl,
 		"cleanup":             s.imgCleanupHndl,
 		"info":                s.imgInfoHndl,