staticupload: don't request empty invalidation (#1870)

If no files have been touched, do not initiate an invalidation.

internal/staticupload/staticupload.go

@@ -125,6 +125,10 @@ func (c *Client) Flush(ctx context.Context) error {
 	c.mux.Lock()
 	defer c.mux.Unlock()
 
+	if len(c.dirtyKeys) == 0 {
+		return nil
+	}
+
 	// invalidate all dirty keys that have not been invalidated yet
 	invalidationID, err := c.invalidateCacheForKeys(ctx, c.dirtyKeys)
 	if err != nil {
@@ -146,6 +150,11 @@ func (c *Client) invalidate(ctx context.Context, keys []string) error {
 		c.dirtyKeys = append(c.dirtyKeys, keys...)
 		return nil
 	}
+
+	if len(keys) == 0 {
+		return nil
+	}
+
 	// eagerly invalidate the CDN cache
 	invalidationID, err := c.invalidateCacheForKeys(ctx, keys)
 	if err != nil {

internal/staticupload/staticupload_test.go

@@ -357,6 +357,7 @@ func TestFlush(t *testing.T) {
 			wantCacheInvalidationErr: true,
 		},
 		"waiting for invalidation times out": {
+			dirtyKeys: []string{"test-key-1"},
 			invalidationIDs: []string{
 				"test-invalidation-id-2",
 				"test-invalidation-id-3",
@@ -364,6 +365,9 @@ func TestFlush(t *testing.T) {
 			cacheInvalidationWaitTimeout: time.Microsecond,
 			wantCacheInvalidationErr:     true,
 		},
+		"no invalidations": {
+			dirtyKeys: []string{},
+		},
 	}
 
 	for name, tc := range testCases {