check srcClosed

Author: FGasper

internal/verifier/compare.go

@@ -154,25 +154,28 @@ func (verifier *Verifier) compareDocsFromChannels(
 		var srcDoc, dstDoc bson.Raw
 
 		eg, egCtx := errgroup.WithContext(ctx)
-		eg.Go(func() error {
-			var alive bool
-			select {
-			case <-egCtx.Done():
-				return egCtx.Err()
-			case <-readTimer.C:
-				return errors.Errorf(
-					"failed to read from source after %s",
-					readTimeout,
-				)
-			case srcDoc, alive = <-srcChannel:
-				if !alive {
-					srcClosed = true
-					break
+
+		if !srcClosed {
+			eg.Go(func() error {
+				var alive bool
+				select {
+				case <-egCtx.Done():
+					return egCtx.Err()
+				case <-readTimer.C:
+					return errors.Errorf(
+						"failed to read from source after %s",
+						readTimeout,
+					)
+				case srcDoc, alive = <-srcChannel:
+					if !alive {
+						srcClosed = true
+						break
+					}
 				}
-			}
 
-			return nil
-		})
+				return nil
+			})
+		}
 
 		if !dstClosed {
 			eg.Go(func() error {