Improve bulk export of posts (#11702)

This change modifies some of the logic for processing posts during
bulk export in order to improve performance.

app/export.go

@@ -52,34 +52,42 @@ var exportablePreferences = map[ComparablePreference]string{{
 }
 
 func (a *App) BulkExport(writer io.Writer, file string, pathToEmojiDir string, dirNameToExportEmoji string) *model.AppError {
+	mlog.Info("Bulk export: exporting version")
 	if err := a.ExportVersion(writer); err != nil {
 		return err
 	}
 
+	mlog.Info("Bulk export: exporting teams")
 	if err := a.ExportAllTeams(writer); err != nil {
 		return err
 	}
 
+	mlog.Info("Bulk export: exporting channels")
 	if err := a.ExportAllChannels(writer); err != nil {
 		return err
 	}
 
+	mlog.Info("Bulk export: exporting users")
 	if err := a.ExportAllUsers(writer); err != nil {
 		return err
 	}
 
+	mlog.Info("Bulk export: exporting posts")
 	if err := a.ExportAllPosts(writer); err != nil {
 		return err
 	}
 
+	mlog.Info("Bulk export: exporting emoji")
 	if err := a.ExportCustomEmoji(writer, file, pathToEmojiDir, dirNameToExportEmoji); err != nil {
 		return err
 	}
 
+	mlog.Info("Bulk export: exporting direct channels")
 	if err := a.ExportAllDirectChannels(writer); err != nil {
 		return err
 	}
 
+	mlog.Info("Bulk export: exporting direct posts")
 	if err := a.ExportAllDirectPosts(writer); err != nil {
 		return err
 	}
@@ -327,15 +335,15 @@ func (a *App) buildUserNotifyProps(notifyProps model.StringMap) *UserNotifyProps
 
 func (a *App) ExportAllPosts(writer io.Writer) *model.AppError {
 	afterId := strings.Repeat("0", 26)
+
 	for {
 		posts, err := a.Srv.Store.Post().GetParentsForExportAfter(1000, afterId)
-
 		if err != nil {
 			return err
 		}
 
 		if len(posts) == 0 {
-			break
+			return nil
 		}
 
 		for _, post := range posts {
@@ -348,47 +356,41 @@ func (a *App) ExportAllPosts(writer io.Writer) *model.AppError {
 
 			postLine := ImportLineForPost(post)
 
-			// Do the Replies.
-			replies, err := a.buildPostReplies(post.Id)
+			postLine.Post.Replies, err = a.buildPostReplies(post.Id)
 			if err != nil {
 				return err
 			}
 
-			reactions, err := a.BuildPostReactions(post.Id)
-			if err != nil {
-				return err
+			postLine.Post.Reactions = &[]ReactionImportData{}
+			if post.HasReactions {
+				postLine.Post.Reactions, err = a.BuildPostReactions(post.Id)
+				if err != nil {
+					return err
+				}
 			}
 
-			postLine.Post.Replies = replies
-
-			postLine.Post.Reactions = reactions
-
 			if err := a.ExportWriteLine(writer, postLine); err != nil {
 				return err
 			}
 		}
 	}
-
-	return nil
 }
 
 func (a *App) buildPostReplies(postId string) (*[]ReplyImportData, *model.AppError) {
 	var replies []ReplyImportData
 
 	replyPosts, err := a.Srv.Store.Post().GetRepliesForExport(postId)
-
 	if err != nil {
 		return nil, err
 	}
 
 	for _, reply := range replyPosts {
 		replyImportObject := ImportReplyFromPost(reply)
-		if reply.HasReactions == true {
-			reactionsOfReply, err := a.BuildPostReactions(reply.Id)
+		if reply.HasReactions {
+			replyImportObject.Reactions, err = a.BuildPostReactions(reply.Id)
 			if err != nil {
 				return nil, err
 			}
-			replyImportObject.Reactions = reactionsOfReply
 		}
 		replies = append(replies, *replyImportObject)
 	}