Emit generated runs in batches, not a write each

1 file changed, 17 insertions, 6 deletions

diff --git a/source/ui-tree.c b/source/ui-tree.c
index bc5986b..64be0b6 100644
--- a/source/ui-tree.c
+++ b/source/ui-tree.c
@@ -38,18 +38,31 @@ static void print_text_buffer(const char *name, char *buf, unsigned long size)
 	html("<table summary='blob content' class='blob'>\n");
 
 	if (ctx.cfg.enable_tree_linenumbers) {
+		struct strbuf numbers = STRBUF_INIT;
+
 		html("<tr><td class='linenumbers'><pre>");
 		idx = 0;
 		lineno = 0;
 
+		// Build the column in batches. A formatted write per line meant
+		// a syscall and a temporary buffer for every line of the file,
+		// which is most of what rendering a large blob cost, and the
+		// whole column at once would come to several times the blob.
 		if (size) {
-			htmlf(numberfmt, ++lineno);
+			strbuf_addf(&numbers, numberfmt, ++lineno);
 			while (idx < size - 1) { // skip absolute last newline
-				if (buf[idx] == '\n')
-					htmlf(numberfmt, ++lineno);
+				if (buf[idx] == '\n') {
+					strbuf_addf(&numbers, numberfmt, ++lineno);
+					if (numbers.len >= HTML_BATCH) {
+						html_raw(numbers.buf, numbers.len);
+						strbuf_reset(&numbers);
+					}
+				}
 				idx++;
 			}
+			html_raw(numbers.buf, numbers.len);
 		}
+		strbuf_release(&numbers);
 		html("</pre></td>\n");
 	}
 	else {
@@ -75,8 +88,6 @@ static void print_text_buffer(const char *name, char *buf, unsigned long size)
 	html("</code></pre></td></tr></table>\n");
 }
 
-#define ROWLEN 32
-
 static void print_binary_buffer(char *buf, unsigned long size)
 {
 	unsigned long ofs, idx;
@@ -105,6 +116,7 @@ static void print_binary_buffer(char *buf, unsigned long size)
 		html_txt(ascii);
 		html("</td></tr>\n");
 	}
+	strbuf_release(&row);
 	html("</table>\n");
 }
 
@@ -393,7 +405,6 @@ static void ls_tree(const struct object_id *oid, const char *path, struct walk_t
 	ls_tail();
 }
 
-
 static int walk_tree(const struct object_id *oid, struct strbuf *base,
 		const char *pathname, unsigned mode, void *cbdata)
 {