From 606c14de59a68ed88bff75f7250c37ad082fbd9f Mon Sep 17 00:00:00 2001
From: John Naylor <john.naylor@postgresql.org>
Date: Thu, 25 Aug 2022 13:32:28 +0700
Subject: [PATCH v9 2/2] Speed up json_lex_string via vector operations

TODO: tests
---
 src/common/jsonapi.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/common/jsonapi.c b/src/common/jsonapi.c
index fefd1d24d9..87e1d0b192 100644
--- a/src/common/jsonapi.c
+++ b/src/common/jsonapi.c
@@ -19,6 +19,7 @@
 
 #include "common/jsonapi.h"
 #include "mb/pg_wchar.h"
+#include "port/pg_lfind.h"
 
 #ifndef FRONTEND
 #include "miscadmin.h"
@@ -844,7 +845,7 @@ json_lex_string(JsonLexContext *lex)
 		}
 		else
 		{
-			char	   *p;
+			char	   *p = s;
 
 			if (hi_surrogate != -1)
 				return JSON_UNICODE_LOW_SURROGATE;
@@ -853,7 +854,13 @@ json_lex_string(JsonLexContext *lex)
 			 * Skip to the first byte that requires special handling, so we
 			 * can batch calls to appendBinaryStringInfo.
 			 */
-			for (p = s; p < end; p++)
+			while (p < end - sizeof(Vector8) &&
+				   !pg_lfind8('\\', (uint8 *) p, sizeof(Vector8)) &&
+				   !pg_lfind8('"', (uint8 *) p, sizeof(Vector8)) &&
+				   !pg_lfind8_le(0x1F, (uint8 *) p, sizeof(Vector8)))
+				p += sizeof(Vector8);
+
+			for (; p < end; p++)
 			{
 				if (*p == '\\' || *p == '"')
 					break;
-- 
2.36.1