From c96faa76a0437a8ed5788d3cadc56a9035346609 Mon Sep 17 00:00:00 2001
From: Clay Mayers <1301632+clay-mayers@users.noreply.github.com>
Date: Mon, 11 Mar 2024 21:50:33 +0000
Subject: [PATCH] Fix: V2 Escape control chars when stringifing JSON (#492)

Only process a single character at a time - Processing 4 at at
a time has more repeatable timing but on average is slower.

Processing an unescaped string can be faster than the original
method of find/find.
---
 .../HollowRecordJsonStringifier.java          | 48 ++++---------------
 1 file changed, 10 insertions(+), 38 deletions(-)

diff --git a/hollow/src/main/java/com/netflix/hollow/tools/stringifier/HollowRecordJsonStringifier.java b/hollow/src/main/java/com/netflix/hollow/tools/stringifier/HollowRecordJsonStringifier.java
index 92700b8532..174095027c 100644
--- a/hollow/src/main/java/com/netflix/hollow/tools/stringifier/HollowRecordJsonStringifier.java
+++ b/hollow/src/main/java/com/netflix/hollow/tools/stringifier/HollowRecordJsonStringifier.java
@@ -423,8 +423,6 @@ private void appendFieldStringify(Writer writer, HollowDataAccess dataAccess, in
 
     /**
      * Returns the category (CAT_*) of ch8 - non-carry bits are garbage
-     * Takes four characters to limit CPU pipeline stalls. Use non-escaped char
-     * (e.g ' '), if you don't have all 4 characters.
      *
      * Works by making 3 copies of the character every 9 bits leaving a "carry" bit
      * to hold the category in front of each copy.  When detecting a specific char,
@@ -434,26 +432,14 @@ private void appendFieldStringify(Writer writer, HollowDataAccess dataAccess, in
      * (e.g, 0x5c ^ 0xa3 + 1 = 0x100).  Detecting < 0x20 is detecting just the upper
      * 3 bits are 0 so, 0x20 is added instead of 1 (e.g., 0x0a ^ e0 + 0x20 = 0x10a).
      */
-    private int categorize(char ch8_1, char ch8_2, char ch8_3, char ch8_4) {
-        int ch1 = 0xff & ch8_1;
-        int ch2 = 0xff & ch8_2;
-        int ch3 = 0xff & ch8_3;
-        int ch4 = 0xff & ch8_4;
-        int c1 = ch1 * DUP3TIMES_WITH_CAT_BIT;
-        int c2 = ch2 * DUP3TIMES_WITH_CAT_BIT;
-        int c3 = ch3 * DUP3TIMES_WITH_CAT_BIT;
-        int c4 = ch4 * DUP3TIMES_WITH_CAT_BIT;
-
-        c1 ^= DETECT_MASK;
-        c2 ^= DETECT_MASK;
-        c3 ^= DETECT_MASK;
-        c4 ^= DETECT_MASK;
-        c1 += CAUSE_CARRY;
-        c2 += CAUSE_CARRY;
-        c3 += CAUSE_CARRY;
-        c4 += CAUSE_CARRY;
-
-        return c1 | c2 | c3 | c4;
+    private int categorize(char ch8) {
+        int ch = 0xff & ch8;
+        int cat = ch * DUP3TIMES_WITH_CAT_BIT;
+
+        cat ^= DETECT_MASK;
+        cat += CAUSE_CARRY;
+
+        return cat;
     }
 
     /**
@@ -461,25 +447,11 @@ private int categorize(char ch8_1, char ch8_2, char ch8_3, char ch8_4) {
      */
     private int categorize(String str) {
         int len = str.length();
-        int len2 = len & ~3;
         int cat = 0;
         int i;
 
-        for(i = 0; i < len2 ; i = i + 4) {
-            cat = cat | categorize(str.charAt(i), str.charAt(i+1), str.charAt(i+2), str.charAt(i+3));
-        }
-        switch(len-len2) {
-            case 0:
-                break;
-            case 1:
-                cat = cat | categorize(str.charAt(i), ' ', ' ', ' ');
-                break;
-            case 2:
-                cat = cat | categorize(str.charAt(i), str.charAt(i+1), ' ', ' ');
-                break;
-            case 3:
-                cat = cat | categorize(str.charAt(i), str.charAt(i+1), str.charAt(i+2), ' ');
-                break;
+        for(i = 0; i < len ; i = i++) {
+            cat = cat | categorize(str.charAt(i));
         }
         return cat & CATEGORY_BITS_MASK;
     }