Optimization for jsonFromStrInternal().

This is an extremely hot code path when saving the manifest so every little bit helps.
pgbackrest · Jan 22, 2022 · ca13f11 · ca13f11
1 parent 61ce586
commit ca13f11
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Showing 2 changed files with 7 additions and 5 deletions.
diff --git a/doc/xml/release.xml b/doc/xml/release.xml
@@ -69,6 +69,7 @@
                         <commit subject="Simplify manifest defaults."/>
                         <commit subject="Convert varNewUInt64() to VARUINT64() where possible in manifest."/>
                         <commit subject="Pack manifest file structs to save memory."/>
+                        <commit subject="Optimization for jsonFromStrInternal()."/>
 
                         <release-item-contributor-list>
                             <release-item-contributor id="david.steele"/>

diff --git a/src/common/type/json.c b/src/common/type/json.c
@@ -682,14 +682,13 @@ jsonFromStrInternal(String *json, const String *string)
         strCatChr(json, '"');
 
         // Track portion of string with no escapes
+        const char *stringPtr = strZ(string);
         const char *noEscape = NULL;
         size_t noEscapeSize = 0;
 
         for (unsigned int stringIdx = 0; stringIdx < strSize(string); stringIdx++)
         {
-            char stringChr = strZ(string)[stringIdx];
-
-            switch (stringChr)
+            switch (*stringPtr)
             {
                 case '"':
                 case '\\':
@@ -706,7 +705,7 @@ jsonFromStrInternal(String *json, const String *string)
                         noEscapeSize = 0;
                     }
 
-                    switch (stringChr)
+                    switch (*stringPtr)
                     {
                         case '"':
                             strCatZ(json, "\\\"");
@@ -744,12 +743,14 @@ jsonFromStrInternal(String *json, const String *string)
                 {
                     // If escape string is zero size then start it
                     if (noEscapeSize == 0)
-                        noEscape = strZ(string) + stringIdx;
+                        noEscape = stringPtr;
 
                     noEscapeSize++;
                     break;
                 }
             }
+
+            stringPtr++;
         }
 
         // Copy portion of string without escapes