Experimental framework upon which to build a better JSON parse structure that

supports cached of modified JSON.  All of these changes are tentative and
subject to change or removal.  Incremental check-in.

FossilOrigin-Name: e384163a4763c10b5838cbf28f9c4d8ea799bbbed6e890e8aa91b2bd1458646d

manifest

@@ -1,5 +1,5 @@
-C Further\simprovement\sto\sJSON\sparser\sperformance.
-D 2023-07-19T17:24:36.452
+C Experimental\sframework\supon\swhich\sto\sbuild\sa\sbetter\sJSON\sparse\sstructure\sthat\nsupports\scached\sof\smodified\sJSON.\s\sAll\sof\sthese\schanges\sare\stentative\sand\nsubject\sto\schange\sor\sremoval.\s\sIncremental\scheck-in.
+D 2023-07-20T17:45:09.052
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -597,7 +597,7 @@ F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
 F src/hwtime.h f9c2dfb84dce7acf95ce6d289e46f5f9d3d1afd328e53da8f8e9008e3b3caae6
 F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 3f0a94082d978bbdd33c38fefea15346c6c6bffb70bc645a71dc0f1f87dd3276
-F src/json.c e48136fce64e5004b1b8be76624cc9a4ac9ff6ae630a97df187c0ea4b9692d1b
+F src/json.c 888fcc121f7466bdf1518a8ae6adbfa7c4562438d046f1f21c942d625a208143
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 176d6b2cb18a6ad73b133db17f6fc351c4d9a2d510deebdb76c22bde9cfd1465
 F src/main.c 512b1d45bc556edf4471a845afb7ba79e64bd5b832ab222dc195c469534cd002
@@ -2043,8 +2043,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P adb4d6b007cbe9d7c9670f5fc196443ebe0f3a89df1f3290ba6247fcf83fe5bd
-R ab82eb710f468841d4023aaae186be2d
+P 144c8ccf6e5bb2527dd98742f0d67e0a16c627e7c67f754ce8ed4c4fb5b8d8b6
+R 086ba0782e2494053078635aa92191a8
 U drh
-Z d9c18383c20eeea0feca70f3dd0775a9
+Z a6562dc595d378e643249c9e30c8bba6
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-144c8ccf6e5bb2527dd98742f0d67e0a16c627e7c67f754ce8ed4c4fb5b8d8b6
+e384163a4763c10b5838cbf28f9c4d8ea799bbbed6e890e8aa91b2bd1458646d

src/json.c

@@ -59,6 +59,7 @@ static const char jsonIsSpace[] = {
 typedef struct JsonString JsonString;
 typedef struct JsonNode JsonNode;
 typedef struct JsonParse JsonParse;
+typedef struct JsonTask JsonTask;
 
 /* An instance of this object represents a JSON string
 ** under construction.  Really, this is a generic string accumulator
@@ -74,6 +75,15 @@ struct JsonString {
   char zSpace[100];        /* Initial static space */
 };
 
+/* A deferred cleanup task.  A list of JsonTask objects might be
+** run when the JsonParse object is destroyed.
+*/
+struct JsonTask {
+  JsonTask *pJTNext;       /* Next in a list */
+  void (*xOp)(void*);      /* Routine to run */
+  void *pArg;              /* Argument to xOp() */
+};
+
 /* JSON type values
 */
 #define JSON_NULL     0
@@ -123,6 +133,7 @@ struct JsonNode {
   } u;
 };
 
+
 /* A completely parsed JSON string
 */
 struct JsonParse {
@@ -131,10 +142,13 @@ struct JsonParse {
   JsonNode *aNode;   /* Array of nodes containing the parse */
   const char *zJson; /* Original JSON string */
   u32 *aUp;          /* Index of parent of each node */
+  JsonTask *pClean;  /* Cleanup operations prior to freeing this object */
   u16 iDepth;        /* Nesting depth */
   u8 nErr;           /* Number of errors seen */
   u8 oom;            /* Set to true if out of memory */
   u8 hasNonstd;      /* True if input uses non-standard features like JSON5 */
+  u8 nJPRef;         /* Number of references to this object */
+  u8 bIgnoreEdits;   /* Ignore edit marks during search */
   int nJson;         /* Length of the zJson string in bytes */
   u32 iErr;          /* Error location in zJson[] */
   u32 iHold;         /* Replace cache line with the lowest iHold value */
@@ -531,6 +545,8 @@ static u32 jsonNodeSize(JsonNode *pNode){
 ** delete the JsonParse object itself.
 */
 static void jsonParseReset(JsonParse *pParse){
+  assert( pParse->pClean==0 );
+  assert( pParse->nJPRef<=1 );
   sqlite3_free(pParse->aNode);
   pParse->aNode = 0;
   pParse->nNode = 0;
@@ -543,6 +559,16 @@ static void jsonParseReset(JsonParse *pParse){
 ** Free a JsonParse object that was obtained from sqlite3_malloc().
 */
 static void jsonParseFree(JsonParse *pParse){
+  if( pParse->nJPRef>1 ){
+    pParse->nJPRef--;
+    return;
+  }
+  while( pParse->pClean ){
+    JsonTask *pTask = pParse->pClean;
+    pParse->pClean = pTask->pJTNext;
+    pTask->xOp(pTask->pArg);
+    sqlite3_free(pTask);
+  }
   jsonParseReset(pParse);
   sqlite3_free(pParse);
 }