From: drh <>
Date: Wed, 26 Jul 2023 23:22:32 +0000 (+0000)
Subject: Reduce the number of memory allocations when parsing JSON.
X-Git-Tag: version-3.43.0~109
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e94e132994e5144c39bbc68aa4a6180a3e60fd7a;p=thirdparty%2Fsqlite.git

Reduce the number of memory allocations when parsing JSON.

FossilOrigin-Name: 9edd67162113df57dae21d4683f9495611e2cf4717c6d12f5b7b8e44156d5fe3
---

diff --git a/manifest b/manifest
index a2ffc6aed4..0f8c113090 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Minor\schanges\sto\smake\scoverage\stesting\seasier.
-D 2023-07-26T21:53:09.569
+C Reduce\sthe\snumber\sof\smemory\sallocations\swhen\sparsing\sJSON.
+D 2023-07-26T23:22:32.813
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -598,7 +598,7 @@ 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 8c21f66368929975ed41e6f5aff141b5ff2706bc0f817b0a99dfea9cb6b1b7cd
+F src/json.c bea467f5bb75311759f2a5f8a7bbf517384f6489bcbe85a41b7c39e8faeea698
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 176d6b2cb18a6ad73b133db17f6fc351c4d9a2d510deebdb76c22bde9cfd1465
 F src/main.c 512b1d45bc556edf4471a845afb7ba79e64bd5b832ab222dc195c469534cd002
@@ -2044,8 +2044,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 04f497074b9210326030f36107a43d6490a2a59c8a574e2c5429cd9bde681bf7
-R b26ff6d575d69d55cdae9f68086f2a13
+P ec8b43382e5402e15d9f2dda3cf21ac8be8c1589ddbe6c9433c33eef0036f764
+R 60fa67ed7b82b4d2c0db2475f139f2f9
 U drh
-Z a6ad53b5bf3028b66640cc0d3b3e396d
+Z 0d5cf9ec935b3fe18206d9fca33e2d88
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 53efddff64..46453a3ccb 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-ec8b43382e5402e15d9f2dda3cf21ac8be8c1589ddbe6c9433c33eef0036f764
\ No newline at end of file
+9edd67162113df57dae21d4683f9495611e2cf4717c6d12f5b7b8e44156d5fe3
\ No newline at end of file
diff --git a/src/json.c b/src/json.c
index 7fb860a6ef..24b3613e14 100644
--- a/src/json.c
+++ b/src/json.c
@@ -144,8 +144,7 @@ struct JsonNode {
 /* A parsed and possibly edited JSON string.  Lifecycle:
 **
 **   1.  JSON comes in and is parsed into an array aNode[].  The original
-**       JSON text is stored in zJson.  This object may or may not be the
-**       owner of the input JSON - the bOwnsJson variables determines which.
+**       JSON text is stored in zJson.
 **
 **   2.  Zero or more changes are made (via json_remove() or json_replace()
 **       or similar) to the aNode[] array.
@@ -176,7 +175,6 @@ struct JsonParse {
   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 bOwnsJson;      /* This object owns zJson and response for freeing it */
   u8 useMod;         /* Actually use the edits contain inside aNode */
   u8 hasMod;         /* aNode contains edits from the original zJson */
   u32 nJPRef;        /* Number of references to this object */
@@ -619,11 +617,6 @@ static void jsonParseReset(JsonParse *pParse){
     sqlite3RCStrUnref(pParse->zAlt);
     pParse->zAlt = 0;
   }
-  if( pParse->bOwnsJson ){
-    pParse->bOwnsJson = 0;
-    sqlite3RCStrUnref(pParse->zJson);
-    pParse->zJson = 0;
-  }
 }
 
 /*
@@ -1759,14 +1752,12 @@ json_parse_restart:
 static int jsonParse(
   JsonParse *pParse,           /* Initialize and fill this JsonParse object */
   sqlite3_context *pCtx,       /* Report errors here */
-  char *zJson,                 /* Input JSON text to be parsed */
-  int bTakeJson                /* Assume ownership of zJson if true */
+  char *zJson                  /* Input JSON text to be parsed */
 ){
   int i;
   memset(pParse, 0, sizeof(*pParse));
   if( zJson==0 ) return 1;
   pParse->zJson = zJson;
-  pParse->bOwnsJson = bTakeJson;
   pParse->nJPRef = 1;
   i = jsonParseValue(pParse, 0);
   if( pParse->oom ) i = -1;
@@ -1933,21 +1924,16 @@ static JsonParse *jsonParseCached(
   /* The input JSON was not found anywhere in the cache.  We will need
   ** to parse it ourselves and generate a new JsonParse object.
   */
-  p = sqlite3_malloc64( sizeof(*p) );
+  p = sqlite3_malloc64( sizeof(*p) + nJson + 1 );
   if( p==0 ){
     sqlite3_result_error_nomem(pCtx);
     return 0;
   }
   memset(p, 0, sizeof(*p));
-  p->zJson = sqlite3RCStrNew( nJson );
-  if( p->zJson==0 ){
-    sqlite3_free(p);
-    sqlite3_result_error_nomem(pCtx);
-    return 0;
-  }
+  p->zJson = (char*)&p[1];
   memcpy(p->zJson, zJson, nJson);
   p->zJson[nJson] = 0;
-  if( jsonParse(p, pErrCtx, p->zJson, 1) ){
+  if( jsonParse(p, pErrCtx, p->zJson) ){
     if( pErrCtx==0 ){
       p->nErr = 1;
       assert( p->nJPRef==1 ); /* Caller will own the new JsonParse object p */
@@ -2365,7 +2351,6 @@ static void jsonParseFunc(
   printf("nErr      = %u\n", p->nErr);
   printf("oom       = %u\n", p->oom);
   printf("hasNonstd = %u\n", p->hasNonstd);
-  printf("bOwnsJson = %u\n", p->bOwnsJson);
   printf("useMod    = %u\n", p->useMod);
   printf("hasMod    = %u\n", p->hasMod);
   printf("nJPRef    = %u\n", p->nJPRef);
@@ -2677,8 +2662,8 @@ static void jsonPatchFunc(
   JsonNode *pResult;   /* The result of the merge */
 
   UNUSED_PARAMETER(argc);
-  if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0]), 0) ) return;
-  if( jsonParse(&y, ctx, (char*)sqlite3_value_text(argv[1]), 0) ){
+  if( jsonParse(&x, ctx, (char*)sqlite3_value_text(argv[0])) ) return;
+  if( jsonParse(&y, ctx, (char*)sqlite3_value_text(argv[1])) ){
     jsonParseReset(&x);
     return;
   }
@@ -3645,7 +3630,7 @@ static int jsonEachFilter(
   p->zJson = sqlite3_malloc64( n+1 );
   if( p->zJson==0 ) return SQLITE_NOMEM;
   memcpy(p->zJson, z, (size_t)n+1);
-  if( jsonParse(&p->sParse, 0, p->zJson, 0) ){
+  if( jsonParse(&p->sParse, 0, p->zJson) ){
     int rc = SQLITE_NOMEM;
     if( p->sParse.oom==0 ){
       sqlite3_free(cur->pVtab->zErrMsg);