Improved JSON parser caching.

FossilOrigin-Name: 58078c0d2647a194279fa80e032670441b296ffc3acee692901faa5beca460b7

ext/misc/json1.c

@@ -172,6 +172,7 @@ struct JsonParse {
   u8 nErr;           /* Number of errors seen */
   u16 iDepth;        /* Nesting depth */
   int nJson;         /* Length of the zJson string in bytes */
+  u32 iHold;         /* Replace cache line with the lowest iHold value */
 };
 
 /*
@@ -976,7 +977,8 @@ static int jsonParseFindParents(JsonParse *pParse){
 /*
 ** Magic number used for the JSON parse cache in sqlite3_get_auxdata()
 */
-#define JSON_CACHE_ID  (-429938)
+#define JSON_CACHE_ID  (-429938)  /* First cache entry */
+#define JSON_CACHE_SZ  4          /* Max number of cache entries */
 
 /*
 ** Obtain a complete parse of the JSON found in the first argument
@@ -988,16 +990,42 @@ static int jsonParseFindParents(JsonParse *pParse){
 */
 static JsonParse *jsonParseCached(
   sqlite3_context *pCtx,
-  sqlite3_value **argv
+  sqlite3_value **argv,
+  sqlite3_context *pErrCtx
 ){
   const char *zJson = (const char*)sqlite3_value_text(argv[0]);
   int nJson = sqlite3_value_bytes(argv[0]);
   JsonParse *p;
+  JsonParse *pMatch = 0;
+  int iKey;
+  int iMinKey = 0;
+  u32 iMinHold = 0xffffffff;
+  u32 iMaxHold = 0;
   if( zJson==0 ) return 0;
-  p = (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID);
+  for(iKey=0; iKey<JSON_CACHE_SZ; iKey++){
-  if( p && p->nJson==nJson && memcmp(p->zJson,zJson,nJson)==0 ){
+    p = (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID+iKey);
+    if( p==0 ){
+      iMinKey = iKey;
+      break;
+    }
+    if( pMatch==0
+     && p->nJson==nJson
+     && memcmp(p->zJson,zJson,nJson)==0
+    ){
       p->nErr = 0;
-    return p; /* The cached entry matches, so return it */
+      pMatch = p;
+    }else if( p->iHold<iMinHold ){
+      iMinHold = p->iHold;
+      iMinKey = iKey;
+    }
+    if( p->iHold>iMaxHold ){
+      iMaxHold = p->iHold;
+    }
+  }
+  if( pMatch ){
+    pMatch->nErr = 0;
+    pMatch->iHold = iMaxHold+1;
+    return pMatch;
   }
   p = sqlite3_malloc( sizeof(*p) + nJson + 1 );
   if( p==0 ){
@@ -1007,13 +1035,15 @@ static JsonParse *jsonParseCached(
   memset(p, 0, sizeof(*p));
   p->zJson = (char*)&p[1];
   memcpy((char*)p->zJson, zJson, nJson+1);
-  if( jsonParse(p, pCtx, p->zJson) ){
+  if( jsonParse(p, pErrCtx, p->zJson) ){
     sqlite3_free(p);
     return 0;
   }
   p->nJson = nJson;
-  sqlite3_set_auxdata(pCtx, JSON_CACHE_ID, p, (void(*)(void*))jsonParseFree);
+  p->iHold = iMaxHold+1;
-  return (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID);
+  sqlite3_set_auxdata(pCtx, JSON_CACHE_ID+iMinKey, p,
+                      (void(*)(void*))jsonParseFree);
+  return (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID+iMinKey);
 }
 
 /*
@@ -1386,7 +1416,7 @@ static void jsonArrayLengthFunc(
   u32 i;
   JsonNode *pNode;
 
-  p = jsonParseCached(ctx, argv);
+  p = jsonParseCached(ctx, argv, ctx);
   if( p==0 ) return;
   assert( p->nNode );
   if( argc==2 ){
@@ -1427,7 +1457,7 @@ static void jsonExtractFunc(
   int i;
 
   if( argc<2 ) return;
-  p = jsonParseCached(ctx, argv);
+  p = jsonParseCached(ctx, argv, ctx);
   if( p==0 ) return;
   jsonInit(&jx, ctx);
   jsonAppendChar(&jx, '[');
@@ -1734,22 +1764,21 @@ static void jsonTypeFunc(
   int argc,
   sqlite3_value **argv
 ){
-  JsonParse x;          /* The parse */
+  JsonParse *p;          /* The parse */
   const char *zPath;
   JsonNode *pNode;
 
-  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  p = jsonParseCached(ctx, argv, ctx);
-  assert( x.nNode );
+  if( p==0 ) return;
   if( argc==2 ){
     zPath = (const char*)sqlite3_value_text(argv[1]);
-    pNode = jsonLookup(&x, zPath, 0, ctx);
+    pNode = jsonLookup(p, zPath, 0, ctx);
   }else{
-    pNode = x.aNode;
+    pNode = p->aNode;
   }
   if( pNode ){
     sqlite3_result_text(ctx, jsonType[pNode->eType], -1, SQLITE_STATIC);
   }
-  jsonParseReset(&x);
 }
 
 /*
@@ -1763,15 +1792,10 @@ static void jsonValidFunc(
   int argc,
   sqlite3_value **argv
 ){
-  JsonParse x;          /* The parse */
+  JsonParse *p;          /* The parse */
-  int rc = 0;
-
   UNUSED_PARAM(argc);
-  if( jsonParse(&x, 0, (const char*)sqlite3_value_text(argv[0]))==0 ){
+  p = jsonParseCached(ctx, argv, 0);
-    rc = 1;
+  sqlite3_result_int(ctx, p!=0);
-  }
-  jsonParseReset(&x);
-  sqlite3_result_int(ctx, rc);
 }
 
 

manifest

@@ -1,5 +1,5 @@
-C Additional\stest\scases\sfor\sgeopoly.
+C Improved\sJSON\sparser\scaching.
-D 2018-08-29T21:01:22.572
+D 2018-08-30T01:52:10.764
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in d06f463c5b623a61ac27f5cb8214fca9e53a6704d34d6b8f2124e2b1b293c88f
@@ -284,7 +284,7 @@ F ext/misc/eval.c 6ea9b22a5fa0dd973b67ca4e53555be177bc0b7b263aadf1024429457c82c0
 F ext/misc/fileio.c 48c7751c78fc4cdd29d8c862fd2f3f98bbfefa2a3cf1ca1496df4bf02eb8cded
 F ext/misc/fuzzer.c 7c64b8197bb77b7d64eff7cac7848870235d4c25
 F ext/misc/ieee754.c f190d0cc5182529acb15babd177781be1ac1718c
-F ext/misc/json1.c 696c596de45d991e6c4617b5a3cb4cc60d231aa4be10edea7d27a4008df2f545
+F ext/misc/json1.c 34a31eac76aeec269657f6f84a72533600d511005efa5dd97034909a2a0fbc9a
 F ext/misc/memvfs.c ab36f49e02ebcdf85a1e08dc4d8599ea8f343e073ac9e0bca18a98b7e1ec9567
 F ext/misc/mmapwarm.c 70b618f2d0bde43fae288ad0b7498a629f2b6f61b50a27e06fae3cd23c83af29
 F ext/misc/nextchar.c 35c8b8baacb96d92abbb34a83a997b797075b342
@@ -1758,7 +1758,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 7c3cee0a2a5ccacff27400c38bd708f7b9b968eb013a8fa685d876dfe85e12a6
+P 19b5eb45e090c4b7169a52d881495ee2eafc59f80e3db2288fc1814ba76134ac
-R 771e2fad0c71e34b021e9df816201c53
+R 6879c3448f3a21f21360b0e010f06ec5
 U drh
-Z fceaa831790380442f9478793a598598
+Z c5fe49b6610cf864d1fad4e0e99d3945

manifest.uuid

@@ -1 +1 @@
-19b5eb45e090c4b7169a52d881495ee2eafc59f80e3db2288fc1814ba76134ac
+58078c0d2647a194279fa80e032670441b296ffc3acee692901faa5beca460b7