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Improved JSON parser caching.

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FossilOrigin-Name: 58078c0d2647a194279fa80e032670441b296ffc3acee692901faa5beca460b7
This commit is contained in:
drh
2018-08-30 01:52:10 +00:00
parent 9c1d7c6d4c
commit e35fc302c3
3 changed files with 56 additions and 32 deletions
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74
ext/misc/json1.c
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@ -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);
if( p && p->nJson==nJson && memcmp(p->zJson,zJson,nJson)==0 ){
p->nErr = 0;
return p; /* The cached entry matches, so return it */
for(iKey=0; iKey<JSON_CACHE_SZ; iKey++){
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;
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);
return (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID);
p->iHold = iMaxHold+1;
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;
assert( x.nNode );
p = jsonParseCached(ctx, argv, ctx);
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 */
int rc = 0;
JsonParse *p; /* The parse */
UNUSED_PARAM(argc);
if( jsonParse(&x, 0, (const char*)sqlite3_value_text(argv[0]))==0 ){
rc = 1;
}
jsonParseReset(&x);
sqlite3_result_int(ctx, rc);
p = jsonParseCached(ctx, argv, 0);
sqlite3_result_int(ctx, p!=0);
}