Performance optimization to the lookaside-memory disabling mechanism.

FossilOrigin-Name: 17ce1c49cb0ed6fdd8c7c33431bc2afa217f1092c99b8dd608890a8e7aec7fb1

manifest

@@ -1,5 +1,5 @@
-C Version\s3.30.0
+C Performance\soptimization\sto\sthe\slookaside-memory\sdisabling\smechanism.
-D 2019-10-04T15:03:17.190
+D 2019-10-05T14:39:36.293
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -460,7 +460,7 @@ F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
 F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
 F src/alter.c 5c3031e45e80f79d7d54c2d32dd3c44926544d4f6a478858bfe4ee3191570190
-F src/analyze.c a3f4ea45cdb4e9df78d4ea7beb87ec8a7a46f494173b641cd28512a40a97bff2
+F src/analyze.c 481d9cf34a3c70631ef5c416be70033e8d4cd85eb5ad1b37286aed8b0e29e889
 F src/attach.c 3ca19504849c2d9be10fc5899d6811f9d6e848665d1a41ffb53df0cd6e7c13ed
 F src/auth.c a3d5bfdba83d25abed1013a8c7a5f204e2e29b0c25242a56bc02bb0c07bf1e06
 F src/backup.c f70077d40c08b7787bfe934e4d1da8030cb0cc57d46b345fba2294b7d1be23ab
@@ -469,7 +469,7 @@ F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
 F src/btree.c fdc4389b271bca30138db27dc2dfb9f52c2a7baaa44845aaf31a3c54663d837f
 F src/btree.h c11446f07ec0e9dc85af8041cb0855c52f5359c8b2a43e47e02a685282504d89
 F src/btreeInt.h 6111c15868b90669f79081039d19e7ea8674013f907710baa3c814dc3f8bfd3f
-F src/build.c 4814d55abb5553ac82763f6df9e185503d913f912cc0abea00965bb02912cc2d
+F src/build.c 13de2fdabbabcf2e2aaf6443a049fb851d9d3170136c08345468e158ceea3dc6
 F src/callback.c 25dda5e1c2334a367b94a64077b1d06b2553369f616261ca6783c48bcb6bda73
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 1b0724e66f95f33b160b1af85caaf9cceb325d22abf39bd24df4f54a73982251
@@ -479,7 +479,7 @@ F src/dbstat.c c12833de69cb655751487d2c5a59607e36be1c58ba1f4bd536609909ad47b319
 F src/delete.c d08c9e01a2664afd12edcfa3a9c6578517e8ff8735f35509582693adbe0edeaf
 F src/expr.c 1e9a6da29e3e13c14783891e867e19a54e2731c6a9b58d011cc4f3b4742a59e4
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
-F src/fkey.c 6b79f4c2447691aa9ac86e2a6a774b65f3b3dd053d4220a4893051a0de20f82e
+F src/fkey.c 6271fda51794b569d736eba4097d28f13080cd0c9eb66d5fcecb4b77336fae50
 F src/func.c ed33e38cd642058182a31a3f518f2e34f4bbe53aa483335705c153c4d3e50b12
 F src/global.c a1a8d698762ddd9a1543aac26c1e0029b20fcc3fcb56bfa41ec8cea2368f2798
 F src/hash.c 8d7dda241d0ebdafb6ffdeda3149a412d7df75102cecfc1021c98d6219823b19
@@ -489,8 +489,8 @@ F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 40557ebd69f4115e7a273f9304a8ab637a47ce44f3c6923396928f023967b5e8
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 4ddc65ae13c0d93db0ceedc8b14a28c8c260513448b0eb8c5a2ac375e3b6a85d
-F src/main.c 3851950717170ade4f6d718c18c6c7400ef5994c2a654679af2cff2ffd0fb2b9
+F src/main.c 3e01f6a1c96643381b5f9d79e4ff7f2520bc5712197746fb0852283e78cccf66
-F src/malloc.c 0f9da2a66b230a5785af94b9672126845099b57b70a32c987d04ac28c69da990
+F src/malloc.c b7640bcf8992cf2e98447da0d27e372abdc4621a6760418bad6d1470f041ada9
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
 F src/mem2.c f1940d9e91948dd6a908fbb9ce3835c36b5d83c3
@@ -514,13 +514,13 @@ F src/os_win.c 035a813cbd17f355bdcad7ab894af214a9c13a1db8aeac902365350b98cd45a7
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c 422fd8cfa59fb9173eff36a95878904a0eeb0dcc62ba49350acc8b1e51c4dc7b
 F src/pager.h 217921e81eb5fe455caa5cda96061959706bcdd29ddb57166198645ef7822ac3
-F src/parse.y 50bfcb34be7320dd0cb875021a93ae6451c8f0b083f21b71934a1a3a9108015a
+F src/parse.y 19c8b65c87a5bec5efcb7eaf44e3178d860bc77baab4b03d7b53b08369ac83bf
 F src/pcache.c 385ff064bca69789d199a98e2169445dc16e4291fa807babd61d4890c3b34177
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c 62714cbd1b7299a6e6a27a587b66b4fd3a836a84e1181e7f96f5c34a50917848
 F src/pragma.c b47bc7db02ab13d04c680aee424466b4e34f4ef5aa7b2e464876ec005806f98f
 F src/pragma.h 40962d65b645bb3f08c1f4c456effd01c6e7f073f68ea25177e0c95e181cff75
-F src/prepare.c 132484635a30f873ee7eccd47f93ed1932503863b93b28423b42332d81adffaf
+F src/prepare.c c89734335c2bcd13c93afd08dd2961a92eda04fc1499f5505d7c730330bf5c20
 F src/printf.c 9be6945837c839ba57837b4bc3af349eba630920fa5532aa518816defe42a7d4
 F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
 F src/resolve.c e021be0c1c4a2125fa38aabcd8dbb764bf5b2c889a948c30d3708430ec6ccd00
@@ -530,7 +530,7 @@ F src/shell.c.in d70bcf630c4073eaa994fa74be98886c781918e794cb8b562be8df10f018e27
 F src/sqlite.h.in 5725a6b20190a1e8d662077a1c1c8ea889ad7be90dd803f914c2de226f5fe6ab
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h cef696ce3293242c67b2339763608427bf72ee66f1f3a05389ac2a7b46001c31
-F src/sqliteInt.h 246740eab76d3ac87f856f8d979567089e8749104c12932143a6ba570e38e415
+F src/sqliteInt.h b70ac8e3e7e74838bc45dca1a3b2c3ef4b4e04a49036448bf462cfd657cc663f
 F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
 F src/status.c 46e7aec11f79dad50965a5ca5fa9de009f7d6bde08be2156f1538a0a296d4d0e
 F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@ -1846,10 +1846,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 7f9a4b6015ac332a04d3e394a6b3210fc95253d8786a261178a5639cb8d9d987
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-R f116075cb1c47b7928f41444f3803579
+R 1bde973211db92f48ce6a8a5d375ada3
-T +bgcolor * #d0c0ff
-T +sym-release *
-T +sym-version-3.30.0 *
 U drh
-Z edadfb0c72633ac9bcd13396063b6815
+Z 45fc3168d771f200d11e6dc1ea8e3734

manifest.uuid

@@ -1 +1 @@
-c20a35336432025445f9f7e289d0cc3e4003fb17f45a4ce74c6269c407c6e09f
+17ce1c49cb0ed6fdd8c7c33431bc2afa217f1092c99b8dd608890a8e7aec7fb1

src/analyze.c

@@ -1854,9 +1854,9 @@ int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
   /* Load the statistics from the sqlite_stat4 table. */
 #ifdef SQLITE_ENABLE_STAT4
   if( rc==SQLITE_OK ){
-    db->lookaside.bDisable++;
+    DisableLookaside;
     rc = loadStat4(db, sInfo.zDatabase);
-    db->lookaside.bDisable--;
+    EnableLookaside;
   }
   for(i=sqliteHashFirst(&pSchema->idxHash); i; i=sqliteHashNext(i)){
     Index *pIdx = sqliteHashData(i);

src/build.c

@@ -2447,7 +2447,7 @@ int sqlite3ViewGetColumnNames(Parse *pParse, Table *pTable){
     n = pParse->nTab;
     sqlite3SrcListAssignCursors(pParse, pSel->pSrc);
     pTable->nCol = -1;
-    db->lookaside.bDisable++;
+    DisableLookaside;
 #ifndef SQLITE_OMIT_AUTHORIZATION
     xAuth = db->xAuth;
     db->xAuth = 0;
@@ -2489,7 +2489,7 @@ int sqlite3ViewGetColumnNames(Parse *pParse, Table *pTable){
     }
     sqlite3DeleteTable(db, pSelTab);
     sqlite3SelectDelete(db, pSel);
-    db->lookaside.bDisable--;
+    EnableLookaside;
 #ifndef SQLITE_OMIT_ALTERTABLE
     pParse->eParseMode = eParseMode;
 #endif

src/fkey.c

@@ -1299,7 +1299,7 @@ static Trigger *fkActionTrigger(
     }
 
     /* Disable lookaside memory allocation */
-    db->lookaside.bDisable++;
+    DisableLookaside;
 
     pTrigger = (Trigger *)sqlite3DbMallocZero(db, 
         sizeof(Trigger) +         /* struct Trigger */
@@ -1321,7 +1321,7 @@ static Trigger *fkActionTrigger(
     }
 
     /* Re-enable the lookaside buffer, if it was disabled earlier. */
-    db->lookaside.bDisable--;
+    EnableLookaside;
 
     sqlite3ExprDelete(db, pWhere);
     sqlite3ExprDelete(db, pWhen);

src/main.c

@@ -715,6 +715,7 @@ static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
   db->lookaside.pInit = 0;
   db->lookaside.pFree = 0;
   db->lookaside.sz = (u16)sz;
+  db->lookaside.szTrue = (u16)sz;
   if( pStart ){
     int i;
     LookasideSlot *p;
@@ -733,6 +734,7 @@ static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
     db->lookaside.pStart = db;
     db->lookaside.pEnd = db;
     db->lookaside.bDisable = 1;
+    db->lookaside.sz = 0;
     db->lookaside.bMalloced = 0;
     db->lookaside.nSlot = 0;
   }
@@ -3064,6 +3066,7 @@ static int openDatabase(
   db->magic = SQLITE_MAGIC_BUSY;
   db->aDb = db->aDbStatic;
   db->lookaside.bDisable = 1;
+  db->lookaside.sz = 0;
 
   assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
   memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));

src/malloc.c

@@ -298,7 +298,7 @@ int sqlite3DbMallocSize(sqlite3 *db, void *p){
     return sqlite3GlobalConfig.m.xSize(p);
   }else{
     assert( sqlite3_mutex_held(db->mutex) );
-    return db->lookaside.sz;
+    return db->lookaside.szTrue;
   }
 }
 sqlite3_uint64 sqlite3_msize(void *p){
@@ -350,7 +350,7 @@ void sqlite3DbFreeNN(sqlite3 *db, void *p){
       LookasideSlot *pBuf = (LookasideSlot*)p;
 #ifdef SQLITE_DEBUG
       /* Trash all content in the buffer being freed */
-      memset(p, 0xaa, db->lookaside.sz);
+      memset(p, 0xaa, db->lookaside.szTrue);
 #endif
       pBuf->pNext = db->lookaside.pFree;
       db->lookaside.pFree = pBuf;
@@ -510,23 +510,21 @@ void *sqlite3DbMallocRawNN(sqlite3 *db, u64 n){
   assert( db!=0 );
   assert( sqlite3_mutex_held(db->mutex) );
   assert( db->pnBytesFreed==0 );
-  if( db->lookaside.bDisable==0 ){
+  if( n>db->lookaside.sz ){
-    assert( db->mallocFailed==0 );
+    if( db->lookaside.bDisable ){
-    if( n>db->lookaside.sz ){
+      return db->mallocFailed ? 0 : dbMallocRawFinish(db, n);
-      db->lookaside.anStat[1]++;
-    }else if( (pBuf = db->lookaside.pFree)!=0 ){
-      db->lookaside.pFree = pBuf->pNext;
-      db->lookaside.anStat[0]++;
-      return (void*)pBuf;
-    }else if( (pBuf = db->lookaside.pInit)!=0 ){
-      db->lookaside.pInit = pBuf->pNext;
-      db->lookaside.anStat[0]++;
-      return (void*)pBuf;
-    }else{
-      db->lookaside.anStat[2]++;
     }
-  }else if( db->mallocFailed ){
+    db->lookaside.anStat[1]++;
-    return 0;
+  }else if( (pBuf = db->lookaside.pFree)!=0 ){
+    db->lookaside.pFree = pBuf->pNext;
+    db->lookaside.anStat[0]++;
+    return (void*)pBuf;
+  }else if( (pBuf = db->lookaside.pInit)!=0 ){
+    db->lookaside.pInit = pBuf->pNext;
+    db->lookaside.anStat[0]++;
+    return (void*)pBuf;
+  }else{
+    db->lookaside.anStat[2]++;
   }
 #else
   assert( db!=0 );
@@ -550,7 +548,7 @@ void *sqlite3DbRealloc(sqlite3 *db, void *p, u64 n){
   assert( db!=0 );
   if( p==0 ) return sqlite3DbMallocRawNN(db, n);
   assert( sqlite3_mutex_held(db->mutex) );
-  if( isLookaside(db,p) && n<=db->lookaside.sz ) return p;
+  if( isLookaside(db,p) && n<=db->lookaside.szTrue ) return p;
   return dbReallocFinish(db, p, n);
 }
 static SQLITE_NOINLINE void *dbReallocFinish(sqlite3 *db, void *p, u64 n){
@@ -561,7 +559,7 @@ static SQLITE_NOINLINE void *dbReallocFinish(sqlite3 *db, void *p, u64 n){
     if( isLookaside(db, p) ){
       pNew = sqlite3DbMallocRawNN(db, n);
       if( pNew ){
-        memcpy(pNew, p, db->lookaside.sz);
+        memcpy(pNew, p, db->lookaside.szTrue);
         sqlite3DbFree(db, p);
       }
     }else{
@@ -660,7 +658,7 @@ void sqlite3OomFault(sqlite3 *db){
     if( db->nVdbeExec>0 ){
       db->u1.isInterrupted = 1;
     }
-    db->lookaside.bDisable++;
+    DisableLookaside;
     if( db->pParse ){
       db->pParse->rc = SQLITE_NOMEM_BKPT;
     }
@@ -679,7 +677,7 @@ void sqlite3OomClear(sqlite3 *db){
     db->mallocFailed = 0;
     db->u1.isInterrupted = 0;
     assert( db->lookaside.bDisable>0 );
-    db->lookaside.bDisable--;
+    EnableLookaside;
   }
 }
 

src/parse.y

@@ -106,8 +106,9 @@ struct FrameBound     { int eType; Expr *pExpr; };
 ** shared across database connections.
 */
 static void disableLookaside(Parse *pParse){
+  sqlite3 *db = pParse->db;
   pParse->disableLookaside++;
-  pParse->db->lookaside.bDisable++;
+  DisableLookaside;
 }
 
 } // end %include

src/prepare.c

@@ -527,6 +527,7 @@ void sqlite3ParserReset(Parse *pParse){
   if( db ){
     assert( db->lookaside.bDisable >= pParse->disableLookaside );
     db->lookaside.bDisable -= pParse->disableLookaside;
+    db->lookaside.sz = db->lookaside.bDisable ? 0 : db->lookaside.szTrue;
   }
   pParse->disableLookaside = 0;
 }
@@ -560,7 +561,7 @@ static int sqlite3Prepare(
   */
   if( prepFlags & SQLITE_PREPARE_PERSISTENT ){
     sParse.disableLookaside++;
-    db->lookaside.bDisable++;
+    DisableLookaside;
   }
   sParse.disableVtab = (prepFlags & SQLITE_PREPARE_NO_VTAB)!=0;
 

src/sqliteInt.h

@@ -1271,10 +1271,17 @@ struct Schema {
 ** is shared by multiple database connections.  Therefore, while parsing
 ** schema information, the Lookaside.bEnabled flag is cleared so that
 ** lookaside allocations are not used to construct the schema objects.
+**
+** New lookaside allocations are only allowed if bDisable==0.  When
+** bDisable is greater than zero, sz is set to zero which effectively
+** disables lookaside without adding a new test for the bDisable flag
+** in a performance-critical path.  sz should be set by to szTrue whenever
+** bDisable changes back to zero.
 */
 struct Lookaside {
   u32 bDisable;           /* Only operate the lookaside when zero */
   u16 sz;                 /* Size of each buffer in bytes */
+  u16 szTrue;             /* True value of sz, even if disabled */
   u8 bMalloced;           /* True if pStart obtained from sqlite3_malloc() */
   u32 nSlot;              /* Number of lookaside slots allocated */
   u32 anStat[3];          /* 0: hits.  1: size misses.  2: full misses */
@@ -1287,6 +1294,10 @@ struct LookasideSlot {
   LookasideSlot *pNext;    /* Next buffer in the list of free buffers */
 };
 
+#define DisableLookaside  db->lookaside.bDisable++;db->lookaside.sz=0
+#define EnableLookaside   db->lookaside.bDisable--;\
+   db->lookaside.sz=db->lookaside.bDisable?0:db->lookaside.szTrue
+
 /*
 ** A hash table for built-in function definitions.  (Application-defined
 ** functions use a regular table table from hash.h.)