Faster memory allocation from lookaside by not trying to keep track of the

number of outstanding allocations, and rather computing that value only
when requested.

FossilOrigin-Name: a06263f1efd2d45eac88b8d59e8fe8e458670fa3808c795feaa7f247fc36cbe9

diff --git a/manifest b/manifest
index c1fc26d824475865bb484a79283c9a971c8da2ea..a460f66c1ff3adca8d4563d2a8e6d07357278c3d 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sthe\s--enable-update-limit\soption\sto\sthe\s./configure\sscript.
-D 2017-08-28T17:00:12.028
+C Faster\smemory\sallocation\sfrom\slookaside\sby\snot\strying\sto\skeep\strack\sof\sthe\nnumber\sof\soutstanding\sallocations,\sand\srather\scomputing\sthat\svalue\sonly\nwhen\srequested.
+D 2017-08-29T20:21:12.167
 F Makefile.in c644bbe8ebe4aae82ad6783eae6b6beea4c727b99ff97568b847ced5e2ac7afb
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 25b154da7f0b3d4924f27378c1f8d006285b80811f1ccf3ed953dbebf6282136
@@ -402,7 +402,7 @@ F src/btmutex.c 0e9ce2d56159b89b9bc8e197e023ee11e39ff8ca
 F src/btree.c 1033b88fe50aba7d364b5a19666a9a274caa8d4c25ab7f3914221997b46af44a
 F src/btree.h 32ef5d3f25dc70ef1ee9cecf84a023c21378f06a57cd701d2e866e141b150f09
 F src/btreeInt.h 55b702efce17e5d1941865464227d3802cfc9c7c832fac81d4c94dced47a71fc
-F src/build.c b47a0320c6d237718b8f493ac97d37d1071bce12aca668b15219187150c41295
+F src/build.c e71e96a67daf3d1dd23188423e66cd6af38017e2ec73fead5d2b57da2d3c7e16
 F src/callback.c 28a8ede982fde4129b828350f78f2c01fe7d12c74d1a0a05d7108ab36f308688
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c ff1be3eed7bdd75aaca61ca8dc848f7c9f850ef2fb9cb56f2734e922a098f9c0
@@ -421,8 +421,8 @@ F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c d2d1bf12d2b5382450620d7cede84c7ffe57e6a89fa9a908f1aba68df2731cd9
 F src/legacy.c 134ab3e3fae00a0f67a5187981d6935b24b337bcf0f4b3e5c9fa5763da95bf4e
 F src/loadext.c 20865b183bb8a3723d59cf1efffc3c50217eb452c1021d077b908c94da26b0b2
-F src/main.c 227a83d3f840d55e40360a1a8370c120f1466ea7d73b1fffb74b8f59ad0f4046
-F src/malloc.c e069cec00407e029d71fbc9440ebbb5833a629416324b592ade8fed93b045c83
+F src/main.c 48a641949ce76c857b8771230c4304501287285714ea796f803b4178629ed560
+F src/malloc.c a02c9e69bc76bee0f639416b947a946412890b606301454727feadcb313536d6
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
 F src/mem2.c f1940d9e91948dd6a908fbb9ce3835c36b5d83c3
@@ -462,9 +462,9 @@ F src/shell.c.in af3fb9eabdc0a95beace2f760597d213be0988c974eca116208eb220cd24469
 F src/sqlite.h.in f18eef5b101d5f33f98ca43decb1f025c1b629f091ad77fe2190128e93938a5a
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h a1fd3aa82f967da436164e0728a7d6841651fd0c6e27b9044e0eb9f6c8462e47
-F src/sqliteInt.h 9a283ecf57bb81e0040d243d56e91beae76f6d5762b3ac33c7f3ec6076a71d99
+F src/sqliteInt.h 60295f5f909e32aef1961075a8fa98df19335a4b7792b4a0b897f1d8789681c9
 F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
-F src/status.c 90450a491f3f59f6978ca9832023c31238f592064e405eeda971f3c0829564eb
+F src/status.c 9737ed017279a9e0c5da748701c3c7bf1e8ae0dae459aad20dd64fcff97a7e35
 F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
 F src/tclsqlite.c 487951d81f9704800fd9f0ffdaa2f935a83ccb6be3575c2c4ef83e4789b4c828
 F src/test1.c 8513b17ca4a7a9ba28748535d178b6e472ec7394ae0eea53907f2d3bcdbab2df
@@ -1651,7 +1651,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 1ba051e34d7512ab5e8fc969c1b5aaaf827b8e6493ba4235895257aca78b500f
-R 7e1ed169d6d4a03a64afe06fcba95957
+P 64a8ae68381b7fbb29b659901ca7ce8d50510e4753758d5761f7e41539288cef
+R bf9afa7c8e223eb9e939beb0ed77930c
 U drh
-Z 13247c5e6bbeac642354740051347480
+Z 4dae0b64b90b0b3580ad9499179d8a8f

diff --git a/manifest.uuid b/manifest.uuid
index 09eebfb4e5e501c678c3861cf65b1b900213f4b0..9d0521f6c3f20c46a769f058d149fe4d014c9b42 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-64a8ae68381b7fbb29b659901ca7ce8d50510e4753758d5761f7e41539288cef
\ No newline at end of file
+a06263f1efd2d45eac88b8d59e8fe8e458670fa3808c795feaa7f247fc36cbe9
\ No newline at end of file

diff --git a/src/build.c b/src/build.c
index 05126f6260cbf61e15ebae76b03fc825ff75318b..6cd23c2abf7a20c3b716b09fd97f74b5c83145c2 100644 (file)
--- a/src/build.c
+++ b/src/build.c
@@ -598,13 +598,16 @@ void sqlite3DeleteColumnNames(sqlite3 *db, Table *pTable){
 */
 static void SQLITE_NOINLINE deleteTable(sqlite3 *db, Table *pTable){
   Index *pIndex, *pNext;
-  TESTONLY( int nLookaside; ) /* Used to verify lookaside not used for schema */
 
+#ifdef SQLITE_DEBUG
   /* Record the number of outstanding lookaside allocations in schema Tables
   ** prior to doing any free() operations.  Since schema Tables do not use
   ** lookaside, this number should not change. */
-  TESTONLY( nLookaside = (db && (pTable->tabFlags & TF_Ephemeral)==0) ?
-                         db->lookaside.nOut : 0 );
+  int nLookaside = 0;
+  if( db && (pTable->tabFlags & TF_Ephemeral)==0 ){
+    nLookaside = sqlite3LookasideUsed(db, 0);
+  }
+#endif
 
   /* Delete all indices associated with this table. */
   for(pIndex = pTable->pIndex; pIndex; pIndex=pNext){
@@ -638,7 +641,7 @@ static void SQLITE_NOINLINE deleteTable(sqlite3 *db, Table *pTable){
   sqlite3DbFree(db, pTable);
 
   /* Verify that no lookaside memory was used by schema tables */
-  assert( nLookaside==0 || nLookaside==db->lookaside.nOut );
+  assert( nLookaside==0 || nLookaside==sqlite3LookasideUsed(db,0) );
 }
 void sqlite3DeleteTable(sqlite3 *db, Table *pTable){
   /* Do not delete the table until the reference count reaches zero. */

diff --git a/src/main.c b/src/main.c
index 212f7d6b5fc500565ff6834c160650b56302d718..168ce851f661e3626fb54c655832519c488f95fb 100644 (file)
--- a/src/main.c
+++ b/src/main.c
@@ -658,7 +658,8 @@ int sqlite3_config(int op, ...){
 static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
 #ifndef SQLITE_OMIT_LOOKASIDE
   void *pStart;
-  if( db->lookaside.nOut ){
+  
+  if( sqlite3LookasideUsed(db,0)>0 ){
     return SQLITE_BUSY;
   }
   /* Free any existing lookaside buffer for this handle before
@@ -686,16 +687,18 @@ static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
     pStart = pBuf;
   }
   db->lookaside.pStart = pStart;
+  db->lookaside.pInit = 0;
   db->lookaside.pFree = 0;
   db->lookaside.sz = (u16)sz;
   if( pStart ){
     int i;
     LookasideSlot *p;
     assert( sz > (int)sizeof(LookasideSlot*) );
+    db->lookaside.nSlot = cnt;
     p = (LookasideSlot*)pStart;
     for(i=cnt-1; i>=0; i--){
-      p->pNext = db->lookaside.pFree;
-      db->lookaside.pFree = p;
+      p->pNext = db->lookaside.pInit;
+      db->lookaside.pInit = p;
       p = (LookasideSlot*)&((u8*)p)[sz];
     }
     db->lookaside.pEnd = p;
@@ -706,6 +709,7 @@ static int setupLookaside(sqlite3 *db, void *pBuf, int sz, int cnt){
     db->lookaside.pEnd = db;
     db->lookaside.bDisable = 1;
     db->lookaside.bMalloced = 0;
+    db->lookaside.nSlot = 0;
   }
 #endif /* SQLITE_OMIT_LOOKASIDE */
   return SQLITE_OK;
@@ -1225,7 +1229,7 @@ void sqlite3LeaveMutexAndCloseZombie(sqlite3 *db){
   sqlite3_mutex_leave(db->mutex);
   db->magic = SQLITE_MAGIC_CLOSED;
   sqlite3_mutex_free(db->mutex);
-  assert( db->lookaside.nOut==0 );  /* Fails on a lookaside memory leak */
+  assert( sqlite3LookasideUsed(db,0)==0 );
   if( db->lookaside.bMalloced ){
     sqlite3_free(db->lookaside.pStart);
   }

diff --git a/src/malloc.c b/src/malloc.c
index 78a50b49c54451dd89daabf019c4591f88aa34ac..b750f6e72f3dc51ca4633899b247b0b441a1c089 100644 (file)
--- a/src/malloc.c
+++ b/src/malloc.c
@@ -354,7 +354,6 @@ void sqlite3DbFreeNN(sqlite3 *db, void *p){
 #endif
       pBuf->pNext = db->lookaside.pFree;
       db->lookaside.pFree = pBuf;
-      db->lookaside.nOut--;
       return;
     }
   }
@@ -515,16 +514,16 @@ void *sqlite3DbMallocRawNN(sqlite3 *db, u64 n){
     assert( db->mallocFailed==0 );
     if( n>db->lookaside.sz ){
       db->lookaside.anStat[1]++;
-    }else if( (pBuf = db->lookaside.pFree)==0 ){
-      db->lookaside.anStat[2]++;
-    }else{
+    }else if( (pBuf = db->lookaside.pFree)!=0 ){
       db->lookaside.pFree = pBuf->pNext;
-      db->lookaside.nOut++;
       db->lookaside.anStat[0]++;
-      if( db->lookaside.nOut>db->lookaside.mxOut ){
-        db->lookaside.mxOut = db->lookaside.nOut;
-      }
       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 ){
     return 0;

diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 55a8efe214884a065703a2c1c7845ba84f7130e4..1c1879a922c8fb1280b89263d36599c9220d5a90 100644 (file)
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1245,9 +1245,9 @@ struct Lookaside {
   u32 bDisable;           /* Only operate the lookaside when zero */
   u16 sz;                 /* Size of each buffer in bytes */
   u8 bMalloced;           /* True if pStart obtained from sqlite3_malloc() */
-  int nOut;               /* Number of buffers currently checked out */
-  int mxOut;              /* Highwater mark for nOut */
-  int anStat[3];          /* 0: hits.  1: size misses.  2: full misses */
+  u32 nSlot;              /* Number of lookaside slots allocated */
+  u32 anStat[3];          /* 0: hits.  1: size misses.  2: full misses */
+  LookasideSlot *pInit;   /* List of buffers not previously used */
   LookasideSlot *pFree;   /* List of available buffers */
   void *pStart;           /* First byte of available memory space */
   void *pEnd;             /* First byte past end of available space */
@@ -3575,6 +3575,7 @@ sqlite3_int64 sqlite3StatusValue(int);
 void sqlite3StatusUp(int, int);
 void sqlite3StatusDown(int, int);
 void sqlite3StatusHighwater(int, int);
+int sqlite3LookasideUsed(sqlite3*,int*);
 
 /* Access to mutexes used by sqlite3_status() */
 sqlite3_mutex *sqlite3Pcache1Mutex(void);

diff --git a/src/status.c b/src/status.c
index b783b395d3ddc4d68a0d63061120202cf67b4547..6e5b0e573b546c8d58402b7c2148435f4caacdd9 100644 (file)
--- a/src/status.c
+++ b/src/status.c
@@ -170,6 +170,28 @@ int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag){
   return rc;
 }
 
+/*
+** Return the number of LookasideSlot elements on the linked list
+*/
+static u32 countLookasideSlots(LookasideSlot *p){
+  u32 cnt = 0;
+  while( p ){
+    p = p->pNext;
+    cnt++;
+  }
+  return cnt;
+}
+
+/*
+** Count the number of slots of lookaside memory that are outstanding
+*/
+int sqlite3LookasideUsed(sqlite3 *db, int *pHighwater){
+  u32 nInit = countLookasideSlots(db->lookaside.pInit);
+  u32 nFree = countLookasideSlots(db->lookaside.pFree);
+  if( pHighwater ) *pHighwater = db->lookaside.nSlot - nInit;
+  return db->lookaside.nSlot - (nInit+nFree);
+}
+
 /*
 ** Query status information for a single database connection
 */
@@ -189,10 +211,15 @@ int sqlite3_db_status(
   sqlite3_mutex_enter(db->mutex);
   switch( op ){
     case SQLITE_DBSTATUS_LOOKASIDE_USED: {
-      *pCurrent = db->lookaside.nOut;
-      *pHighwater = db->lookaside.mxOut;
+      *pCurrent = sqlite3LookasideUsed(db, pHighwater);
       if( resetFlag ){
-        db->lookaside.mxOut = db->lookaside.nOut;
+        LookasideSlot *p = db->lookaside.pFree;
+        if( p ){
+          while( p->pNext ) p = p->pNext;
+          p->pNext = db->lookaside.pInit;
+          db->lookaside.pInit = db->lookaside.pFree;
+          db->lookaside.pFree = 0;
+        }
       }
       break;
     }