[sql] Import SQLite 3.17.0.

third_party/sqlite/src/src/btmutex.c

Index: third_party/sqlite/src/src/btmutex.c
diff --git a/third_party/sqlite/src/src/btmutex.c b/third_party/sqlite/src/src/btmutex.c
index c9c8572dfb2544616f576f33bbf0b15631f54fce..ddffb67fa4ecf774d5da8400fa3763c5bdabff64 100644
--- a/third_party/sqlite/src/src/btmutex.c
+++ b/third_party/sqlite/src/src/btmutex.c
@@ -169,21 +169,6 @@ int sqlite3BtreeHoldsMutex(Btree *p){
 #endif
 
 
-#ifndef SQLITE_OMIT_INCRBLOB
-/*
-** Enter and leave a mutex on a Btree given a cursor owned by that
-** Btree.  These entry points are used by incremental I/O and can be
-** omitted if that module is not used.
-*/
-void sqlite3BtreeEnterCursor(BtCursor *pCur){
-  sqlite3BtreeEnter(pCur->pBtree);
-}
-void sqlite3BtreeLeaveCursor(BtCursor *pCur){
-  sqlite3BtreeLeave(pCur->pBtree);
-}
-#endif /* SQLITE_OMIT_INCRBLOB */
-
-
 /*
 ** Enter the mutex on every Btree associated with a database
 ** connection.  This is needed (for example) prior to parsing
@@ -198,16 +183,24 @@ void sqlite3BtreeLeaveCursor(BtCursor *pCur){
 ** two or more btrees in common both try to lock all their btrees
 ** at the same instant.
 */
-void sqlite3BtreeEnterAll(sqlite3 *db){
+static void SQLITE_NOINLINE btreeEnterAll(sqlite3 *db){
   int i;
+  int skipOk = 1;
   Btree *p;
   assert( sqlite3_mutex_held(db->mutex) );
   for(i=0; i<db->nDb; i++){
     p = db->aDb[i].pBt;
-    if( p ) sqlite3BtreeEnter(p);
+    if( p && p->sharable ){
+      sqlite3BtreeEnter(p);
+      skipOk = 0;
+    }
   }
+  db->skipBtreeMutex = skipOk;
 }
-void sqlite3BtreeLeaveAll(sqlite3 *db){
+void sqlite3BtreeEnterAll(sqlite3 *db){
+  if( db->skipBtreeMutex==0 ) btreeEnterAll(db);
+}
+static void SQLITE_NOINLINE btreeLeaveAll(sqlite3 *db){
   int i;
   Btree *p;
   assert( sqlite3_mutex_held(db->mutex) );
@@ -216,13 +209,8 @@ void sqlite3BtreeLeaveAll(sqlite3 *db){
     if( p ) sqlite3BtreeLeave(p);
   }
 }
-
-/*
-** Return true if a particular Btree requires a lock.  Return FALSE if
-** no lock is ever required since it is not sharable.
-*/
-int sqlite3BtreeSharable(Btree *p){
-  return p->sharable;
+void sqlite3BtreeLeaveAll(sqlite3 *db){
+  if( db->skipBtreeMutex==0 ) btreeLeaveAll(db);
 }
 
 #ifndef NDEBUG
@@ -298,4 +286,23 @@ void sqlite3BtreeEnterAll(sqlite3 *db){
   }
 }
 #endif /* if SQLITE_THREADSAFE */
+
+#ifndef SQLITE_OMIT_INCRBLOB
+/*
+** Enter a mutex on a Btree given a cursor owned by that Btree. 
+**
+** These entry points are used by incremental I/O only. Enter() is required 
+** any time OMIT_SHARED_CACHE is not defined, regardless of whether or not 
+** the build is threadsafe. Leave() is only required by threadsafe builds.
+*/
+void sqlite3BtreeEnterCursor(BtCursor *pCur){
+  sqlite3BtreeEnter(pCur->pBtree);
+}
+# if SQLITE_THREADSAFE
+void sqlite3BtreeLeaveCursor(BtCursor *pCur){
+  sqlite3BtreeLeave(pCur->pBtree);
+}
+# endif
+#endif /* ifndef SQLITE_OMIT_INCRBLOB */
+
 #endif /* ifndef SQLITE_OMIT_SHARED_CACHE */