Add the SQLITE_OPEN_NOMUTEX flag. Used for opening connections that are not protected by an internal mutex. (CVS 5387)

FossilOrigin-Name: 7e58b78712420b3bd4320192a58d89eb71eecc9c

4 files changed, 35 insertions, 10 deletions

diff --git a/src/main.c b/src/main.c
index c3a89488c..e8c47ac56 100644
--- a/src/main.c
+++ b/src/main.c
@@ -14,7 +14,7 @@
 ** other files are for internal use by SQLite and should not be
 ** accessed by users of the library.
 **
-** $Id: main.c,v 1.473 2008/07/09 13:28:54 drh Exp $
+** $Id: main.c,v 1.474 2008/07/10 17:52:49 danielk1977 Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -1247,12 +1247,17 @@ static int openDatabase(
   sqlite3 *db;
   int rc;
   CollSeq *pColl;
+  int isThreadsafe = 1;
 
 #ifndef SQLITE_OMIT_AUTOINIT
   rc = sqlite3_initialize();
   if( rc ) return rc;
 #endif
 
+  if( flags&SQLITE_OPEN_NOMUTEX ){
+    isThreadsafe = 0;
+  }
+
   /* Remove harmful bits from the flags parameter */
   flags &=  ~( SQLITE_OPEN_DELETEONCLOSE |
                SQLITE_OPEN_MAIN_DB |
@@ -1261,13 +1266,14 @@ static int openDatabase(
                SQLITE_OPEN_MAIN_JOURNAL | 
                SQLITE_OPEN_TEMP_JOURNAL | 
                SQLITE_OPEN_SUBJOURNAL | 
-               SQLITE_OPEN_MASTER_JOURNAL
+               SQLITE_OPEN_MASTER_JOURNAL |
+               SQLITE_OPEN_NOMUTEX
              );
 
   /* Allocate the sqlite data structure */
   db = sqlite3MallocZero( sizeof(sqlite3) );
   if( db==0 ) goto opendb_out;
-  if( sqlite3Config.bFullMutex ){
+  if( sqlite3Config.bFullMutex && isThreadsafe ){
     db->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
     if( db->mutex==0 ){
       sqlite3_free(db);
@@ -1424,7 +1430,7 @@ static int openDatabase(
 
 opendb_out:
   if( db ){
-    assert( db->mutex!=0 || sqlite3Config.bFullMutex==0 );
+    assert( db->mutex!=0 || isThreadsafe==0 || sqlite3Config.bFullMutex==0 );
     sqlite3_mutex_leave(db->mutex);
   }
   if( SQLITE_NOMEM==(rc = sqlite3_errcode(db)) ){
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index bb4ba97ad..ab433fdf0 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -30,7 +30,7 @@
 ** the version number) and changes its name to "sqlite3.h" as
 ** part of the build process.
 **
-** @(#) $Id: sqlite.h.in,v 1.365 2008/07/09 13:28:54 drh Exp $
+** @(#) $Id: sqlite.h.in,v 1.366 2008/07/10 17:52:49 danielk1977 Exp $
 */
 #ifndef _SQLITE3_H_
 #define _SQLITE3_H_
@@ -512,6 +512,7 @@ int sqlite3_exec(
 #define SQLITE_OPEN_TEMP_JOURNAL     0x00001000
 #define SQLITE_OPEN_SUBJOURNAL       0x00002000
 #define SQLITE_OPEN_MASTER_JOURNAL   0x00004000
+#define SQLITE_OPEN_NOMUTEX          0x00008000
 
 /*
 ** CAPI3REF: Device Characteristics {F10240}
@@ -2296,7 +2297,9 @@ void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
 **
 ** The sqlite3_open_v2() interface works like sqlite3_open()
 ** except that it accepts two additional parameters for additional control
-** over the new database connection.  The flags parameter can be one of:
+** over the new database connection.  The flags parameter can take one of
+** the following three values, optionally combined with the 
+** SQLITE_OPEN_NOMUTEX flag:
 **
 ** <dl>
 ** <dt>[SQLITE_OPEN_READONLY]</dt>
@@ -2315,7 +2318,13 @@ void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
 ** </dl>
 **
 ** If the 3rd parameter to sqlite3_open_v2() is not one of the
-** combinations shown above then the behavior is undefined.
+** combinations shown above or one of the combinations shown above combined
+** with the SQLITE_OPEN_NOMUTEX flag, then the behavior is undefined.
+**
+** If the SQLITE_OPEN_NOMUTEX flag is set, then the opened database handle  
+** is not threadsafe. If two threads attempt to use the database handle or
+** any of it's statement handles simultaneously, the results will be 
+** unpredictable.
 **
 ** If the filename is ":memory:", then a private, temporary in-memory database
 ** is created for the connection.  This in-memory database will vanish when
diff --git a/src/tclsqlite.c b/src/tclsqlite.c
index ab00763db..35a69b8c1 100644
--- a/src/tclsqlite.c
+++ b/src/tclsqlite.c
@@ -12,7 +12,7 @@
 ** A TCL Interface to SQLite.  Append this file to sqlite3.c and
 ** compile the whole thing to build a TCL-enabled version of SQLite.
 **
-** $Id: tclsqlite.c,v 1.218 2008/06/18 09:45:56 danielk1977 Exp $
+** $Id: tclsqlite.c,v 1.219 2008/07/10 17:52:49 danielk1977 Exp $
 */
 #include "tcl.h"
 #include <errno.h>
@@ -2299,7 +2299,7 @@ static int DbObjCmd(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
 
 /*
 **   sqlite3 DBNAME FILENAME ?-vfs VFSNAME? ?-key KEY? ?-readonly BOOLEAN?
-**                           ?-create BOOLEAN?
+**                           ?-create BOOLEAN? ?-nomutex BOOLEAN?
 **
 ** This is the main Tcl command.  When the "sqlite" Tcl command is
 ** invoked, this routine runs to process that command.
@@ -2363,6 +2363,14 @@ static int DbMain(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
       }else{
         flags &= ~SQLITE_OPEN_CREATE;
       }
+    }else if( strcmp(zArg, "-nomutex")==0 ){
+      int b;
+      if( Tcl_GetBooleanFromObj(interp, objv[i+1], &b) ) return TCL_ERROR;
+      if( b ){
+        flags |= SQLITE_OPEN_NOMUTEX;
+      }else{
+        flags &= ~SQLITE_OPEN_NOMUTEX;
+      }
     }else{
       Tcl_AppendResult(interp, "unknown option: ", zArg, (char*)0);
       return TCL_ERROR;
@@ -2371,6 +2379,7 @@ static int DbMain(void *cd, Tcl_Interp *interp, int objc,Tcl_Obj *const*objv){
   if( objc<3 || (objc&1)!=1 ){
     Tcl_WrongNumArgs(interp, 1, objv, 
       "HANDLE FILENAME ?-vfs VFSNAME? ?-readonly BOOLEAN? ?-create BOOLEAN?"
+      " ?-nomutex BOOLEAN?"
 #ifdef SQLITE_HAS_CODEC
       " ?-key CODECKEY?"
 #endif
diff --git a/src/test_mutex.c b/src/test_mutex.c
index 817de93ac..2de4a1b9c 100644
--- a/src/test_mutex.c
+++ b/src/test_mutex.c
@@ -10,7 +10,7 @@
 **
 *************************************************************************
 ** 
-** $Id: test_mutex.c,v 1.6 2008/07/08 02:12:37 drh Exp $
+** $Id: test_mutex.c,v 1.7 2008/07/10 17:52:49 danielk1977 Exp $
 */
 
 #include "tcl.h"
@@ -18,6 +18,7 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <string.h>
+#include "mutex.h"
 
 /* defined in test1.c */
 const char *sqlite3TestErrorName(int);