Index: src/main.c
==================================================================
--- src/main.c
+++ src/main.c
@@ -1054,11 +1054,11 @@
 
 /*
 ** Return a static string containing the name corresponding to the error code
 ** specified in the argument.
 */
-#if defined(SQLITE_TEST)
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
 const char *sqlite3ErrName(int rc){
   const char *zName = 0;
   int i, origRc = rc;
   for(i=0; i<2 && zName==0; i++, rc &= 0xff){
     switch( rc ){

Index: src/mutex_w32.c
==================================================================
--- src/mutex_w32.c
+++ src/mutex_w32.c
@@ -7,24 +7,29 @@
 **    May you do good and not evil.
 **    May you find forgiveness for yourself and forgive others.
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
-** This file contains the C functions that implement mutexes for win32
+** This file contains the C functions that implement mutexes for Win32.
 */
 #include "sqliteInt.h"
 
 #if SQLITE_OS_WIN
+/*
+** Include code that is common to all os_*.c files
+*/
+#include "os_common.h"
+
 /*
 ** Include the header file for the Windows VFS.
 */
 #include "os_win.h"
 #endif
 
 /*
 ** The code in this file is only used if we are compiling multithreaded
-** on a win32 system.
+** on a Win32 system.
 */
 #ifdef SQLITE_MUTEX_W32
 
 /*
 ** Each recursive mutex is an instance of the following structure.
@@ -33,71 +38,46 @@
   CRITICAL_SECTION mutex;    /* Mutex controlling the lock */
   int id;                    /* Mutex type */
 #ifdef SQLITE_DEBUG
   volatile int nRef;         /* Number of enterances */
   volatile DWORD owner;      /* Thread holding this mutex */
-  int trace;                 /* True to trace changes */
+  volatile int trace;        /* True to trace changes */
 #endif
 };
+
+/*
+** These are the initializer values used when declaring a "static" mutex
+** on Win32.  It should be noted that all mutexes require initialization
+** on the Win32 platform.
+*/
 #define SQLITE_W32_MUTEX_INITIALIZER { 0 }
+
 #ifdef SQLITE_DEBUG
-#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, 0L, (DWORD)0, 0 }
+#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, \
+                                    0L, (DWORD)0, 0 }
 #else
 #define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0 }
 #endif
 
-/*
-** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
-** or WinCE.  Return false (zero) for Win95, Win98, or WinME.
-**
-** Here is an interesting observation:  Win95, Win98, and WinME lack
-** the LockFileEx() API.  But we can still statically link against that
-** API as long as we don't call it win running Win95/98/ME.  A call to
-** this routine is used to determine if the host is Win95/98/ME or
-** WinNT/2K/XP so that we will know whether or not we can safely call
-** the LockFileEx() API.
-**
-** mutexIsNT() is only used for the TryEnterCriticalSection() API call,
-** which is only available if your application was compiled with 
-** _WIN32_WINNT defined to a value >= 0x0400.  Currently, the only
-** call to TryEnterCriticalSection() is #ifdef'ed out, so #ifdef 
-** this out as well.
-*/
-#if 0
-#if SQLITE_OS_WINCE || SQLITE_OS_WINRT
-# define mutexIsNT()  (1)
-#else
-  static int mutexIsNT(void){
-    static int osType = 0;
-    if( osType==0 ){
-      OSVERSIONINFO sInfo;
-      sInfo.dwOSVersionInfoSize = sizeof(sInfo);
-      GetVersionEx(&sInfo);
-      osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
-    }
-    return osType==2;
-  }
-#endif /* SQLITE_OS_WINCE || SQLITE_OS_WINRT */
-#endif
-
 #ifdef SQLITE_DEBUG
 /*
 ** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
 ** intended for use only inside assert() statements.
 */
 static int winMutexHeld(sqlite3_mutex *p){
   return p->nRef!=0 && p->owner==GetCurrentThreadId();
 }
+
 static int winMutexNotheld2(sqlite3_mutex *p, DWORD tid){
   return p->nRef==0 || p->owner!=tid;
 }
+
 static int winMutexNotheld(sqlite3_mutex *p){
-  DWORD tid = GetCurrentThreadId(); 
+  DWORD tid = GetCurrentThreadId();
   return winMutexNotheld2(p, tid);
 }
 #endif
-
 
 /*
 ** Initialize and deinitialize the mutex subsystem.
 */
 static sqlite3_mutex winMutex_staticMutexes[6] = {
@@ -106,21 +86,24 @@
   SQLITE3_MUTEX_INITIALIZER,
   SQLITE3_MUTEX_INITIALIZER,
   SQLITE3_MUTEX_INITIALIZER,
   SQLITE3_MUTEX_INITIALIZER
 };
+
 static int winMutex_isInit = 0;
-/* As winMutexInit() and winMutexEnd() are called as part
-** of the sqlite3_initialize and sqlite3_shutdown()
-** processing, the "interlocked" magic is probably not
-** strictly necessary.
+
+/* As winMutexInit() and winMutexEnd() are called as part of the
+** sqlite3_initialize() and sqlite3_shutdown() processing, the
+** "interlocked" magic used in this section may not strictly
+** necessary.
 */
 static LONG winMutex_lock = 0;
 
+int sqlite3_win32_is_nt(void); /* os_win.c */
 void sqlite3_win32_sleep(DWORD milliseconds); /* os_win.c */
 
-static int winMutexInit(void){ 
+static int winMutexInit(void){
   /* The first to increment to 1 does actual initialization */
   if( InterlockedCompareExchange(&winMutex_lock, 1, 0)==0 ){
     int i;
     for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
 #if SQLITE_OS_WINRT
@@ -129,20 +112,21 @@
       InitializeCriticalSection(&winMutex_staticMutexes[i].mutex);
 #endif
     }
     winMutex_isInit = 1;
   }else{
-    /* Someone else is in the process of initing the static mutexes */
+    /* Another thread is (in the process of) initializing the static
+    ** mutexes */
     while( !winMutex_isInit ){
       sqlite3_win32_sleep(1);
     }
   }
-  return SQLITE_OK; 
+  return SQLITE_OK;
 }
 
-static int winMutexEnd(void){ 
-  /* The first to decrement to 0 does actual shutdown 
+static int winMutexEnd(void){
+  /* The first to decrement to 0 does actual shutdown
   ** (which should be the last to shutdown.) */
   if( InterlockedCompareExchange(&winMutex_lock, 0, 1)==1 ){
     if( winMutex_isInit==1 ){
       int i;
       for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
@@ -149,11 +133,11 @@
         DeleteCriticalSection(&winMutex_staticMutexes[i].mutex);
       }
       winMutex_isInit = 0;
     }
   }
-  return SQLITE_OK; 
+  return SQLITE_OK;
 }
 
 /*
 ** The sqlite3_mutex_alloc() routine allocates a new
 ** mutex and returns a pointer to it.  If it returns NULL
@@ -190,11 +174,11 @@
 ** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
 ** SQLITE_MUTEX_RECURSIVE.
 **
 ** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
 ** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
-** returns a different mutex on every call.  But for the static 
+** returns a different mutex on every call.  But for the static
 ** mutex types, the same mutex is returned on every call that has
 ** the same type number.
 */
 static sqlite3_mutex *winMutexAlloc(int iType){
   sqlite3_mutex *p;
@@ -201,13 +185,16 @@
 
   switch( iType ){
     case SQLITE_MUTEX_FAST:
     case SQLITE_MUTEX_RECURSIVE: {
       p = sqlite3MallocZero( sizeof(*p) );
-      if( p ){  
+      if( p ){
 #ifdef SQLITE_DEBUG
         p->id = iType;
+#ifdef SQLITE_WIN32_MUTEX_TRACE_DYNAMIC
+        p->trace = 1;
+#endif
 #endif
 #if SQLITE_OS_WINRT
         InitializeCriticalSectionEx(&p->mutex, 0, 0);
 #else
         InitializeCriticalSection(&p->mutex);
@@ -214,16 +201,19 @@
 #endif
       }
       break;
     }
     default: {
-      assert( winMutex_isInit==1 );
       assert( iType-2 >= 0 );
       assert( iType-2 < ArraySize(winMutex_staticMutexes) );
+      assert( winMutex_isInit==1 );
       p = &winMutex_staticMutexes[iType-2];
 #ifdef SQLITE_DEBUG
       p->id = iType;
+#ifdef SQLITE_WIN32_MUTEX_TRACE_STATIC
+      p->trace = 1;
+#endif
 #endif
       break;
     }
   }
   return p;
@@ -235,12 +225,14 @@
 ** allocated mutex.  SQLite is careful to deallocate every
 ** mutex that it allocates.
 */
 static void winMutexFree(sqlite3_mutex *p){
   assert( p );
+#ifdef SQLITE_DEBUG
   assert( p->nRef==0 && p->owner==0 );
   assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+#endif
   DeleteCriticalSection(&p->mutex);
   sqlite3_free(p);
 }
 
 /*
@@ -253,53 +245,64 @@
 ** mutex must be exited an equal number of times before another thread
 ** can enter.  If the same thread tries to enter any other kind of mutex
 ** more than once, the behavior is undefined.
 */
 static void winMutexEnter(sqlite3_mutex *p){
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  DWORD tid = GetCurrentThreadId();
+#endif
 #ifdef SQLITE_DEBUG
-  DWORD tid = GetCurrentThreadId(); 
+  assert( p );
   assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
+#else
+  assert( p );
 #endif
   EnterCriticalSection(&p->mutex);
 #ifdef SQLITE_DEBUG
   assert( p->nRef>0 || p->owner==0 );
-  p->owner = tid; 
+  p->owner = tid;
   p->nRef++;
   if( p->trace ){
-    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+    OSTRACE(("ENTER-MUTEX tid=%lu, mutex=%p (%d), nRef=%d\n",
+             tid, p, p->trace, p->nRef));
   }
 #endif
 }
+
 static int winMutexTry(sqlite3_mutex *p){
-#ifndef NDEBUG
-  DWORD tid = GetCurrentThreadId(); 
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+  DWORD tid = GetCurrentThreadId();
 #endif
   int rc = SQLITE_BUSY;
+  assert( p );
   assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
   /*
   ** The sqlite3_mutex_try() routine is very rarely used, and when it
   ** is used it is merely an optimization.  So it is OK for it to always
-  ** fail.  
+  ** fail.
   **
   ** The TryEnterCriticalSection() interface is only available on WinNT.
   ** And some windows compilers complain if you try to use it without
   ** first doing some #defines that prevent SQLite from building on Win98.
   ** For that reason, we will omit this optimization for now.  See
   ** ticket #2685.
   */
-#if 0
-  if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){
+#if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0400
+  if( sqlite3_win32_is_nt() && TryEnterCriticalSection(&p->mutex) ){
+#ifdef SQLITE_DEBUG
     p->owner = tid;
     p->nRef++;
+#endif
     rc = SQLITE_OK;
   }
 #else
   UNUSED_PARAMETER(p);
 #endif
 #ifdef SQLITE_DEBUG
-  if( rc==SQLITE_OK && p->trace ){
-    printf("try mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  if( p->trace ){
+    OSTRACE(("TRY-MUTEX tid=%lu, mutex=%p (%d), owner=%lu, nRef=%d, rc=%s\n",
+             tid, p, p->trace, p->owner, p->nRef, sqlite3ErrName(rc)));
   }
 #endif
   return rc;
 }
 
@@ -308,22 +311,26 @@
 ** previously entered by the same thread.  The behavior
 ** is undefined if the mutex is not currently entered or
 ** is not currently allocated.  SQLite will never do either.
 */
 static void winMutexLeave(sqlite3_mutex *p){
-#ifndef NDEBUG
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
   DWORD tid = GetCurrentThreadId();
+#endif
+  assert( p );
+#ifdef SQLITE_DEBUG
   assert( p->nRef>0 );
   assert( p->owner==tid );
   p->nRef--;
   if( p->nRef==0 ) p->owner = 0;
   assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
 #endif
   LeaveCriticalSection(&p->mutex);
 #ifdef SQLITE_DEBUG
   if( p->trace ){
-    printf("leave mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+    OSTRACE(("LEAVE-MUTEX tid=%lu, mutex=%p (%d), nRef=%d\n",
+             tid, p, p->trace, p->nRef));
   }
 #endif
 }
 
 sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
@@ -341,9 +348,9 @@
 #else
     0,
     0
 #endif
   };
-
   return &sMutex;
 }
+
 #endif /* SQLITE_MUTEX_W32 */

Index: src/os_win.c
==================================================================
--- src/os_win.c
+++ src/os_win.c
@@ -1296,26 +1296,32 @@
 #elif SQLITE_OS_WINCE || SQLITE_OS_WINRT || !defined(SQLITE_WIN32_HAS_ANSI)
 # define osIsNT()  (1)
 #elif !defined(SQLITE_WIN32_HAS_WIDE)
 # define osIsNT()  (0)
 #else
-  static int osIsNT(void){
-    if( sqlite3_os_type==0 ){
+# define osIsNT()  (sqlite3_win32_is_nt())
+#endif
+
+/*
+** This function determines if the machine is running a version of Windows
+** based on the NT kernel.
+*/
+int sqlite3_win32_is_nt(void){
+  if( sqlite3_os_type==0 ){
 #if defined(NTDDI_VERSION) && NTDDI_VERSION >= NTDDI_WIN8
-      OSVERSIONINFOW sInfo;
-      sInfo.dwOSVersionInfoSize = sizeof(sInfo);
-      osGetVersionExW(&sInfo);
+    OSVERSIONINFOW sInfo;
+    sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+    osGetVersionExW(&sInfo);
 #else
-      OSVERSIONINFOA sInfo;
-      sInfo.dwOSVersionInfoSize = sizeof(sInfo);
-      osGetVersionExA(&sInfo);
-#endif
-      sqlite3_os_type = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
-    }
-    return sqlite3_os_type==2;
-  }
-#endif
+    OSVERSIONINFOA sInfo;
+    sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+    osGetVersionExA(&sInfo);
+#endif
+    sqlite3_os_type = (sInfo.dwPlatformId == VER_PLATFORM_WIN32_NT) ? 2 : 1;
+  }
+  return (sqlite3_os_type == 2);
+}
 
 #ifdef SQLITE_WIN32_MALLOC
 /*
 ** Allocate nBytes of memory.
 */