wasCSharpSQLite – Rev 1
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using System.Diagnostics;
using DWORD = System.Int32;
using System.Threading;
using System;
namespace Community.CsharpSqlite
{
public partial class Sqlite3
{
/*
** 2007 August 14
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** 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
*************************************************************************
** Included in SQLite3 port to C#-SQLite; 2008 Noah B Hart
** C#-SQLite is an independent reimplementation of the SQLite software library
**
** SQLITE_SOURCE_ID: 2010-03-09 19:31:43 4ae453ea7be69018d8c16eb8dabe05617397dc4d
**
*************************************************************************
*/
//#include "sqliteInt.h"
/*
** The code in this file is only used if we are compiling multithreaded
** on a win32 system.
*/
#if SQLITE_MUTEX_W32
/*
** Each recursive mutex is an instance of the following structure.
*/
public partial class sqlite3_mutex
{
public Object mutex; /* Mutex controlling the lock */
public int id; /* Mutex type */
public int nRef; /* Number of enterances */
public DWORD owner; /* Thread holding this mutex */
#if SQLITE_DEBUG
public int trace; /* True to trace changes */
#endif
public sqlite3_mutex()
{
mutex = new Object();
}
public sqlite3_mutex( Mutex mutex, int id, int nRef, DWORD owner
#if SQLITE_DEBUG
, int trace
#endif
)
{
this.mutex = mutex;
this.id = id;
this.nRef = nRef;
this.owner = owner;
#if SQLITE_DEBUG
this.trace = 0;
#endif
}
};
//#define SQLITE_W32_MUTEX_INITIALIZER { 0 }
static Mutex SQLITE_W32_MUTEX_INITIALIZER = null;
#if SQLITE_DEBUG
//#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, 0L, (DWORD)0, 0 }
#else
//#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, 0L, (DWORD)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 #if
** this out as well.
*/
#if FALSE
#if SQLITE_OS_WINCE
//# 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 */
#endif
#if SQLITE_DEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use only inside Debug.Assert() statements.
*/
static bool winMutexHeld( sqlite3_mutex p )
{
return p.nRef != 0 && p.owner == GetCurrentThreadId();
}
static bool winMutexNotheld2( sqlite3_mutex p, DWORD tid )
{
return p.nRef == 0 || p.owner != tid;
}
static bool winMutexNotheld( sqlite3_mutex p )
{
DWORD tid = GetCurrentThreadId();
return winMutexNotheld2( p, tid );
}
#endif
/*
** Initialize and deinitialize the mutex subsystem.
*/
//No MACROS under C#; Cannot use SQLITE3_MUTEX_INITIALIZER,
static sqlite3_mutex[] winMutex_staticMutexes = new sqlite3_mutex[]{
new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
#if SQLITE_DEBUG
, 0
#endif
),// SQLITE3_MUTEX_INITIALIZER,
new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
#if SQLITE_DEBUG
, 0
#endif
),// SQLITE3_MUTEX_INITIALIZER,
new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
#if SQLITE_DEBUG
, 0
#endif
),// SQLITE3_MUTEX_INITIALIZER,
new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
#if SQLITE_DEBUG
, 0
#endif
),// SQLITE3_MUTEX_INITIALIZER,
new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
#if SQLITE_DEBUG
, 0
#endif
),// SQLITE3_MUTEX_INITIALIZER,
new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
#if SQLITE_DEBUG
, 0
#endif
),// 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.
*/
static long winMutex_lock = 0;
private static System.Object lockThis = new System.Object();
static int winMutexInit()
{
/* The first to increment to 1 does actual initialization */
lock ( lockThis )
//if ( Interlocked.CompareExchange(ref winMutex_lock, 1, 0 ) == 0 )
{
int i;
for ( i = 0; i < ArraySize( winMutex_staticMutexes ); i++ )
{
if (winMutex_staticMutexes[i].mutex== null) winMutex_staticMutexes[i].mutex = new Mutex();
//InitializeCriticalSection( winMutex_staticMutexes[i].mutex );
}
winMutex_isInit = 1;
}
//else
//{
// /* Someone else is in the process of initing the static mutexes */
// while ( 0 == winMutex_isInit )
// {
// Thread.Sleep( 1 );
// }
//}
return SQLITE_OK;
}
static int winMutexEnd()
{
/* The first to decrement to 0 does actual shutdown
** (which should be the last to shutdown.) */
if ( Interlocked.CompareExchange( ref winMutex_lock, 0, 1 ) == 1 )
{
if ( winMutex_isInit == 1 )
{
int i;
for ( i = 0; i < ArraySize( winMutex_staticMutexes ); i++ )
{
DeleteCriticalSection( winMutex_staticMutexes[i].mutex );
}
winMutex_isInit = 0;
}
}
return SQLITE_OK;
}
/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it. If it returns NULL
** that means that a mutex could not be allocated. SQLite
** will unwind its stack and return an error. The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li> SQLITE_MUTEX_FAST
** <li> SQLITE_MUTEX_RECURSIVE
** <li> SQLITE_MUTEX_STATIC_MASTER
** <li> SQLITE_MUTEX_STATIC_MEM
** <li> SQLITE_MUTEX_STATIC_MEM2
** <li> SQLITE_MUTEX_STATIC_PRNG
** <li> SQLITE_MUTEX_STATIC_LRU
** <li> SQLITE_MUTEX_STATIC_LRU2
** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex. The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to. But SQLite will only request a recursive mutex in
** cases where it really needs one. If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** The other allowed parameters to sqlite3_mutex_alloc() each return
** a pointer to a static preexisting mutex. Six static mutexes are
** used by the current version of SQLite. Future versions of SQLite
** may add additional static mutexes. Static mutexes are for internal
** use by SQLite only. Applications that use SQLite mutexes should
** 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
** 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;
switch ( iType )
{
case SQLITE_MUTEX_FAST:
case SQLITE_MUTEX_RECURSIVE:
{
p = new sqlite3_mutex();//sqlite3MallocZero( sizeof(*p) );
if ( p != null )
{
p.id = iType;
InitializeCriticalSection( p.mutex );
}
break;
}
default:
{
Debug.Assert( winMutex_isInit == 1 );
Debug.Assert( iType - 2 >= 0 );
Debug.Assert( iType - 2 < ArraySize( winMutex_staticMutexes ) );
p = winMutex_staticMutexes[iType - 2];
p.id = iType;
break;
}
}
return p;
}
/*
** This routine deallocates a previously
** allocated mutex. SQLite is careful to deallocate every
** mutex that it allocates.
*/
static void winMutexFree( sqlite3_mutex p )
{
Debug.Assert( p != null );
Debug.Assert( p.nRef == 0 );
Debug.Assert( p.id == SQLITE_MUTEX_FAST || p.id == SQLITE_MUTEX_RECURSIVE );
DeleteCriticalSection( p.mutex );
p.owner = 0;
//sqlite3_free( p );
}
/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex. If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY. The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry. Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread. In such cases the,
** 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 )
{
DWORD tid = GetCurrentThreadId();
Debug.Assert( p.id == SQLITE_MUTEX_RECURSIVE || winMutexNotheld2( p, tid ) );
EnterCriticalSection( p.mutex );
p.owner = tid;
p.nRef++;
#if SQLITE_DEBUG
if ( p.trace != 0 )
{
printf( "enter mutex {0} ({1}) with nRef={2}\n", p.GetHashCode(), p.owner, p.nRef );
}
#endif
}
static int winMutexTry( sqlite3_mutex p )
{
#if !NDEBUG
DWORD tid = GetCurrentThreadId();
#endif
int rc = SQLITE_BUSY;
Debug.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.
**
** 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 FALSE
if( mutexIsNT() && TryEnterCriticalSection(p.mutex) ){
p.owner = tid;
p.nRef++;
rc = SQLITE_OK;
}
#else
UNUSED_PARAMETER( p );
#endif
#if SQLITE_DEBUG
if ( rc == SQLITE_OK && p.trace != 0 )
{
printf( "try mutex {0} ({1}) with nRef={2}\n", p.GetHashCode(), p.owner, p.nRef );
}
#endif
return rc;
}
/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** 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 )
{
#if !NDEBUG
DWORD tid = GetCurrentThreadId();
#endif
Debug.Assert( p.nRef > 0 );
Debug.Assert( p.owner == tid );
p.nRef--;
Debug.Assert( p.nRef == 0 || p.id == SQLITE_MUTEX_RECURSIVE );
if (p.nRef == 0) p.owner = 0;
LeaveCriticalSection( p.mutex );
#if SQLITE_DEBUG
if ( p.trace != 0 )
{
printf( "leave mutex {0} ({1}) with nRef={2}\n", p.GetHashCode(), p.owner, p.nRef );
}
#endif
}
static sqlite3_mutex_methods sqlite3DefaultMutex()
{
sqlite3_mutex_methods sMutex = new sqlite3_mutex_methods (
(dxMutexInit)winMutexInit,
(dxMutexEnd)winMutexEnd,
(dxMutexAlloc)winMutexAlloc,
(dxMutexFree)winMutexFree,
(dxMutexEnter)winMutexEnter,
(dxMutexTry)winMutexTry,
(dxMutexLeave)winMutexLeave,
#if SQLITE_DEBUG
(dxMutexHeld)winMutexHeld,
(dxMutexNotheld)winMutexNotheld
#else
null,
null
#endif
);
return sMutex;
}
#endif // * SQLITE_MUTEX_W32 */
}
}