435 lines
No EOL
12 KiB
C#
435 lines
No EOL
12 KiB
C#
using System;
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using System.Diagnostics;
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using System.Threading;
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using DWORD = System.Int32;
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namespace Community.CsharpSqlite
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{
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public partial class Sqlite3
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{
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/*
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** 2007 August 14
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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** This file contains the C functions that implement mutexes for win32
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*************************************************************************
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** Included in SQLite3 port to C#-SQLite; 2008 Noah B Hart
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** C#-SQLite is an independent reimplementation of the SQLite software library
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**
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** SQLITE_SOURCE_ID: 2010-03-09 19:31:43 4ae453ea7be69018d8c16eb8dabe05617397dc4d
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**
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*************************************************************************
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*/
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//#include "sqliteInt.h"
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/*
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** The code in this file is only used if we are compiling multithreaded
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** on a win32 system.
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*/
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#if SQLITE_MUTEX_W32
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/*
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** Each recursive mutex is an instance of the following structure.
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*/
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public partial class sqlite3_mutex
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{
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public Object mutex; /* Mutex controlling the lock */
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public int id; /* Mutex type */
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public int nRef; /* Number of enterances */
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public DWORD owner; /* Thread holding this mutex */
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#if SQLITE_DEBUG
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public int trace; /* True to trace changes */
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#endif
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public sqlite3_mutex()
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{
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mutex = new Object();
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}
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public sqlite3_mutex(Mutex mutex, int id, int nRef, DWORD owner
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#if SQLITE_DEBUG
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, int trace
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#endif
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)
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{
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this.mutex = mutex;
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this.id = id;
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this.nRef = nRef;
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this.owner = owner;
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#if SQLITE_DEBUG
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this.trace = 0;
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#endif
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}
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};
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//#define SQLITE_W32_MUTEX_INITIALIZER { 0 }
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private static Mutex SQLITE_W32_MUTEX_INITIALIZER = null;
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#if SQLITE_DEBUG
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//#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, 0L, (DWORD)0, 0 }
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#else
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//#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, 0L, (DWORD)0 }
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#endif
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/*
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** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
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** or WinCE. Return false (zero) for Win95, Win98, or WinME.
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**
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** Here is an interesting observation: Win95, Win98, and WinME lack
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** the LockFileEx() API. But we can still statically link against that
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** API as long as we don't call it win running Win95/98/ME. A call to
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** this routine is used to determine if the host is Win95/98/ME or
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** WinNT/2K/XP so that we will know whether or not we can safely call
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** the LockFileEx() API.
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**
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** mutexIsNT() is only used for the TryEnterCriticalSection() API call,
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** which is only available if your application was compiled with
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** _WIN32_WINNT defined to a value >= 0x0400. Currently, the only
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** call to TryEnterCriticalSection() is #ifdef'ed out, so #if
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** this out as well.
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*/
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#if FALSE
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#if SQLITE_OS_WINCE
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//# define mutexIsNT() (1)
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#else
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static int mutexIsNT(void){
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static int osType = 0;
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if( osType==0 ){
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OSVERSIONINFO sInfo;
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sInfo.dwOSVersionInfoSize = sizeof(sInfo);
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GetVersionEx(&sInfo);
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osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
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}
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return osType==2;
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}
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#endif //* SQLITE_OS_WINCE */
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#endif
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#if SQLITE_DEBUG
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/*
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** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
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** intended for use only inside Debug.Assert() statements.
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*/
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private static bool winMutexHeld(sqlite3_mutex p)
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{
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return p.nRef != 0 && p.owner == GetCurrentThreadId();
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}
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private static bool winMutexNotheld2(sqlite3_mutex p, DWORD tid)
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{
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return p.nRef == 0 || p.owner != tid;
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}
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private static bool winMutexNotheld(sqlite3_mutex p)
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{
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DWORD tid = GetCurrentThreadId();
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return winMutexNotheld2(p, tid);
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}
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#endif
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/*
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** Initialize and deinitialize the mutex subsystem.
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*/
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//No MACROS under C#; Cannot use SQLITE3_MUTEX_INITIALIZER,
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private static sqlite3_mutex[] winMutex_staticMutexes = new sqlite3_mutex[]{
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new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
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#if SQLITE_DEBUG
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, 0
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#endif
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),// SQLITE3_MUTEX_INITIALIZER,
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new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
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#if SQLITE_DEBUG
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, 0
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#endif
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),// SQLITE3_MUTEX_INITIALIZER,
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new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
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#if SQLITE_DEBUG
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, 0
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#endif
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),// SQLITE3_MUTEX_INITIALIZER,
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new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
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#if SQLITE_DEBUG
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, 0
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#endif
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),// SQLITE3_MUTEX_INITIALIZER,
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new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
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#if SQLITE_DEBUG
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, 0
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#endif
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),// SQLITE3_MUTEX_INITIALIZER,
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new sqlite3_mutex( SQLITE_W32_MUTEX_INITIALIZER, 0, 0, (DWORD)0
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#if SQLITE_DEBUG
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, 0
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#endif
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),// SQLITE3_MUTEX_INITIALIZER,
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};
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private static int winMutex_isInit = 0;
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/* As winMutexInit() and winMutexEnd() are called as part
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** of the sqlite3_initialize and sqlite3_shutdown()
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** processing, the "interlocked" magic is probably not
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** strictly necessary.
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*/
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private static long winMutex_lock = 0;
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private static System.Object lockThis = new System.Object();
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private static int winMutexInit()
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{
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/* The first to increment to 1 does actual initialization */
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lock (lockThis)
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//if ( Interlocked.CompareExchange(ref winMutex_lock, 1, 0 ) == 0 )
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{
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int i;
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for (i = 0; i < ArraySize(winMutex_staticMutexes); i++)
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{
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if (winMutex_staticMutexes[i].mutex == null) winMutex_staticMutexes[i].mutex = new Mutex();
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//InitializeCriticalSection( winMutex_staticMutexes[i].mutex );
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}
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winMutex_isInit = 1;
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}
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//else
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//{
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// /* Someone else is in the process of initing the static mutexes */
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// while ( 0 == winMutex_isInit )
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// {
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// Thread.Sleep( 1 );
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// }
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//}
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return SQLITE_OK;
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}
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private static int winMutexEnd()
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{
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/* The first to decrement to 0 does actual shutdown
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** (which should be the last to shutdown.) */
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if (Interlocked.CompareExchange(ref winMutex_lock, 0, 1) == 1)
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{
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if (winMutex_isInit == 1)
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{
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int i;
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for (i = 0; i < ArraySize(winMutex_staticMutexes); i++)
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{
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DeleteCriticalSection(winMutex_staticMutexes[i].mutex);
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}
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winMutex_isInit = 0;
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}
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}
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return SQLITE_OK;
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}
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/*
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** The sqlite3_mutex_alloc() routine allocates a new
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** mutex and returns a pointer to it. If it returns NULL
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** that means that a mutex could not be allocated. SQLite
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** will unwind its stack and return an error. The argument
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** to sqlite3_mutex_alloc() is one of these integer constants:
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**
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** <ul>
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** <li> SQLITE_MUTEX_FAST
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** <li> SQLITE_MUTEX_RECURSIVE
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** <li> SQLITE_MUTEX_STATIC_MASTER
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** <li> SQLITE_MUTEX_STATIC_MEM
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** <li> SQLITE_MUTEX_STATIC_MEM2
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** <li> SQLITE_MUTEX_STATIC_PRNG
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** <li> SQLITE_MUTEX_STATIC_LRU
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** <li> SQLITE_MUTEX_STATIC_LRU2
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** </ul>
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**
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** The first two constants cause sqlite3_mutex_alloc() to create
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** a new mutex. The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
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** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
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** The mutex implementation does not need to make a distinction
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** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
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** not want to. But SQLite will only request a recursive mutex in
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** cases where it really needs one. If a faster non-recursive mutex
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** implementation is available on the host platform, the mutex subsystem
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** might return such a mutex in response to SQLITE_MUTEX_FAST.
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**
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** The other allowed parameters to sqlite3_mutex_alloc() each return
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** a pointer to a static preexisting mutex. Six static mutexes are
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** used by the current version of SQLite. Future versions of SQLite
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** may add additional static mutexes. Static mutexes are for internal
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** use by SQLite only. Applications that use SQLite mutexes should
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** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
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** SQLITE_MUTEX_RECURSIVE.
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**
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** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
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** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
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** returns a different mutex on every call. But for the static
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** mutex types, the same mutex is returned on every call that has
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** the same type number.
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*/
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private static sqlite3_mutex winMutexAlloc(int iType)
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{
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sqlite3_mutex p;
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switch (iType)
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{
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case SQLITE_MUTEX_FAST:
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case SQLITE_MUTEX_RECURSIVE:
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{
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p = new sqlite3_mutex();//sqlite3MallocZero( sizeof(*p) );
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if (p != null)
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{
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p.id = iType;
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InitializeCriticalSection(p.mutex);
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}
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break;
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}
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default:
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{
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Debug.Assert(winMutex_isInit == 1);
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Debug.Assert(iType - 2 >= 0);
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Debug.Assert(iType - 2 < ArraySize(winMutex_staticMutexes));
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p = winMutex_staticMutexes[iType - 2];
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p.id = iType;
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break;
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}
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}
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return p;
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}
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/*
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** This routine deallocates a previously
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** allocated mutex. SQLite is careful to deallocate every
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** mutex that it allocates.
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*/
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private static void winMutexFree(sqlite3_mutex p)
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{
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Debug.Assert(p != null);
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Debug.Assert(p.nRef == 0);
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Debug.Assert(p.id == SQLITE_MUTEX_FAST || p.id == SQLITE_MUTEX_RECURSIVE);
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DeleteCriticalSection(p.mutex);
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p.owner = 0;
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//sqlite3_free( p );
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}
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/*
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** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
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** to enter a mutex. If another thread is already within the mutex,
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** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
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** SQLITE_BUSY. The sqlite3_mutex_try() interface returns SQLITE_OK
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** upon successful entry. Mutexes created using SQLITE_MUTEX_RECURSIVE can
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** be entered multiple times by the same thread. In such cases the,
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** mutex must be exited an equal number of times before another thread
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** can enter. If the same thread tries to enter any other kind of mutex
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** more than once, the behavior is undefined.
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*/
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private static void winMutexEnter(sqlite3_mutex p)
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{
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DWORD tid = GetCurrentThreadId();
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Debug.Assert(p.id == SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid));
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EnterCriticalSection(p.mutex);
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p.owner = tid;
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p.nRef++;
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#if SQLITE_DEBUG
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if (p.trace != 0)
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{
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printf("enter mutex {0} ({1}) with nRef={2}\n", p.GetHashCode(), p.owner, p.nRef);
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}
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#endif
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}
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private static int winMutexTry(sqlite3_mutex p)
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{
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#if !NDEBUG
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DWORD tid = GetCurrentThreadId();
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#endif
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int rc = SQLITE_BUSY;
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Debug.Assert(p.id == SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid));
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/*
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** The sqlite3_mutex_try() routine is very rarely used, and when it
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** is used it is merely an optimization. So it is OK for it to always
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** fail.
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**
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** The TryEnterCriticalSection() interface is only available on WinNT.
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** And some windows compilers complain if you try to use it without
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** first doing some #defines that prevent SQLite from building on Win98.
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** For that reason, we will omit this optimization for now. See
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** ticket #2685.
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*/
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#if FALSE
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if( mutexIsNT() && TryEnterCriticalSection(p.mutex) ){
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p.owner = tid;
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p.nRef++;
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rc = SQLITE_OK;
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}
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#else
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UNUSED_PARAMETER(p);
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#endif
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#if SQLITE_DEBUG
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if (rc == SQLITE_OK && p.trace != 0)
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{
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printf("try mutex {0} ({1}) with nRef={2}\n", p.GetHashCode(), p.owner, p.nRef);
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}
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#endif
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return rc;
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}
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/*
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** The sqlite3_mutex_leave() routine exits a mutex that was
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** previously entered by the same thread. The behavior
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** is undefined if the mutex is not currently entered or
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** is not currently allocated. SQLite will never do either.
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*/
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private static void winMutexLeave(sqlite3_mutex p)
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{
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#if !NDEBUG
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DWORD tid = GetCurrentThreadId();
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#endif
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Debug.Assert(p.nRef > 0);
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Debug.Assert(p.owner == tid);
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p.nRef--;
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Debug.Assert(p.nRef == 0 || p.id == SQLITE_MUTEX_RECURSIVE);
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if (p.nRef == 0) p.owner = 0;
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LeaveCriticalSection(p.mutex);
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#if SQLITE_DEBUG
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if (p.trace != 0)
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{
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printf("leave mutex {0} ({1}) with nRef={2}\n", p.GetHashCode(), p.owner, p.nRef);
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}
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#endif
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}
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private static sqlite3_mutex_methods sqlite3DefaultMutex()
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{
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sqlite3_mutex_methods sMutex = new sqlite3_mutex_methods(
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(dxMutexInit)winMutexInit,
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(dxMutexEnd)winMutexEnd,
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(dxMutexAlloc)winMutexAlloc,
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(dxMutexFree)winMutexFree,
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(dxMutexEnter)winMutexEnter,
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(dxMutexTry)winMutexTry,
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(dxMutexLeave)winMutexLeave,
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#if SQLITE_DEBUG
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(dxMutexHeld)winMutexHeld,
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(dxMutexNotheld)winMutexNotheld
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#else
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null,
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null
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#endif
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);
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return sMutex;
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}
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#endif // * SQLITE_MUTEX_W32 */
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}
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} |