From 7bb481fda9ecb134804b49c2ce77ca28f7eea583 Mon Sep 17 00:00:00 2001 From: Hans-Christoph Steiner Date: Fri, 30 Mar 2012 20:42:12 -0400 Subject: Imported Upstream version 2.0.3 --- src/mutex_w32.c | 332 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 332 insertions(+) create mode 100644 src/mutex_w32.c (limited to 'src/mutex_w32.c') diff --git a/src/mutex_w32.c b/src/mutex_w32.c new file mode 100644 index 0000000..bfd9dac --- /dev/null +++ b/src/mutex_w32.c @@ -0,0 +1,332 @@ +/* +** 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 +*/ +#include "sqliteInt.h" + +/* +** The code in this file is only used if we are compiling multithreaded +** on a win32 system. +*/ +#ifdef SQLITE_MUTEX_W32 + +/* +** Each recursive mutex is an instance of the following structure. +*/ +struct sqlite3_mutex { + 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 */ +#endif +}; +#define SQLITE_W32_MUTEX_INITIALIZER { 0 } +#ifdef 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 } +#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 +# 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 + +#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(); + return winMutexNotheld2(p, tid); +} +#endif + + +/* +** Initialize and deinitialize the mutex subsystem. +*/ +static sqlite3_mutex winMutex_staticMutexes[6] = { + SQLITE3_MUTEX_INITIALIZER, + SQLITE3_MUTEX_INITIALIZER, + 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. +*/ +static long winMutex_lock = 0; + +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 +**
  • SQLITE_MUTEX_FAST +**
  • SQLITE_MUTEX_RECURSIVE +**
  • SQLITE_MUTEX_STATIC_MASTER +**
  • SQLITE_MUTEX_STATIC_MEM +**
  • SQLITE_MUTEX_STATIC_MEM2 +**
  • SQLITE_MUTEX_STATIC_PRNG +**
  • SQLITE_MUTEX_STATIC_LRU +**
  • SQLITE_MUTEX_STATIC_PMEM +** +** +** 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 = sqlite3MallocZero( sizeof(*p) ); + if( p ){ +#ifdef SQLITE_DEBUG + p->id = iType; +#endif + InitializeCriticalSection(&p->mutex); + } + break; + } + default: { + assert( winMutex_isInit==1 ); + assert( iType-2 >= 0 ); + assert( iType-2 < ArraySize(winMutex_staticMutexes) ); + p = &winMutex_staticMutexes[iType-2]; +#ifdef SQLITE_DEBUG + p->id = iType; +#endif + 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){ + assert( p ); + assert( p->nRef==0 && p->owner==0 ); + assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE ); + DeleteCriticalSection(&p->mutex); + 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){ +#ifdef SQLITE_DEBUG + DWORD tid = GetCurrentThreadId(); + assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) ); +#endif + EnterCriticalSection(&p->mutex); +#ifdef SQLITE_DEBUG + assert( p->nRef>0 || p->owner==0 ); + p->owner = tid; + p->nRef++; + if( p->trace ){ + printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef); + } +#endif +} +static int winMutexTry(sqlite3_mutex *p){ +#ifndef NDEBUG + DWORD tid = GetCurrentThreadId(); +#endif + int rc = SQLITE_BUSY; + 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 0 + if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){ + p->owner = tid; + p->nRef++; + 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); + } +#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){ +#ifndef NDEBUG + DWORD tid = GetCurrentThreadId(); + 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); + } +#endif +} + +sqlite3_mutex_methods const *sqlite3DefaultMutex(void){ + static const sqlite3_mutex_methods sMutex = { + winMutexInit, + winMutexEnd, + winMutexAlloc, + winMutexFree, + winMutexEnter, + winMutexTry, + winMutexLeave, +#ifdef SQLITE_DEBUG + winMutexHeld, + winMutexNotheld +#else + 0, + 0 +#endif + }; + + return &sMutex; +} +#endif /* SQLITE_MUTEX_W32 */ -- cgit v1.2.3