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Diffstat (limited to 'src/mutex_w32.c')
| -rw-r--r-- | src/mutex_w32.c | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/src/mutex_w32.c b/src/mutex_w32.c new file mode 100644 index 0000000..7eb5b50 --- /dev/null +++ b/src/mutex_w32.c @@ -0,0 +1,399 @@ +/* +** 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" + +#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. +*/ +#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 entrances */ + volatile DWORD owner; /* Thread holding this mutex */ + volatile LONG 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(id) { SQLITE_W32_MUTEX_INITIALIZER, id, \ + 0L, (DWORD)0, 0 } +#else +#define SQLITE3_MUTEX_INITIALIZER(id) { SQLITE_W32_MUTEX_INITIALIZER, id } +#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 + +/* +** Try to provide a memory barrier operation, needed for initialization +** and also for the xShmBarrier method of the VFS in cases when SQLite is +** compiled without mutexes (SQLITE_THREADSAFE=0). +*/ +void sqlite3MemoryBarrier(void){ +#if defined(SQLITE_MEMORY_BARRIER) + SQLITE_MEMORY_BARRIER; +#elif defined(__GNUC__) + __sync_synchronize(); +#elif MSVC_VERSION>=1400 + _ReadWriteBarrier(); +#elif defined(MemoryBarrier) + MemoryBarrier(); +#endif +} + +/* +** Initialize and deinitialize the mutex subsystem. +*/ +static sqlite3_mutex winMutex_staticMutexes[] = { + SQLITE3_MUTEX_INITIALIZER(2), + SQLITE3_MUTEX_INITIALIZER(3), + SQLITE3_MUTEX_INITIALIZER(4), + SQLITE3_MUTEX_INITIALIZER(5), + SQLITE3_MUTEX_INITIALIZER(6), + SQLITE3_MUTEX_INITIALIZER(7), + SQLITE3_MUTEX_INITIALIZER(8), + SQLITE3_MUTEX_INITIALIZER(9), + SQLITE3_MUTEX_INITIALIZER(10), + SQLITE3_MUTEX_INITIALIZER(11), + SQLITE3_MUTEX_INITIALIZER(12), + SQLITE3_MUTEX_INITIALIZER(13) +}; + +static int winMutex_isInit = 0; +static int winMutex_isNt = -1; /* <0 means "need to query" */ + +/* As the winMutexInit() and winMutexEnd() functions are called as part +** of the sqlite3_initialize() and sqlite3_shutdown() processing, the +** "interlocked" magic used here is probably not strictly necessary. +*/ +static LONG SQLITE_WIN32_VOLATILE 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){ + /* 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 + InitializeCriticalSectionEx(&winMutex_staticMutexes[i].mutex, 0, 0); +#else + InitializeCriticalSection(&winMutex_staticMutexes[i].mutex); +#endif + } + winMutex_isInit = 1; + }else{ + /* Another thread is (in the process of) initializing the static + ** mutexes */ + while( !winMutex_isInit ){ + sqlite3_win32_sleep(1); + } + } + return SQLITE_OK; +} + +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++){ + 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_MAIN +** <li> SQLITE_MUTEX_STATIC_MEM +** <li> SQLITE_MUTEX_STATIC_OPEN +** <li> SQLITE_MUTEX_STATIC_PRNG +** <li> SQLITE_MUTEX_STATIC_LRU +** <li> SQLITE_MUTEX_STATIC_PMEM +** <li> SQLITE_MUTEX_STATIC_APP1 +** <li> SQLITE_MUTEX_STATIC_APP2 +** <li> SQLITE_MUTEX_STATIC_APP3 +** <li> SQLITE_MUTEX_STATIC_VFS1 +** <li> SQLITE_MUTEX_STATIC_VFS2 +** <li> SQLITE_MUTEX_STATIC_VFS3 +** </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 = sqlite3MallocZero( sizeof(*p) ); + if( p ){ + p->id = iType; +#ifdef SQLITE_DEBUG +#ifdef SQLITE_WIN32_MUTEX_TRACE_DYNAMIC + p->trace = 1; +#endif +#endif +#if SQLITE_OS_WINRT + InitializeCriticalSectionEx(&p->mutex, 0, 0); +#else + InitializeCriticalSection(&p->mutex); +#endif + } + break; + } + default: { +#ifdef SQLITE_ENABLE_API_ARMOR + if( iType-2<0 || iType-2>=ArraySize(winMutex_staticMutexes) ){ + (void)SQLITE_MISUSE_BKPT; + return 0; + } +#endif + p = &winMutex_staticMutexes[iType-2]; +#ifdef SQLITE_DEBUG +#ifdef SQLITE_WIN32_MUTEX_TRACE_STATIC + InterlockedCompareExchange(&p->trace, 1, 0); +#endif +#endif + break; + } + } + assert( p==0 || p->id==iType ); + 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 ); + if( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE ){ + DeleteCriticalSection(&p->mutex); + sqlite3_free(p); + }else{ +#ifdef SQLITE_ENABLE_API_ARMOR + (void)SQLITE_MISUSE_BKPT; +#endif + } +} + +/* +** 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){ +#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST) + DWORD tid = GetCurrentThreadId(); +#endif +#ifdef SQLITE_DEBUG + assert( p ); + assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) ); +#else + assert( p ); +#endif + assert( winMutex_isInit==1 ); + EnterCriticalSection(&p->mutex); +#ifdef SQLITE_DEBUG + assert( p->nRef>0 || p->owner==0 ); + p->owner = tid; + p->nRef++; + if( p->trace ){ + OSTRACE(("ENTER-MUTEX tid=%lu, mutex(%d)=%p (%d), nRef=%d\n", + tid, p->id, p, p->trace, p->nRef)); + } +#endif +} + +static int winMutexTry(sqlite3_mutex *p){ +#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. + ** + ** 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 defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0400 + assert( winMutex_isInit==1 ); + assert( winMutex_isNt>=-1 && winMutex_isNt<=1 ); + if( winMutex_isNt<0 ){ + winMutex_isNt = sqlite3_win32_is_nt(); + } + assert( winMutex_isNt==0 || winMutex_isNt==1 ); + if( winMutex_isNt && TryEnterCriticalSection(&p->mutex) ){ +#ifdef SQLITE_DEBUG + p->owner = tid; + p->nRef++; +#endif + rc = SQLITE_OK; + } +#else + UNUSED_PARAMETER(p); +#endif +#ifdef SQLITE_DEBUG + if( p->trace ){ + OSTRACE(("TRY-MUTEX tid=%lu, mutex(%d)=%p (%d), owner=%lu, nRef=%d, rc=%s\n", + tid, p->id, p, p->trace, p->owner, p->nRef, sqlite3ErrName(rc))); + } +#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 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 + assert( winMutex_isInit==1 ); + LeaveCriticalSection(&p->mutex); +#ifdef SQLITE_DEBUG + if( p->trace ){ + OSTRACE(("LEAVE-MUTEX tid=%lu, mutex(%d)=%p (%d), nRef=%d\n", + tid, p->id, 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 */ |