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Diffstat (limited to 'ext/pdo_sqlite/sqlite/src/mutex_w32.c')
| -rw-r--r-- | ext/pdo_sqlite/sqlite/src/mutex_w32.c | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/ext/pdo_sqlite/sqlite/src/mutex_w32.c b/ext/pdo_sqlite/sqlite/src/mutex_w32.c new file mode 100644 index 0000000000..9843c5222d --- /dev/null +++ b/ext/pdo_sqlite/sqlite/src/mutex_w32.c @@ -0,0 +1,219 @@ +/* +** 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 +** +** $Id$ +*/ +#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 */ + int nRef; /* Number of enterances */ + DWORD owner; /* Thread holding this mutex */ +}; + +/* +** 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. +*/ +#if 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 /* OS_WINCE */ + + +/* +** 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 0 +** <li> SQLITE_MUTEX_RECURSIVE 1 +** <li> SQLITE_MUTEX_STATIC_MASTER 2 +** <li> SQLITE_MUTEX_STATIC_MEM 3 +** <li> SQLITE_MUTEX_STATIC_PRNG 4 +** </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. Three 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. +*/ +sqlite3_mutex *sqlite3_mutex_alloc(int iType){ + sqlite3_mutex *p; + + switch( iType ){ + case SQLITE_MUTEX_FAST: + case SQLITE_MUTEX_RECURSIVE: { + p = sqlite3MallocZero( sizeof(*p) ); + if( p ){ + p->id = iType; + InitializeCriticalSection(&p->mutex); + } + break; + } + default: { + static sqlite3_mutex staticMutexes[5]; + static int isInit = 0; + while( !isInit ){ + static long lock = 0; + if( InterlockedIncrement(&lock)==1 ){ + int i; + for(i=0; i<sizeof(staticMutexes)/sizeof(staticMutexes[0]); i++){ + InitializeCriticalSection(&staticMutexes[i].mutex); + } + isInit = 1; + }else{ + Sleep(1); + } + } + assert( iType-2 >= 0 ); + assert( iType-2 < sizeof(staticMutexes)/sizeof(staticMutexes[0]) ); + p = &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. +*/ +void sqlite3_mutex_free(sqlite3_mutex *p){ + assert( p ); + assert( p->nRef==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. +*/ +void sqlite3_mutex_enter(sqlite3_mutex *p){ + assert( p ); + assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) ); + EnterCriticalSection(&p->mutex); + p->owner = GetCurrentThreadId(); + p->nRef++; +} +int sqlite3_mutex_try(sqlite3_mutex *p){ + int rc = SQLITE_BUSY; + assert( p ); + assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) ); + /* + ** 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 = GetCurrentThreadId(); + p->nRef++; + rc = SQLITE_OK; + } +#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. +*/ +void sqlite3_mutex_leave(sqlite3_mutex *p){ + assert( p->nRef>0 ); + assert( p->owner==GetCurrentThreadId() ); + p->nRef--; + assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE ); + LeaveCriticalSection(&p->mutex); +} + +/* +** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are +** intended for use only inside assert() statements. +*/ +int sqlite3_mutex_held(sqlite3_mutex *p){ + return p==0 || (p->nRef!=0 && p->owner==GetCurrentThreadId()); +} +int sqlite3_mutex_notheld(sqlite3_mutex *p){ + return p==0 || p->nRef==0 || p->owner!=GetCurrentThreadId(); +} +#endif /* SQLITE_MUTEX_W32 */ |
