From 354ea97baf765759911f0c56d3ed511350ebe348 Mon Sep 17 00:00:00 2001 From: dan miller Date: Sat, 20 Oct 2007 05:34:26 +0000 Subject: sqlite 3.5.1 windows source --- libraries/sqlite/win32/mutex_unix.c | 223 ++++++++++++++++++++++++++++++++++++ 1 file changed, 223 insertions(+) create mode 100755 libraries/sqlite/win32/mutex_unix.c (limited to 'libraries/sqlite/win32/mutex_unix.c') diff --git a/libraries/sqlite/win32/mutex_unix.c b/libraries/sqlite/win32/mutex_unix.c new file mode 100755 index 0000000..ff088fb --- /dev/null +++ b/libraries/sqlite/win32/mutex_unix.c @@ -0,0 +1,223 @@ +/* +** 2007 August 28 +** +** 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 pthreads +** +** $Id: mutex_unix.c,v 1.2 2007/08/28 22:24:35 drh Exp $ +*/ +#include "sqliteInt.h" + +/* +** The code in this file is only used if we are compiling threadsafe +** under unix with pthreads. +** +** Note that this implementation requires a version of pthreads that +** supports recursive mutexes. +*/ +#ifdef SQLITE_MUTEX_PTHREADS + +#include + +/* +** Each recursive mutex is an instance of the following structure. +*/ +struct sqlite3_mutex { + pthread_mutex_t mutex; /* Mutex controlling the lock */ + int id; /* Mutex type */ + int nRef; /* Number of entrances */ + pthread_t owner; /* Thread that is within this mutex */ +#ifdef SQLITE_DEBUG + int trace; /* True to trace changes */ +#endif +}; + +/* +** 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: +** +** +** +** 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){ + static sqlite3_mutex staticMutexes[] = { + { PTHREAD_MUTEX_INITIALIZER, }, + { PTHREAD_MUTEX_INITIALIZER, }, + { PTHREAD_MUTEX_INITIALIZER, }, + { PTHREAD_MUTEX_INITIALIZER, }, + { PTHREAD_MUTEX_INITIALIZER, }, + }; + sqlite3_mutex *p; + switch( iType ){ + case SQLITE_MUTEX_RECURSIVE: { + p = sqlite3MallocZero( sizeof(*p) ); + if( p ){ + pthread_mutexattr_t recursiveAttr; + pthread_mutexattr_init(&recursiveAttr); + pthread_mutexattr_settype(&recursiveAttr, PTHREAD_MUTEX_RECURSIVE); + pthread_mutex_init(&p->mutex, &recursiveAttr); + pthread_mutexattr_destroy(&recursiveAttr); + p->id = iType; + } + break; + } + case SQLITE_MUTEX_FAST: { + p = sqlite3MallocZero( sizeof(*p) ); + if( p ){ + p->id = iType; + pthread_mutex_init(&p->mutex, 0); + } + break; + } + default: { + 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 ); + pthread_mutex_destroy(&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) ); + pthread_mutex_lock(&p->mutex); + p->owner = pthread_self(); + p->nRef++; +#ifdef SQLITE_DEBUG + if( p->trace ){ + printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef); + } +#endif +} +int sqlite3_mutex_try(sqlite3_mutex *p){ + int rc; + assert( p ); + assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) ); + if( pthread_mutex_trylock(&p->mutex)==0 ){ + p->owner = pthread_self(); + p->nRef++; + rc = SQLITE_OK; +#ifdef SQLITE_DEBUG + if( p->trace ){ + printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef); + } +#endif + }else{ + rc = SQLITE_BUSY; + } + 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 ); + assert( sqlite3_mutex_held(p) ); + p->nRef--; + assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE ); +#ifdef SQLITE_DEBUG + if( p->trace ){ + printf("leave mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef); + } +#endif + pthread_mutex_unlock(&p->mutex); +} + +/* +** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are +** intended for use only inside assert() statements. On some platforms, +** there might be race conditions that can cause these routines to +** deliver incorrect results. In particular, if pthread_equal() is +** not an atomic operation, then these routines might delivery +** incorrect results. On most platforms, pthread_equal() is a +** comparison of two integers and is therefore atomic. But we are +** told that HPUX is not such a platform. If so, then these routines +** will not always work correctly on HPUX. +** +** On those platforms where pthread_equal() is not atomic, SQLite +** should be compiled without -DSQLITE_DEBUG and with -DNDEBUG to +** make sure no assert() statements are evaluated and hence these +** routines are never called. +*/ +#ifndef NDEBUG +int sqlite3_mutex_held(sqlite3_mutex *p){ + return p==0 || (p->nRef!=0 && pthread_equal(p->owner, pthread_self())); +} +int sqlite3_mutex_notheld(sqlite3_mutex *p){ + return p==0 || p->nRef==0 || pthread_equal(p->owner, pthread_self())==0; +} +#endif +#endif /* SQLITE_MUTEX_PTHREAD */ -- cgit v1.1