diff options
Diffstat (limited to 'include/my_pthread.h')
| -rw-r--r-- | include/my_pthread.h | 206 |
1 files changed, 145 insertions, 61 deletions
diff --git a/include/my_pthread.h b/include/my_pthread.h index 8a7976bb334..c0321cde6ed 100644 --- a/include/my_pthread.h +++ b/include/my_pthread.h @@ -1,4 +1,4 @@ -/* Copyright (C) 2000-2008 MySQL AB, 2008-2009 Sun Microsystems, Inc. +/* Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -48,19 +48,30 @@ typedef struct st_pthread_link { struct st_pthread_link *next; } pthread_link; -typedef struct { - uint32 waiting; - CRITICAL_SECTION lock_waiting; - - enum { - SIGNAL= 0, - BROADCAST= 1, - MAX_EVENTS= 2 - } EVENTS; - - HANDLE events[MAX_EVENTS]; - HANDLE broadcast_block_event; - +/** + Implementation of Windows condition variables. + We use native conditions on Vista and later, and fallback to own + implementation on earlier OS version. +*/ +typedef union +{ + /* Native condition (used on Vista and later) */ + CONDITION_VARIABLE native_cond; + + /* Own implementation (used on XP) */ + struct + { + uint32 waiting; + CRITICAL_SECTION lock_waiting; + enum + { + SIGNAL= 0, + BROADCAST= 1, + MAX_EVENTS= 2 + } EVENTS; + HANDLE events[MAX_EVENTS]; + HANDLE broadcast_block_event; + }; } pthread_cond_t; @@ -206,7 +217,11 @@ int pthread_cancel(pthread_t thread); typedef void *(* pthread_handler)(void *); #define my_pthread_once_t pthread_once_t +#if defined(PTHREAD_ONCE_INITIALIZER) +#define MY_PTHREAD_ONCE_INIT PTHREAD_ONCE_INITIALIZER +#else #define MY_PTHREAD_ONCE_INIT PTHREAD_ONCE_INIT +#endif #define my_pthread_once(C,F) pthread_once(C,F) /* Test first for RTS or FSU threads */ @@ -488,7 +503,8 @@ int safe_mutex_destroy(safe_mutex_t *mp,const char *file, uint line); int safe_cond_wait(pthread_cond_t *cond, safe_mutex_t *mp,const char *file, uint line); int safe_cond_timedwait(pthread_cond_t *cond, safe_mutex_t *mp, - struct timespec *abstime, const char *file, uint line); + const struct timespec *abstime, + const char *file, uint line); void safe_mutex_global_init(void); void safe_mutex_end(FILE *file); void safe_mutex_free_deadlock_data(safe_mutex_t *mp); @@ -598,7 +614,7 @@ int my_pthread_fastmutex_lock(my_pthread_fastmutex_t *mp); /* Use our own version of read/write locks */ #define NEED_MY_RW_LOCK 1 #define rw_lock_t my_rw_lock_t -#define my_rwlock_init(A,B) my_rw_init((A), 0) +#define my_rwlock_init(A,B) my_rw_init((A)) #define rw_rdlock(A) my_rw_rdlock((A)) #define rw_wrlock(A) my_rw_wrlock((A)) #define rw_tryrdlock(A) my_rw_tryrdlock((A)) @@ -610,49 +626,123 @@ int my_pthread_fastmutex_lock(my_pthread_fastmutex_t *mp); #endif /* USE_MUTEX_INSTEAD_OF_RW_LOCKS */ -/* - Portable read-write locks which prefer readers. - - Required by some algorithms in order to provide correctness. +/** + Portable implementation of special type of read-write locks. + + These locks have two properties which are unusual for rwlocks: + 1) They "prefer readers" in the sense that they do not allow + situations in which rwlock is rd-locked and there is a + pending rd-lock which is blocked (e.g. due to pending + request for wr-lock). + This is a stronger guarantee than one which is provided for + PTHREAD_RWLOCK_PREFER_READER_NP rwlocks in Linux. + MDL subsystem deadlock detector relies on this property for + its correctness. + 2) They are optimized for uncontended wr-lock/unlock case. + This is scenario in which they are most oftenly used + within MDL subsystem. Optimizing for it gives significant + performance improvements in some of tests involving many + connections. + + Another important requirement imposed on this type of rwlock + by the MDL subsystem is that it should be OK to destroy rwlock + object which is in unlocked state even though some threads might + have not yet fully left unlock operation for it (of course there + is an external guarantee that no thread will try to lock rwlock + which is destroyed). + Putting it another way the unlock operation should not access + rwlock data after changing its state to unlocked. + + TODO/FIXME: We should consider alleviating this requirement as + it blocks us from doing certain performance optimizations. */ -#if defined(HAVE_PTHREAD_RWLOCK_RDLOCK) && defined(HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP) -/* - On systems which have a way to specify that readers should - be preferred through attribute mechanism (e.g. Linux) we use - system implementation of read/write locks. -*/ -#define rw_pr_lock_t pthread_rwlock_t +typedef struct st_rw_pr_lock_t { + /** + Lock which protects the structure. + Also held for the duration of wr-lock. + */ + pthread_mutex_t lock; + /** + Condition variable which is used to wake-up + writers waiting for readers to go away. + */ + pthread_cond_t no_active_readers; + /** Number of active readers. */ + uint active_readers; + /** Number of writers waiting for readers to go away. */ + uint writers_waiting_readers; + /** Indicates whether there is an active writer. */ + my_bool active_writer; +#ifdef SAFE_MUTEX + /** Thread holding wr-lock (for debug purposes only). */ + pthread_t writer_thread; +#endif +} rw_pr_lock_t; + extern int rw_pr_init(rw_pr_lock_t *); -#define rw_pr_rdlock(A) pthread_rwlock_rdlock(A) -#define rw_pr_wrlock(A) pthread_rwlock_wrlock(A) -#define rw_pr_tryrdlock(A) pthread_rwlock_tryrdlock(A) -#define rw_pr_trywrlock(A) pthread_rwlock_trywrlock(A) -#define rw_pr_unlock(A) pthread_rwlock_unlock(A) -#define rw_pr_destroy(A) pthread_rwlock_destroy(A) +extern int rw_pr_rdlock(rw_pr_lock_t *); +extern int rw_pr_wrlock(rw_pr_lock_t *); +extern int rw_pr_unlock(rw_pr_lock_t *); +extern int rw_pr_destroy(rw_pr_lock_t *); +#ifdef SAFE_MUTEX +#define rw_pr_lock_assert_write_owner(A) \ + DBUG_ASSERT((A)->active_writer && pthread_equal(pthread_self(), \ + (A)->writer_thread)) +#define rw_pr_lock_assert_not_write_owner(A) \ + DBUG_ASSERT(! (A)->active_writer || ! pthread_equal(pthread_self(), \ + (A)->writer_thread)) +#else #define rw_pr_lock_assert_write_owner(A) #define rw_pr_lock_assert_not_write_owner(A) -#else -/* Otherwise we have to use our own implementation of read/write locks. */ -#define NEED_MY_RW_LOCK 1 -struct st_my_rw_lock_t; -#define rw_pr_lock_t my_rw_lock_t -extern int rw_pr_init(struct st_my_rw_lock_t *); -#define rw_pr_rdlock(A) my_rw_rdlock((A)) -#define rw_pr_wrlock(A) my_rw_wrlock((A)) -#define rw_pr_tryrdlock(A) my_rw_tryrdlock((A)) -#define rw_pr_trywrlock(A) my_rw_trywrlock((A)) -#define rw_pr_unlock(A) my_rw_unlock((A)) -#define rw_pr_destroy(A) my_rw_destroy((A)) -#define rw_pr_lock_assert_write_owner(A) my_rw_lock_assert_write_owner((A)) -#define rw_pr_lock_assert_not_write_owner(A) my_rw_lock_assert_not_write_owner((A)) -#endif /* defined(HAVE_PTHREAD_RWLOCK_RDLOCK) && defined(HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP) */ +#endif /* SAFE_MUTEX */ #ifdef NEED_MY_RW_LOCK + +#ifdef _WIN32 + +/** + Implementation of Windows rwlock. + + We use native (slim) rwlocks on Win7 and later, and fallback to portable + implementation on earlier Windows. + + slim rwlock are also available on Vista/WS2008, but we do not use it + ("trylock" APIs are missing on Vista) +*/ +typedef union +{ + /* Native rwlock (is_srwlock == TRUE) */ + struct + { + SRWLOCK srwlock; /* native reader writer lock */ + BOOL have_exclusive_srwlock; /* used for unlock */ + }; + + /* + Portable implementation (is_srwlock == FALSE) + Fields are identical with Unix my_rw_lock_t fields. + */ + struct + { + pthread_mutex_t lock; /* lock for structure */ + pthread_cond_t readers; /* waiting readers */ + pthread_cond_t writers; /* waiting writers */ + int state; /* -1:writer,0:free,>0:readers */ + int waiters; /* number of waiting writers */ +#ifdef SAFE_MUTEX + pthread_t write_thread; +#endif + }; +} my_rw_lock_t; + + +#else /* _WIN32 */ + /* - On systems which don't support native read/write locks, or don't support - read/write locks which prefer readers we have to use own implementation. + On systems which don't support native read/write locks we have + to use own implementation. */ typedef struct st_my_rw_lock_t { pthread_mutex_t lock; /* lock for structure */ @@ -660,13 +750,14 @@ typedef struct st_my_rw_lock_t { pthread_cond_t writers; /* waiting writers */ int state; /* -1:writer,0:free,>0:readers */ int waiters; /* number of waiting writers */ - my_bool prefer_readers; #ifdef SAFE_MUTEX pthread_t write_thread; #endif } my_rw_lock_t; -extern int my_rw_init(my_rw_lock_t *, my_bool *); +#endif /*! _WIN32 */ + +extern int my_rw_init(my_rw_lock_t *); extern int my_rw_destroy(my_rw_lock_t *); extern int my_rw_rdlock(my_rw_lock_t *); extern int my_rw_wrlock(my_rw_lock_t *); @@ -720,8 +811,7 @@ typedef ulong my_thread_id; extern void my_threadattr_global_init(void); extern my_bool my_thread_global_init(void); -extern my_bool my_thread_basic_global_init(void); -extern void my_thread_basic_global_reinit(void); +extern void my_thread_global_reinit(void); extern void my_thread_global_end(void); extern my_bool my_thread_init(void); extern void my_thread_end(void); @@ -800,12 +890,6 @@ extern uint thd_lib_detected; to use my_atomic operations instead. */ -/* - Warning: - When compiling without threads, this file is not included. - See the *other* declarations of thread_safe_xxx in include/my_global.h -*/ -#ifdef THREAD #ifndef thread_safe_increment #ifdef _WIN32 #define thread_safe_increment(V,L) InterlockedIncrement((long*) &(V)) @@ -829,7 +913,7 @@ extern uint thd_lib_detected; (mysql_mutex_lock((L)), (V)-=(C), mysql_mutex_unlock((L))) #endif #endif -#endif + /* statistics_xxx functions are for non critical statistic, |