X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fovs-thread.h;h=b6d973f6e46beffd20f107970988d4eb5474ed24;hb=4b0424809b823101c969a0691fc1db0c880ae64a;hp=0a5a4337293b1100c9c77a52d4c8a3ab3cda653d;hpb=c22095a5fb199723cbccc7156cc345260fe99731;p=sliver-openvswitch.git diff --git a/lib/ovs-thread.h b/lib/ovs-thread.h index 0a5a43372..b6d973f6e 100644 --- a/lib/ovs-thread.h +++ b/lib/ovs-thread.h @@ -18,58 +18,102 @@ #define OVS_THREAD_H 1 #include +#include +#include +#include "ovs-atomic.h" #include "util.h" -/* glibc has some non-portable mutex types and initializers: - * - * - PTHREAD_MUTEX_ADAPTIVE_NP is a mutex type that works as a spinlock that - * falls back to a mutex after spinning for some number of iterations. - * - * - PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP is a non-portable initializer - * for an error-checking mutex. - * - * We use these definitions to fall back to PTHREAD_MUTEX_NORMAL instead in - * these cases. - * - * (glibc has other non-portable initializers, but we can't reasonably - * substitute for them here.) */ -#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP -#define PTHREAD_MUTEX_ADAPTIVE PTHREAD_MUTEX_ADAPTIVE_NP -#define PTHREAD_ADAPTIVE_MUTEX_INITIALIZER \ - PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP -#else -#define PTHREAD_MUTEX_ADAPTIVE PTHREAD_MUTEX_NORMAL -#define PTHREAD_ADAPTIVE_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER -#endif +/* Mutex. */ +struct OVS_LOCKABLE ovs_mutex { + pthread_mutex_t lock; + const char *where; +}; + +/* "struct ovs_mutex" initializer. */ #ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP -#define PTHREAD_ERRORCHECK_MUTEX_INITIALIZER \ - PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP +#define OVS_MUTEX_INITIALIZER { PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, NULL } #else -#define PTHREAD_ERRORCHECK_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER +#define OVS_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER, NULL } #endif - -/* Simple wrappers for pthreads functions. Most of these functions abort the - * process with an error message on any error. The *_trylock() functions are - * exceptions: they pass through a 0 or EBUSY return value to the caller and - * abort on any other error. */ -void xpthread_mutex_init(pthread_mutex_t *, pthread_mutexattr_t *); -void xpthread_mutex_lock(pthread_mutex_t *mutex) OVS_ACQUIRES(mutex); -void xpthread_mutex_unlock(pthread_mutex_t *mutex) OVS_RELEASES(mutex); -int xpthread_mutex_trylock(pthread_mutex_t *); - -void xpthread_rwlock_init(pthread_rwlock_t *, pthread_rwlockattr_t *); -void xpthread_rwlock_rdlock(pthread_rwlock_t *rwlock) OVS_ACQUIRES(rwlock); -void xpthread_rwlock_wrlock(pthread_rwlock_t *rwlock) OVS_ACQUIRES(rwlock); -void xpthread_rwlock_unlock(pthread_rwlock_t *rwlock) OVS_RELEASES(rwlock); -int xpthread_rwlock_tryrdlock(pthread_rwlock_t *); -int xpthread_rwlock_trywrlock(pthread_rwlock_t *); +/* ovs_mutex functions analogous to pthread_mutex_*() functions. + * + * Most of these functions abort the process with an error message on any + * error. ovs_mutex_trylock() is an exception: it passes through a 0 or EBUSY + * return value to the caller and aborts on any other error. */ +void ovs_mutex_init(const struct ovs_mutex *); +void ovs_mutex_init_recursive(const struct ovs_mutex *); +void ovs_mutex_destroy(const struct ovs_mutex *); +void ovs_mutex_unlock(const struct ovs_mutex *mutex) OVS_RELEASES(mutex); +void ovs_mutex_lock_at(const struct ovs_mutex *mutex, const char *where) + OVS_ACQUIRES(mutex); +#define ovs_mutex_lock(mutex) \ + ovs_mutex_lock_at(mutex, SOURCE_LOCATOR) + +int ovs_mutex_trylock_at(const struct ovs_mutex *mutex, const char *where) + OVS_TRY_LOCK(0, mutex); +#define ovs_mutex_trylock(mutex) \ + ovs_mutex_trylock_at(mutex, SOURCE_LOCATOR) + +void ovs_mutex_cond_wait(pthread_cond_t *, const struct ovs_mutex *); + +/* Wrappers for pthread_mutex_*() that abort the process on any error. + * This is still needed when ovs-atomic-pthreads.h is used. */ +void xpthread_mutex_lock(pthread_mutex_t *mutex); +void xpthread_mutex_unlock(pthread_mutex_t *mutex); + +/* Wrappers for pthread_mutexattr_*() that abort the process on any error. */ +void xpthread_mutexattr_init(pthread_mutexattr_t *); +void xpthread_mutexattr_destroy(pthread_mutexattr_t *); +void xpthread_mutexattr_settype(pthread_mutexattr_t *, int type); +void xpthread_mutexattr_gettype(pthread_mutexattr_t *, int *typep); + +/* Read-write lock. */ +struct OVS_LOCKABLE ovs_rwlock { + pthread_rwlock_t lock; + const char *where; +}; + +/* Initializer. */ +#define OVS_RWLOCK_INITIALIZER { PTHREAD_RWLOCK_INITIALIZER, NULL } + +/* ovs_rwlock functions analogous to pthread_rwlock_*() functions. + * + * Most of these functions abort the process with an error message on any + * error. The "trylock" functions are exception: they pass through a 0 or + * EBUSY return value to the caller and abort on any other error. */ +void ovs_rwlock_init(const struct ovs_rwlock *); +void ovs_rwlock_destroy(const struct ovs_rwlock *); +void ovs_rwlock_unlock(const struct ovs_rwlock *rwlock) OVS_RELEASES(rwlock); + +void ovs_rwlock_wrlock_at(const struct ovs_rwlock *rwlock, const char *where) + OVS_ACQ_WRLOCK(rwlock); +#define ovs_rwlock_wrlock(rwlock) \ + ovs_rwlock_wrlock_at(rwlock, SOURCE_LOCATOR) + +int ovs_rwlock_trywrlock_at(const struct ovs_rwlock *rwlock, const char *where) + OVS_TRY_WRLOCK(0, rwlock); +#define ovs_rwlock_trywrlock(rwlock) \ + ovs_rwlock_trywrlock_at(rwlock, SOURCE_LOCATOR) + +void ovs_rwlock_rdlock_at(const struct ovs_rwlock *rwlock, const char *where) + OVS_ACQ_RDLOCK(rwlock); +#define ovs_rwlock_rdlock(rwlock) \ + ovs_rwlock_rdlock_at(rwlock, SOURCE_LOCATOR) + +int ovs_rwlock_tryrdlock_at(const struct ovs_rwlock *rwlock, const char *where) + OVS_TRY_RDLOCK(0, rwlock); +#define ovs_rwlock_tryrdlock(rwlock) \ + ovs_rwlock_tryrdlock_at(rwlock, SOURCE_LOCATOR) + +/* Wrappers for xpthread_cond_*() that abort the process on any error. + * + * Use ovs_mutex_cond_wait() to wait for a condition. */ void xpthread_cond_init(pthread_cond_t *, pthread_condattr_t *); +void xpthread_cond_destroy(pthread_cond_t *); void xpthread_cond_signal(pthread_cond_t *); void xpthread_cond_broadcast(pthread_cond_t *); -void xpthread_cond_wait(pthread_cond_t *, pthread_mutex_t *mutex) - OVS_MUST_HOLD(mutex); #ifdef __CHECKER__ /* Replace these functions by the macros already defined in the @@ -83,8 +127,10 @@ void xpthread_cond_wait(pthread_cond_t *, pthread_mutex_t *mutex) #endif void xpthread_key_create(pthread_key_t *, void (*destructor)(void *)); +void xpthread_setspecific(pthread_key_t, const void *); void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *); +void xpthread_join(pthread_t, void **); /* Per-thread data. * @@ -122,7 +168,15 @@ void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *); * cross-thread access? yes no yes */ -/* DEFINE_PER_THREAD_DATA(TYPE, NAME, INITIALIZER). +/* For static data, use this macro in a source file: + * + * DEFINE_STATIC_PER_THREAD_DATA(TYPE, NAME, INITIALIZER). + * + * For global data, "declare" the data in the header and "define" it in + * the source file, with: + * + * DECLARE_EXTERN_PER_THREAD_DATA(TYPE, NAME). + * DEFINE_EXTERN_PER_THREAD_DATA(NAME, INITIALIZER). * * One should prefer to use POSIX per-thread data, via pthread_key_t, when its * performance is acceptable, because of its portability (see the table above). @@ -160,23 +214,40 @@ void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *); #error #endif -#define DEFINE_PER_THREAD_DATA(TYPE, NAME, ...) \ - typedef TYPE NAME##_type; \ - static thread_local NAME##_type NAME##_var = __VA_ARGS__; \ - \ - static NAME##_type * \ - NAME##_get_unsafe(void) \ - { \ - return &NAME##_var; \ - } \ - \ - static NAME##_type * \ - NAME##_get(void) \ - { \ - return NAME##_get_unsafe(); \ +#define DEFINE_STATIC_PER_THREAD_DATA(TYPE, NAME, ...) \ + typedef TYPE NAME##_type; \ + \ + static NAME##_type * \ + NAME##_get_unsafe(void) \ + { \ + static thread_local NAME##_type var = __VA_ARGS__; \ + return &var; \ + } \ + \ + static NAME##_type * \ + NAME##_get(void) \ + { \ + return NAME##_get_unsafe(); \ + } +#define DECLARE_EXTERN_PER_THREAD_DATA(TYPE, NAME) \ + typedef TYPE NAME##_type; \ + extern thread_local NAME##_type NAME##_var; \ + \ + static inline NAME##_type * \ + NAME##_get_unsafe(void) \ + { \ + return &NAME##_var; \ + } \ + \ + static inline NAME##_type * \ + NAME##_get(void) \ + { \ + return NAME##_get_unsafe(); \ } +#define DEFINE_EXTERN_PER_THREAD_DATA(NAME, ...) \ + thread_local NAME##_type NAME##_var = __VA_ARGS__; #else /* no C implementation support for thread-local storage */ -#define DEFINE_PER_THREAD_DATA(TYPE, NAME, ...) \ +#define DEFINE_STATIC_PER_THREAD_DATA(TYPE, NAME, ...) \ typedef TYPE NAME##_type; \ static pthread_key_t NAME##_key; \ \ @@ -205,9 +276,52 @@ void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *); if (!value) { \ static const NAME##_type initial_value = __VA_ARGS__; \ \ - value = xmalloc(sizeof *value); \ + value = malloc(sizeof *value); \ + if (value == NULL) { \ + out_of_memory(); \ + } \ *value = initial_value; \ - pthread_setspecific(NAME##_key, value); \ + xpthread_setspecific(NAME##_key, value); \ + } \ + return value; \ + } +#define DECLARE_EXTERN_PER_THREAD_DATA(TYPE, NAME) \ + typedef TYPE NAME##_type; \ + static pthread_key_t NAME##_key; \ + \ + static inline NAME##_type * \ + NAME##_get_unsafe(void) \ + { \ + return pthread_getspecific(NAME##_key); \ + } \ + \ + NAME##_type *NAME##_get(void); +#define DEFINE_EXTERN_PER_THREAD_DATA(NAME, ...) \ + static void \ + NAME##_once_init(void) \ + { \ + if (pthread_key_create(&NAME##_key, free)) { \ + abort(); \ + } \ + } \ + \ + NAME##_type * \ + NAME##_get(void) \ + { \ + static pthread_once_t once = PTHREAD_ONCE_INIT; \ + NAME##_type *value; \ + \ + pthread_once(&once, NAME##_once_init); \ + value = NAME##_get_unsafe(); \ + if (!value) { \ + static const NAME##_type initial_value = __VA_ARGS__; \ + \ + value = malloc(sizeof *value); \ + if (value == NULL) { \ + out_of_memory(); \ + } \ + *value = initial_value; \ + xpthread_setspecific(NAME##_key, value); \ } \ return value; \ } @@ -278,7 +392,7 @@ void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *); NAME##_set_unsafe(TYPE value) \ { \ TYPE old_value = NAME##_get_unsafe(); \ - pthread_setspecific(NAME##_key, value); \ + xpthread_setspecific(NAME##_key, value); \ return old_value; \ } \ \ @@ -289,5 +403,108 @@ void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *); return NAME##_set_unsafe(value); \ } +/* Convenient once-only execution. + * + * + * Problem + * ======= + * + * POSIX provides pthread_once_t and pthread_once() as primitives for running a + * set of code only once per process execution. They are used like this: + * + * static void run_once(void) { ...initialization... } + * static pthread_once_t once = PTHREAD_ONCE_INIT; + * ... + * pthread_once(&once, run_once); + * + * pthread_once() does not allow passing any parameters to the initialization + * function, which is often inconvenient, because it means that the function + * can only access data declared at file scope. + * + * + * Solution + * ======== + * + * Use ovsthread_once, like this, instead: + * + * static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER; + * + * if (ovsthread_once_start(&once)) { + * ...initialization... + * ovsthread_once_done(&once); + * } + */ + +struct ovsthread_once { + atomic_bool done; + struct ovs_mutex mutex; +}; + +#define OVSTHREAD_ONCE_INITIALIZER \ + { \ + ATOMIC_VAR_INIT(false), \ + OVS_MUTEX_INITIALIZER, \ + } + +static inline bool ovsthread_once_start(struct ovsthread_once *once) + OVS_TRY_LOCK(true, once->mutex); +void ovsthread_once_done(struct ovsthread_once *once) + OVS_RELEASES(once->mutex); + +bool ovsthread_once_start__(struct ovsthread_once *once) + OVS_TRY_LOCK(false, once->mutex); + +static inline bool +ovsthread_once_is_done__(struct ovsthread_once *once) +{ + bool done; + + atomic_read_explicit(&once->done, &done, memory_order_relaxed); + return done; +} + +/* Returns true if this is the first call to ovsthread_once_start() for + * 'once'. In this case, the caller should perform whatever initialization + * actions it needs to do, then call ovsthread_once_done() for 'once'. + * + * Returns false if this is not the first call to ovsthread_once_start() for + * 'once'. In this case, the call will not return until after + * ovsthread_once_done() has been called. */ +static inline bool +ovsthread_once_start(struct ovsthread_once *once) +{ + return OVS_UNLIKELY(!ovsthread_once_is_done__(once) + && !ovsthread_once_start__(once)); +} + +/* Thread ID. + * + * pthread_t isn't so nice for some purposes. Its size and representation are + * implementation dependent, which means that there is no way to hash it. + * This thread ID avoids the problem. + */ + +DECLARE_EXTERN_PER_THREAD_DATA(unsigned int, ovsthread_id); + +/* Returns a per-thread identifier unique within the lifetime of the + * process. */ +static inline unsigned int +ovsthread_id_self(void) +{ + return *ovsthread_id_get(); +} + +void assert_single_threaded_at(const char *where); +#define assert_single_threaded() assert_single_threaded_at(SOURCE_LOCATOR) + +pid_t xfork_at(const char *where); +#define xfork() xfork_at(SOURCE_LOCATOR) + +void forbid_forking(const char *reason); +bool may_fork(void); + +/* Useful functions related to threading. */ + +int count_cpu_cores(void); #endif /* ovs-thread.h */