From 904e0804430e5526752fe75637df48a3e9467deb Mon Sep 17 00:00:00 2001 From: Thomas Graf Date: Mon, 15 Dec 2014 14:10:38 +0100 Subject: [PATCH] lib: Expose ovs_mutex and ovsthread_once in This picks the ovs_mutex and ovsthread_once API from lib/ovs-thread.h and exposes it in . Signed-off-by: Thomas Graf Acked-by: Ben Pfaff --- include/openvswitch/automake.mk | 1 + include/openvswitch/thread.h | 137 ++++++++++++++++++++++++++++++++ lib/ovs-thread.h | 112 +------------------------- 3 files changed, 139 insertions(+), 111 deletions(-) create mode 100644 include/openvswitch/thread.h diff --git a/include/openvswitch/automake.mk b/include/openvswitch/automake.mk index b35bfce34..d9f551d6b 100644 --- a/include/openvswitch/automake.mk +++ b/include/openvswitch/automake.mk @@ -1,6 +1,7 @@ openvswitchincludedir = $(includedir)/openvswitch openvswitchinclude_HEADERS = \ include/openvswitch/compiler.h \ + include/openvswitch/thread.h \ include/openvswitch/types.h \ include/openvswitch/util.h \ include/openvswitch/version.h diff --git a/include/openvswitch/thread.h b/include/openvswitch/thread.h new file mode 100644 index 000000000..8a398af0a --- /dev/null +++ b/include/openvswitch/thread.h @@ -0,0 +1,137 @@ +/* + * Copyright (c) 2013, 2014 Nicira, Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef OPENVSWITCH_THREAD_H +#define OPENVSWITCH_THREAD_H 1 + +#include +#include +#include +#include +#include "util.h" + +/* Mutex. */ +struct OVS_LOCKABLE ovs_mutex { + pthread_mutex_t lock; + const char *where; /* NULL if and only if uninitialized. */ +}; + +/* "struct ovs_mutex" initializer. */ +#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP +#define OVS_MUTEX_INITIALIZER { PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, \ + "" } +#else +#define OVS_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER, "" } +#endif + +#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP +#define OVS_ADAPTIVE_MUTEX_INITIALIZER \ + { PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP, "" } +#else +#define OVS_ADAPTIVE_MUTEX_INITIALIZER OVS_MUTEX_INITIALIZER +#endif + +/* 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_init_adaptive(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, OVS_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, OVS_SOURCE_LOCATOR) + +void ovs_mutex_cond_wait(pthread_cond_t *, const struct ovs_mutex *); + +/* 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 { + bool done; /* Non-atomic, false negatives possible. */ + struct ovs_mutex mutex; +}; + +#define OVSTHREAD_ONCE_INITIALIZER \ + { \ + 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(true, once->mutex); + +/* 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) +{ + /* We may be reading 'done' at the same time as the first thread + * is writing on it, or we can be using a stale copy of it. The + * worst that can happen is that we call ovsthread_once_start__() + * once when strictly not necessary. */ + return OVS_UNLIKELY(!once->done && ovsthread_once_start__(once)); +} + +#endif /* ovs-thread.h */ diff --git a/lib/ovs-thread.h b/lib/ovs-thread.h index dfbd8915f..26b2ccdc2 100644 --- a/lib/ovs-thread.h +++ b/lib/ovs-thread.h @@ -21,16 +21,11 @@ #include #include #include "ovs-atomic.h" +#include "openvswitch/thread.h" #include "util.h" struct seq; -/* Mutex. */ -struct OVS_LOCKABLE ovs_mutex { - pthread_mutex_t lock; - const char *where; /* NULL if and only if uninitialized. */ -}; - /* Poll-block()-able barrier similar to pthread_barrier_t. */ struct ovs_barrier { uint32_t size; /* Number of threads to wait. */ @@ -38,43 +33,6 @@ struct ovs_barrier { struct seq *seq; }; -/* "struct ovs_mutex" initializer. */ -#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP -#define OVS_MUTEX_INITIALIZER { PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, \ - "" } -#else -#define OVS_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER, "" } -#endif - -#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP -#define OVS_ADAPTIVE_MUTEX_INITIALIZER \ - { PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP, "" } -#else -#define OVS_ADAPTIVE_MUTEX_INITIALIZER OVS_MUTEX_INITIALIZER -#endif - -/* 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_init_adaptive(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, OVS_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, OVS_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); @@ -500,74 +458,6 @@ void ovsthread_key_delete(ovsthread_key_t); void ovsthread_setspecific(ovsthread_key_t, const void *); void *ovsthread_getspecific(ovsthread_key_t); -/* 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 { - bool done; /* Non-atomic, false negatives possible. */ - struct ovs_mutex mutex; -}; - -#define OVSTHREAD_ONCE_INITIALIZER \ - { \ - 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(true, once->mutex); - -/* 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) -{ - /* We may be reading 'done' at the same time as the first thread - * is writing on it, or we can be using a stale copy of it. The - * worst that can happen is that we call ovsthread_once_start__() - * once when strictly not necessary. */ - return OVS_UNLIKELY(!once->done && ovsthread_once_start__(once)); -} - /* Thread ID. * * pthread_t isn't so nice for some purposes. Its size and representation are -- 2.20.1