#define OVS_THREAD_H 1
#include <pthread.h>
+#include <stddef.h>
+#include <sys/types.h>
+#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
-\f
-/* 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 <pthread.h>
#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 **);
+\f
+/* Per-thread data.
+ *
+ * Multiple forms of per-thread data exist, each with its own pluses and
+ * minuses:
+ *
+ * - POSIX per-thread data via pthread_key_t is portable to any pthreads
+ * implementation, and allows a destructor function to be defined. It
+ * only (directly) supports per-thread pointers, which are always
+ * initialized to NULL. It requires once-only allocation of a
+ * pthread_key_t value. It is relatively slow.
+ *
+ * - The thread_local feature newly defined in C11 <threads.h> works with
+ * any data type and initializer, and it is fast. thread_local does not
+ * require once-only initialization like pthread_key_t. C11 does not
+ * define what happens if one attempts to access a thread_local object
+ * from a thread other than the one to which that object belongs. There
+ * is no provision to call a user-specified destructor when a thread
+ * ends.
+ *
+ * - The __thread keyword is a GCC extension similar to thread_local but
+ * with a longer history. __thread is not portable to every GCC version
+ * or environment. __thread does not restrict the use of a thread-local
+ * object outside its own thread.
+ *
+ * Here's a handy summary:
+ *
+ * pthread_key_t thread_local __thread
+ * ------------- ------------ -------------
+ * portability high low medium
+ * speed low high high
+ * supports destructors? yes no no
+ * needs key allocation? yes no no
+ * arbitrary initializer? no yes yes
+ * cross-thread access? yes no yes
+ */
+
+/* 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).
+ * This macro is an alternatives that takes advantage of thread_local (and
+ * __thread), for its performance, when it is available, and falls back to
+ * POSIX per-thread data otherwise.
+ *
+ * Defines per-thread variable NAME with the given TYPE, initialized to
+ * INITIALIZER (which must be valid as an initializer for a variable with
+ * static lifetime).
+ *
+ * The public interface to the variable is:
+ *
+ * TYPE *NAME_get(void)
+ * TYPE *NAME_get_unsafe(void)
+ *
+ * Returns the address of this thread's instance of NAME.
+ *
+ * Use NAME_get() in a context where this might be the first use of the
+ * per-thread variable in the program. Use NAME_get_unsafe(), which
+ * avoids a conditional test and is thus slightly faster, in a context
+ * where one knows that NAME_get() has already been called previously.
+ *
+ * There is no "NAME_set()" (or "NAME_set_unsafe()") function. To set the
+ * value of the per-thread variable, dereference the pointer returned by
+ * TYPE_get() or TYPE_get_unsafe(), e.g. *TYPE_get() = 0.
+ */
+#if HAVE_THREAD_LOCAL || HAVE___THREAD
+
+#if HAVE_THREAD_LOCAL
+#include <threads.h>
+#elif HAVE___THREAD
+#define thread_local __thread
+#else
+#error
+#endif
+
+#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_STATIC_PER_THREAD_DATA(TYPE, NAME, ...) \
+ typedef TYPE NAME##_type; \
+ static pthread_key_t NAME##_key; \
+ \
+ static NAME##_type * \
+ NAME##_get_unsafe(void) \
+ { \
+ return pthread_getspecific(NAME##_key); \
+ } \
+ \
+ static void \
+ NAME##_once_init(void) \
+ { \
+ if (pthread_key_create(&NAME##_key, free)) { \
+ abort(); \
+ } \
+ } \
+ \
+ static 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; \
+ }
+#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; \
+ }
+#endif
+
+/* DEFINE_PER_THREAD_MALLOCED_DATA(TYPE, NAME).
+ *
+ * This is a simple wrapper around POSIX per-thread data primitives. It
+ * defines per-thread variable NAME with the given TYPE, which must be a
+ * pointer type. In each thread, the per-thread variable is initialized to
+ * NULL. When a thread terminates, the variable is freed with free().
+ *
+ * The public interface to the variable is:
+ *
+ * TYPE NAME_get(void)
+ * TYPE NAME_get_unsafe(void)
+ *
+ * Returns the value of per-thread variable NAME in this thread.
+ *
+ * Use NAME_get() in a context where this might be the first use of the
+ * per-thread variable in the program. Use NAME_get_unsafe(), which
+ * avoids a conditional test and is thus slightly faster, in a context
+ * where one knows that NAME_get() has already been called previously.
+ *
+ * TYPE NAME_set(TYPE new_value)
+ * TYPE NAME_set_unsafe(TYPE new_value)
+ *
+ * Sets the value of per-thread variable NAME to 'new_value' in this
+ * thread, and returns its previous value.
+ *
+ * Use NAME_set() in a context where this might be the first use of the
+ * per-thread variable in the program. Use NAME_set_unsafe(), which
+ * avoids a conditional test and is thus slightly faster, in a context
+ * where one knows that NAME_set() has already been called previously.
+ */
+#define DEFINE_PER_THREAD_MALLOCED_DATA(TYPE, NAME) \
+ static pthread_key_t NAME##_key; \
+ \
+ static void \
+ NAME##_once_init(void) \
+ { \
+ if (pthread_key_create(&NAME##_key, free)) { \
+ abort(); \
+ } \
+ } \
+ \
+ static void \
+ NAME##_init(void) \
+ { \
+ static pthread_once_t once = PTHREAD_ONCE_INIT; \
+ pthread_once(&once, NAME##_once_init); \
+ } \
+ \
+ static TYPE \
+ NAME##_get_unsafe(void) \
+ { \
+ return pthread_getspecific(NAME##_key); \
+ } \
+ \
+ static OVS_UNUSED TYPE \
+ NAME##_get(void) \
+ { \
+ NAME##_init(); \
+ return NAME##_get_unsafe(); \
+ } \
+ \
+ static TYPE \
+ NAME##_set_unsafe(TYPE value) \
+ { \
+ TYPE old_value = NAME##_get_unsafe(); \
+ xpthread_setspecific(NAME##_key, value); \
+ return old_value; \
+ } \
+ \
+ static OVS_UNUSED TYPE \
+ NAME##_set(TYPE value) \
+ { \
+ NAME##_init(); \
+ return NAME##_set_unsafe(value); \
+ }
+\f
+/* 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));
+}
+\f
+/* 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();
+}
+\f
+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);
+\f
+/* Useful functions related to threading. */
+
+int count_cpu_cores(void);
#endif /* ovs-thread.h */