/*
- * Copyright (c) 2013 Nicira, Inc.
+ * 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.
#include <stddef.h>
#include <sys/types.h>
#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;
+/* Poll-block()-able barrier similar to pthread_barrier_t. */
+struct ovs_barrier {
+ uint32_t size; /* Number of threads to wait. */
+ atomic_count count; /* Number of threads already hit the barrier. */
+ struct seq *seq;
};
-/* "struct ovs_mutex" initializer. */
-#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
-#define OVS_MUTEX_INITIALIZER { PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, NULL }
-#else
-#define OVS_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER, NULL }
-#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_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_mutexattr_settype(pthread_mutexattr_t *, int type);
void xpthread_mutexattr_gettype(pthread_mutexattr_t *, int *typep);
-/* Read-write lock. */
+/* Read-write lock.
+ *
+ * An ovs_rwlock does not support recursive readers, because POSIX allows
+ * taking the reader lock recursively to deadlock when a thread is waiting on
+ * the write-lock. (NetBSD does deadlock.) glibc rwlocks in their default
+ * configuration do not deadlock, but ovs_rwlock_init() initializes rwlocks as
+ * non-recursive (which will deadlock) for two reasons:
+ *
+ * - glibc only provides fairness to writers in this mode.
+ *
+ * - It's better to find bugs in the primary Open vSwitch target rather
+ * than exposing them only to porters. */
struct OVS_LOCKABLE ovs_rwlock {
pthread_rwlock_t lock;
- const char *where;
+ const char *where; /* NULL if and only if uninitialized. */
};
/* Initializer. */
-#define OVS_RWLOCK_INITIALIZER { PTHREAD_RWLOCK_INITIALIZER, NULL }
+#ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
+#define OVS_RWLOCK_INITIALIZER \
+ { PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP, "<unlocked>" }
+#else
+#define OVS_RWLOCK_INITIALIZER { PTHREAD_RWLOCK_INITIALIZER, "<unlocked>" }
+#endif
/* ovs_rwlock functions analogous to pthread_rwlock_*() functions.
*
void ovs_rwlock_destroy(const struct ovs_rwlock *);
void ovs_rwlock_unlock(const struct ovs_rwlock *rwlock) OVS_RELEASES(rwlock);
+/* Wrappers for pthread_rwlockattr_*() that abort the process on any error. */
+void xpthread_rwlockattr_init(pthread_rwlockattr_t *);
+void xpthread_rwlockattr_destroy(pthread_rwlockattr_t *);
+#ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
+void xpthread_rwlockattr_setkind_np(pthread_rwlockattr_t *, int kind);
+#endif
+
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)
+ ovs_rwlock_wrlock_at(rwlock, OVS_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)
+ ovs_rwlock_trywrlock_at(rwlock, OVS_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)
+ ovs_rwlock_rdlock_at(rwlock, OVS_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)
+ ovs_rwlock_tryrdlock_at(rwlock, OVS_SOURCE_LOCATOR)
+
+/* ovs_barrier functions analogous to pthread_barrier_*() functions. */
+void ovs_barrier_init(struct ovs_barrier *, uint32_t count);
+void ovs_barrier_destroy(struct ovs_barrier *);
+void ovs_barrier_block(struct ovs_barrier *);
/* Wrappers for xpthread_cond_*() that abort the process on any error.
*
void xpthread_cond_signal(pthread_cond_t *);
void xpthread_cond_broadcast(pthread_cond_t *);
-#ifdef __CHECKER__
-/* Replace these functions by the macros already defined in the <pthread.h>
- * annotations, because the macro definitions have correct semantics for the
- * conditional acquisition that can't be captured in a function annotation.
- * The difference in semantics from pthread_*() to xpthread_*() does not matter
- * because sparse is not a compiler. */
-#define xpthread_mutex_trylock pthread_mutex_trylock
-#define xpthread_rwlock_tryrdlock pthread_rwlock_tryrdlock
-#define xpthread_rwlock_trywrlock pthread_rwlock_trywrlock
-#endif
-
void xpthread_key_create(pthread_key_t *, void (*destructor)(void *));
+void xpthread_key_delete(pthread_key_t);
void xpthread_setspecific(pthread_key_t, const void *);
-void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *);
+#ifndef _WIN32
+void xpthread_sigmask(int, const sigset_t *, sigset_t *);
+#endif
+
+pthread_t ovs_thread_create(const char *name, 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:
+ *
+ * Standard Forms
+ * ==============
+ *
+ * Multiple forms of standard per-thread data exist, each with its own pluses
+ * and minuses. In general, if one of these forms is appropriate, then it's a
+ * good idea to use it:
*
* - 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.
+ * pthread_key_t value. It is relatively slow. Typically few
+ * "pthread_key_t"s are available (POSIX requires only at least 128,
+ * glibc supplies only 1024).
*
* - 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
* 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.
+ * ends. Typical implementations allow for an arbitrary amount of
+ * thread_local storage, but statically allocated only.
*
* - The __thread keyword is a GCC extension similar to thread_local but
* with a longer history. __thread is not portable to every GCC version
* needs key allocation? yes no no
* arbitrary initializer? no yes yes
* cross-thread access? yes no yes
+ * amount available? few arbitrary arbitrary
+ * dynamically allocated? yes no no
+ *
+ *
+ * Extensions
+ * ==========
+ *
+ * OVS provides some extensions and wrappers:
+ *
+ * - In a situation where the performance of thread_local or __thread is
+ * desirable, but portability is required, DEFINE_STATIC_PER_THREAD_DATA
+ * and DECLARE_EXTERN_PER_THREAD_DATA/DEFINE_EXTERN_PER_THREAD_DATA may
+ * be appropriate (see below).
+ *
+ * - DEFINE_PER_THREAD_MALLOCED_DATA can be convenient for simple
+ * per-thread malloc()'d buffers.
+ *
+ * - struct ovs_tsd provides an alternative to pthread_key_t that isn't
+ * limited to a small number of keys.
*/
/* For static data, use this macro in a source file:
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.
+
+/* Dynamically allocated thread-specific data with lots of slots.
*
+ * pthread_key_t can provide as few as 128 pieces of thread-specific data (even
+ * glibc is limited to 1,024). Thus, one must be careful to allocate only a
+ * few keys globally. One cannot, for example, allocate a key for every
+ * instance of a data structure if there might be an arbitrary number of those
+ * data structures.
*
- * Solution
- * ========
+ * This API is similar to the pthread one (simply search and replace pthread_
+ * by ovsthread_) but it a much larger limit that can be raised if necessary
+ * (by recompiling). Thus, one may more freely use this form of
+ * thread-specific data.
*
- * Use ovsthread_once, like this, instead:
+ * ovsthread_key_t also differs from pthread_key_t in the following ways:
*
- * static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
+ * - Destructors must not access thread-specific data (via ovsthread_key).
*
- * if (ovsthread_once_start(&once)) {
- * ...initialization...
- * ovsthread_once_done(&once);
- * }
+ * - The pthread_key_t API allows concurrently exiting threads to start
+ * executing the destructor after pthread_key_delete() returns. The
+ * ovsthread_key_t API guarantees that, when ovsthread_key_delete()
+ * returns, all destructors have returned and no new ones will start
+ * execution.
*/
+typedef struct ovsthread_key *ovsthread_key_t;
-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;
-}
+void ovsthread_key_create(ovsthread_key_t *, void (*destructor)(void *));
+void ovsthread_key_delete(ovsthread_key_t);
-/* 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));
-}
+void ovsthread_setspecific(ovsthread_key_t, const void *);
+void *ovsthread_getspecific(ovsthread_key_t);
\f
/* Thread ID.
*
*
* Fully thread-safe. */
-struct ovsthread_counter *ovsthread_counter_create(void);
-void ovsthread_counter_destroy(struct ovsthread_counter *);
-void ovsthread_counter_inc(struct ovsthread_counter *, unsigned long long int);
-unsigned long long int ovsthread_counter_read(
- const struct ovsthread_counter *);
+struct ovsthread_stats {
+ struct ovs_mutex mutex;
+ void *volatile buckets[16];
+};
+
+void ovsthread_stats_init(struct ovsthread_stats *);
+void ovsthread_stats_destroy(struct ovsthread_stats *);
+
+void *ovsthread_stats_bucket_get(struct ovsthread_stats *,
+ void *(*new_bucket)(void));
+
+#define OVSTHREAD_STATS_FOR_EACH_BUCKET(BUCKET, IDX, STATS) \
+ for ((IDX) = ovs_thread_stats_next_bucket(STATS, 0); \
+ ((IDX) < ARRAY_SIZE((STATS)->buckets) \
+ ? ((BUCKET) = (STATS)->buckets[IDX], true) \
+ : false); \
+ (IDX) = ovs_thread_stats_next_bucket(STATS, (IDX) + 1))
+size_t ovs_thread_stats_next_bucket(const struct ovsthread_stats *, size_t);
\f
+bool single_threaded(void);
+
void assert_single_threaded_at(const char *where);
-#define assert_single_threaded() assert_single_threaded_at(SOURCE_LOCATOR)
+#define assert_single_threaded() assert_single_threaded_at(OVS_SOURCE_LOCATOR)
+#ifndef _WIN32
pid_t xfork_at(const char *where);
-#define xfork() xfork_at(SOURCE_LOCATOR)
+#define xfork() xfork_at(OVS_SOURCE_LOCATOR)
+#endif
void forbid_forking(const char *reason);
bool may_fork(void);
/* Useful functions related to threading. */
int count_cpu_cores(void);
+bool thread_is_pmd(void);
#endif /* ovs-thread.h */
projects / cascardo / ovs.git / blobdiff