--- /dev/null
+#ifndef _URCU_WFCQUEUE_H
+#define _URCU_WFCQUEUE_H
+
+/*
+ * urcu/wfcqueue.h
+ *
+ * Userspace RCU library - Concurrent Queue with Wait-Free Enqueue/Blocking Dequeue
+ *
+ * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright 2011-2012 - Lai Jiangshan <laijs@cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <pthread.h>
+#include <assert.h>
+#include <stdbool.h>
+#include <urcu/compiler.h>
+#include <urcu/arch.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Concurrent queue with wait-free enqueue/blocking dequeue.
+ *
+ * This queue has been designed and implemented collaboratively by
+ * Mathieu Desnoyers and Lai Jiangshan. Inspired from
+ * half-wait-free/half-blocking queue implementation done by Paul E.
+ * McKenney.
+ */
+
+#define CDS_WFCQ_WOULDBLOCK ((struct cds_wfcq_node *) -1UL)
+
+enum cds_wfcq_ret {
+ CDS_WFCQ_RET_WOULDBLOCK = -1,
+ CDS_WFCQ_RET_DEST_EMPTY = 0,
+ CDS_WFCQ_RET_DEST_NON_EMPTY = 1,
+ CDS_WFCQ_RET_SRC_EMPTY = 2,
+};
+
+enum cds_wfcq_state {
+ CDS_WFCQ_STATE_LAST = (1U << 0),
+};
+
+struct cds_wfcq_node {
+ struct cds_wfcq_node *next;
+};
+
+/*
+ * Do not put head and tail on the same cache-line if concurrent
+ * enqueue/dequeue are expected from many CPUs. This eliminates
+ * false-sharing between enqueue and dequeue.
+ */
+struct __cds_wfcq_head {
+ struct cds_wfcq_node node;
+};
+
+struct cds_wfcq_head {
+ struct cds_wfcq_node node;
+ pthread_mutex_t lock;
+};
+
+#ifndef __cplusplus
+/*
+ * The transparent union allows calling functions that work on both
+ * struct cds_wfcq_head and struct __cds_wfcq_head on any of those two
+ * types.
+ */
+typedef union {
+ struct __cds_wfcq_head *_h;
+ struct cds_wfcq_head *h;
+} __attribute__((__transparent_union__)) cds_wfcq_head_ptr_t;
+
+/*
+ * This static inline is only present for compatibility with C++. It is
+ * effect-less in C.
+ */
+static inline struct __cds_wfcq_head *__cds_wfcq_head_cast(struct __cds_wfcq_head *head)
+{
+ return head;
+}
+
+/*
+ * This static inline is only present for compatibility with C++. It is
+ * effect-less in C.
+ */
+static inline struct cds_wfcq_head *cds_wfcq_head_cast(struct cds_wfcq_head *head)
+{
+ return head;
+}
+#else /* #ifndef __cplusplus */
+
+/* C++ ignores transparent union. */
+typedef union {
+ struct __cds_wfcq_head *_h;
+ struct cds_wfcq_head *h;
+} cds_wfcq_head_ptr_t;
+
+/* C++ ignores transparent union. Requires an explicit conversion. */
+static inline cds_wfcq_head_ptr_t __cds_wfcq_head_cast(struct __cds_wfcq_head *head)
+{
+ cds_wfcq_head_ptr_t ret = { ._h = head };
+ return ret;
+}
+/* C++ ignores transparent union. Requires an explicit conversion. */
+static inline cds_wfcq_head_ptr_t cds_wfcq_head_cast(struct cds_wfcq_head *head)
+{
+ cds_wfcq_head_ptr_t ret = { .h = head };
+ return ret;
+}
+#endif /* #else #ifndef __cplusplus */
+
+struct cds_wfcq_tail {
+ struct cds_wfcq_node *p;
+};
+
+#ifdef _LGPL_SOURCE
+
+#include <urcu/static/wfcqueue.h>
+
+#define cds_wfcq_node_init _cds_wfcq_node_init
+#define cds_wfcq_init _cds_wfcq_init
+#define __cds_wfcq_init ___cds_wfcq_init
+#define cds_wfcq_destroy _cds_wfcq_destroy
+#define cds_wfcq_empty _cds_wfcq_empty
+#define cds_wfcq_enqueue _cds_wfcq_enqueue
+
+/* Dequeue locking */
+#define cds_wfcq_dequeue_lock _cds_wfcq_dequeue_lock
+#define cds_wfcq_dequeue_unlock _cds_wfcq_dequeue_unlock
+
+/* Locking performed within cds_wfcq calls. */
+#define cds_wfcq_dequeue_blocking _cds_wfcq_dequeue_blocking
+#define cds_wfcq_dequeue_with_state_blocking \
+ _cds_wfcq_dequeue_with_state_blocking
+#define cds_wfcq_splice_blocking _cds_wfcq_splice_blocking
+#define cds_wfcq_first_blocking _cds_wfcq_first_blocking
+#define cds_wfcq_next_blocking _cds_wfcq_next_blocking
+
+/* Locking ensured by caller by holding cds_wfcq_dequeue_lock() */
+#define __cds_wfcq_dequeue_blocking ___cds_wfcq_dequeue_blocking
+#define __cds_wfcq_dequeue_with_state_blocking \
+ ___cds_wfcq_dequeue_with_state_blocking
+#define __cds_wfcq_splice_blocking ___cds_wfcq_splice_blocking
+#define __cds_wfcq_first_blocking ___cds_wfcq_first_blocking
+#define __cds_wfcq_next_blocking ___cds_wfcq_next_blocking
+
+/*
+ * Locking ensured by caller by holding cds_wfcq_dequeue_lock().
+ * Non-blocking: deque, first, next return CDS_WFCQ_WOULDBLOCK if they
+ * need to block. splice returns nonzero if it needs to block.
+ */
+#define __cds_wfcq_dequeue_nonblocking ___cds_wfcq_dequeue_nonblocking
+#define __cds_wfcq_dequeue_with_state_nonblocking \
+ ___cds_wfcq_dequeue_with_state_nonblocking
+#define __cds_wfcq_splice_nonblocking ___cds_wfcq_splice_nonblocking
+#define __cds_wfcq_first_nonblocking ___cds_wfcq_first_nonblocking
+#define __cds_wfcq_next_nonblocking ___cds_wfcq_next_nonblocking
+
+#else /* !_LGPL_SOURCE */
+
+/*
+ * Mutual exclusion of cds_wfcq_* / __cds_wfcq_* API
+ *
+ * Synchronization table:
+ *
+ * External synchronization techniques described in the API below is
+ * required between pairs marked with "X". No external synchronization
+ * required between pairs marked with "-".
+ *
+ * Legend:
+ * [1] cds_wfcq_enqueue
+ * [2] __cds_wfcq_splice (destination queue)
+ * [3] __cds_wfcq_dequeue
+ * [4] __cds_wfcq_splice (source queue)
+ * [5] __cds_wfcq_first
+ * [6] __cds_wfcq_next
+ *
+ * [1] [2] [3] [4] [5] [6]
+ * [1] - - - - - -
+ * [2] - - - - - -
+ * [3] - - X X X X
+ * [4] - - X - X X
+ * [5] - - X X - -
+ * [6] - - X X - -
+ *
+ * Mutual exclusion can be ensured by holding cds_wfcq_dequeue_lock().
+ *
+ * For convenience, cds_wfcq_dequeue_blocking() and
+ * cds_wfcq_splice_blocking() hold the dequeue lock.
+ *
+ * Besides locking, mutual exclusion of dequeue, splice and iteration
+ * can be ensured by performing all of those operations from a single
+ * thread, without requiring any lock.
+ */
+
+/*
+ * cds_wfcq_node_init: initialize wait-free queue node.
+ */
+extern void cds_wfcq_node_init(struct cds_wfcq_node *node);
+
+/*
+ * cds_wfcq_init: initialize wait-free queue. Pair with
+ * cds_wfcq_destroy().
+ */
+extern void cds_wfcq_init(struct cds_wfcq_head *head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * cds_wfcq_destroy: destroy wait-free queue. Pair with
+ * cds_wfcq_init().
+ */
+extern void cds_wfcq_destroy(struct cds_wfcq_head *head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * __cds_wfcq_init: initialize wait-free queue (without lock). Don't
+ * pair with any destroy function.
+ */
+extern void __cds_wfcq_init(struct __cds_wfcq_head *head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * cds_wfcq_empty: return whether wait-free queue is empty.
+ *
+ * No memory barrier is issued. No mutual exclusion is required.
+ */
+extern bool cds_wfcq_empty(cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * cds_wfcq_dequeue_lock: take the dequeue mutual exclusion lock.
+ */
+extern void cds_wfcq_dequeue_lock(struct cds_wfcq_head *head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * cds_wfcq_dequeue_unlock: release the dequeue mutual exclusion lock.
+ */
+extern void cds_wfcq_dequeue_unlock(struct cds_wfcq_head *head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * cds_wfcq_enqueue: enqueue a node into a wait-free queue.
+ *
+ * Issues a full memory barrier before enqueue. No mutual exclusion is
+ * required.
+ *
+ * Returns false if the queue was empty prior to adding the node.
+ * Returns true otherwise.
+ */
+extern bool cds_wfcq_enqueue(cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail,
+ struct cds_wfcq_node *node);
+
+/*
+ * cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue.
+ *
+ * Content written into the node before enqueue is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ * It is valid to reuse and free a dequeued node immediately.
+ * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is
+ * ensured.
+ */
+extern struct cds_wfcq_node *cds_wfcq_dequeue_blocking(
+ struct cds_wfcq_head *head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * cds_wfcq_dequeue_with_state_blocking: dequeue with state.
+ *
+ * Same as cds_wfcq_dequeue_blocking, but saves whether dequeueing the
+ * last node of the queue into state (CDS_WFCQ_STATE_LAST).
+ */
+extern struct cds_wfcq_node *cds_wfcq_dequeue_with_state_blocking(
+ struct cds_wfcq_head *head,
+ struct cds_wfcq_tail *tail,
+ int *state);
+
+/*
+ * cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q.
+ *
+ * Dequeue all nodes from src_q.
+ * dest_q must be already initialized.
+ * Content written into the node before enqueue is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is
+ * ensured.
+ *
+ * Returns enum cds_wfcq_ret which indicates the state of the src or
+ * dest queue.
+ */
+extern enum cds_wfcq_ret cds_wfcq_splice_blocking(
+ struct cds_wfcq_head *dest_q_head,
+ struct cds_wfcq_tail *dest_q_tail,
+ struct cds_wfcq_head *src_q_head,
+ struct cds_wfcq_tail *src_q_tail);
+
+/*
+ * __cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue.
+ *
+ * Content written into the node before enqueue is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ * It is valid to reuse and free a dequeued node immediately.
+ * Dequeue/splice/iteration mutual exclusion should be ensured by the
+ * caller.
+ */
+extern struct cds_wfcq_node *__cds_wfcq_dequeue_blocking(
+ cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * __cds_wfcq_dequeue_with_state_blocking: dequeue with state.
+ *
+ * Same as __cds_wfcq_dequeue_blocking, but saves whether dequeueing the
+ * last node of the queue into state (CDS_WFCQ_STATE_LAST).
+ */
+extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_blocking(
+ cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail,
+ int *state);
+
+/*
+ * __cds_wfcq_dequeue_nonblocking: dequeue a node from a wait-free queue.
+ *
+ * Same as __cds_wfcq_dequeue_blocking, but returns CDS_WFCQ_WOULDBLOCK
+ * if it needs to block.
+ */
+extern struct cds_wfcq_node *__cds_wfcq_dequeue_nonblocking(
+ cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * __cds_wfcq_dequeue_with_state_blocking: dequeue with state.
+ *
+ * Same as __cds_wfcq_dequeue_nonblocking, but saves whether dequeueing
+ * the last node of the queue into state (CDS_WFCQ_STATE_LAST).
+ */
+extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_nonblocking(
+ cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail,
+ int *state);
+
+/*
+ * __cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q.
+ *
+ * Dequeue all nodes from src_q.
+ * dest_q must be already initialized.
+ * Mutual exclusion for src_q should be ensured by the caller as
+ * specified in the "Synchronisation table".
+ * Returns enum cds_wfcq_ret which indicates the state of the src or
+ * dest queue. Never returns CDS_WFCQ_RET_WOULDBLOCK.
+ */
+extern enum cds_wfcq_ret __cds_wfcq_splice_blocking(
+ cds_wfcq_head_ptr_t dest_q_head,
+ struct cds_wfcq_tail *dest_q_tail,
+ cds_wfcq_head_ptr_t src_q_head,
+ struct cds_wfcq_tail *src_q_tail);
+
+/*
+ * __cds_wfcq_splice_nonblocking: enqueue all src_q nodes at the end of dest_q.
+ *
+ * Same as __cds_wfcq_splice_blocking, but returns
+ * CDS_WFCQ_RET_WOULDBLOCK if it needs to block.
+ */
+extern enum cds_wfcq_ret __cds_wfcq_splice_nonblocking(
+ cds_wfcq_head_ptr_t dest_q_head,
+ struct cds_wfcq_tail *dest_q_tail,
+ cds_wfcq_head_ptr_t src_q_head,
+ struct cds_wfcq_tail *src_q_tail);
+
+/*
+ * __cds_wfcq_first_blocking: get first node of a queue, without dequeuing.
+ *
+ * Content written into the node before enqueue is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ * Dequeue/splice/iteration mutual exclusion should be ensured by the
+ * caller.
+ *
+ * Used by for-like iteration macros:
+ * __cds_wfcq_for_each_blocking()
+ * __cds_wfcq_for_each_blocking_safe()
+ *
+ * Returns NULL if queue is empty, first node otherwise.
+ */
+extern struct cds_wfcq_node *__cds_wfcq_first_blocking(
+ cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * __cds_wfcq_first_nonblocking: get first node of a queue, without dequeuing.
+ *
+ * Same as __cds_wfcq_first_blocking, but returns CDS_WFCQ_WOULDBLOCK if
+ * it needs to block.
+ */
+extern struct cds_wfcq_node *__cds_wfcq_first_nonblocking(
+ cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail);
+
+/*
+ * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing.
+ *
+ * Content written into the node before enqueue is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ * Dequeue/splice/iteration mutual exclusion should be ensured by the
+ * caller.
+ *
+ * Used by for-like iteration macros:
+ * __cds_wfcq_for_each_blocking()
+ * __cds_wfcq_for_each_blocking_safe()
+ *
+ * Returns NULL if reached end of queue, non-NULL next queue node
+ * otherwise.
+ */
+extern struct cds_wfcq_node *__cds_wfcq_next_blocking(
+ cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail,
+ struct cds_wfcq_node *node);
+
+/*
+ * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing.
+ *
+ * Same as __cds_wfcq_next_blocking, but returns CDS_WFCQ_WOULDBLOCK if
+ * it needs to block.
+ */
+extern struct cds_wfcq_node *__cds_wfcq_next_nonblocking(
+ cds_wfcq_head_ptr_t head,
+ struct cds_wfcq_tail *tail,
+ struct cds_wfcq_node *node);
+
+#endif /* !_LGPL_SOURCE */
+
+/*
+ * __cds_wfcq_for_each_blocking: Iterate over all nodes in a queue,
+ * without dequeuing them.
+ * @head: head of the queue (struct cds_wfcq_head or __cds_wfcq_head pointer).
+ * @tail: tail of the queue (struct cds_wfcq_tail pointer).
+ * @node: iterator on the queue (struct cds_wfcq_node pointer).
+ *
+ * Content written into each node before enqueue is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ * Dequeue/splice/iteration mutual exclusion should be ensured by the
+ * caller.
+ */
+#define __cds_wfcq_for_each_blocking(head, tail, node) \
+ for (node = __cds_wfcq_first_blocking(head, tail); \
+ node != NULL; \
+ node = __cds_wfcq_next_blocking(head, tail, node))
+
+/*
+ * __cds_wfcq_for_each_blocking_safe: Iterate over all nodes in a queue,
+ * without dequeuing them. Safe against deletion.
+ * @head: head of the queue (struct cds_wfcq_head or __cds_wfcq_head pointer).
+ * @tail: tail of the queue (struct cds_wfcq_tail pointer).
+ * @node: iterator on the queue (struct cds_wfcq_node pointer).
+ * @n: struct cds_wfcq_node pointer holding the next pointer (used
+ * internally).
+ *
+ * Content written into each node before enqueue is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ * Dequeue/splice/iteration mutual exclusion should be ensured by the
+ * caller.
+ */
+#define __cds_wfcq_for_each_blocking_safe(head, tail, node, n) \
+ for (node = __cds_wfcq_first_blocking(head, tail), \
+ n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL); \
+ node != NULL; \
+ node = n, n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL))
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _URCU_WFCQUEUE_H */
projects / userspace-rcu.git / blobdiff