Add isc_queue implementation on top of cds_wfcq

Add an isc_queue implementation that hides the gory details of cds_wfcq
into more neat API.  The same caveats as with cds_wfcq.

TODO: Add documentation to the API.

lib/isc/Makefile.am

@@ -64,6 +64,7 @@ libisc_la_HEADERS =			\
 	include/isc/pause.h		\
 	include/isc/portset.h		\
 	include/isc/proxy2.h		\
+	include/isc/queue.h		\
 	include/isc/quota.h		\
 	include/isc/radix.h		\
 	include/isc/random.h		\

lib/isc/include/isc/queue.h

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#include <isc/os.h>
+#include <isc/urcu.h>
+
+STATIC_ASSERT(sizeof(struct __cds_wfcq_head) <= ISC_OS_CACHELINE_SIZE,
+	      "size of struct __cds_wfcq_head must be smaller than "
+	      "ISC_OS_CACHELINE_SIZE");
+
+typedef struct isc_queue {
+	struct __cds_wfcq_head head;
+	uint8_t		       __padding[ISC_OS_CACHELINE_SIZE -
+				 sizeof(struct __cds_wfcq_head)];
+	struct cds_wfcq_tail   tail;
+} isc_queue_t;
+
+typedef struct cds_wfcq_node isc_queue_node_t;
+
+static inline void
+isc_queue_node_init(isc_queue_node_t *node) {
+	cds_wfcq_node_init(node);
+}
+
+static inline void
+isc_queue_init(isc_queue_t *queue) {
+	__cds_wfcq_init(&(queue)->head, &(queue)->tail);
+}
+
+static inline void
+isc_queue_destroy(isc_queue_t *queue) {
+	UNUSED(queue);
+}
+
+static inline bool
+isc_queue_empty(isc_queue_t *queue) {
+	return (cds_wfcq_empty(&(queue)->head, &(queue)->tail));
+}
+
+static inline bool
+isc_queue_enqueue(isc_queue_t *queue, isc_queue_node_t *node) {
+	return (cds_wfcq_enqueue(&(queue)->head, &(queue)->tail, node));
+}
+
+#define isc_queue_enqueue_entry(queue, entry, member) \
+	cds_wfcq_enqueue(&(queue)->head, &(queue)->tail, &((entry)->member))
+
+static inline isc_queue_node_t *
+isc_queue_dequeue(isc_queue_t *queue) {
+	return (__cds_wfcq_dequeue_nonblocking(&(queue)->head, &(queue)->tail));
+}
+
+#define isc_queue_entry(ptr, type, member) \
+	caa_container_of_check_null(ptr, type, member)
+
+#define isc_queue_dequeue_entry(queue, type, member) \
+	isc_queue_entry(isc_queue_dequeue(queue), type, member)
+
+static inline bool
+isc_queue_splice(isc_queue_t *dest, isc_queue_t *src) {
+	enum cds_wfcq_ret ret = __cds_wfcq_splice_blocking(
+		&dest->head, &dest->tail, &src->head, &src->tail);
+	INSIST(ret != CDS_WFCQ_RET_WOULDBLOCK &&
+	       ret != CDS_WFCQ_RET_DEST_NON_EMPTY);
+
+	return (ret != CDS_WFCQ_RET_SRC_EMPTY);
+}
+
+#define isc_queue_first_entry(queue, type, member)                         \
+	isc_queue_entry(                                                   \
+		__cds_wfcq_first_blocking(&(queue)->head, &(queue)->tail), \
+		type, member)
+
+#define isc_queue_next_entry(queue, node, type, member)                 \
+	isc_queue_entry(__cds_wfcq_next_blocking(&(queue)->head,        \
+						 &(queue)->tail, node), \
+			type, member)
+
+#define isc_queue_for_each_entry(queue, pos, member)                       \
+	for (pos = isc_queue_first_entry(queue, __typeof__(*pos), member); \
+	     pos != NULL;                                                  \
+	     pos = isc_queue_next_entry(queue, &(pos)->member,             \
+					__typeof__(*pos), member))
+
+#define isc_queue_for_each_entry_safe(queue, pos, next, member)            \
+	for (pos = isc_queue_first_entry(queue, __typeof__(*pos), member), \
+	    next = (pos ? isc_queue_next_entry(queue, &(pos)->member,      \
+					       __typeof__(*pos), member)   \
+			: NULL);                                           \
+	     pos != NULL; pos = next,                                      \
+	    next = (pos ? isc_queue_next_entry(queue, &(pos)->member,      \
+					       __typeof__(*pos), member)   \
+			: NULL))