X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=include%2Furcu%2Fwfcqueue.h;h=bd920ca488b6b0feedb243383fe641b0741842a2;hb=HEAD;hp=2119e8d24ce49a431d70e133d5bf766e4eb2cec4;hpb=ee990caca068cbc4618c4b10956096c40ab0b330;p=urcu.git

diff --git a/include/urcu/wfcqueue.h b/include/urcu/wfcqueue.h
index 2119e8d..5a4add4 100644
--- a/include/urcu/wfcqueue.h
+++ b/include/urcu/wfcqueue.h
@@ -1,27 +1,13 @@
+// SPDX-FileCopyrightText: 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+// SPDX-FileCopyrightText: 2011-2012 Lai Jiangshan <laijs@cn.fujitsu.com>
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 #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>
@@ -80,11 +66,26 @@ struct cds_wfcq_head {
  *
  * In C++, implement static inline wrappers using function overloading
  * to obtain an API similar to C.
+ *
+ * Avoid complaints from clang++ not knowing the transparent union
+ * attribute.
  */
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wignored-attributes"
+#endif
 typedef union {
 	struct __cds_wfcq_head *_h;
 	struct cds_wfcq_head *h;
-} caa_c_transparent_union cds_wfcq_head_ptr_t;
+} __attribute__((__transparent_union__)) cds_wfcq_head_ptr_t;
+
+typedef union {
+	const struct __cds_wfcq_head *_h;
+	const struct cds_wfcq_head *h;
+} __attribute__((__transparent_union__)) cds_wfcq_head_const_ptr_t;
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif
 
 #ifndef __cplusplus
 /*
@@ -104,6 +105,25 @@ static inline struct cds_wfcq_head *cds_wfcq_head_cast(struct cds_wfcq_head *hea
 {
 	return head;
 }
+
+/*
+ * This static inline is only present for compatibility with C++. It is
+ * effect-less in C.
+ */
+static inline const struct __cds_wfcq_head *__cds_wfcq_head_const_cast(const 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 const struct cds_wfcq_head *cds_wfcq_head_const_cast(const struct cds_wfcq_head *head)
+{
+	return head;
+}
+
 #else /* #ifndef __cplusplus */
 
 /*
@@ -125,6 +145,27 @@ 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;
 }
+
+/*
+ * This static inline is used by internally in the static inline
+ * implementation of the API.
+ */
+static inline cds_wfcq_head_const_ptr_t __cds_wfcq_head_const_cast(const struct __cds_wfcq_head *head)
+{
+	cds_wfcq_head_const_ptr_t ret = { ._h = head };
+	return ret;
+}
+
+/*
+ * This static inline is used by internally in the static inline
+ * implementation of the API.
+ */
+static inline cds_wfcq_head_const_ptr_t cds_wfcq_head_const_cast(const struct cds_wfcq_head *head)
+{
+	cds_wfcq_head_const_ptr_t ret = { .h = head };
+	return ret;
+}
+
 #endif /* #else #ifndef __cplusplus */
 
 struct cds_wfcq_tail {
@@ -242,8 +283,8 @@ extern void __cds_wfcq_init(struct __cds_wfcq_head *head,
  *
  * 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);
+extern bool cds_wfcq_empty(cds_wfcq_head_const_ptr_t head,
+		const struct cds_wfcq_tail *tail);
 
 /*
  * cds_wfcq_dequeue_lock: take the dequeue mutual exclusion lock.
@@ -504,10 +545,22 @@ static inline cds_wfcq_head_ptr_t cds_wfcq_head_cast_cpp(struct cds_wfcq_head *h
 	return ret;
 }
 
+static inline cds_wfcq_head_const_ptr_t cds_wfcq_head_const_cast_cpp(const struct __cds_wfcq_head *head)
+{
+	cds_wfcq_head_const_ptr_t ret = { ._h = head };
+	return ret;
+}
+
+static inline cds_wfcq_head_const_ptr_t cds_wfcq_head_const_cast_cpp(const struct cds_wfcq_head *head)
+{
+	cds_wfcq_head_const_ptr_t ret = { .h = head };
+	return ret;
+}
+
 template<typename T> static inline bool cds_wfcq_empty(T head,
-		struct cds_wfcq_tail *tail)
+		const struct cds_wfcq_tail *tail)
 {
-	return cds_wfcq_empty(cds_wfcq_head_cast_cpp(head), tail);
+	return cds_wfcq_empty(cds_wfcq_head_const_cast_cpp(head), tail);
 }
 
 template<typename T> static inline bool cds_wfcq_enqueue(T head,