From f16b5406f08078996fcacb6d388e376f90f8975d Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 30 Jul 2024 02:35:32 +0000
Subject: [PATCH] urcu: add list_iteration_adapter
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
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Add a type-safe cds_list iteration adapter. Like those provided for
the lfht, this adapter provides type-safe range-for semantics for
cds_list structures.

Change-Id: I03d3b3c31911d495c9c6187000400563a3d05ad8
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/common/urcu.hpp | 73 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/src/common/urcu.hpp b/src/common/urcu.hpp
index 659e3c3d0..b59c2282c 100644
--- a/src/common/urcu.hpp
+++ b/src/common/urcu.hpp
@@ -16,6 +16,7 @@
 #include <iterator>
 #include <mutex>
 #include <urcu.h>
+#include <urcu/list.h>
 #include <urcu/rculfhash.h>
 
 namespace lttng {
@@ -293,6 +294,78 @@ private:
 	const cds_lfht_match_fct _match_function;
 };
 
+template <typename ContainedType, cds_list_head ContainedType::*Member>
+class list_iteration_adapter {
+public:
+	/* Nested iterator class defines the iterator for list_iteration_adapter. */
+	class iterator : public std::iterator<std::input_iterator_tag, std::uint64_t> {
+		/* Allow list_iteration_adapter to access private members of iterator. */
+		friend list_iteration_adapter;
+
+	public:
+		iterator(const iterator& other) = default;
+		iterator(iterator&& other) noexcept = default;
+		~iterator() = default;
+		iterator& operator=(const iterator&) = delete;
+		iterator& operator=(iterator&&) noexcept = delete;
+
+		/* Move to the next element in the hash table. */
+		iterator& operator++()
+		{
+			_node = _node_contents.next;
+			_node_contents = *_node;
+			return *this;
+		}
+
+		bool operator==(const iterator& other) const noexcept
+		{
+			return other._node == _node;
+		}
+
+		bool operator!=(const iterator& other) const noexcept
+		{
+			return !(*this == other);
+		}
+
+		/* Dereference the iterator to access the contained element. */
+		ContainedType *operator*() const
+		{
+			/* Retrieve the element from the node. */
+			return lttng::utils::container_of(_node, Member);
+		}
+
+	protected:
+		explicit iterator(const cds_list_head& node) : _node(&node), _node_contents(node)
+		{
+		}
+
+		/* Current node. */
+		const cds_list_head *_node;
+		/* Copy of node contents to allow safe deletion during the iteration. */
+		cds_list_head _node_contents;
+	};
+
+	explicit list_iteration_adapter(cds_list_head& list) : _list(list)
+	{
+	}
+
+	/* Return an iterator to the beginning of the hash table. */
+	iterator begin() const noexcept
+	{
+		return iterator(*_list.next);
+	}
+
+	/* Return an iterator to the end of the hash table. */
+	iterator end() const noexcept
+	{
+		return iterator(_list);
+	}
+
+protected:
+	/* Reference to the list being iterated over. */
+	cds_list_head& _list;
+};
+
 } /* namespace urcu */
 } /* namespace lttng */
 
-- 
2.34.1