Add C++ wrappers for pthread mutex and rcu read lock

[lttng-tools.git] / src / common / urcu.hpp

diff --git a/src/common/urcu.hpp b/src/common/urcu.hpp
new file mode 100644 (file)
index 0000000..2ea2001
--- /dev/null
+++ b/src/common/urcu.hpp
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2022 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#ifndef LTTNG_URCU_H
+#define LTTNG_URCU_H
+
+#define _LGPL_SOURCE
+#include <urcu.h>
+#include <mutex>
+
+namespace lttng {
+namespace urcu {
+
+namespace details {
+/*
+ * Wrapper around an urcu read lock which satisfies the 'Mutex' named
+ * requirements of C++11. Satisfying those requirements facilitates the use of
+ * standard concurrency support library facilities.
+ *
+ * read_lock is under the details namespace since it is unlikely to be used
+ * directly by exception-safe code. See read_lock_guard.
+ */
+class read_lock {
+public:
+       read_lock() = default;
+
+       /* "Not copyable" and "not moveable" Mutex requirements. */
+       read_lock(read_lock const &) = delete;
+       read_lock &operator=(read_lock const &) = delete;
+
+       void lock()
+       {
+               rcu_read_lock();
+       }
+
+       bool try_lock()
+       {
+               lock();
+               return true;
+       }
+
+       void unlock()
+       {
+               rcu_read_unlock();
+       }
+};
+} /* namespace details */
+
+/*
+ * Provides the basic concept of std::lock_guard for rcu reader locks.
+ *
+ * The RCU reader lock is held for the duration of lock_guard's lifetime.
+ */
+class read_lock_guard {
+public:
+       read_lock_guard() : _guard(_lock)
+       {
+       }
+
+       read_lock_guard(const read_lock_guard &) = delete;
+
+private:
+       details::read_lock _lock;
+       std::lock_guard<details::read_lock> _guard;
+};
+
+} /* namespace urcu */
+} /* namespace lttng */
+
+#endif /* LTTNG_URCU_H */