Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 212 insertions, 0 deletions

diff --git a/src/common/async/shared_mutex.h b/src/common/async/shared_mutex.h
new file mode 100644
index 000000000..3e471a4df
--- /dev/null
+++ b/src/common/async/shared_mutex.h
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+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2018 Red Hat
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation. See file COPYING.
+ *
+ */
+
+#pragma once
+
+#include "common/async/detail/shared_mutex.h"
+
+namespace ceph::async {
+
+/**
+ * An asynchronous shared mutex for use with boost::asio.
+ *
+ * A shared mutex class with asynchronous lock operations that complete on a
+ * boost::asio executor. The class also has synchronous interfaces that meet
+ * most of the standard library's requirements for the SharedMutex concept,
+ * which makes it compatible with lock_guard, unique_lock, and shared_lock.
+ *
+ * All lock requests can fail with operation_aborted on cancel() or destruction.
+ * The non-error_code overloads of lock() and lock_shared() will throw this
+ * error as an exception of type boost::system::system_error.
+ *
+ * Exclusive locks are prioritized over shared locks. Locks of the same type
+ * are granted in fifo order. The implementation defines a limit on the number
+ * of shared locks to 65534 at a time.
+ *
+ * Example use:
+ *
+ *   boost::asio::io_context context;
+ *   SharedMutex mutex{context.get_executor()};
+ *
+ *   mutex.async_lock([&] (boost::system::error_code ec, auto lock) {
+ *       if (!ec) {
+ *         // mutate shared state ...
+ *       }
+ *     });
+ *   mutex.async_lock_shared([&] (boost::system::error_code ec, auto lock) {
+ *       if (!ec) {
+ *         // read shared state ...
+ *       }
+ *     });
+ *
+ *   context.run();
+ */
+template <typename Executor>
+class SharedMutex {
+ public:
+  explicit SharedMutex(const Executor& ex);
+
+  /// on destruction, all pending lock requests are canceled
+  ~SharedMutex();
+
+  using executor_type = Executor;
+  executor_type get_executor() const noexcept { return ex; }
+
+  /// initiate an asynchronous request for an exclusive lock. when the lock is
+  /// granted, the completion handler is invoked with a successful error code
+  /// and a std::unique_lock that owns this mutex.
+  /// Signature = void(boost::system::error_code, std::unique_lock)
+  template <typename CompletionToken>
+  auto async_lock(CompletionToken&& token);
+
+  /// wait synchronously for an exclusive lock. if an error occurs before the
+  /// lock is granted, that error is thrown as an exception
+  void lock();
+
+  /// wait synchronously for an exclusive lock. if an error occurs before the
+  /// lock is granted, that error is assigned to 'ec'
+  void lock(boost::system::error_code& ec);
+
+  /// try to acquire an exclusive lock. if the lock is not immediately
+  /// available, returns false
+  bool try_lock();
+
+  /// releases an exclusive lock. not required to be called from the same thread
+  /// that initiated the lock
+  void unlock();
+
+  /// initiate an asynchronous request for a shared lock. when the lock is
+  /// granted, the completion handler is invoked with a successful error code
+  /// and a std::shared_lock that owns this mutex.
+  /// Signature = void(boost::system::error_code, std::shared_lock)
+  template <typename CompletionToken>
+  auto async_lock_shared(CompletionToken&& token);
+
+  /// wait synchronously for a shared lock. if an error occurs before the
+  /// lock is granted, that error is thrown as an exception
+  void lock_shared();
+
+  /// wait synchronously for a shared lock. if an error occurs before the lock
+  /// is granted, that error is assigned to 'ec'
+  void lock_shared(boost::system::error_code& ec);
+
+  /// try to acquire a shared lock. if the lock is not immediately available,
+  /// returns false
+  bool try_lock_shared();
+
+  /// releases a shared lock. not required to be called from the same thread
+  /// that initiated the lock
+  void unlock_shared();
+
+  /// cancel any pending requests for exclusive or shared locks with an
+  /// operation_aborted error
+  void cancel();
+
+ private:
+  Executor ex; //< default callback executor
+  boost::intrusive_ptr<detail::SharedMutexImpl> impl;
+
+  // allow lock guards to access impl
+  friend class std::unique_lock<SharedMutex>;
+  friend class std::shared_lock<SharedMutex>;
+};
+
+
+template <typename Executor>
+SharedMutex<Executor>::SharedMutex(const Executor& ex)
+  : ex(ex), impl(new detail::SharedMutexImpl)
+{
+}
+
+template <typename Executor>
+SharedMutex<Executor>::~SharedMutex()
+{
+  try {
+    impl->cancel();
+  } catch (const std::exception&) {
+    // swallow any exceptions, the destructor can't throw
+  }
+}
+
+template <typename Executor>
+template <typename CompletionToken>
+auto SharedMutex<Executor>::async_lock(CompletionToken&& token)
+{
+  return impl->async_lock(*this, std::forward<CompletionToken>(token));
+}
+
+template <typename Executor>
+void SharedMutex<Executor>::lock()
+{
+  impl->lock();
+}
+
+template <typename Executor>
+void SharedMutex<Executor>::lock(boost::system::error_code& ec)
+{
+  impl->lock(ec);
+}
+
+template <typename Executor>
+bool SharedMutex<Executor>::try_lock()
+{
+  return impl->try_lock();
+}
+
+template <typename Executor>
+void SharedMutex<Executor>::unlock()
+{
+  impl->unlock();
+}
+
+template <typename Executor>
+template <typename CompletionToken>
+auto SharedMutex<Executor>::async_lock_shared(CompletionToken&& token)
+{
+  return impl->async_lock_shared(*this, std::forward<CompletionToken>(token));
+}
+
+template <typename Executor>
+void SharedMutex<Executor>::lock_shared()
+{
+  impl->lock_shared();
+}
+
+template <typename Executor>
+void SharedMutex<Executor>::lock_shared(boost::system::error_code& ec)
+{
+  impl->lock_shared(ec);
+}
+
+template <typename Executor>
+bool SharedMutex<Executor>::try_lock_shared()
+{
+  return impl->try_lock_shared();
+}
+
+template <typename Executor>
+void SharedMutex<Executor>::unlock_shared()
+{
+  impl->unlock_shared();
+}
+
+template <typename Executor>
+void SharedMutex<Executor>::cancel()
+{
+  impl->cancel();
+}
+
+} // namespace ceph::async
+
+#include "common/async/detail/shared_lock.h"