update source to Ceph Pacific 16.2.2

[ceph.git] / ceph / src / common / async / context_pool.h

diff --git a/ceph/src/common/async/context_pool.h b/ceph/src/common/async/context_pool.h
new file mode 100644 (file)
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+++ b/ceph/src/common/async/context_pool.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 <contact@redhat.com>
+ * Author: Adam C. Emerson <aemerson@redhat.com>
+ *
+ * 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.
+ *
+ */
+
+#ifndef CEPH_COMMON_ASYNC_CONTEXT_POOL_H
+#define CEPH_COMMON_ASYNC_CONTEXT_POOL_H
+
+#include <cstddef>
+#include <cstdint>
+#include <mutex>
+#include <optional>
+#include <thread>
+#include <vector>
+
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/executor_work_guard.hpp>
+
+#include "common/ceph_mutex.h"
+#include "common/Thread.h"
+
+namespace ceph::async {
+class io_context_pool {
+  std::vector<std::thread> threadvec;
+  boost::asio::io_context ioctx;
+  std::optional<boost::asio::executor_work_guard<
+                 boost::asio::io_context::executor_type>> guard;
+  ceph::mutex m = make_mutex("ceph::io_context_pool::m");
+
+  void cleanup() noexcept {
+    guard = std::nullopt;
+    for (auto& th : threadvec) {
+      th.join();
+    }
+    threadvec.clear();
+  }
+public:
+  io_context_pool() noexcept {}
+  io_context_pool(std::int16_t threadcnt) noexcept {
+    start(threadcnt);
+  }
+  ~io_context_pool() {
+    stop();
+  }
+  void start(std::int16_t threadcnt) noexcept {
+    auto l = std::scoped_lock(m);
+    if (threadvec.empty()) {
+      guard.emplace(boost::asio::make_work_guard(ioctx));
+      ioctx.restart();
+      for (std::int16_t i = 0; i < threadcnt; ++i) {
+       // Mark this function as noexcept so any uncaught exceptions
+       // call terminate at point of throw. Otherwise, under
+       // libstdc++, they get caught by the thread cancellation
+       // infrastructure, unwinding the stack and making debugging
+       // much more difficult.
+       threadvec.emplace_back(make_named_thread("io_context_pool",
+                                                [this]() noexcept {
+                                                  ioctx.run();
+                                                }));
+      }
+    }
+  }
+  void finish() noexcept {
+    auto l = std::scoped_lock(m);
+    if (!threadvec.empty()) {
+      cleanup();
+    }
+  }
+  void stop() noexcept {
+    auto l = std::scoped_lock(m);
+    if (!threadvec.empty()) {
+      ioctx.stop();
+      cleanup();
+    }
+  }
+
+  boost::asio::io_context& get_io_context() {
+    return ioctx;
+  }
+  operator boost::asio::io_context&() {
+    return ioctx;
+  }
+  boost::asio::io_context::executor_type get_executor() {
+    return ioctx.get_executor();
+  }
+};
+}
+
+#endif // CEPH_COMMON_ASYNC_CONTEXT_POOL_H