add a wrapper NavyThread for EventBase and FiberManager

Summary:
This change adds a NavyThread class which wraps around the worker thread providing EventBase and
FiberManager execution environment.

Reviewed By: therealgymmy

Differential Revision: D45931594

fbshipit-source-id: b8082bf9000694e40cc991c672c9aef5f4f5345d

Author: Jaesoo Lee

cachelib/navy/common/NavyThread.h

@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <folly/fibers/FiberManager.h>
+#include <folly/fibers/FiberManagerMap.h>
+#include <folly/io/async/EventBase.h>
+#include <folly/io/async/ScopedEventBaseThread.h>
+
+#include <memory>
+
+namespace facebook {
+namespace cachelib {
+namespace navy {
+
+/**
+ * NavyThread is a wrapper class that wraps folly::ScopedEventBaseThread and
+ * FiberManager. The purpose of NavyThread is to start a new thread running
+ * an EventBase loop and FiberManager loop along with providing an deligate
+ * interface to add tasks to the FiberManager.
+ *
+ * NavyThread is not CopyConstructible nor CopyAssignable nor
+ * MoveConstructible nor MoveAssignable.
+ */
+class NavyThread {
+ public:
+  /**
+   * Initializes with current EventBaseManager and passed-in thread name.
+   */
+  explicit NavyThread(folly::StringPiece name)
+      : th_(name), fm_(&folly::fibers::getFiberManager(*th_.getEventBase())) {}
+
+  ~NavyThread() = default;
+
+  /**
+   * Add the passed-in task to the FiberManager.
+   *
+   * @param func Task functor; must have a signature of `void func()`.
+   *             The object will be destroyed once task execution is complete.
+   */
+  void addTaskRemote(folly::Func func) { fm_->addTaskRemote(std::move(func)); }
+
+  /**
+   * Add the passed-in task to the FiberManager.
+   * Must be called from FiberManager's thread.
+   *
+   * @param func Task functor; must have a signature of `void func()`.
+   *             The object will be destroyed once task execution is complete.
+   */
+  void addTask(folly::Func func) { fm_->addTask(std::move(func)); }
+
+ private:
+  NavyThread(NavyThread&& other) = delete;
+  NavyThread& operator=(NavyThread&& other) = delete;
+
+  NavyThread(const NavyThread& other) = delete;
+  NavyThread& operator=(const NavyThread& other) = delete;
+
+  // Actual worker thread running EventBase and FiberManager loop
+  folly::ScopedEventBaseThread th_;
+
+  // FiberManager which are driven by the thread
+  folly::fibers::FiberManager* fm_;
+};
+
+} // namespace navy
+} // namespace cachelib
+} // namespace facebook