From afcc695edf6a43b6e037c2856c51d55837da3b74 Mon Sep 17 00:00:00 2001
From: Lorenzo Blasa <lblasa@fb.com>
Date: Thu, 12 May 2022 07:37:11 -0700
Subject: [PATCH] Scheduler

Summary: Introduce a 'Scheduler' interface which will allow to decouple from the existing used Folly scheduler.

Reviewed By: fabiomassimo

Differential Revision: D36245587

fbshipit-source-id: 2f28bc1612e37ae53060a134d1c8059231fbc8ad
---
 xplat/Flipper/FlipperFollyScheduler.h         | 40 +++++++++++++++++++
 .../FlipperFollyScopedThreadScheduler.h       | 40 +++++++++++++++++++
 xplat/Flipper/FlipperScheduler.h              | 26 ++++++++++++
 3 files changed, 106 insertions(+)
 create mode 100644 xplat/Flipper/FlipperFollyScheduler.h
 create mode 100644 xplat/Flipper/FlipperFollyScopedThreadScheduler.h
 create mode 100644 xplat/Flipper/FlipperScheduler.h

diff --git a/xplat/Flipper/FlipperFollyScheduler.h b/xplat/Flipper/FlipperFollyScheduler.h
new file mode 100644
index 000000000..12620bf67
--- /dev/null
+++ b/xplat/Flipper/FlipperFollyScheduler.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include "FlipperScheduler.h"
+
+#include <folly/futures/Future.h>
+#include <folly/io/async/EventBase.h>
+#include <folly/io/async/ScopedEventBaseThread.h>
+
+namespace facebook {
+namespace flipper {
+
+struct FollyScheduler : public facebook::flipper::Scheduler {
+  FollyScheduler(folly::EventBase* eventLoop) : eventLoop_(eventLoop) {}
+  virtual void schedule(Func&& t) override {
+    eventLoop_->add(t);
+  }
+  virtual void scheduleAfter(Func&& t, unsigned int ms) override {
+    folly::makeFuture()
+        .via(eventLoop_)
+        .delayed(std::chrono::milliseconds(ms))
+        .thenValue([t](auto&&) { t(); });
+  }
+
+  virtual bool isRunningInOwnThread() override {
+    return eventLoop_->isInEventBaseThread();
+  }
+
+ private:
+  folly::EventBase* eventLoop_;
+};
+
+} // namespace flipper
+} // namespace facebook
diff --git a/xplat/Flipper/FlipperFollyScopedThreadScheduler.h b/xplat/Flipper/FlipperFollyScopedThreadScheduler.h
new file mode 100644
index 000000000..7fc8b5b44
--- /dev/null
+++ b/xplat/Flipper/FlipperFollyScopedThreadScheduler.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include "FlipperScheduler.h"
+
+#include <folly/futures/Future.h>
+#include <folly/io/async/EventBase.h>
+#include <folly/io/async/ScopedEventBaseThread.h>
+
+namespace facebook {
+namespace flipper {
+
+struct FollyScopedThreadScheduler : public Scheduler {
+  virtual void schedule(Func&& t) override {
+    thread_.getEventBase()->add(t);
+  }
+
+  virtual void scheduleAfter(Func&& t, unsigned int ms) override {
+    folly::makeFuture()
+        .via(thread_.getEventBase())
+        .delayed(std::chrono::milliseconds(ms))
+        .thenValue([t](auto&&) { t(); });
+  }
+
+  virtual bool isRunningInOwnThread() override {
+    return thread_.getEventBase()->isInEventBaseThread();
+  }
+
+ private:
+  folly::ScopedEventBaseThread thread_;
+};
+
+} // namespace flipper
+} // namespace facebook
diff --git a/xplat/Flipper/FlipperScheduler.h b/xplat/Flipper/FlipperScheduler.h
new file mode 100644
index 000000000..a8b2f545a
--- /dev/null
+++ b/xplat/Flipper/FlipperScheduler.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <functional>
+
+namespace facebook {
+namespace flipper {
+
+using Func = std::function<void()>;
+
+struct Scheduler {
+  virtual ~Scheduler() {}
+  virtual void schedule(Func&& t) = 0;
+
+  virtual void scheduleAfter(Func&& t, unsigned int ms) = 0;
+  virtual bool isRunningInOwnThread() = 0;
+};
+
+} // namespace flipper
+} // namespace facebook