From 9917cdab81a12f1a06dbefc811f782d1cf76c7e3 Mon Sep 17 00:00:00 2001
From: Yedidya Feldblum <yfeldblum@fb.com>
Date: Tue, 17 Oct 2017 13:09:48 -0700
Subject: [PATCH] An InlineExecutor singleton

Summary:
[Folly] An `InlineExecutor` singleton.

Using the Leaky Meyers Singleton pattern, so that it is always available whenever required.

Differential Revision: D6074534

fbshipit-source-id: bd4c9cd6a1e60c80de5d2eef1cb6a1e7f16b4e50
---
 folly/futures/InlineExecutor.cpp | 28 ++++++++++++++++++++++++++++
 folly/futures/InlineExecutor.h   | 22 ++++++++++++----------
 2 files changed, 40 insertions(+), 10 deletions(-)
 create mode 100644 folly/futures/InlineExecutor.cpp

diff --git a/folly/futures/InlineExecutor.cpp b/folly/futures/InlineExecutor.cpp
new file mode 100644
index 00000000..848e7f26
--- /dev/null
+++ b/folly/futures/InlineExecutor.cpp
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2017 Facebook, Inc.
+ *
+ * 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.
+ */
+
+#include <folly/futures/InlineExecutor.h>
+
+#include <folly/Indestructible.h>
+
+namespace folly {
+
+InlineExecutor& InlineExecutor::instance() {
+  static auto instance = Indestructible<InlineExecutor>{};
+  return *instance;
+}
+
+} // namespace folly
diff --git a/folly/futures/InlineExecutor.h b/folly/futures/InlineExecutor.h
index 5f1ae691..644ff7bf 100644
--- a/folly/futures/InlineExecutor.h
+++ b/folly/futures/InlineExecutor.h
@@ -19,14 +19,16 @@
 
 namespace folly {
 
-  /// When work is "queued", execute it immediately inline.
-  /// Usually when you think you want this, you actually want a
-  /// QueuedImmediateExecutor.
-  class InlineExecutor : public Executor {
-   public:
-    void add(Func f) override {
-      f();
-    }
-  };
+/// When work is "queued", execute it immediately inline.
+/// Usually when you think you want this, you actually want a
+/// QueuedImmediateExecutor.
+class InlineExecutor : public Executor {
+ public:
+  static InlineExecutor& instance();
 
-}
+  void add(Func f) override {
+    f();
+  }
+};
+
+} // namespace folly
-- 
2.34.1