From 5e8c4bb2a1f76c3ddf60df5142628fedc0052596 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Mon, 19 Sep 2016 20:07:30 -0700
Subject: [PATCH] ircd::ctx: Add async() function.

---
 include/ircd/ctx_async.h  | 95 +++++++++++++++++++++++++++++++++++++++
 include/ircd/ctx_future.h | 14 +++---
 include/ircd/stdinc.h     |  1 +
 3 files changed, 103 insertions(+), 7 deletions(-)
 create mode 100644 include/ircd/ctx_async.h

diff --git a/include/ircd/ctx_async.h b/include/ircd/ctx_async.h
new file mode 100644
index 000000000..09b1e3d42
--- /dev/null
+++ b/include/ircd/ctx_async.h
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2016 Charybdis Development Team
+ * Copyright (C) 2016 Jason Volk <jason@zemos.net>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice is present in all copies.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+#define HAVE_IRCD_CTX_ASYNC_H
+
+namespace ircd {
+namespace ctx  {
+
+template<class F,
+         class... A>
+constexpr bool
+is_void_result()
+{
+	return std::is_void<typename std::result_of<F (A...)>::type>::value;
+}
+
+template<class F,
+         class... A>
+using future_void = typename std::enable_if<is_void_result<F, A...>(), future<void>>::type;
+
+template<class F,
+         class... A>
+using future_value = typename std::enable_if<!is_void_result<F, A...>(),
+                     future<typename std::result_of<F (A...)>::type>>::type;
+
+template<size_t stack_size = DEFAULT_STACK_SIZE,
+         enum flags flags = (enum flags)0,
+         class F,
+         class... A>
+future_value<F, A...>
+async(F&& f,
+      A&&... a)
+{
+	using R = typename std::result_of<F (A...)>::type;
+
+	auto func(std::bind(std::forward<F>(f), std::forward<A>(a)...));
+	auto p(std::make_shared<promise<R>>());
+	auto wrapper([p, func(std::move(func))]
+	() mutable -> void
+	{
+		p->set_value(func());
+	});
+
+	future<R> ret(*p);
+	//TODO: DEFER_POST?
+	context(stack_size, std::move(wrapper), SELF_DESTRUCT | DEFER_POST | flags);
+	return ret;
+}
+
+template<size_t stack_size = DEFAULT_STACK_SIZE,
+         enum flags flags = (enum flags)0,
+         class F,
+         class... A>
+future_void<F, A...>
+async(F&& f,
+      A&&... a)
+{
+	using R = typename std::result_of<F (A...)>::type;
+
+	auto func(std::bind(std::forward<F>(f), std::forward<A>(a)...));
+	auto p(std::make_shared<promise<R>>());
+	auto wrapper([p, func(std::move(func))]
+	() mutable -> void
+	{
+		func();
+		p->set_value();
+	});
+
+	future<R> ret(*p);
+	//TODO: DEFER_POST?
+	context(stack_size, std::move(wrapper), SELF_DESTRUCT | DEFER_POST | flags);
+	return ret;
+}
+
+} // namespace ctx
+} // namespace ircd
diff --git a/include/ircd/ctx_future.h b/include/ircd/ctx_future.h
index f8b897663..6a71cba4e 100644
--- a/include/ircd/ctx_future.h
+++ b/include/ircd/ctx_future.h
@@ -42,16 +42,16 @@ class future
 	using pointer_type                           = typename shared_state<T>::pointer_type;
 	using reference_type                         = typename shared_state<T>::reference_type;
 
-	bool valid() const                           { return bool(st);                       }
-	bool operator!() const                       { return !valid();                       }
-	operator bool() const                        { return valid();                        }
+	bool valid() const                           { return bool(st);                                }
+	bool operator!() const                       { return !valid();                                }
+	operator bool() const                        { return valid();                                 }
 
 	template<class time_point> future_status wait_until(const time_point &) const;
 	template<class duration> future_status wait(const duration &d) const;
 	void wait() const;
 
 	T get();
-	operator T()                                 { return get();                          }
+	operator T()                                 { return get();                                   }
 
 	future();
 	future(promise<T> &promise);
@@ -65,9 +65,9 @@ class future<void>
   public:
 	using value_type                             = typename shared_state<void>::value_type;
 
-	bool valid() const                           { return bool(st);                       }
-	bool operator!() const                       { return !valid();                       }
-	operator bool() const                        { return valid();                        }
+	bool valid() const                           { return bool(st);                                }
+	bool operator!() const                       { return !valid();                                }
+	operator bool() const                        { return valid();                                 }
 
 	template<class time_point> future_status wait_until(const time_point &) const;
 	template<class duration> future_status wait(const duration &d) const;
diff --git a/include/ircd/stdinc.h b/include/ircd/stdinc.h
index 210745100..d1165ec65 100644
--- a/include/ircd/stdinc.h
+++ b/include/ircd/stdinc.h
@@ -95,6 +95,7 @@ namespace ircd
 #include "ctx_shared_state.h"
 #include "ctx_promise.h"
 #include "ctx_future.h"
+#include "ctx_async.h"
 
 #include "line.h"
 #include "tape.h"