ircd::ctx: Add scope_notify device.

include/ircd/ctx/ctx.h

@@ -87,6 +87,7 @@ namespace ircd::ctx
 #include "upgrade_lock.h"
 #include "unlock_guard.h"
 #include "condition_variable.h"
+#include "scope_notify.h"
 #include "view.h"
 #include "shared_state.h"
 #include "promise.h"

include/ircd/ctx/scope_notify.h

@@ -0,0 +1,102 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2019 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. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_CTX_SCOPE_NOTIFY_H
+
+namespace ircd::ctx
+{
+	struct scope_notify;
+}
+
+struct ircd::ctx::scope_notify
+{
+	IRCD_OVERLOAD(all)
+	IRCD_OVERLOAD(one)
+
+	dock *d {nullptr};
+	bool _all {false};
+	bool _one {false};
+
+	scope_notify(dock &d);
+	scope_notify(dock &d, one_t);
+	scope_notify(dock &d, all_t);
+	scope_notify(scope_notify &&) noexcept;
+	scope_notify(const scope_notify &) = delete;
+	scope_notify &operator=(scope_notify &&) noexcept;
+	scope_notify &operator=(const scope_notify &) = delete;
+	~scope_notify() noexcept;
+};
+
+namespace ircd
+{
+	using ctx::scope_notify;
+}
+
+/// Notify the dock at destruction time with dock::notify() (reminder, that
+/// is a single notify with fairness).
+inline
+ircd::ctx::scope_notify::scope_notify(dock &d)
+:d{&d}
+{}
+
+/// Notify the dock at destruction time with a notify_one() (reminder, that
+/// is a single notify of the first ctx waiting in the dock only).
+inline
+ircd::ctx::scope_notify::scope_notify(dock &d,
+                                      one_t)
+:d{&d}
+,_one{true}
+{}
+
+/// Notify the dock at destruction time with a notify_all().
+inline
+ircd::ctx::scope_notify::scope_notify(dock &d,
+                                      all_t)
+:d{&d}
+,_all{true}
+{}
+
+inline
+ircd::ctx::scope_notify::scope_notify(scope_notify &&other)
+noexcept
+:d{std::move(other.d)}
+,_all{std::move(other._all)}
+,_one{std::move(other._one)}
+{
+	other.d = nullptr;
+}
+
+inline
+ircd::ctx::scope_notify &
+ircd::ctx::scope_notify::operator=(scope_notify &&other)
+noexcept
+{
+	this->~scope_notify();
+	d = std::move(other.d);
+	_all = std::move(other._all);
+	_one = std::move(other._one);
+	other.d = nullptr;
+	return *this;
+}
+
+inline
+ircd::ctx::scope_notify::~scope_notify()
+noexcept
+{
+	if(!d)
+		return;
+	else if(_all)
+		d->notify_all();
+	else if(_one)
+		d->notify_one();
+	else
+		d->notify();
+}