event/PipeEvent: new class wrapping SocketEvent

src/db/update/InotifySource.cxx

@@ -37,7 +37,7 @@ InotifySource::OnSocketReady([[maybe_unused]] unsigned flags) noexcept
 	static_assert(sizeof(buffer) >= sizeof(struct inotify_event) + NAME_MAX + 1,
 		      "inotify buffer too small");
 
-	auto ifd = socket_event.GetSocket().ToFileDescriptor();
+	auto ifd = socket_event.GetFileDescriptor();
 	ssize_t nbytes = ifd.Read(buffer, sizeof(buffer));
 	if (nbytes < 0)
 		FatalSystemError("Failed to read from inotify");
@@ -78,7 +78,7 @@ InotifyInit()
 InotifySource::InotifySource(EventLoop &_loop,
 			     mpd_inotify_callback_t _callback, void *_ctx)
 	:socket_event(_loop, BIND_THIS_METHOD(OnSocketReady),
-		      SocketDescriptor::FromFileDescriptor(InotifyInit())),
+		      InotifyInit()),
 	 callback(_callback), callback_ctx(_ctx)
 {
 	socket_event.ScheduleRead();
@@ -87,7 +87,7 @@ InotifySource::InotifySource(EventLoop &_loop,
 int
 InotifySource::Add(const char *path_fs, unsigned mask)
 {
-	auto ifd = socket_event.GetSocket().ToFileDescriptor();
+	auto ifd = socket_event.GetFileDescriptor();
 	int wd = inotify_add_watch(ifd.Get(), path_fs, mask);
 	if (wd < 0)
 		throw MakeErrno("inotify_add_watch() has failed");
@@ -98,7 +98,7 @@ InotifySource::Add(const char *path_fs, unsigned mask)
 void
 InotifySource::Remove(unsigned wd) noexcept
 {
-	auto ifd = socket_event.GetSocket().ToFileDescriptor();
+	auto ifd = socket_event.GetFileDescriptor();
 	int ret = inotify_rm_watch(ifd.Get(), wd);
 	if (ret < 0 && errno != EINVAL)
 		LogErrno(inotify_domain, "inotify_rm_watch() has failed");

src/db/update/InotifySource.hxx

@@ -20,13 +20,13 @@
 #ifndef MPD_INOTIFY_SOURCE_HXX
 #define MPD_INOTIFY_SOURCE_HXX
 
-#include "event/SocketEvent.hxx"
+#include "event/PipeEvent.hxx"
 
 typedef void (*mpd_inotify_callback_t)(int wd, unsigned mask,
 				       const char *name, void *ctx);
 
 class InotifySource final {
-	SocketEvent socket_event;
+	PipeEvent socket_event;
 
 	mpd_inotify_callback_t callback;
 	void *callback_ctx;

src/event/PipeEvent.hxx

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2007-2021 CM4all GmbH
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``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
+ * FOUNDATION OR CONTRIBUTORS 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
+
+#include "SocketEvent.hxx"
+#include "io/FileDescriptor.hxx"
+
+/**
+ * A variant of #SocketEvent for pipes (and other kinds of
+ * #FileDescriptor which can be used with epoll).
+ */
+class PipeEvent final {
+	SocketEvent event;
+
+public:
+	template<typename C>
+	PipeEvent(EventLoop &event_loop, C callback,
+		  FileDescriptor fd=FileDescriptor::Undefined()) noexcept
+		:event(event_loop, callback,
+		       SocketDescriptor::FromFileDescriptor(fd)) {}
+
+	EventLoop &GetEventLoop() const noexcept {
+		return event.GetEventLoop();
+	}
+
+	bool IsDefined() const noexcept {
+		return event.IsDefined();
+	}
+
+	FileDescriptor GetFileDescriptor() const noexcept {
+		return event.GetSocket().ToFileDescriptor();
+	}
+
+	FileDescriptor ReleaseFileDescriptor() noexcept {
+		return event.ReleaseSocket().ToFileDescriptor();
+	}
+
+	void Open(FileDescriptor fd) noexcept {
+		event.Open(SocketDescriptor::FromFileDescriptor(fd));
+	}
+
+	void Close() noexcept {
+		event.Close();
+	}
+
+	bool Schedule(unsigned flags) noexcept {
+		return event.Schedule(flags);
+	}
+
+	void Cancel() noexcept {
+		event.Cancel();
+	}
+
+	bool ScheduleRead() noexcept {
+		return event.ScheduleRead();
+	}
+
+	bool ScheduleWrite() noexcept {
+		return event.ScheduleWrite();
+	}
+
+	void CancelRead() noexcept {
+		event.CancelRead();
+	}
+
+	void CancelWrite() noexcept {
+		event.CancelWrite();
+	}
+
+	void ScheduleImplicit() noexcept {
+		event.ScheduleImplicit();
+	}
+};

src/event/UringManager.hxx

@@ -19,21 +19,21 @@
 
 #pragma once
 
-#include "SocketEvent.hxx"
+#include "PipeEvent.hxx"
 #include "IdleEvent.hxx"
 #include "io/uring/Queue.hxx"
 
 namespace Uring {
 
 class Manager final : public Queue {
-	SocketEvent event;
+	PipeEvent event;
 	IdleEvent idle_event;
 
 public:
 	explicit Manager(EventLoop &event_loop)
 		:Queue(1024, 0),
 		 event(event_loop, BIND_THIS_METHOD(OnSocketReady),
-		       SocketDescriptor::FromFileDescriptor(GetFileDescriptor())),
+		       GetFileDescriptor()),
 		 idle_event(event_loop, BIND_THIS_METHOD(OnIdle))
 	{
 		event.ScheduleRead();