event/EPollFD: basic support for Linux epoll

Makefile.am

@@ -289,6 +289,7 @@ libsystem_a_SOURCES = \
 	src/system/EventPipe.cxx src/system/EventPipe.hxx \
 	src/system/EventFD.cxx src/system/EventFD.hxx \
 	src/system/SignalFD.cxx src/system/SignalFD.hxx \
+	src/system/EPollFD.cxx src/system/EPollFD.hxx \
 	src/system/clock.c src/system/clock.h
 
 # Event loop library

configure.ac

@@ -142,6 +142,7 @@ AC_SEARCH_LIBS([gethostbyname], [nsl])
 AC_CHECK_FUNCS(pipe2 accept4)
 MPD_OPTIONAL_FUNC(eventfd, eventfd, USE_EVENTFD)
 MPD_OPTIONAL_FUNC(signalfd, signalfd, USE_SIGNALFD)
+MPD_OPTIONAL_FUNC(epoll, epoll_create1, USE_EPOLL)
 
 AC_SEARCH_LIBS([exp], [m],,
 	[AC_MSG_ERROR([exp() not found])])

src/system/EPollFD.cxx

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#ifdef USE_EPOLL
+#include "EPollFD.hxx"
+#include "FatalError.hxx"
+
+EPollFD::EPollFD()
+	:fd(::epoll_create1(EPOLL_CLOEXEC))
+{
+	if (fd < 0)
+		FatalSystemError("epoll_create1() failed");
+}
+
+#endif /* USE_EPOLL */

src/system/EPollFD.hxx

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_EPOLL_FD_HXX
+#define MPD_EPOLL_FD_HXX
+
+#include <assert.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+
+#include "check.h"
+
+struct epoll_event;
+
+/**
+ * A class that wraps Linux epoll.
+ *
+ * Errors in the constructor are fatal.
+ */
+class EPollFD {
+	const int fd;
+
+public:
+	EPollFD();
+
+	~EPollFD() {
+		assert(fd >= 0);
+
+		::close(fd);
+	}
+
+	EPollFD(const EPollFD &other) = delete;
+	EPollFD &operator=(const EPollFD &other) = delete;
+
+	int Wait(epoll_event *events, int maxevents, int timeout) {
+		return ::epoll_wait(fd, events, maxevents, timeout);
+	}
+
+	bool Control(int op, int _fd, epoll_event *event) {
+		return ::epoll_ctl(fd, op, _fd, event) >= 0;
+	}
+
+	bool Add(int _fd, uint32_t events, void *ptr) {
+		epoll_event e;
+		e.events = events;
+		e.data.ptr = ptr;
+
+		return Control(EPOLL_CTL_DEL, _fd, &e);
+	}
+
+	bool Modify(int _fd, uint32_t events, void *ptr) {
+		epoll_event e;
+		e.events = events;
+		e.data.ptr = ptr;
+
+		return Control(EPOLL_CTL_MOD, _fd, &e);
+	}
+
+	bool Remove(int _fd) {
+		return Control(EPOLL_CTL_DEL, _fd, nullptr);
+	}
+};
+
+#endif