event: add poll() based PollGroup implementation

Makefile.am

@@ -309,6 +309,7 @@ libevent_a_SOURCES = \
 	src/event/WakeFD.hxx \
 	src/event/PollGroup.hxx \
 	src/event/PollGroupEPoll.hxx \
+	src/event/PollGroupPoll.hxx src/event/PollGroupPoll.cxx \
 	src/event/PollGroupWinSelect.hxx src/event/PollGroupWinSelect.cxx \
 	src/event/PollResultGeneric.hxx \
 	src/event/SignalMonitor.hxx src/event/SignalMonitor.cxx \

configure.ac

@@ -160,6 +160,7 @@ dnl ---------------------------------------------------------------------------
 dnl Event loop selection
 dnl ---------------------------------------------------------------------------
 
+MPD_OPTIONAL_FUNC_NODEF(poll, poll)
 MPD_OPTIONAL_FUNC_NODEF(epoll, epoll_create1)
 
 AC_ARG_WITH(eventloop,
@@ -170,7 +171,7 @@ AC_ARG_WITH(eventloop,
 
 AC_ARG_WITH(pollmethod,
 	AS_HELP_STRING(
-		[--with-pollmethod=@<:@epoll|winselect|auto@:>@],
+		[--with-pollmethod=@<:@epoll|poll|winselect|auto@:>@],
 		[specify poll method for internal event loop (default=auto)]),,
 	[with_pollmethod=auto])
 
@@ -202,6 +203,8 @@ if test "x$with_eventloop" = xinternal; then
 	if test "x$with_pollmethod" = xauto; then
 		if test "x$enable_epoll" = xyes; then
 			with_pollmethod=epoll
+		elif test "x$enable_poll" = xyes; then
+			with_pollmethod=poll
 		elif test "x$host_is_windows" = xyes; then
 			with_pollmethod=winselect
 		else
@@ -212,6 +215,9 @@ if test "x$with_eventloop" = xinternal; then
 	epoll)
 		AC_DEFINE(USE_EPOLL, 1, [Define to poll sockets with epoll])
 		;;
+	poll)
+		AC_DEFINE(USE_POLL, 1, [Define to poll sockets with poll])
+		;;
 	winselect)
 		AC_DEFINE(USE_WINSELECT, 1,
 			[Define to poll sockets with Windows select])

src/event/PollGroup.hxx

@@ -32,4 +32,10 @@ typedef PollResultGeneric  PollResult;
 typedef PollGroupWinSelect PollGroup;
 #endif
 
+#ifdef USE_POLL
+#include "PollGroupPoll.hxx"
+typedef PollResultGeneric PollResult;
+typedef PollGroupPoll     PollGroup;
+#endif
+
 #endif

src/event/PollGroupPoll.cxx

@@ -0,0 +1,88 @@
+/*
+ * 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_POLL
+
+#include "PollGroupPoll.hxx"
+
+#include <assert.h>
+
+PollGroupPoll::PollGroupPoll() { }
+PollGroupPoll::~PollGroupPoll() { }
+
+bool PollGroupPoll::Add(int fd, unsigned events, void *obj)
+{
+	assert(items.find(fd) == items.end());
+	poll_events.resize(poll_events.size() + 1);
+	size_t index = poll_events.size() - 1;
+	auto &e = poll_events[index];
+	e.fd = fd;
+	e.events = events;
+	e.revents = 0;
+	auto &item = items[fd];
+	item.index = index;
+	item.obj = obj;
+	return true;
+}
+
+bool PollGroupPoll::Modify(int fd, unsigned events, void *obj)
+{
+	auto item_iter = items.find(fd);
+	assert(item_iter != items.end());
+	auto &item = item_iter->second;
+	item.obj = obj;
+	auto &e = poll_events[item.index];
+	e.events = events;
+	e.revents &= events;
+	return true;
+}
+
+bool PollGroupPoll::Remove(int fd)
+{
+	auto item_iter = items.find(fd);
+	assert(item_iter != items.end());
+	auto &item = item_iter->second;
+	size_t index = item.index;
+	size_t last_index = poll_events.size() - 1;
+	if (index != last_index) {
+		std::swap(poll_events[index], poll_events[last_index]);
+		items[poll_events[index].fd].index = index;
+	}
+	poll_events.pop_back();
+	items.erase(item_iter);
+	return true;
+}
+
+void PollGroupPoll::ReadEvents(PollResultGeneric &result, int timeout_ms)
+{
+	int n = poll(poll_events.empty() ? nullptr : &poll_events[0],
+		     poll_events.size(), timeout_ms);
+
+	for (size_t i = 0; n > 0 && i < poll_events.size(); ++i) {
+		const auto &e = poll_events[i];
+		if (e.revents != 0) {
+			result.Add(e.revents, items[e.fd].obj);
+			--n;
+		}
+	}
+}
+
+#endif

src/event/PollGroupPoll.hxx

@@ -0,0 +1,62 @@
+/*
+ * 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_EVENT_POLLGROUP_POLL_HXX
+#define MPD_EVENT_POLLGROUP_POLL_HXX
+
+#include "check.h"
+#include "PollResultGeneric.hxx"
+
+#include <string.h> // for size_t
+#include <vector>
+#include <unordered_map>
+#include <sys/poll.h>
+
+class PollGroupPoll
+{
+	struct Item
+	{
+		size_t index;
+		void *obj;
+	};
+
+	std::vector<pollfd> poll_events;
+	std::unordered_map<int, Item> items;
+
+	PollGroupPoll(PollGroupPoll &) = delete;
+	PollGroupPoll &operator=(PollGroupPoll &) = delete;
+public:
+	static constexpr unsigned READ = POLLIN;
+	static constexpr unsigned WRITE = POLLOUT;
+	static constexpr unsigned ERROR = POLLERR;
+	static constexpr unsigned HANGUP = POLLHUP;
+
+	PollGroupPoll();
+	~PollGroupPoll();
+
+	void ReadEvents(PollResultGeneric &result, int timeout_ms);
+	bool Add(int fd, unsigned events, void *obj);
+	bool Modify(int fd, unsigned events, void *obj);
+	bool Remove(int fd);
+	bool Abandon(int fd) {
+		return Remove(fd);
+	}
+};
+
+#endif