thread/Id: new class replacing GThread pointers

Remove a GLib dependencies from class EventLoop and DatabaseLock.

src/thread/Id.hxx

@@ -0,0 +1,99 @@
+/*
+ * 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_THREAD_ID_HXX
+#define MPD_THREAD_ID_HXX
+
+#include "gcc.h"
+
+#ifdef WIN32
+#include <windows.h>
+#else
+#include <pthread.h>
+#endif
+
+/**
+ * A low-level identification for a thread.  Designed to work with
+ * existing threads, such as the main thread.  Mostly useful for
+ * debugging code.
+ */
+class ThreadId {
+#ifdef WIN32
+	DWORD id;
+#else
+	pthread_t id;
+#endif
+
+public:
+	/**
+	 * No initialisation.
+	 */
+	ThreadId() = default;
+
+#ifdef WIN32
+	constexpr ThreadId(DWORD _id):id(_id) {}
+#else
+	constexpr ThreadId(pthread_t _id):id(_id) {}
+#endif
+
+	gcc_const
+	static ThreadId Null() {
+#ifdef WIN32
+		return 0;
+#else
+		static ThreadId null;
+		return null;
+#endif
+	}
+
+	gcc_pure
+	bool IsNull() const {
+		return *this == Null();
+	}
+
+	/**
+	 * Return the current thread's id .
+	 */
+	gcc_pure
+	static const ThreadId GetCurrent() {
+#ifdef WIN32
+		return ::GetCurrentThreadId();
+#else
+		return ::pthread_self();
+#endif
+	}
+
+	gcc_pure
+	bool operator==(const ThreadId &other) const {
+#ifdef WIN32
+		return id == other.id;
+#else
+		return ::pthread_equal(id, other.id);
+#endif
+	}
+
+	/**
+	 * Check if this thread is the current thread.
+	 */
+	bool IsInside() const {
+		return *this == GetCurrent();
+	}
+};
+
+#endif