mixer/Control: move some code to Lock*() methods

src/mixer/Mixer.cxx

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2003-2022 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 "Mixer.hxx"
+
+#include <cassert>
+
+void
+Mixer::LockOpen()
+{
+	const std::scoped_lock lock{mutex};
+
+	if (open)
+		return;
+
+	_Open();
+}
+
+void
+Mixer::_Open()
+{
+	assert(!open);
+
+	try {
+		Open();
+		open = true;
+		failure = {};
+	} catch (...) {
+		failure = std::current_exception();
+		throw;
+	}
+}
+
+void
+Mixer::LockClose() noexcept
+{
+	const std::scoped_lock lock{mutex};
+
+	if (open)
+		_Close();
+}
+
+void
+Mixer::_Close() noexcept
+{
+	assert(open);
+
+	Close();
+	open = false;
+	failure = {};
+}
+
+int
+Mixer::LockGetVolume()
+{
+	if (IsGlobal() && !failure)
+		LockOpen();
+
+	const std::scoped_lock lock{mutex};
+
+	if (open) {
+		try {
+			return GetVolume();
+		} catch (...) {
+			_Close();
+			failure = std::current_exception();
+			throw;
+		}
+	} else
+		return -1;
+}
+
+void
+Mixer::LockSetVolume(unsigned volume)
+{
+	assert(volume <= 100);
+
+	if (IsGlobal() && !failure)
+		LockOpen();
+
+	const std::scoped_lock lock{mutex};
+
+	if (open)
+		SetVolume(volume);
+	else if (failure)
+		std::rethrow_exception(failure);
+}