storage/nfs: use the libnfs async API

Share the NFS connection with the NFS input plugin.

src/lib/nfs/Blocking.cxx

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2003-2014 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"
+#include "Blocking.hxx"
+#include "Connection.hxx"
+#include "event/Call.hxx"
+
+bool
+BlockingNfsOperation::Run(Error &_error)
+{
+	/* subscribe to the connection, which will invoke either
+	   OnNfsConnectionReady() or OnNfsConnectionFailed() */
+	BlockingCall(connection.GetEventLoop(),
+		    [this](){ connection.AddLease(*this); });
+
+	/* wait for completion */
+	LockWaitFinished();
+
+	/* check for error */
+	if (error.IsDefined()) {
+		_error = std::move(error);
+		return false;
+	}
+
+	return true;
+}
+
+void
+BlockingNfsOperation::OnNfsConnectionReady()
+{
+	if (!Start(error)) {
+		connection.RemoveLease(*this);
+		LockSetFinished();
+	}
+}
+
+void
+BlockingNfsOperation::OnNfsConnectionFailed(const Error &_error)
+{
+	error.Set(_error);
+	LockSetFinished();
+}
+
+void
+BlockingNfsOperation::OnNfsConnectionDisconnected(const Error &_error)
+{
+	error.Set(_error);
+	LockSetFinished();
+}
+
+void
+BlockingNfsOperation::OnNfsCallback(unsigned status, void *data)
+{
+	connection.RemoveLease(*this);
+
+	HandleResult(status, data);
+	LockSetFinished();
+}
+
+void
+BlockingNfsOperation::OnNfsError(Error &&_error)
+{
+	connection.RemoveLease(*this);
+
+	error = std::move(_error);
+	LockSetFinished();
+}

src/lib/nfs/Blocking.hxx

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2003-2014 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_BLOCKING_NFS_CALLBACK_HXX
+#define MPD_BLOCKING_NFS_CALLBACK_HXX
+
+#include "check.h"
+#include "Callback.hxx"
+#include "Lease.hxx"
+#include "thread/Mutex.hxx"
+#include "thread/Cond.hxx"
+#include "util/Error.hxx"
+
+class NfsConnection;
+
+/**
+ * Utility class to implement a blocking NFS call using the libnfs
+ * async API.  The actual method call is deferred to the #EventLoop
+ * thread, and method Run() waits for completion.
+ */
+class BlockingNfsOperation : protected NfsCallback, NfsLease {
+	Mutex mutex;
+	Cond cond;
+
+	bool finished;
+
+	Error error;
+
+protected:
+	NfsConnection &connection;
+
+public:
+	BlockingNfsOperation(NfsConnection &_connection)
+		:finished(false), connection(_connection) {}
+
+	bool Run(Error &error);
+
+private:
+	void LockWaitFinished() {
+		const ScopeLock protect(mutex);
+		while (!finished)
+			cond.wait(mutex);
+	}
+
+	/**
+	 * Mark the operation as "finished" and wake up the waiting
+	 * thread.
+	 */
+	void LockSetFinished() {
+		const ScopeLock protect(mutex);
+		finished = true;
+		cond.signal();
+	}
+
+	/* virtual methods from NfsLease */
+	void OnNfsConnectionReady() final;
+	void OnNfsConnectionFailed(const Error &error) final;
+	void OnNfsConnectionDisconnected(const Error &error) final;
+
+	/* virtual methods from NfsCallback */
+	void OnNfsCallback(unsigned status, void *data) final;
+	void OnNfsError(Error &&error) final;
+
+protected:
+	virtual bool Start(Error &error) = 0;
+	virtual void HandleResult(unsigned status, void *data) = 0;
+};
+
+#endif