lang/cs/Org.Apache.REEF.Wake/Remote/Impl/StreamingLink.cs

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;
using Org.Apache.REEF.Tang.Exceptions;
using Org.Apache.REEF.Utilities.Diagnostics;
using Org.Apache.REEF.Utilities.Logging;
using Org.Apache.REEF.Wake.StreamingCodec;
using Org.Apache.REEF.Wake.Util;

namespace Org.Apache.REEF.Wake.Remote.Impl
{
    /// <summary>
    /// Represents an open connection between remote hosts. This class is not thread safe
    /// </summary>
    /// <typeparam name="T">Generic Type of message.</typeparam>
    internal sealed class StreamingLink<T> : ILink<T>
    {
        private static readonly Logger Logger = Logger.GetLogger(typeof(StreamingLink<T>));

        private readonly IPEndPoint _localEndpoint;
        private bool _disposed;
        private readonly IStreamingCodec<T> _streamingCodec;
        private readonly TcpClient _client;

        /// <summary>
        /// Stream reader to be passed to codec
        /// </summary>
        private readonly StreamDataReader _reader;

        /// <summary>
        /// Stream writer from which to read from in codec
        /// </summary>
        private readonly StreamDataWriter _writer;

        /// <summary>
        /// Constructs a Link object.
        /// Connects to the specified remote endpoint.
        /// </summary>
        /// <param name="remoteEndpoint">The remote endpoint to connect to</param>
        /// <param name="streamingCodec">Streaming codec</param>
        /// <param name="tcpClientFactory">TcpClient factory</param>
        internal StreamingLink(IPEndPoint remoteEndpoint, IStreamingCodec<T> streamingCodec, ITcpClientConnectionFactory tcpClientFactory)
        {
            if (remoteEndpoint == null)
            {
                throw new ArgumentNullException("remoteEndpoint");
            }

            _client = tcpClientFactory.Connect(remoteEndpoint);
            var stream = _client.GetStream();
            _localEndpoint = GetLocalEndpoint();
            _disposed = false;
            _reader = new StreamDataReader(stream);
            _writer = new StreamDataWriter(stream);
            _streamingCodec = streamingCodec;
        }

        /// <summary>
        /// Constructs a Link object.
        /// Uses the already connected TcpClient.
        /// </summary>
        /// <param name="client">The already connected client</param>
        /// <param name="streamingCodec">Streaming codec</param>
        internal StreamingLink(TcpClient client, IStreamingCodec<T> streamingCodec)
        {
            if (client == null)
            {
                throw new ArgumentNullException("client");
            }

            _client = client;
            var stream = _client.GetStream();
            _localEndpoint = GetLocalEndpoint();
            _disposed = false;
            _reader = new StreamDataReader(stream);
            _writer = new StreamDataWriter(stream);
            _streamingCodec = streamingCodec;
        }

        /// <summary>
        /// Returns the local socket address
        /// </summary>
        public IPEndPoint LocalEndpoint
        {
            get { return _localEndpoint; }
        }

        /// <summary>
        /// Returns the remote socket address
        /// </summary>
        public IPEndPoint RemoteEndpoint
        {
            get { return (IPEndPoint)_client.Client.RemoteEndPoint; }
        }

        /// <summary>
        /// Writes the message to the remote host
        /// </summary>
        /// <param name="value">The data to write</param>
        public void Write(T value)
        {
            if (value == null)
            {
                throw new ArgumentNullException("value");
            }
            if (_disposed)
            {
                Exceptions.Throw(new IllegalStateException("StreamingLink has been closed."), Logger);
            }

            _streamingCodec.Write(value, _writer);
        }

        /// <summary>
        /// Writes the value to this link asynchronously
        /// </summary>
        /// <param name="value">The data to write</param>
        /// <param name="token">The cancellation token</param>
        public async Task WriteAsync(T value, CancellationToken token)
        {
            if (_disposed)
            {
                Exceptions.Throw(new IllegalStateException("StreamingLink has been closed."), Logger);
            }

            await _streamingCodec.WriteAsync(value, _writer, token);
        }

        /// <summary>
        /// Reads the value from the link synchronously
        /// </summary>
        public T Read()
        {
            if (_disposed)
            {
                Exceptions.Throw(new IllegalStateException("Link has been disposed."), Logger);
            }

            try
            {
                T value = _streamingCodec.Read(_reader);
                return value;
            }
            catch (Exception e)
            {
                Logger.Log(Level.Warning, "In Read function unable to read the message.");
                Exceptions.CaughtAndThrow(e, Level.Error, Logger);
                throw;
            }
        }

        /// <summary>
        /// Reads the value from the link asynchronously
        /// </summary>
        /// <param name="token">The cancellation token</param>
        public async Task<T> ReadAsync(CancellationToken token)
        {
            if (_disposed)
            {
                Exceptions.Throw(new IllegalStateException("Link has been disposed."), Logger);
            }

            try
            {
                T value = await _streamingCodec.ReadAsync(_reader, token);
                return value;
            }
            catch (Exception e)
            {
                Logger.Log(Level.Warning, "In ReadAsync function unable to read the message.");
                Exceptions.CaughtAndThrow(e, Level.Error, Logger);
                throw;
            }
        }

        /// <summary>
        /// Close the client connection
        /// </summary>
        public void Dispose()
        {
            if (_disposed)
            {
                return;
            }

            try
            {
                _client.GetStream().Close();
            }
            catch (InvalidOperationException)
            {
                Logger.Log(Level.Warning, "failed to close stream on a non-connected socket.");
            }

            _client.Close();
            _disposed = true;
        }

        /// <summary>
        /// Overrides Equals. Two Link objects are equal if they are connected
        /// to the same remote endpoint.
        /// </summary>
        /// <param name="obj">The object to compare</param>
        /// <returns>True if the object is equal to this Link, otherwise false</returns>
        public override bool Equals(object obj)
        {
            Link<T> other = obj as Link<T>;
            if (other == null)
            {
                return false;
            }

            return other.RemoteEndpoint.Equals(RemoteEndpoint);
        }

        /// <summary>
        /// Gets the hash code for the Link object.
        /// </summary>
        /// <returns>The object's hash code</returns>
        public override int GetHashCode()
        {
            return RemoteEndpoint.GetHashCode();
        }

        /// <summary>
        /// Discovers the IPEndpoint for the current machine.
        /// </summary>
        /// <returns>The local IPEndpoint</returns>
        private IPEndPoint GetLocalEndpoint()
        {
            IPAddress address = NetworkUtils.LocalIPAddress;
            int port = ((IPEndPoint)_client.Client.LocalEndPoint).Port;
            return new IPEndPoint(address, port);
        }
    }
}