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239 lines (212 loc) · 10.2 KB
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using System.IO;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.NodeServices.HostingModels;
using Microsoft.AspNetCore.NodeServices.Sockets.PhysicalConnections;
using Microsoft.AspNetCore.NodeServices.Sockets.VirtualConnections;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
namespace Microsoft.AspNetCore.NodeServices.Sockets
{
/// <summary>
/// A specialisation of the OutOfProcessNodeInstance base class that uses a lightweight binary streaming protocol
/// to perform RPC invocations. The physical transport is Named Pipes on Windows, or Domain Sockets on Linux/Mac.
/// For details on the binary streaming protocol, see
/// Microsoft.AspNetCore.NodeServices.HostingModels.VirtualConnections.VirtualConnectionClient.
/// The advantage versus using HTTP for RPC is that this is faster (not surprisingly - there's much less overhead
/// because we don't need most of the functionality of HTTP.
///
/// The address of the pipe/socket is selected randomly here on the .NET side and sent to the child process as a
/// command-line argument (the address space is wide enough that there's no real risk of a clash, unlike when
/// selecting TCP port numbers).
/// </summary>
/// <seealso cref="Microsoft.AspNetCore.NodeServices.HostingModels.OutOfProcessNodeInstance" />
internal class SocketNodeInstance : OutOfProcessNodeInstance
{
private readonly static JsonSerializerSettings jsonSerializerSettings = new JsonSerializerSettings
{
ContractResolver = new CamelCasePropertyNamesContractResolver(),
TypeNameHandling = TypeNameHandling.None
};
private readonly static int streamBufferSize = 16 * 1024;
private readonly static UTF8Encoding utf8EncodingWithoutBom = new UTF8Encoding(false);
private readonly SemaphoreSlim _connectionCreationSemaphore = new SemaphoreSlim(1);
private bool _connectionHasFailed;
private StreamConnection _physicalConnection;
private string _socketAddress;
private VirtualConnectionClient _virtualConnectionClient;
public SocketNodeInstance(NodeServicesOptions options, string socketAddress)
: base(
EmbeddedResourceReader.Read(
typeof(SocketNodeInstance),
"/Content/Node/entrypoint-socket.js"),
options.ProjectPath,
options.WatchFileExtensions,
MakeNewCommandLineOptions(socketAddress),
options.NodeInstanceOutputLogger,
options.EnvironmentVariables,
options.InvocationTimeoutMilliseconds,
options.LaunchWithDebugging,
options.DebuggingPort)
{
_socketAddress = socketAddress;
}
protected override async Task<T> InvokeExportAsync<T>(NodeInvocationInfo invocationInfo, CancellationToken cancellationToken)
{
if (_connectionHasFailed)
{
// _connectionHasFailed implies a protocol-level error. The old instance is no longer of any use.
var allowConnectionDraining = false;
// This special exception type forces NodeServicesImpl to restart the Node instance
throw new NodeInvocationException(
"The SocketNodeInstance socket connection failed. See logs to identify the reason.",
details: null,
nodeInstanceUnavailable: true,
allowConnectionDraining: allowConnectionDraining);
}
if (_virtualConnectionClient == null)
{
// Although we could pass the cancellationToken into EnsureVirtualConnectionClientCreated and
// have it signal cancellations upstream, that would be a bad thing to do, because all callers
// wait for the same connection task. There's no reason why the first caller should have the
// special ability to cancel the connection process in a way that would affect subsequent
// callers. So, each caller just independently stops awaiting connection if that call is cancelled.
await ThrowOnCancellation(EnsureVirtualConnectionClientCreated(), cancellationToken);
}
// For each invocation, we open a new virtual connection. This gives an API equivalent to opening a new
// physical connection to the child process, but without the overhead of doing so, because it's really
// just multiplexed into the existing physical connection stream.
bool shouldDisposeVirtualConnection = true;
Stream virtualConnection = null;
try
{
virtualConnection = _virtualConnectionClient.OpenVirtualConnection();
// Send request
WriteJsonLine(virtualConnection, invocationInfo);
// Determine what kind of response format is expected
if (typeof(T) == typeof(Stream))
{
// Pass through streamed binary response
// It is up to the consumer to dispose this stream, so don't do so here
shouldDisposeVirtualConnection = false;
return (T)(object)virtualConnection;
}
else
{
// Parse and return non-streamed JSON response
var response = await ReadJsonAsync<RpcJsonResponse<T>>(virtualConnection, cancellationToken);
if (response.ErrorMessage != null)
{
throw new NodeInvocationException(response.ErrorMessage, response.ErrorDetails);
}
return response.Result;
}
}
finally
{
if (shouldDisposeVirtualConnection)
{
virtualConnection.Dispose();
}
}
}
private async Task EnsureVirtualConnectionClientCreated()
{
// Asynchronous equivalent to a 'lock(...) { ... }'
await _connectionCreationSemaphore.WaitAsync();
try
{
if (_virtualConnectionClient == null)
{
_physicalConnection = StreamConnection.Create();
var connection = await _physicalConnection.Open(_socketAddress);
_virtualConnectionClient = new VirtualConnectionClient(connection);
_virtualConnectionClient.OnError += (ex) =>
{
// This callback is fired only if there's a protocol-level failure (e.g., child process disconnected
// unexpectedly). It does *not* fire when RPC calls return errors. Since there's been a protocol-level
// failure, this Node instance is no longer usable and should be discarded.
_connectionHasFailed = true;
OutputLogger.LogError(0, ex, ex.Message);
};
}
}
finally
{
_connectionCreationSemaphore.Release();
}
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (_virtualConnectionClient != null)
{
_virtualConnectionClient.Dispose();
_virtualConnectionClient = null;
}
if (_physicalConnection != null)
{
_physicalConnection.Dispose();
_physicalConnection = null;
}
}
base.Dispose(disposing);
}
private static void WriteJsonLine(Stream stream, object serializableObject)
{
using (var streamWriter = new StreamWriter(stream, utf8EncodingWithoutBom, streamBufferSize, true))
using (var jsonWriter = new JsonTextWriter(streamWriter))
{
jsonWriter.CloseOutput = false;
var serializer = JsonSerializer.Create(jsonSerializerSettings);
serializer.Serialize(jsonWriter, serializableObject);
jsonWriter.Flush();
streamWriter.WriteLine();
streamWriter.Flush();
}
}
private static async Task<T> ReadJsonAsync<T>(Stream stream, CancellationToken cancellationToken)
{
var json = Encoding.UTF8.GetString(await ReadAllBytesAsync(stream, cancellationToken));
return JsonConvert.DeserializeObject<T>(json, jsonSerializerSettings);
}
private static async Task<byte[]> ReadAllBytesAsync(Stream input, CancellationToken cancellationToken)
{
byte[] buffer = new byte[streamBufferSize];
using (var ms = new MemoryStream())
{
int read;
while ((read = await input.ReadAsync(buffer, 0, buffer.Length, cancellationToken)) > 0)
{
ms.Write(buffer, 0, read);
}
return ms.ToArray();
}
}
private static string MakeNewCommandLineOptions(string listenAddress)
{
return $"--listenAddress {listenAddress}";
}
private static Task ThrowOnCancellation(Task task, CancellationToken cancellationToken)
{
return task.IsCompleted
? task // If the task is already completed, no need to wrap it in a further layer of task
: task.ContinueWith(
_ => {}, // If the task completes, allow execution to continue
cancellationToken,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
#pragma warning disable 649 // These properties are populated via JSON deserialization
private class RpcJsonResponse<TResult>
{
public TResult Result { get; set; }
public string ErrorMessage { get; set; }
public string ErrorDetails { get; set; }
}
#pragma warning restore 649
}
}