#region Copyright notice and license
// Copyright 2015 gRPC authors.
//
// Licensed 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.
#endregion
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Grpc.Core.Internal;
using Grpc.Core.Logging;
using Grpc.Core.Utils;
namespace Grpc.Core
{
///
/// Represents a gRPC channel. Channels are an abstraction of long-lived connections to remote servers.
/// More client objects can reuse the same channel. Creating a channel is an expensive operation compared to invoking
/// a remote call so in general you should reuse a single channel for as many calls as possible.
///
public class Channel
{
static readonly ILogger Logger = GrpcEnvironment.Logger.ForType();
readonly object myLock = new object();
readonly AtomicCounter activeCallCounter = new AtomicCounter();
readonly CancellationTokenSource shutdownTokenSource = new CancellationTokenSource();
readonly string target;
readonly GrpcEnvironment environment;
readonly CompletionQueueSafeHandle completionQueue;
readonly ChannelSafeHandle handle;
readonly Dictionary options;
readonly Task connectivityWatcherTask;
bool shutdownRequested;
///
/// Creates a channel that connects to a specific host.
/// Port will default to 80 for an unsecure channel and to 443 for a secure channel.
///
/// Target of the channel.
/// Credentials to secure the channel.
public Channel(string target, ChannelCredentials credentials) :
this(target, credentials, null)
{
}
///
/// Creates a channel that connects to a specific host.
/// Port will default to 80 for an unsecure channel and to 443 for a secure channel.
///
/// Target of the channel.
/// Credentials to secure the channel.
/// Channel options.
public Channel(string target, ChannelCredentials credentials, IEnumerable options)
{
this.target = GrpcPreconditions.CheckNotNull(target, "target");
this.options = CreateOptionsDictionary(options);
EnsureUserAgentChannelOption(this.options);
this.environment = GrpcEnvironment.AddRef();
this.completionQueue = this.environment.PickCompletionQueue();
using (var nativeCredentials = credentials.ToNativeCredentials())
using (var nativeChannelArgs = ChannelOptions.CreateChannelArgs(this.options.Values))
{
if (nativeCredentials != null)
{
this.handle = ChannelSafeHandle.CreateSecure(nativeCredentials, target, nativeChannelArgs);
}
else
{
this.handle = ChannelSafeHandle.CreateInsecure(target, nativeChannelArgs);
}
}
// TODO(jtattermusch): Workaround for https://github.com/GoogleCloudPlatform/google-cloud-dotnet/issues/822.
// Remove once retries are supported in C core
this.connectivityWatcherTask = RunConnectivityWatcherAsync();
GrpcEnvironment.RegisterChannel(this);
}
///
/// Creates a channel that connects to a specific host and port.
///
/// The name or IP address of the host.
/// The port.
/// Credentials to secure the channel.
public Channel(string host, int port, ChannelCredentials credentials) :
this(host, port, credentials, null)
{
}
///
/// Creates a channel that connects to a specific host and port.
///
/// The name or IP address of the host.
/// The port.
/// Credentials to secure the channel.
/// Channel options.
public Channel(string host, int port, ChannelCredentials credentials, IEnumerable options) :
this(string.Format("{0}:{1}", host, port), credentials, options)
{
}
///
/// Gets current connectivity state of this channel.
/// After channel is has been shutdown, ChannelState.Shutdown will be returned.
///
public ChannelState State
{
get
{
return GetConnectivityState(false);
}
}
///
/// Returned tasks completes once channel state has become different from
/// given lastObservedState.
/// If deadline is reached or and error occurs, returned task is cancelled.
///
public Task WaitForStateChangedAsync(ChannelState lastObservedState, DateTime? deadline = null)
{
GrpcPreconditions.CheckArgument(lastObservedState != ChannelState.Shutdown,
"Shutdown is a terminal state. No further state changes can occur.");
var tcs = new TaskCompletionSource