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#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.Threading;
using Grpc.Core.Internal;
using Grpc.Core.Utils;
namespace Grpc.Core
{
/// <summary>
/// Token for propagating context of server side handlers to child calls.
/// In situations when a backend is making calls to another backend,
/// it makes sense to propagate properties like deadline and cancellation
/// token of the server call to the child call.
/// The gRPC native layer provides some other contexts (like tracing context) that
/// are not accessible to explicitly C# layer, but this token still allows propagating them.
/// </summary>
public class ContextPropagationToken
{
/// <summary>
/// Default propagation mask used by C core.
/// </summary>
private const ContextPropagationFlags DefaultCoreMask = (ContextPropagationFlags)0xffff;
/// <summary>
/// Default propagation mask used by C# - we want to propagate deadline
/// and cancellation token by our own means.
/// </summary>
internal const ContextPropagationFlags DefaultMask = DefaultCoreMask
& ~ContextPropagationFlags.Deadline & ~ContextPropagationFlags.Cancellation;
readonly CallSafeHandle parentCall;
readonly DateTime deadline;
readonly CancellationToken cancellationToken;
readonly ContextPropagationOptions options;
internal ContextPropagationToken(CallSafeHandle parentCall, DateTime deadline, CancellationToken cancellationToken, ContextPropagationOptions options)
{
this.parentCall = GrpcPreconditions.CheckNotNull(parentCall);
this.deadline = deadline;
this.cancellationToken = cancellationToken;
this.options = options ?? ContextPropagationOptions.Default;
}
/// <summary>
/// Gets the native handle of the parent call.
/// </summary>
internal CallSafeHandle ParentCall
{
get
{
return this.parentCall;
}
}
/// <summary>
/// Gets the parent call's deadline.
/// </summary>
internal DateTime ParentDeadline
{
get
{
return this.deadline;
}
}
/// <summary>
/// Gets the parent call's cancellation token.
/// </summary>
internal CancellationToken ParentCancellationToken
{
get
{
return this.cancellationToken;
}
}
/// <summary>
/// Get the context propagation options.
/// </summary>
internal ContextPropagationOptions Options
{
get
{
return this.options;
}
}
}
/// <summary>
/// Options for <see cref="ContextPropagationToken"/>.
/// </summary>
public class ContextPropagationOptions
{
/// <summary>
/// The context propagation options that will be used by default.
/// </summary>
public static readonly ContextPropagationOptions Default = new ContextPropagationOptions();
bool propagateDeadline;
bool propagateCancellation;
/// <summary>
/// Creates new context propagation options.
/// </summary>
/// <param name="propagateDeadline">If set to <c>true</c> parent call's deadline will be propagated to the child call.</param>
/// <param name="propagateCancellation">If set to <c>true</c> parent call's cancellation token will be propagated to the child call.</param>
public ContextPropagationOptions(bool propagateDeadline = true, bool propagateCancellation = true)
{
this.propagateDeadline = propagateDeadline;
this.propagateCancellation = propagateCancellation;
}
/// <summary><c>true</c> if parent call's deadline should be propagated to the child call.</summary>
public bool IsPropagateDeadline
{
get { return this.propagateDeadline; }
}
/// <summary><c>true</c> if parent call's cancellation token should be propagated to the child call.</summary>
public bool IsPropagateCancellation
{
get { return this.propagateCancellation; }
}
}
/// <summary>
/// Context propagation flags from grpc/grpc.h.
/// </summary>
[Flags]
internal enum ContextPropagationFlags
{
Deadline = 1,
CensusStatsContext = 2,
CensusTracingContext = 4,
Cancellation = 8
}
}
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