CallOptions.cs

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#endregion

using System;
using System.Threading;

using Grpc.Core.Internal;
using Grpc.Core.Utils;

namespace Grpc.Core
{
    /// <summary>
    /// Options for calls made by client.
    /// </summary>
    public struct CallOptions
    {
        Metadata headers;
        DateTime? deadline;
        CancellationToken cancellationToken;
        WriteOptions writeOptions;
        ContextPropagationToken propagationToken;
        Credentials credentials;

        /// <summary>
        /// Creates a new instance of <c>CallOptions</c> struct.
        /// </summary>
        /// <param name="headers">Headers to be sent with the call.</param>
        /// <param name="deadline">Deadline for the call to finish. null means no deadline.</param>
        /// <param name="cancellationToken">Can be used to request cancellation of the call.</param>
        /// <param name="writeOptions">Write options that will be used for this call.</param>
        /// <param name="propagationToken">Context propagation token obtained from <see cref="ServerCallContext"/>.</param>
        /// <param name="credentials">Credentials to use for this call.</param>
        public CallOptions(Metadata headers = null, DateTime? deadline = null, CancellationToken cancellationToken = default(CancellationToken),
                           WriteOptions writeOptions = null, ContextPropagationToken propagationToken = null, Credentials credentials = null)
        {
            this.headers = headers;
            this.deadline = deadline;
            this.cancellationToken = cancellationToken;
            this.writeOptions = writeOptions;
            this.propagationToken = propagationToken;
            this.credentials = credentials;
        }

        /// <summary>
        /// Headers to send at the beginning of the call.
        /// </summary>
        public Metadata Headers
        {
            get { return headers; }
        }

        /// <summary>
        /// Call deadline.
        /// </summary>
        public DateTime? Deadline
        {
            get { return deadline; }
        }

        /// <summary>
        /// Token that can be used for cancelling the call.
        /// </summary>
        public CancellationToken CancellationToken
        {
            get { return cancellationToken; }
        }

        /// <summary>
        /// Write options that will be used for this call.
        /// </summary>
        public WriteOptions WriteOptions
        {
            get
            {
                return this.writeOptions;
            }
        }

        /// <summary>
        /// Token for propagating parent call context.
        /// </summary>
        public ContextPropagationToken PropagationToken
        {
            get
            {
                return this.propagationToken;
            }
        }

        /// <summary>
        /// Credentials to use for this call.
        /// </summary>
        public Credentials Credentials
        {
            get
            {
                return this.credentials;
            }
        }

        /// <summary>
        /// Returns new instance of <see cref="CallOptions"/> with
        /// <c>Headers</c> set to the value provided. Values of all other fields are preserved.
        /// </summary>
        /// <param name="headers">The headers.</param>
        public CallOptions WithHeaders(Metadata headers)
        {
            var newOptions = this;
            newOptions.headers = headers;
            return newOptions;
        }

        /// <summary>
        /// Returns new instance of <see cref="CallOptions"/> with
        /// <c>Deadline</c> set to the value provided. Values of all other fields are preserved.
        /// </summary>
        /// <param name="deadline">The deadline.</param>
        public CallOptions WithDeadline(DateTime deadline)
        {
            var newOptions = this;
            newOptions.deadline = deadline;
            return newOptions;
        }

        /// <summary>
        /// Returns new instance of <see cref="CallOptions"/> with
        /// <c>CancellationToken</c> set to the value provided. Values of all other fields are preserved.
        /// </summary>
        /// <param name="cancellationToken">The cancellation token.</param>
        public CallOptions WithCancellationToken(CancellationToken cancellationToken)
        {
            var newOptions = this;
            newOptions.cancellationToken = cancellationToken;
            return newOptions;
        }

        /// <summary>
        /// Returns a new instance of <see cref="CallOptions"/> with 
        /// all previously unset values set to their defaults and deadline and cancellation
        /// token propagated when appropriate.
        /// </summary>
        internal CallOptions Normalize()
        {
            var newOptions = this;
            if (propagationToken != null)
            {
                if (propagationToken.Options.IsPropagateDeadline)
                {
                    Preconditions.CheckArgument(!newOptions.deadline.HasValue,
                        "Cannot propagate deadline from parent call. The deadline has already been set explicitly.");
                    newOptions.deadline = propagationToken.ParentDeadline;
                }
                if (propagationToken.Options.IsPropagateCancellation)
                {
                    Preconditions.CheckArgument(!newOptions.cancellationToken.CanBeCanceled,
                        "Cannot propagate cancellation token from parent call. The cancellation token has already been set to a non-default value.");
                }
            }
                
            newOptions.headers = newOptions.headers ?? Metadata.Empty;
            newOptions.deadline = newOptions.deadline ?? DateTime.MaxValue;
            return newOptions;
        }
    }
}