src/DurableTask.Core/TraceContextFactory.cs

//  ----------------------------------------------------------------------------------
//  Copyright Microsoft Corporation
//  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.
//  ----------------------------------------------------------------------------------

namespace DurableTask.Core
{
    using System;
    using System.Collections.Generic;
    using System.Diagnostics;
    using System.Dynamic;
    using System.Text;
    using DurableTask.Core.Settings;

    /// <summary>
    /// Factory of TraceContext
    /// </summary>
    public class TraceContextFactory
    {
        /// <summary>
        /// Create an instance of TraceContext
        /// </summary>
        /// <param name="operationName">Operation name for the TraceContext</param>
        /// <returns></returns>
        public static TraceContextBase Create(string operationName)
        {
            return CreateFactory().Create(operationName);
        }

        /// <summary>
        /// Create an instance of TraceContext
        /// </summary>
        /// <param name="activity">Activity already started</param>
        /// <returns></returns>
        public static TraceContextBase Create(Activity activity)
        {
            return CreateFactory().Create(activity);
        }

        /// <summary>
        /// Create a default context of TraceContext
        /// returns NullObjectTraceContext object
        /// </summary>
        public static TraceContextBase Empty { get; } = new NullObjectTraceContext();

        static ITraceContextFactory CreateFactory()
        {
            switch (CorrelationSettings.Current.Protocol)
            {
                case Protocol.W3CTraceContext:
                    return new W3CTraceContextFactory();                
                case Protocol.HttpCorrelationProtocol:
                    return new HttpCorrelationProtocolTraceContextFactory();
                default:
                    throw new NotSupportedException($"{CorrelationSettings.Current.Protocol} is not supported. Check the CorrelationSettings.Current.Protocol");
            }
        }

        interface ITraceContextFactory
        {
            TraceContextBase Create(Activity activity);

            TraceContextBase Create(string operationName);
        }

        class W3CTraceContextFactory : ITraceContextFactory
        {
            public TraceContextBase Create(Activity activity)
            {
                return new W3CTraceContext()
                {
                    OperationName = activity.OperationName,
                    StartTime = activity.StartTimeUtc,
                    TraceParent = activity.Id,
                    TraceState = activity.TraceStateString,
                    ParentSpanId = activity.ParentSpanId.ToHexString(),
                    // ParentId = activity.Id // TODO check if it necessary
                    CurrentActivity = activity
                };
            }

            public TraceContextBase Create(string operationName)
            {
                return new W3CTraceContext()
                {
                    OperationName = operationName
                };
            }
        }

        class HttpCorrelationProtocolTraceContextFactory : ITraceContextFactory
        {
            public TraceContextBase Create(Activity activity)
            {
                return new HttpCorrelationProtocolTraceContext()
                {
                    OperationName = activity.OperationName,
                    StartTime = activity.StartTimeUtc,
                    ParentId = activity.Id,
                    CurrentActivity = activity
                };
            }

            public TraceContextBase Create(string operationName)
            {
                return new HttpCorrelationProtocolTraceContext()
                {
                    OperationName = operationName
                };
            }
        }
    }
}