InMemoryExporter.cs

// <copyright file="InMemoryExporter.cs" company="OpenTelemetry Authors">
// Copyright The OpenTelemetry 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.
// </copyright>

using System;
using System.Collections.Generic;

namespace OpenTelemetry.Exporter
{
    public class InMemoryExporter<T> : BaseExporter<T>
        where T : class
    {
        private readonly ICollection<T> exportedItems;
        private readonly ExportFunc onExport;
        private bool disposed;

        public InMemoryExporter(ICollection<T> exportedItems)
        {
            this.exportedItems = exportedItems;
            this.onExport = this.DefaultExport;
        }

        internal InMemoryExporter(ExportFunc exportFunc)
        {
            this.onExport = exportFunc;
        }

        internal delegate ExportResult ExportFunc(in Batch<T> batch);

        public override ExportResult Export(in Batch<T> batch)
        {
            if (this.disposed)
            {
                // Since in-memory exporter is designed for testing purpose, having an early error would help developers to catch the bug during early stage of the development.
                throw new ObjectDisposedException(this.GetType().Name, "The in-memory exporter is still being invoked after it is disposed. This indicates a wrong use of the OpenTelemetry .NET SDK, where the object lifecycle is not properly managed.");
            }

            return this.onExport(batch);
        }

        /// <inheritdoc/>
        protected override void Dispose(bool disposing)
        {
            if (!this.disposed)
            {
                this.disposed = true;
            }

            base.Dispose(disposing);
        }

        private ExportResult DefaultExport(in Batch<T> batch)
        {
            if (this.exportedItems == null)
            {
                return ExportResult.Failure;
            }

            foreach (var data in batch)
            {
                this.exportedItems.Add(data);
            }

            return ExportResult.Success;
        }
    }
}