[Otlp] Add persistent storage transmission handler

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/OpenTelemetryProtocolExporterEventSource.cs

@@ -40,6 +40,15 @@ public void TrySubmitRequestException(Exception ex)
         }
     }
 
+    [NonEvent]
+    public void RetryStoredRequestException(Exception ex)
+    {
+        if (Log.IsEnabled(EventLevel.Error, EventKeywords.All))
+        {
+            this.RetryStoredRequestException(ex.ToInvariantString());
+        }
+    }
+
     [Event(2, Message = "Exporter failed send data to collector to {0} endpoint. Data will not be sent. Exception: {1}", Level = EventLevel.Error)]
     public void FailedToReachCollector(string rawCollectorUri, string ex)
     {
@@ -94,6 +103,12 @@ public void TrySubmitRequestException(string ex)
         this.WriteEvent(12, ex);
     }
 
+    [Event(13, Message = "Error while attempting to re-transmit data from disk. Message: '{0}'", Level = EventLevel.Error)]
+    public void RetryStoredRequestException(string ex)
+    {
+        this.WriteEvent(13, ex);
+    }
+
     void IConfigurationExtensionsLogger.LogInvalidConfigurationValue(string key, string value)
     {
         this.InvalidConfigurationValue(key, value);

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/Transmission/OtlpExporterPersistentStorageTransmissionHandler.cs

@@ -0,0 +1,190 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#nullable enable
+
+using System.Diagnostics;
+using Google.Protobuf;
+using Google.Rpc;
+using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.ExportClient;
+using OpenTelemetry.PersistentStorage.Abstractions;
+using OpenTelemetry.PersistentStorage.FileSystem;
+using OpenTelemetry.Proto.Collector.Logs.V1;
+using OpenTelemetry.Proto.Collector.Metrics.V1;
+using OpenTelemetry.Proto.Collector.Trace.V1;
+
+namespace OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.Transmission;
+
+internal sealed class OtlpExporterPersistentStorageTransmissionHandler<TRequest> : OtlpExporterTransmissionHandler<TRequest>, IDisposable
+{
+    private const int RetryIntervalInMilliseconds = 60000;
+    private readonly ManualResetEvent shutdownEvent = new(false);
+    private readonly ManualResetEvent dataExportNotification = new(false);
+    private readonly AutoResetEvent exportEvent = new(false);
+    private readonly Thread thread;
+    private readonly PersistentBlobProvider persistentBlobProvider;
+    private readonly Func<byte[], TRequest> requestFactory;
+    private bool disposed;
+
+    public OtlpExporterPersistentStorageTransmissionHandler(IExportClient<TRequest> exportClient, double timeoutMilliseconds, Func<byte[], TRequest> requestFactory, string storagePath)
+        : this(new FileBlobProvider(storagePath), exportClient, timeoutMilliseconds, requestFactory)
+    {
+    }
+
+    internal OtlpExporterPersistentStorageTransmissionHandler(PersistentBlobProvider persistentBlobProvider, IExportClient<TRequest> exportClient, double timeoutMilliseconds, Func<byte[], TRequest> requestFactory)
+        : base(exportClient, timeoutMilliseconds)
+    {
+        Debug.Assert(persistentBlobProvider != null, "persistentBlobProvider was null");
+        Debug.Assert(requestFactory != null, "requestFactory was null");
+
+        this.persistentBlobProvider = persistentBlobProvider!;
+        this.requestFactory = requestFactory!;
+
+        this.thread = new Thread(this.RetryStoredRequests)
+        {
+            Name = $"OtlpExporter Persistent Retry Storage - {typeof(TRequest)}",
+            IsBackground = true,
+        };
+
+        this.thread.Start();
+    }
+
+    // Used for test.
+    internal bool InitiateAndWaitForRetryProcess(int timeOutMilliseconds)
+    {
+        this.exportEvent.Set();
+
+        return this.dataExportNotification.WaitOne(timeOutMilliseconds);
+    }
+
+    protected override bool OnSubmitRequestFailure(TRequest request, ExportClientResponse response)
+    {
+        if (RetryHelper.ShouldRetryRequest(request, response, OtlpRetry.InitialBackoffMilliseconds, out _))
+        {
+            byte[]? data = null;
+            if (request is ExportTraceServiceRequest traceRequest)
+            {
+                data = traceRequest.ToByteArray();
+            }
+            else if (request is ExportMetricsServiceRequest metricsRequest)
+            {
+                data = metricsRequest.ToByteArray();
+            }
+            else if (request is ExportLogsServiceRequest logsRequest)
+            {
+                data = logsRequest.ToByteArray();
+            }
+            else
+            {
+                Debug.Fail("Unexpected request type encountered");
+                data = null;
+            }
+
+            if (data != null)
+            {
+                return this.persistentBlobProvider.TryCreateBlob(data, out _);
+            }
+        }
+
+        return false;
+    }
+
+    protected override void OnShutdown(int timeoutMilliseconds)
+    {
+        var sw = timeoutMilliseconds == Timeout.Infinite ? null : Stopwatch.StartNew();
+
+        try
+        {
+            this.shutdownEvent.Set();
+        }
+        catch (ObjectDisposedException)
+        {
+            // Dispose was called before shutdown.
+        }
+
+        this.thread.Join(timeoutMilliseconds);
+
+        if (sw != null)
+        {
+            var timeout = timeoutMilliseconds - sw.ElapsedMilliseconds;
+
+            base.OnShutdown((int)Math.Max(timeout, 0));
+        }
+        else
+        {
+            base.OnShutdown(timeoutMilliseconds);
+        }
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        if (!this.disposed)
+        {
+            if (disposing)
+            {
+                this.shutdownEvent.Dispose();
+                this.exportEvent.Dispose();
+                this.dataExportNotification.Dispose();
+                (this.persistentBlobProvider as IDisposable)?.Dispose();
+            }
+
+            this.disposed = true;
+        }
+    }
+
+    private void RetryStoredRequests()
+    {
+        var handles = new WaitHandle[] { this.shutdownEvent, this.exportEvent };
+        while (true)
+        {
+            try
+            {
+                var index = WaitHandle.WaitAny(handles, RetryIntervalInMilliseconds);
+                if (index == 0)
+                {
+                    // Shutdown signaled
+                    break;
+                }
+
+                int fileCount = 0;
+
+                // TODO: Run maintenance job.
+                // Transmit 10 files at a time.
+                while (fileCount < 10 && !this.shutdownEvent.WaitOne(0))
+                {
+                    if (!this.persistentBlobProvider.TryGetBlob(out var blob))
+                    {
+                        break;
+                    }
+
+                    if (blob.TryLease((int)this.TimeoutMilliseconds) && blob.TryRead(out var data))
+                    {
+                        var deadlineUtc = DateTime.UtcNow.AddMilliseconds(this.TimeoutMilliseconds);
+                        var request = this.requestFactory.Invoke(data);
+                        if (this.TryRetryRequest(request, deadlineUtc, out var response) || !RetryHelper.ShouldRetryRequest(request, response, OtlpRetry.InitialBackoffMilliseconds, out var retryInfo))
+                        {
+                            blob.TryDelete();
+                        }
+                        else
+                        {
+                            // Extend the lease period so that it is retried before the intended retry interval.
+                            blob.TryLease(retryInfo.RetryDelay.Milliseconds);
+                        }
+                    }
+
+                    fileCount++;
+                }
+
+                // Set and reset the handle to notify export and wait for next signal.
+                // This is used for InitiateAndWaitForRetryProcess.
+                this.dataExportNotification.Set();
+                this.dataExportNotification.Reset();
+            }
+            catch (Exception ex)
+            {
+                OpenTelemetryProtocolExporterEventSource.Log.RetryStoredRequestException(ex);
+                return;
+            }
+        }
+    }
+}

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/Transmission/OtlpExporterTransmissionHandler.cs

@@ -9,7 +9,7 @@
 
 namespace OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.Transmission;
 
-internal class OtlpExporterTransmissionHandler<TRequest>
+internal class OtlpExporterTransmissionHandler<TRequest> : IDisposable
 {
     public OtlpExporterTransmissionHandler(IExportClient<TRequest> exportClient, double timeoutMilliseconds)
     {
@@ -80,6 +80,13 @@ public bool Shutdown(int timeoutMilliseconds)
         return this.ExportClient.Shutdown(timeoutMilliseconds);
     }
 
+    /// <inheritdoc/>
+    public void Dispose()
+    {
+        this.Dispose(true);
+        GC.SuppressFinalize(this);
+    }
+
     /// <summary>
     /// Fired when the transmission handler is shutdown.
     /// </summary>
@@ -122,4 +129,16 @@ protected bool TryRetryRequest(TRequest request, DateTime deadlineUtc, out Expor
 
         return true;
     }
+
+    /// <summary>
+    /// Releases the unmanaged resources used by this class and optionally
+    /// releases the managed resources.
+    /// </summary>
+    /// <param name="disposing">
+    /// <see langword="true"/> to release both managed and unmanaged resources;
+    /// <see langword="false"/> to release only unmanaged resources.
+    /// </param>
+    protected virtual void Dispose(bool disposing)
+    {
+    }
 }