From 92a21bbc65d6e5ba00f13407ba21ef2e5169f44f Mon Sep 17 00:00:00 2001
From: Aleksandar Milicevic <almili@microsoft.com>
Date: Thu, 7 Nov 2019 10:33:35 -0800
Subject: [PATCH] Handle IOException when reading sideband files (#1178)

---
 Public/Src/Engine/Dll/EngineSchedule.cs       | 19 ++++++++++++++-----
 Public/Src/Engine/Dll/Tracing/Log.cs          |  9 +++++++++
 .../Utilities/Utilities/Tracing/EventId.cs    |  1 +
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/Public/Src/Engine/Dll/EngineSchedule.cs b/Public/Src/Engine/Dll/EngineSchedule.cs
index 561ef8b9b..0448fc3be 100644
--- a/Public/Src/Engine/Dll/EngineSchedule.cs
+++ b/Public/Src/Engine/Dll/EngineSchedule.cs
@@ -30,6 +30,7 @@ using BuildXL.Scheduler.Tracing;
 using BuildXL.Storage;
 using BuildXL.Tracing;
 using BuildXL.Utilities;
+using BuildXL.Utilities.Collections;
 using BuildXL.Utilities.Configuration;
 using BuildXL.Utilities.Instrumentation.Common;
 using BuildXL.Utilities.Qualifier;
@@ -785,7 +786,7 @@ namespace BuildXL.Engine
                 .AsParallel()
                 .WithDegreeOfParallelism(Environment.ProcessorCount)
                 .WithCancellation(scheduler.Context.CancellationToken)
-                .SelectMany(ReadSidebandFile)
+                .SelectMany(fileName => ReadSidebandFile(loggingContext, fileName))
                 .ToArray();
 
             if (distinctRecordedWrites.Any())
@@ -838,13 +839,21 @@ namespace BuildXL.Engine
             }
         }
 
-        private static string[] ReadSidebandFile(string sidebandFile)
+        private static string[] ReadSidebandFile(LoggingContext loggingContext, string sidebandFile)
         {
             using (var sidebandReader = new SidebandReader(sidebandFile))
             {
-                sidebandReader.ReadHeader(ignoreChecksum: true);
-                sidebandReader.ReadMetadata();
-                return sidebandReader.ReadRecordedPaths().ToArray();
+                try
+                {
+                    sidebandReader.ReadHeader(ignoreChecksum: true);
+                    sidebandReader.ReadMetadata();
+                    return sidebandReader.ReadRecordedPaths().ToArray();
+                }
+                catch (IOException e)
+                {
+                    Logger.Log.CannotReadSidebandFile(loggingContext, sidebandFile, e.Message);
+                    return CollectionUtilities.EmptyArray<string>();
+                }
             }
         }
 
diff --git a/Public/Src/Engine/Dll/Tracing/Log.cs b/Public/Src/Engine/Dll/Tracing/Log.cs
index c13cac980..8e282dc9d 100644
--- a/Public/Src/Engine/Dll/Tracing/Log.cs
+++ b/Public/Src/Engine/Dll/Tracing/Log.cs
@@ -1868,6 +1868,15 @@ If you can't update and need this feature after July 2018 please reach out to th
             Message = "/unsafe_DisableSharedOpaqueEmptyDirectoryScrubbing: removal of empty directories within shared opaques has been disabled. This is an unsafe configuration since it may work in detriment of build correctness.")]
         public abstract void ConfigUnsafeDisableSharedOpaqueEmptyDirectoryScrubbing(LoggingContext context);
 
+        [GeneratedEvent(
+            (ushort)EventId.CannotReadSidebandFile,
+            EventGenerators = EventGenerators.LocalOnly,
+            EventLevel = Level.Warning,
+            Keywords = (int)Keywords.UserMessage,
+            EventTask = (int)Tasks.Engine,
+            Message = "Cannot read sideband file '{fileName}': {error}")]
+        public abstract void CannotReadSidebandFile(LoggingContext context, string fileName, string error);
+
         [GeneratedEvent(
             (int)EventId.DeletingOutputsFromSharedOpaqueSidebandFilesStarted,
             EventGenerators = EventGenerators.LocalOnly,
diff --git a/Public/Src/Utilities/Utilities/Tracing/EventId.cs b/Public/Src/Utilities/Utilities/Tracing/EventId.cs
index 9327a67ba..c9e69bee2 100644
--- a/Public/Src/Utilities/Utilities/Tracing/EventId.cs
+++ b/Public/Src/Utilities/Utilities/Tracing/EventId.cs
@@ -540,6 +540,7 @@ namespace BuildXL.Utilities.Tracing
         DeletingOutputsFromSharedOpaqueSidebandFilesStarted = 867,
         DeletingSharedOpaqueSidebandFilesStarted = 868,
         ScrubbingProgress = 869,
+        CannotReadSidebandFile = 870,
 
         // Config
         ConfigUnsafeDisabledFileAccessMonitoring = 900,