File: src\VisualStudio\Core\Def\Watson\FaultReporter.cs
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Project: src\src\Workspaces\Remote\ServiceHub\Microsoft.CodeAnalysis.Remote.ServiceHub.csproj (Microsoft.CodeAnalysis.Remote.ServiceHub)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Threading;
using Microsoft.CodeAnalysis.Internal.Log;
using Microsoft.CodeAnalysis.Remote;
using Microsoft.CodeAnalysis.Telemetry;
using Microsoft.VisualStudio.Telemetry;
 
namespace Microsoft.CodeAnalysis.ErrorReporting;
 
internal static class FaultReporter
{
    /// <summary>
    /// We can no longer use the common fault description property as it has to be suppressed due to poisoned data in past releases.
    /// This means that prism will no longer show the fault description either.  We'll store the clean description in a custom
    /// property so we can access it manually if needed.
    /// </summary>
    private const string CustomFaultDescriptionPropertyName = "roslyn.fault.description";
 
    private static readonly object _guard = new();
    private static ImmutableArray<TelemetrySession> s_telemetrySessions = [];
    private static ImmutableArray<TraceSource> s_loggers = [];
 
    private static int s_dumpsSubmitted;
 
    public static void InitializeFatalErrorHandlers()
    {
        FatalError.ErrorReporterHandler handler = static (exception, severity, forceDump) => ReportFault(exception, ConvertSeverity(severity), forceDump);
        FatalError.SetHandlers(handler, nonFatalHandler: handler);
        FatalError.CopyHandlersTo(typeof(Compilation).Assembly);
    }
 
    private static FaultSeverity ConvertSeverity(ErrorSeverity severity)
    {
        return severity switch
        {
            ErrorSeverity.Uncategorized => FaultSeverity.Uncategorized,
            ErrorSeverity.Diagnostic => FaultSeverity.Diagnostic,
            ErrorSeverity.General => FaultSeverity.General,
            ErrorSeverity.Critical => FaultSeverity.Critical,
            _ => FaultSeverity.Uncategorized
        };
    }
 
    public static void RegisterTelemetrySesssion(TelemetrySession session)
    {
        lock (_guard)
        {
            s_telemetrySessions = s_telemetrySessions.Add(session);
        }
    }
 
    public static void UnregisterTelemetrySesssion(TelemetrySession session)
    {
        lock (_guard)
        {
            s_telemetrySessions = s_telemetrySessions.Remove(session);
        }
    }
 
    public static void RegisterLogger(TraceSource logger)
    {
        lock (_guard)
        {
            s_loggers = s_loggers.Add(logger);
        }
    }
 
    public static void UnregisterLogger(TraceSource logger)
    {
        lock (_guard)
        {
            s_loggers = s_loggers.Remove(logger);
        }
    }
 
    /// <summary>
    /// The bucket parameter for the blamed module.
    /// </summary>
    private const int P4ModuleNameDefaultIndex = 4;
 
    /// <summary>
    /// The bucket parameter for the blamed method.
    /// </summary>
    private const int P5MethodNameDefaultIndex = 5;
 
    private static readonly ImmutableArray<string> UnblameableMethodPrefixes =
    [
        "Microsoft.CodeAnalysis.Shared.Extensions.ISolutionExtensions.GetRequired",
        "Microsoft.CodeAnalysis.Host.HostLanguageServices.GetRequiredService",
        "Roslyn.Utilities.Contract.",
        "System.Linq.",
    ];
 
    /// <summary>
    /// Report Non-Fatal Watson for a given unhandled exception.
    /// </summary>
    /// <param name="exception">Exception that triggered this non-fatal error</param>
    /// <param name="forceDump">Force a dump to be created, even if the telemetry system is not
    /// requesting one; we will still do a client-side limit to avoid sending too much at once.</param>
    public static void ReportFault(Exception exception, FaultSeverity severity, bool forceDump)
    {
        try
        {
            if (exception is OperationCanceledException { InnerException: { } oceInnerException })
            {
                ReportFault(oceInnerException, severity, forceDump);
                return;
            }
 
            if (exception is AggregateException aggregateException)
            {
                // We (potentially) have multiple exceptions; let's just report each of them
                foreach (var innerException in aggregateException.Flatten().InnerExceptions)
                    ReportFault(innerException, severity, forceDump);
 
                return;
            }
 
            var currentProcess = Process.GetCurrentProcess();
 
            // write the exception to a log file:
            var logMessage = $"[{currentProcess.ProcessName}:{currentProcess.Id}] Unexpected exception: {exception}";
            foreach (var logger in s_loggers)
            {
                logger.TraceEvent(TraceEventType.Error, 1, logMessage);
            }
 
            var description = GetDescription(exception);
            var faultEvent = new FaultEvent(
                eventName: TelemetryLogger.GetEventName(FunctionId.NonFatalWatson),
                description: description,
                severity,
                exceptionObject: exception,
                gatherEventDetails: faultUtility =>
                {
                    if (forceDump)
                    {
                        // Let's just send a maximum of three; number chosen arbitrarily
                        if (Interlocked.Increment(ref s_dumpsSubmitted) <= 3)
                            faultUtility.AddProcessDump(currentProcess.Id);
                    }
 
                    UpdateBlamedMethod(faultUtility, exception);
 
                    if (faultUtility is FaultEvent { IsIncludedInWatsonSample: true })
                    {
                        // add ServiceHub log files:
                        foreach (var path in CollectServiceHubLogFilePaths())
                        {
                            faultUtility.AddFile(path);
                        }
 
                        foreach (var loghubPath in CollectLogHubFilePaths())
                        {
                            faultUtility.AddFile(loghubPath);
                        }
                    }
 
                    // Returning "0" signals that, if sampled, we should send data to Watson. 
                    // Any other value will cancel the Watson report. We never want to trigger a process dump manually, 
                    // we'll let TargetedNotifications determine if a dump should be collected.
                    // See https://aka.ms/roslynnfwdocs for more details
                    return 0;
                });
 
            faultEvent.Properties[CustomFaultDescriptionPropertyName] = description;
 
            foreach (var session in s_telemetrySessions)
            {
                session.PostEvent(faultEvent);
            }
        }
        catch (OutOfMemoryException)
        {
            FailFast.OnFatalException(exception);
        }
        catch (Exception e)
        {
            FailFast.OnFatalException(e);
        }
    }
 
    private static void UpdateBlamedMethod(IFaultUtility faultUtility, Exception exception)
    {
        var blamedMethod = faultUtility.GetBucketParameter(P5MethodNameDefaultIndex);
 
        // We'll only override anything if the default logic blamed something we didn't want
        if (!UnblameableMethodPrefixes.Any(p => blamedMethod.StartsWith(p)))
        {
            return;
        }
 
        // If anything fails here, we'll just keep the failure as is rather than potentially losing it
        try
        {
            var stackTrace = new StackTrace(exception);
            foreach (var stackFrame in stackTrace.GetFrames())
            {
                var method = stackFrame.GetMethod();
                if (method != null && method.DeclaringType != null)
                {
                    // Get the full name of the method, without parameters
                    var methodName = method.DeclaringType.FullName + "." + method.Name;
                    if (!UnblameableMethodPrefixes.Any(p => methodName.StartsWith(p)))
                    {
                        faultUtility.SetBucketParameter(P4ModuleNameDefaultIndex, method.DeclaringType.Assembly.GetName().Name);
                        faultUtility.SetBucketParameter(P5MethodNameDefaultIndex, methodName);
                        return;
                    }
                }
            }
        }
        catch { }
    }
 
    private static string GetDescription(Exception exception)
    {
        const string CodeAnalysisNamespace = nameof(Microsoft) + "." + nameof(CodeAnalysis);
 
        // Be resilient to failing here.  If we can't get a suitable name, just fall back to the standard name we
        // used to report.
        try
        {
            // walk up the stack looking for the first call from a type that isn't in the ErrorReporting namespace.
            var frames = new StackTrace(exception).GetFrames();
 
            // On the .NET Framework, GetFrames() can return null even though it's not documented as such.
            // At least one case here is if the exception's stack trace itself is null.
            if (frames != null)
            {
                foreach (var frame in frames)
                {
                    var method = frame?.GetMethod();
                    var methodName = method?.Name;
                    if (methodName == null)
                        continue;
 
                    var declaringTypeName = method?.DeclaringType?.FullName;
                    if (declaringTypeName == null)
                        continue;
 
                    if (!declaringTypeName.StartsWith(CodeAnalysisNamespace))
                        continue;
 
                    return declaringTypeName + "." + methodName;
                }
            }
        }
        catch
        {
        }
 
        // If we couldn't get a stack, report a generic message.
        // The exception message is already reported in a separate cred-scanned property.
        return "Roslyn NonFatal Watson";
    }
 
    private static IList<string> CollectLogHubFilePaths()
    {
        try
        {
            var logPath = Path.Combine(Path.GetTempPath(), "VSLogs");
            var logs = CollectFilePaths(logPath, "*.svclog", shouldExcludeLogFile: (name) => !name.Contains("Roslyn") && !name.Contains("LSPClient"));
            return logs;
        }
        catch (Exception)
        {
            // ignore failures
        }
 
        return [];
    }
 
    private static IList<string> CollectServiceHubLogFilePaths()
    {
        try
        {
            var logPath = Path.Combine(Path.GetTempPath(), "servicehub", "logs");
 
            // TODO: https://github.com/dotnet/roslyn/issues/42582 
            // name our services more consistently to simplify filtering
            var logs = CollectFilePaths(logPath, "*.log", shouldExcludeLogFile: (name) => !name.Contains("-" + ServiceDescriptor.ServiceNameTopLevelPrefix) &&
                    !name.Contains("-CodeLens") &&
                    !name.Contains("-ManagedLanguage.IDE.RemoteHostClient") &&
                    !name.Contains("-hub"));
            return logs;
        }
        catch (Exception)
        {
            // ignore failures
        }
 
        return [];
    }
 
    private static List<string> CollectFilePaths(string logDirectoryPath, string logFileExtension, Func<string, bool> shouldExcludeLogFile)
    {
        var paths = new List<string>();
 
        if (!Directory.Exists(logDirectoryPath))
        {
            return paths;
        }
 
        // attach all log files that are modified less than 1 day before.
        var now = DateTime.UtcNow;
        var oneDay = TimeSpan.FromDays(1);
 
        foreach (var path in Directory.EnumerateFiles(logDirectoryPath, logFileExtension))
        {
            try
            {
                var name = Path.GetFileNameWithoutExtension(path);
 
                // filter logs that are not relevant to Roslyn investigation
                if (shouldExcludeLogFile(name))
                {
                    continue;
                }
 
                var lastWrite = File.GetLastWriteTimeUtc(path);
                if (now - lastWrite > oneDay)
                {
                    continue;
                }
 
                paths.Add(path);
            }
            catch
            {
                // ignore file that can't be accessed
            }
        }
 
        return paths;
    }
}