/// <summary>
/// Processes a <see cref="ReflectionTypeLoadException"/> in order to makes sure
/// type information is included and all <see cref="ReflectionTypeLoadException.LoaderExceptions"/>
/// are recursively parsed.
/// </summary>
internal static void ProcessTypeLoadException(ExceptionData exceptionData, ReflectionTypeLoadException typeLoadException, StringBuilder builder, int indent)
{
AppendFormat(builder, indent, "ReflectionTypeLoadException (possibility: MEF composition error): {0}",
typeLoadException.Message);
builder.AppendLine();
Append(builder, indent, "- Types: ");
IEnumerable <string> typeNames = typeLoadException.Types.Select(t => t == null ? "[null]" : t.Name);
builder.AppendLine(String.Join(",", typeNames));
AppendLine(builder, indent, "- Loader exceptions:");
//keep that line above the if statement below, even if there were no Errors
if (typeLoadException.LoaderExceptions != null)
{
foreach (Exception loaderException in typeLoadException.LoaderExceptions)
{
//the loader exceptions array may contain null references!
if (loaderException == null)
{
continue;
}
//store hidden exception and recurse
exceptionData.HiddenExceptions.Add(loaderException);
Parse(exceptionData, loaderException, builder, indent + 1);
}
}
}
/// <summary>
/// Gets a string representation of the submitted <paramref name="data"/>.
/// </summary>
/// <param name="data">Processed exception data.</param>
/// <param name="includeRootExceptionStack">Whether to include the
/// stack trace of the root exception in the returned string. Not needed if
/// the root exception is being logged anyway.</param>
/// <returns>A formatted string reflecting the exception hierarchy.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="data"/>
/// is a null reference.</exception>
public static string Print(ExceptionData data, bool includeRootExceptionStack)
{
if (data == null)
{
throw new ArgumentNullException(nameof(data));
}
//get builder message
var sb = new StringBuilder(data.FormattedException);
//add full string representation of the root exception
if (includeRootExceptionStack)
{
sb.AppendLine();
AppendLine(sb, 0, "-");
sb.AppendLine(data.RootException.ToString());
}
if (data.HiddenExceptions.Any())
{
//add additional exception stack traces
sb.AppendLine();
sb.AppendLine("---");
sb.AppendLine("NESTED / HIDDEN EXCEPTIONS:");
foreach (var exception in data.HiddenExceptions)
{
sb.AppendLine();
AppendLine(sb, 1, exception.ToString());
AppendLine(sb, 0, "---");
}
}
return(sb.ToString());
}
/// <summary>
/// Main routine that analyzes the currently processed <paramref name="exception"/>.
/// </summary>
internal static void Parse(ExceptionData exceptionData, Exception exception, StringBuilder builder, int indent)
{
var typeLoadException = exception as ReflectionTypeLoadException;
var aggregateException = exception as AggregateException;
exceptionData.AllExceptions.Add(exception);
if (aggregateException != null)
{
ProcessAggregateException(exceptionData, aggregateException, builder, indent);
//skip recursion to InnerException - covered by the InnerExceptions loop
return;
}
if (typeLoadException != null)
{
ProcessTypeLoadException(exceptionData, typeLoadException, builder, indent);
}
else
{
//default exception header
AppendFormat(builder, indent, "{0}: {1}", exception.GetType().Name, exception.Message);
builder.AppendLine();
}
//recurse inner exception
RecurseInnerException(exceptionData, exception, builder, indent);
}
/// <summary>
/// Triggers recursive parsing of the inner exception of the currently processed exception.
/// </summary>
internal static void RecurseInnerException(ExceptionData exceptionData, Exception exception, StringBuilder builder, int indent)
{
//recurse inner exception
if (exception.InnerException != null)
{
AppendLine(builder, indent, "- Inner exception:");
Parse(exceptionData, exception.InnerException, builder, indent + 1);
}
}
public static LogEntryDto ParseLogEntry(LogEntry entry, string appName, string environment)
{
var exception = entry.Exception;
ExceptionInfo exceptionInfo = null;
if (exception != null)
{
ExceptionData exceptionData = ExceptionParser.GetExceptionData(exception);
exceptionInfo = new ExceptionInfo
{
ExceptionType = exception.GetType().Name,
ErrorMessage = exception.Message,
ExceptionHash = exceptionData.ExceptionHash,
StackTrace = ExceptionParser.Print(exceptionData, true)
};
}
//transparently assign string values to the message
//if there is none, otherwise wrap into an object to
//ensure a logged payload is always a JSON object rather
//then a scalar.
//We don't care about other primitives etc. If somebody
//is stupid enough to log an int, it'll just get serialized
var payload = entry.Payload;
var message = entry.Message;
if (payload is string)
{
if (String.IsNullOrEmpty(message))
{
//do not change the original entry - causes issues with multiple sinks
message = payload as string;
payload = null;
}
else
{
payload = new { Message = payload };
}
}
return(new LogEntryDto
{
Timestamp = entry.TimestampOverride,
AppName = appName,
Environment = environment,
Level = entry.LogLevel.ToString(),
Context = entry.Context ?? "",
Message = String.IsNullOrEmpty(message) ? null : message,
PayloadType = entry.PayloadType,
Payload = payload,
ExceptionInfo = exceptionInfo,
ContextData = entry.ContextData.Count == 0 ? null : entry.ContextData
});
}
/// <summary>
/// Recursively processes a given <paramref name="exception"/> and
/// returns a verbose string that reflects exception hierarchies and
/// stack traces of the submitted root exception and nested (hidden)
/// exceptions that are not be included in the stack trace.
/// </summary>
/// <param name="exception">The root exception to be processed.</param>
/// <param name="includeRootExceptionStack">Whether to include the
/// stack trace of the root exception in the returned string. Not needed if
/// the root exception is being logged anyway.</param>
/// <returns>A formatted string reflecting the exception hierarchy.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="exception"/>
/// is a null reference.</exception>
public static string Parse(Exception exception, bool includeRootExceptionStack)
{
if (exception == null)
{
throw new ArgumentNullException(nameof(exception));
}
ExceptionData ed = GetExceptionData(exception);
return(Print(ed, includeRootExceptionStack));
}
/// <summary>
/// Processes an <see cref="AggregateException"/> in order to make sure
/// all inner exceptions are recursively parsed.
/// </summary>
internal static void ProcessAggregateException(ExceptionData exceptionData, AggregateException aggregateException, StringBuilder builder, int indent)
{
AppendFormat(builder, indent, "AggregateException: {0}", aggregateException.Message);
builder.AppendLine();
AppendLine(builder, indent, "- Inner exceptions:"); //keep that line above the if statement below, even if there were no Errors
//flatten nested aggregate exceptions
var flattened = aggregateException.Flatten();
foreach (var innerException in flattened.InnerExceptions)
{
Parse(exceptionData, innerException, builder, indent + 1);
}
}
/// <summary>
/// Parses a given <paramref name="exception"/>, and returns a
/// <see cref="ExceptionData"/> object that contains the root
/// exception plus hidden exceptions as well as a well-formatted
/// stack trace.
/// </summary>
/// <exception cref="ArgumentNullException">If <paramref name="exception"/>
/// is a null reference.</exception>
public static ExceptionData GetExceptionData(Exception exception)
{
if (exception == null)
{
throw new ArgumentNullException(nameof(exception));
}
var sb = new StringBuilder();
var ed = new ExceptionData(exception);
Parse(ed, ed.RootException, sb, 0);
ed.FormattedException = sb.ToString();
ed.ExceptionHash = CalculateHash(ed);
return(ed);
}
/// <summary>
/// Gets a hash built based on all exceptions in the submitted <see cref="ExceptionData"/>
/// object. Hidden exceptions result in multiple dotted hashes, to enable comparison of
/// other hashes that ultimately result in the same exception.<br/>
/// Note that if more than 10 exceptions occur, the last hash represents multiple exceptions
/// (10th and higher).
/// </summary>
/// <returns></returns>
internal static string CalculateHash(ExceptionData exceptionData)
{
var list = new List <Exception>(exceptionData.HiddenExceptions);
list.Insert(0, exceptionData.RootException);
using (MD5 md5 = MD5.Create())
{
List <string> sourceStrings = list.Select(e => GetStackTraces(e)).ToList();
//TBD: this routine would just create a single (32 character) hash of all exceptions:
//var unhashed = Encoding.Unicode.GetBytes(String.Concat(sourceStrings));
//var hash = md5.ComputeHash(unhashed);
//return String.Concat(hash.Select(b => b.ToString("X2")));
//if the list contains more than 10 hashes, trim it down by concatenating some
while (sourceStrings.Count > 10)
{
string st = sourceStrings[9];
sourceStrings.RemoveAt(9);
sourceStrings[9] = String.Concat(sourceStrings[9], st);
}
IEnumerable <string> hashes = from sourceString in sourceStrings
let stack = Encoding.Unicode.GetBytes(sourceString)
let hash = md5.ComputeHash(stack)
select String.Concat(hash.Select(b => b.ToString("X2")));
//an MD5 hash has 32 characters - trim it down to 8 chars, risk of collisions is basically zero
//and it's wouldn't even be that much of a problem with proper logging (different context info, too)
hashes = hashes.Select(h => h.Substring(0, 8));
return(String.Join(".", hashes));
}
}