private static async Task <HandlerResult> EnumerateHandlers(
HttpContext context,
Type exceptionType,
Exception exception,
ExceptionHandlingPolicyOptions policyOptions,
ILogger logger)
{
bool handlerExecuted = false;
HandlerResult handleResult = HandlerResult.ReThrow;
IEnumerable <Type> handlers = policyOptions.GetHandlersInternal(exceptionType);
foreach (Type handlerType in handlers)
{
try
{
IExceptionHandler handler =
context.RequestServices.GetService(handlerType) as IExceptionHandler;
if (handler == null)
{
handlerExecuted = false;
logger.LogError(Events.HandlerNotCreated,
"Handler type {handlerType} can't be created because it not registered in IServiceProvider. RequestId: {RequestId}",
handlerType, context.TraceIdentifier);
}
else
{
handleResult = await handler.Handle(context, exception);
handlerExecuted = true;
}
}
catch (Exception e)
{
logger.LogError(Events.HandlerError, e,
"Unhandled exception executing handler of type {handlerType} on exception of type {exceptionType}. RequestId: {RequestId}",
handlerType, exceptionType, context.TraceIdentifier);
return(HandlerResult.ReThrow);
}
if (handleResult != HandlerResult.NextHandler)
{
break;
}
}
if (!handlerExecuted)
{
logger.LogWarning(Events.HandlersNotFound,
"Handlers collection for exception type {exceptionType} is empty. Exception will be re-thrown. RequestId: {RequestId}",
exceptionType, context.TraceIdentifier);
return(HandlerResult.ReThrow);
}
return(handleResult);
}
private static async Task <HandlerResult> EnumerateExceptionMapping(
HttpContext context,
ExceptionHandlingPolicyOptions policyOptions,
Exception exception,
ILogger logger)
{
Type exceptionType = exception.GetType();
bool mappingExists = false;
HandlerResult handleResult = HandlerResult.ReThrow;
foreach (Type type in policyOptions.GetExceptionsInternal())
{
if (type.IsAssignableFrom(exceptionType))
{
mappingExists = true;
handleResult = await EnumerateHandlers(context, type, exception, policyOptions, logger);
if (handleResult != HandlerResult.NextChain)
{
break;
}
}
}
if (!mappingExists)
{
logger.LogWarning(Events.PolicyNotFound,
"Handlers mapping for exception type {exceptionType} not exists. Exception will be re-thrown. RequestId: {RequestId}",
exceptionType, context.TraceIdentifier);
return(HandlerResult.ReThrow);
}
return(handleResult);
}
private async Task InvokeWithRetryAsync(HttpContext context, RequestDelegate next, ILogger logger, int iteration)
{
try
{
await next(context);
}
catch (Exception exception)
{
ExceptionHandlingPolicyOptions policyOptions = this.options.Value;
var result = await EnumerateExceptionMapping(context, policyOptions, exception, logger);
if (result == HandlerResult.ReThrow)
{
throw;
}
if (result == HandlerResult.Retry)
{
// We can't do anything if the response has already started, just abort.
if (context.Response.HasStarted)
{
logger.LogWarning(Events.RetryForStartedResponce,
exception,
"Retry requested when responce already started. Exception will be re-thrown. RequestId: {RequestId}",
context.TraceIdentifier);
throw;
}
if (iteration > MaxRetryIterations)
{
logger.LogCritical(Events.RetryIterationExceedLimit,
exception,
"Retry iterations count exceed limit of {limit}. Possible issues with retry policy configuration. Exception will be re-thrown. RequestId: {RequestId}",
MaxRetryIterations,
context.TraceIdentifier);
throw;
}
logger.LogWarning(Events.Retry,
exception,
"Retry requested. Iteration {iteration} RequestId: {RequestId}",
iteration,
context.TraceIdentifier);
context.Response.Headers.Clear();
await InvokeWithRetryAsync(context, next, logger, iteration + 1);
}
if (result != HandlerResult.Handled)
{
logger.LogWarning(Events.UnhandledResult,
exception,
"After execution of all handlers exception was not marked as handled and will be re thrown. RequestId: {RequestId}",
context.TraceIdentifier);
throw;
}
}
}