protected virtual async Task <PipelineContinuation> ExecuteContributor(ICommunicationContext context, ContributorCall call)
{
using (
PipelineLog.Operation(this,
"Executing contributor {0}.{1}".With(call.ContributorTypeName, call.Action.Method.Name)))
{
PipelineContinuation nextStep;
try
{
nextStep = await call.Action(context);
}
catch (Exception e)
{
context.Response.StatusCode = 500;
context.ServerErrors.Add(new Error
{
Title = "Fatal error",
Message = "An exception was thrown while processing a pipeline contributor",
Exception = e
});
nextStep = PipelineContinuation.Abort;
}
return(nextStep);
}
}
async Task RenderNow(ICommunicationContext context, PipelineStage stage)
{
PipelineLog.WriteDebug("Pipeline is in RenderNow mode.");
if (!stage.ResumeFrom <KnownStages.IOperationResultInvocation>())
{
if (stage.OwnerStage != null)
{
PipelineLog.WriteError("Trying to launch nested pipeline to render error failed.");
AttemptCatastrophicErrorNotification(context);
return;
}
using (
PipelineLog.Operation(this,
"Rendering contributor has already been executed. Calling a nested pipeline to render the error."))
{
var nestedPipeline = new PipelineStage(this, stage);
if (!nestedPipeline.ResumeFrom <KnownStages.IOperationResultInvocation>())
{
throw new InvalidOperationException("Could not find an IOperationResultInvocation in the new pipeline.");
}
await RunCallGraph(context, nestedPipeline);
}
}
}
protected virtual void FinishPipeline(ICommunicationContext context)
{
context.Request.Entity?.Dispose();
context.Response.Entity?.Dispose();
PipelineLog.WriteInfo("Pipeline finished.");
}
bool CanBeExecuted(ContributorCall call)
{
if (call.Action == null)
{
PipelineLog.WriteWarning("Contributor call for {0} had a null Action.", call.ContributorTypeName);
return(false);
}
return(true);
}
void LogContributorCallChainCreated(IEnumerable <ContributorCall> callGraph)
{
PipelineLog.WriteInfo("Contributor call chain has been processed and results in the following pipeline:");
int pos = 0;
foreach (var contributor in callGraph)
{
PipelineLog.WriteInfo("{0} {1}", pos++, contributor.ContributorTypeName);
}
}
public IPipelineExecutionOrder Notify(Func <ICommunicationContext, PipelineContinuation> action)
{
if (IsInitialized)
{
PipelineLog.WriteWarning("A pipeline registration through Notify() has been done after the pipeline was initialized. Ignoring.");
return(new Notification(this, action));
}
var notification = new Notification(this, action);
_notificationRegistrations.Add(notification);
return(notification);
}
protected virtual void AbortPipeline(ICommunicationContext context)
{
PipelineLog.WriteError("Aborting the pipeline and rendering the errors.");
context.OperationResult = new OperationResult.InternalServerError
{
Title = "The request could not be processed because of a fatal error. See log below.",
ResponseResource = context.ServerErrors
};
context.PipelineData.ResponseCodec = null;
context.Response.Entity.Instance = context.ServerErrors;
context.Response.Entity.Codec = null;
context.Response.Entity.ContentLength = null;
Log.WriteError("An error has occurred and the processing of the request has stopped.\r\n{0}", context.ServerErrors.Aggregate(string.Empty, (str, error) => str + "\r\n" + error.ToString()));
}
public void Initialize()
{
if (IsInitialized)
{
return;
}
using (PipelineLog.Operation(this, "Initializing the pipeline."))
{
foreach (var item in _resolver.ResolveAll <IPipelineContributor>())
{
PipelineLog.WriteDebug("Initialized contributor {0}.", item.GetType().Name);
_contributors.Add(item);
}
_callGraph = GenerateCallGraph();
}
IsInitialized = true;
PipelineLog.WriteInfo("Pipeline has been successfully initialized.");
}
IEnumerable <ContributorCall> GenerateCallGraph()
{
var bootstrapper = _contributors.OfType <KnownStages.IBegin>().Single();
var tree = new DependencyTree <ContributorNotification>(
new ContributorNotification(bootstrapper, new Notification(this, null)));
foreach (var contrib in _contributors.Where(x => x != bootstrapper))
{
_notificationRegistrations.Clear();
using (PipelineLog.Operation(this, "Initializing contributor {0}.".With(contrib.GetType().Name)))
contrib.Initialize(this);
foreach (var reg in _notificationRegistrations.DefaultIfEmpty(new Notification(this, null)))
{
tree.CreateNode(new ContributorNotification(contrib, reg));
}
}
foreach (var notificationNode in tree.Nodes)
{
foreach (var parentNode in GetCompatibleTypes(tree,
notificationNode,
notificationNode.Value.Notification.AfterTypes))
{
parentNode.ChildNodes.Add(notificationNode);
}
foreach (var childNode in GetCompatibleTypes(tree,
notificationNode,
notificationNode.Value.Notification.BeforeTypes))
{
childNode.ParentNodes.Add(notificationNode);
}
}
var graph = tree.GetCallGraph().Select(x =>
new ContributorCall(x.Value.Contributor, x.Value.Notification.Target, x.Value.Notification.Description));
LogContributorCallChainCreated(graph);
return(graph);
}
protected virtual void FinishPipeline(ICommunicationContext context)
{
PipelineLog.WriteInfo("Pipeline finished.");
}