/// <summary>
/// Process method checks for presence of a session id and sequence
/// number. If they do not exist then they are initialized in evidence.
/// If they do exist in evidence then the sequence number is incremented
/// and added back to the evidence.
/// </summary>
/// <param name="data">
/// The <see cref="IFlowData"/> instance to process.
/// </param>
/// <exception cref="ArgumentNullException">
/// Thrown if the supplied data instance is null
/// </exception>
protected override void ProcessInternal(IFlowData data)
{
if (data == null)
{
throw new ArgumentNullException(nameof(data));
}
var evidence = data.GetEvidence().AsDictionary();
// If the evidence does not contain a session id then create a new one.
if (evidence.ContainsKey(Constants.EVIDENCE_SESSIONID) == false)
{
data.AddEvidence(Constants.EVIDENCE_SESSIONID, GetNewSessionId());
}
// If the evidence does not have a sequence then add one. Otherwise
// increment it.
if (evidence.ContainsKey(Constants.EVIDENCE_SEQUENCE) == false)
{
data.AddEvidence(Constants.EVIDENCE_SEQUENCE, 1);
}
else if (evidence.TryGetValue(Constants.EVIDENCE_SEQUENCE, out object sequence))
{
if (sequence is int result || (sequence is string seq && int.TryParse(seq, out result)))
{
data.AddEvidence(Constants.EVIDENCE_SEQUENCE, result + 1);
}
else
{
data.AddError(new Exception(Messages.MessageFailSequenceNumberParse), this);
Logger.LogError(Messages.MessageFailSequenceNumberIncrement);
}
}
/// <summary>
/// Called by the Process method on the
/// <see cref="FlowElementBase{T, TMeta}"/> base class.
/// Executes all child elements in parallel.
/// </summary>
/// <param name="data">
/// The data to use when executing the flow elements.
/// </param>
protected override void ProcessInternal(IFlowData data)
{
List <Task> allTasks = new List <Task>();
foreach (var element in _flowElements)
{
allTasks.Add(
// Run each element on a new thread.
Task.Run(() =>
{
element.Process(data);
}).ContinueWith(t =>
{
// If any exceptions occurred then add them to the
// flow data.
if (t.Exception != null)
{
foreach (var innerException in t.Exception.InnerExceptions)
{
data.AddError(innerException, element);
}
}
}, TaskScheduler.Default));
}
// Wait until all tasks have completed.
Task.WhenAll(allTasks).Wait();
}
/// <summary>
/// Process the given <see cref="IFlowData"/> using the
/// <see cref="IFlowElement"/>s in the pipeline.
/// </summary>
/// <param name="data">
/// The <see cref="IFlowData"/> that contains the evidence and will
/// allow the user to access the results.
/// </param>
public void Process(IFlowData data)
{
if (data == null)
{
throw new ArgumentNullException(nameof(data));
}
_logger.LogDebug($"Pipeline '{GetHashCode()}' started processing.");
foreach (var element in _flowElements)
{
try
{
element.Process(data);
#pragma warning disable CS0618 // Type or member is obsolete
// This usage will be replaced once the Cancellation Token
// mechanism is available.
if (data.Stop)
{
break;
}
#pragma warning restore CS0618 // Type or member is obsolete
}
#pragma warning disable CA1031 // Do not catch general exception types
// We want to catch any exception here so that the
// Pipeline can manage it.
catch (Exception ex)
#pragma warning restore CA1031 // Do not catch general exception types
{
// If an error occurs then store it in the
// FlowData object.
data.AddError(ex, element);
}
}
// If any errors have occurred and exceptions are not
// suppressed, then throw an aggregate exception.
if (data.Errors != null &&
data.Errors.Count > 0 &&
_suppressProcessExceptions == false)
{
throw new AggregateException(data.Errors
.Where(e => e.ShouldThrow == true)
.Select(e => e.ExceptionData));
}
_logger.LogDebug($"Pipeline '{GetHashCode()}' finished processing.");
}
/// <summary>
/// Create and populate a JSON string from the specified data.
/// </summary>
/// <param name="data"></param>
/// <param name="config">The configuration to use</param>
/// <returns>
/// A string containing the data in JSON format.
/// </returns>
protected virtual string BuildJson(IFlowData data, PipelineConfig config)
{
int sequenceNumber = GetSequenceNumber(data);
// Get property values from all the elements and add the ones that
// are accessible to a dictionary.
Dictionary <String, object> allProperties = GetAllProperties(data, config);
// Only populate the JavaScript properties if the sequence
// has not reached max iterations.
if (sequenceNumber < Constants.MAX_JAVASCRIPT_ITERATIONS)
{
AddJavaScriptProperties(data, allProperties);
}
AddErrors(data, allProperties);
try
{
return(BuildJson(allProperties));
}
catch (JsonWriterException jsonEx)
{
StringBuilder msg = new StringBuilder();
msg.AppendLine("Error converting data to json string");
msg.AppendLine("[");
foreach (var entry in allProperties)
{
msg.AppendLine($" '{entry.Key}' = {GetObjectAsString(entry.Value, 2)}");
}
msg.AppendLine("]");
var exception = new PipelineDataException(msg.ToString(), jsonEx);
data.AddError(exception, this);
}
return("{ \"error\": \"see flow data errors for more detail\" }");
}