Event Processors

Event processors can enrich events with additional, either globally or within a particular scope. Though event processors are similar to BeforeSend and BeforeSendTransaction, there are two key differences:

1. BeforeSend and BeforeSendTransaction are guaranteed to be run after all other processing, just before an event gets sent. Event processors run in an undetermined order, so changes to the event may still be made after the event processor runs.
2. BeforeSend and BeforeSendTransaction always run globally. Processors can be configured to run either globally or only within a particular scope.

Duplicate Event Detection

By default, Sentry includes a global processor that detects and drops duplicate events.

This processor be configured by via SentryOptions.DeduplicateMode when initialising the Sentry SDK. This is a flag enum consisting of the following values:

• DeduplicateMode.SameEvent: Same event instance. Assumes no object reuse/pooling.
• DeduplicateMode.SameExceptionInstance: An exception that was captured twice.
• DeduplicateMode.InnerException: An exception already captured exists as an inner exception.
• DeduplicateMode.AggregateException: An exception already captured is part of the aggregate exception.
• DeduplicateMode.All: All modes combined.

The default value for SentryOptions.DeduplicateMode is DeduplicateMode.All ^ DeduplicateMode.InnerException (so all detected duplicate events will be dropped except those from inner exceptions). However, if we only wanted SameEvent and SameExceptionInstance events to be dropped, we could initialize the SDK as follows:

SentrySdk.Init(options => {
  // ... configure other options here
  options.DeduplicateMode = DeduplicateMode.SameEvent | DeduplicateMode.SameExceptionInstance;
})

Alternatively, duplicate event detection can be disabled entirely by calling DisableDuplicateEventDetection:

SentrySdk.Init(options => {
  // ... configure other options here
  options.DisableDuplicateEventDetection();
})

Custom event processors

You can create your own event processors by implementing the ISentryEventProcessor interface. You can also create custom processors for transactions by implementing the ISentryTransactionProcessor.

using Sentry.Extensibility;

public class CustomEventProcessor : ISentryEventProcessor
{
    public SentryEvent? Process(SentryEvent @event)
    {
        // Add anything to the event here
        // returning `null` will drop the event
        return @event;
    }
}

Processors run on every event sent once they've been added. While there are multiple ways of doing this, adding processors to the options ensures that they run with every event after initialization.

options.AddEventProcessor(new CustomEventProcessor());

If AddEventProcessor has been added to the scope, it'll apply to both the current and the following scopes:

SentrySdk.ConfigureScope(scope => scope.AddEventProcessor(new CustomEventProcessor()));

But if an event processor has only been added to a local scope using withScope, it'll only apply to events captured inside that scope.

SentrySdk.WithScope(scope => scope.AddEventProcessor(new CustomEventProcessor()));