Asset Bundle Instrumentation

AssetBundle instrumentation provides insight into how long your app takes to load its assets, such as files.

Instrumentation Behaviour

The instrumentation starts a span from an active transaction that's bound to the scope of the following calls:

• load and loadString - The SDK sets the span operation to file.read.
• loadStructuredData - The SDK sets the span operation to serialize.

Prerequisites

Before starting, ensure:

1. The Sentry Flutter SDK is initialized. Learn more here.
2. Tracing is set up. Learn more here.

Configure

Wrap the runApp method with a DefaultAssetBundle and SentryAssetBundle.

import 'package:flutter/widgets.dart';
import 'package:sentry_flutter/sentry_flutter.dart';

Future<void> main() async {
  await SentryFlutter.init(
    (options) => options.dsn = '___PUBLIC_DSN___',
      appRunner: () => runApp(
        DefaultAssetBundle(
          bundle: SentryAssetBundle(),
          child: MyApp(),
        ),
    ),
  );
}

import 'package:flutter/widgets.dart';
import 'package:sentry_flutter/sentry_flutter.dart';

Future<void> main() async {
  await SentryFlutter.init(
    (options) => options.dsn = '___PUBLIC_DSN___',
      appRunner: () => runApp(
        DefaultAssetBundle(
          bundle: SentryAssetBundle(),
          child: MyApp(),
        ),
    ),
  );
}

Verify

1. Execute the Code

final transaction = Sentry.startTransaction(
  'asset-bundle-transaction',
  'load',
  bindToScope: true,
);

final text = await DefaultAssetBundle.of(context).loadString('assets/lorem-ipsum.txt');

await transaction.finish(status: const SpanStatus.ok());

final transaction = Sentry.startTransaction(
  'asset-bundle-transaction',
  'load',
  bindToScope: true,
);

final text = await DefaultAssetBundle.of(context).loadString('assets/lorem-ipsum.txt');

await transaction.finish(status: const SpanStatus.ok());

2. View the Transaction on Sentry.io

To view the recorded transaction, log into sentry.io and open your project. Clicking Performance will open a page with transactions, where you can select the just recorded transaction with the name asset-bundle-transaction.

Additional Configuration

Disabling the loadStructuredData Feature

The loadStructuredData is an opt-out feature. The following example shows how to disable it:

import 'package:sentry_flutter/sentry_flutter.dart';

SentryAssetBundle(enableStructuredDataTracing: false)

import 'package:sentry_flutter/sentry_flutter.dart';

SentryAssetBundle(enableStructuredDataTracing: false)