DevTools Profiler Protocol

devtools_profiler_protocol contains the small set of shared types used by the region helper and profiler backend.

Most users should not need this package directly. Import devtools_region_profiler when marking regions in an app, or use devtools_profiler_cli when running the profiler. Use this package directly only when you are building another integration that needs to share the same region options and wire values.

End users normally install and run the CLI with:

dart pub global activate devtools_profiler_cli
devtools-profiler help

For the full CLI guide, see the profiler README.

Shared Types

The package exports:

• ProfileCaptureKind: capture kinds requested for a region.
• ProfileIsolateScope: whether a region captures the current isolate or all app isolates.
• ProfileRegionOptions: JSON-friendly region options shared between the helper and backend.
• defaultProfileCaptureKinds: the default region capture kinds.
• normalizeProfileCaptureKinds: removes duplicate capture kinds while preserving order.
• normalizeProfileIsolateScopes: removes duplicate isolate scopes while preserving order.

Capture Kinds

const options = ProfileRegionOptions(
  captureKinds: [
    ProfileCaptureKind.cpu,
    ProfileCaptureKind.memory,
  ],
);

Supported by the current backend:

• ProfileCaptureKind.cpu
• ProfileCaptureKind.memory

Reserved for the protocol, but not implemented by the current backend:

• ProfileCaptureKind.timeline

Isolate Scope

Capture only the isolate that starts the region:

const options = ProfileRegionOptions(
  isolateScope: ProfileIsolateScope.current,
);

Capture all non-system app isolates:

const options = ProfileRegionOptions(
  isolateScope: ProfileIsolateScope.all,
);

Use all-isolate capture only when the profiled work intentionally crosses isolate boundaries. Current-isolate capture is easier to interpret for most regions.

JSON Round Trip

ProfileRegionOptions can be serialized and deserialized:

const options = ProfileRegionOptions(
  captureKinds: [ProfileCaptureKind.cpu],
  isolateScope: ProfileIsolateScope.current,
  parentRegionId: 'parent-region-id',
);

final json = options.toJson();
final restored = ProfileRegionOptions.fromJson(json);

The region helper uses this shape when it notifies the profiler backend through DTD.

Defaults

When no options are provided, a region uses:

• captureKinds: cpu and memory
• isolateScope: current
• parentRegionId: inherited by devtools_region_profiler when regions are nested

Empty capture-kind lists normalize back to the default CPU and memory capture kinds.

Package Role

This package intentionally has no dependency on the CLI, backend, DTD, VM service, Flutter, or web UI packages. It is the shared contract between the profiler packages.