squadron_sample

Flutter demo for Squadron with sample use-cases:

• parallel computation of hexadecimal digits of Pi.
• parallel thumbnail generation

Also includes a minimal example of using Squadron annotations together with squadron_builder to generate the actual Web Worker/Isolate workers and pools.

See Squadron Dart package for more information on Squadron.

Pi Digits

The source code should be easy to understand:

• pi_digits_service.dart implements the math to compute hexadecimal digits of Pi based on the Bailey–Borwein–Plouffe formula.

• pi_digits_worker.dart implements the code used to proxy calls from the main thread to the platform workers (Isolates in native scenarios, WebWorkers in browser environment).

• pi_worker_pool.dart implements the worker pool depending on the target platform (browser or native). It will instantiate workers either from browser/pi_digits_worker.dart or from vm/pi_digits_worker.dart via the corresponding pi_digits_worker_activator.dart.

• browser/pi_digits_worker.dart and vm/pi_digits_worker.dart install and run the worker for their respective platform, relying on the service implemented in pi_digits_service.dart.

Squadron takes care of all the rest: bootstrapping the workers, communicating to/from the workers, distributing tasks to the worker service, cancellation notifications...

The main app uses the worker pool to have 5,000 digits of Pi computed in parallel (see _loadDigitsWithWorkerPool() in pi_digits_page.dart).

Thumbnails

The structure of the code is very similar to that for pi digits:

• thumbnail_service.dart implements the generation of the thumbnail via image.

• thumbnail_worker.dart implements the code used to proxy calls from the main thread to the platform workers (Isolates in native scenarios, WebWorkers in browser environment).

• thumbnail_pool.dart implements the worker pool depending on the target platform (browser or native). It will instantiate workers either from browser/thumbnail_worker.dart or from vm/thumbnail_worker.dart via the corresponding thumbnail_worker_activator.dart.

• browser/thumbnail_worker.dart and vm/thumbnail_worker.dart install and run the worker for their respective platform, relying on the service implemented in thumbnail_service.dart.

Squadron takes care of all the rest: bootstrapping the workers, communicating to/from the workers, distributing tasks to the worker service, cancellation notifications...

The main app uses the Flutter icon as a sample image. In a production app, you'd ask the user to pick images or take pictures with the camera.

Codegen and Perf

Provided as examples of code generation using Squadron annotations with squadron_builder.

Codegen is a basic example while Perf leverages more advanced features such as platform-specific marshallers to try and control serialization overhead.

To generate the code for workers and worker pools, run the following command:

dart run build_runner build

Parser, Parser1 and Parser2

Various attempts at parsing a (somewhat large) Value Change Dump dataset (see https://en.wikipedia.org/wiki/Value_change_dump).

Note

This sample must be built using:

dart run build_runner build

Before running the Web-version of the sample, the Web workers must also be compiled. The sample provides a script to automate building the Web workers, cf. build_web_worker.bat. Rebuilding Web Workers is mandatory whenever a worker service or one of its dependencies has been modified or updated.