[vm/isolate] Add TransferableTypedData class that allows low-cost passing of Uint8List between isolates.

TransferableTypedData instances are one-use kind of thing: once receiver materializes it, it can't be used
again, once sender sends it out to an isolate, sender can't send it to different isolate.

Example of use:

sender isolate:

```
Future<TransferableTypedData> consolidateHttpClientResponseBytes(HttpClientResponse response) {
  final completer = Completer<TransferableTypedData>();
  final chunks = <Uint8List>[];
  response.listen((List<int> chunk) {
    chunks.add(chunk);
  }, onDone: () {
    completer.complete(TransferableTypedData.fromList(chunks));
  });
  return completer.future;
}
...
sendPort.send(await consolidateHttpClientResponseBytes(response));
```

receiver isolate:
```
    RawReceivePort port = RawReceivePort((TransferableTypedData transferable) {
      Uint8List content = transferable.materialize().asUint8List();
      ...
    });
```

31959[tr] and 31960[tr] tests were inspired by dartbug.com/31959, dartbug.com/31960 that this CL attempts to address:
```
╰─➤  out/ReleaseX64/dart 31960.dart
sending...
163ms for round-trip
sending...
81ms for round-trip
sending...
20ms for round-trip
sending...
14ms for round-trip
sending...
20ms for round-trip
sending...
14ms for round-trip
```

(notice no "since last checking" pauses") vs

```
╰─➤  out/ReleaseX64/dart 31960.dart
sending...
154ms since last checkin
174ms for round-trip
sending...
68ms since last checkin
9ms since last checkin
171ms for round-trip
sending...
13ms since last checkin
108ms for round-trip
sending...
14ms since last checkin
108ms for round-trip
sending...
14ms since last checkin
107ms for round-trip
```

Change-Id: I0fcb5ce285394f498c3f1db4414204531f98199d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/99623
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
27 files changed
tree: 131de3c19a5bdd62c3e3bc4bde15e18ccae3eac2
  1. .github/
  2. build/
  3. client/
  4. docs/
  5. pkg/
  6. runtime/
  7. samples/
  8. samples-dev/
  9. sdk/
  10. tests/
  11. third_party/
  12. tools/
  13. utils/
  14. .clang-format
  15. .gitattributes
  16. .gitconfig
  17. .gitignore
  18. .gn
  19. .mailmap
  20. .packages
  21. .vpython
  22. AUTHORS
  23. BUILD.gn
  24. CHANGELOG.md
  25. codereview.settings
  26. CONTRIBUTING.md
  27. DEPS
  28. LICENSE
  29. PATENTS
  30. PRESUBMIT.py
  31. README.dart-sdk
  32. README.md
  33. WATCHLISTS
README.md

Dart

A client-optimized language for fast apps on any platform

Dart is:

  • Optimized for UI: Develop with a programming language specialized around the needs of user interface creation

  • Productive: Make changes iteratively: use hot reload to see the result instantly in your running app

  • Fast on all platforms: Compile to ARM & x64 machine code for mobile, desktop, and backend. Or compile to JavaScript for the web

Dart has flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:

  • Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.

  • Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).

Dart platforms illustration

License & patents

Dart is free and open source.

See LICENSE and PATENTS.

Using Dart

Visit the dart.dev to learn more about the language, tools, getting started, and more.

Browse pub.dev for more packages and libraries contributed by the community and the Dart team.

Building Dart

If you want to build Dart yourself, here is a guide to getting the source, preparing your machine to build the SDK, and building.

There are more documents on our wiki.

Contributing to Dart

The easiest way to contribute to Dart is to file issues.

You can also contribute patches, as described in Contributing.