Would be nice if flutter run only downloaded the necessary artifacts

[eseidelGoogle]

I was on a train with bad wifi. It was painful.

I was trying to run the gallery on an iOS Simulator.

%flutter run
Building flutter tool...
Downloading package sky_engine...                    8101ms
Running 'pub get' in sky_engine...                   450ms
Downloading package sky_services...                  596ms
Running 'pub get' in sky_services...                 3139ms
Downloading package flutter_services...              1929ms
Running 'pub get' in flutter_services...             2294ms
Building Dart SDK summary...                         1753ms
Downloading engine artifacts android-arm...          177027ms
Downloading engine artifacts android-arm-profile...  164117ms
Downloading engine artifacts android-arm-release...  115925ms
Downloading engine artifacts android-x64...          78964ms
Downloading engine artifacts android-x86...          78600ms
Downloading engine artifacts ios...                  178979ms
Downloading engine artifacts ios-profile...          189778ms
Downloading engine artifacts ios-release...          152586ms
Downloading darwin-x64 tools...                      232022ms
Downloading android-arm-profile/darwin-x64 tools...  34656ms
Downloading android-arm-release/darwin-x64 tools...  139862ms
Running 'pub get' in flutter_gallery...              870ms

FYI @danrubel

[eseidelGoogle]

We've had a couple complaints about downloads being slow or not resuming well from users in china who have network issues. Unclear if this specific bug would help them though.

[olostan]

Faced same issue when decided to do some coding in airport while waiting for the flight. Had to restart downloading couple of times, downloads were failing.

As an idea (except limitation of needed resources) - may be download in parallel? Sometimes on bad connections that helps.

[Hixie]

I just had this with flutter analyze. There's really no reason to download an ARM engine if I want to analyze things... especially when I'm in a rush.

cc @danrubel @devoncarew @jason-simmons

[eseidelGoogle]

The flutter-intellij plugin has considered even working around this issue themselves: flutter/flutter-intellij#730

[xster]

Hard to work on flutter tools too on slow networks. Each dev cycle involves changing some code of the tools, clear the tool's snapshot but building the new flutter tools is a network dependent operation which can take a while.

[eseidelGoogle]

I'm confused. Rebuilding the flutter_tools snapshot shouldn't involve the network. Only downloading the engine artifacts should?

[Hixie]

This would also solve the issue where "flutter upgrade" fails because you're on a version that is unable to download all the artifacts for whatever reason (e.g. we failed to upload them).

[Hixie]

cc @jonahwilliams

[jonahwilliams]

This is somewhat blocked by the tree status, but is also related to how Gradle and XCode use artifacts. Currently they require everything up front, which we need to change eventually to make this work.

[jonahwilliams]

We've made good progress on this. All new artifacts (macOS, Linux, Windows, Web, and Fuchsia) are lazy by default. There are still a few places in the tools where we end up downloading all of Android and iOS.

[jonahwilliams]

For additional context from #64446 (which I am de-duping into this bug). There are some remaining cases where we eagerly download artifacts for devices that are connected but that we do not intend to use - this has mostly come up with the non-ephemeral devices.

A reasonable fix would be to defer additional artifact downloading until after we have selected a device.

[xster]

+1 I still run into this on scenarios like downloading ios-release tools when I flutter run (debug) on iOS devices etc.

[jonahwilliams]

That one is slightly separate, we download all of the bundles (debug/profile/release) all at once because splitting them up ended up breaking too many integration tests (at the time). it might be easier now that the build systems have been cleaned up

[pedromassango]

A possible related issue #64822 (Cache the SDK on switching channel).