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Cannot call Path.transform with internal Float64List #6456

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Cannot call Path.transform with internal Float64List#6456
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abarth

Description

@kasperl
kasperl
opened on Oct 21, 2016

It looks like Path.transform cannot accept an internal Float64List as its argument. I've done a little digging and I think what happens is the following:

First we invoke this method:

static void Path_transform(Dart_NativeArguments args) {
  DartCall(&CanvasPath::transform, args);
}

In return, this converts the Float64List argument to a tonic::Float64List. This ends up calling Dart_TypedDataAcquireData and when the argument is a Float64List allocated internally (not an external one), then the VM disallows using any part of its API that might lead to garbage collections until Dart_TypedDataReleaseData has been called.

I think the issue is that the tonic::Float64List deconstructor hasn't been called when we need to create the Dart wrapper for the result of calling CanvasPath::transform. That means that we have a need to call into the VM before Dart_TypedDataReleaseData has been called. That breaks.

Maybe this issue can be worked around at the tonic level. Right now, hidden in sea of templates, it appears that the DartCall in Path_transform unfolds to something like this:

static void Path_transform(Dart_NativeArguments args) {
  DartConverter<ftl::RefPtr<CanvasPath>>::SetReturnValue(args,
     ... // call CanvasPath::transform with the right receiver an this argument:
     DartConverter<const tonic::Float64List&>::FromArguments(args, 1)
     ...
  );
}

Maybe that could be changed to something like this to allow the tonic:Float64List to be destroyed before we need to set the return value?

static void Path_transform(Dart_NativeArguments args) {
  ftl::RefPtr<CanvasPath> result = 
     ... // call CanvasPath::transform with the right receiver an this argument:
     DartConverter<const tonic::Float64List&>::FromArguments(args, 1)
     ...
  ;
  DartConverter<ftl::RefPtr<CanvasPath>>::SetReturnValue(args, result);
}

Steps to Reproduce

Run the following program:

import 'dart:ui' show Path;
import 'dart:typed_data' show Float64List;

main() {
  new Path().transform(new Float64List(16));
}

Logs

[FATAL:../../lib/tonic/dart_class_provider.cc(24)] Check failed: !Dart_IsError(class_handle). Path: Internal Dart data pointers have been acquired, please release them using Dart_TypedDataReleaseData.

Flutter Doctor

[✓] Flutter (on Linux, channel master)
• Flutter at /usr/local/google/home/kasperl/Dart/flutter
• Framework revision b00e6cd (2 weeks ago), 2016-10-04 20:29:10
• Engine revision 27d012a
• Tools Dart version 1.20.0-dev.5.0

[✓] Android toolchain - develop for Android devices (Android SDK 24.0.3)
• Android SDK at /usr/local/google/home/kasperl/Android/Sdk
• Platform android-24, build-tools 24.0.3
• OpenJDK Runtime Environment (build 1.8.0-google-v7-132676107-132666263)

[✓] Atom - a lightweight development environment for Flutter
• flutter plugin version 0.2.1
• dartlang plugin version 0.6.6

[✓] Connected devices
• None

Activity

  1. abarth commented on Oct 21, 2016

    @abarth
    abarth
    on Oct 21, 2016
    Contributor

    Yeah, maybe something like this:

    diff --git a/dart_args.h b/dart_args.h
index 190fcdc..379eb0a 100644
--- a/dart_args.h
+++ b/dart_args.h
@@ -121,8 +121,9 @@ struct DartDispatcher<IndicesHolder<indices...>, ResultType (*)(ArgTypes...)>
       : DartArgHolder<indices, ArgTypes>(it)..., it_(it) {}

   void Dispatch(FunctionPtr func) {
-    DartReturn((*func)(DartArgHolder<indices, ArgTypes>::value...),
-               it_->args());
+    ResultType result = (*func)(
+        DartArgHolder<indices, ArgTypes>::value...), it_->args();
+    DartReturn(std::move(result));
   }

   ResultType DispatchCtor(FunctionPtr func) {
@@ -160,9 +161,9 @@ struct DartDispatcher<IndicesHolder<indices...>, ResultType (C::*)(ArgTypes...)>
       : DartArgHolder<indices, ArgTypes>(it)..., it_(it) {}

   void Dispatch(FunctionPtr func) {
-    DartReturn((GetReceiver<C>(it_->args())->*func)(
-                   DartArgHolder<indices, ArgTypes>::value...),
-               it_->args());
+    ResultType result = (GetReceiver<C>(it_->args())->*func)(
+        DartArgHolder<indices, ArgTypes>::value...), it_->args();
+    DartReturn(std::move(result));
   }
 };
  2. abarth
    self-assigned this
    on Oct 21, 2016

  3. abarth commented on Oct 21, 2016

    @abarth
    abarth
    on Oct 21, 2016
    Contributor

    That trick didn't help

  4. abarth commented on Oct 21, 2016

    @abarth
    abarth
    on Oct 21, 2016
    Contributor

    I haz a fix.

  5. abarth
    added 2 commits that reference this issue on Oct 21, 2016

    Path.transform doesn't work

    4d8eb68

    Path.transform doesn't work

    78ba5f6
  6. abarth
    closed this as completedin flutter-team-archive/engine#3164on Oct 21, 2016
  7. abarth
    added a commit that references this issue on Oct 21, 2016

    Path.transform doesn't work (#3164)

    0c212af

  8. github-actions commented on Sep 5, 2021

    @github-actions
    github-actionsbot
    on Sep 5, 2021

    This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

  9. github-actions
    locked as resolved and limited conversation to collaborators on Sep 5, 2021
  10. zhongdaiqi
    added a commit that references this issue on Oct 9, 2026

    Path.transform doesn't work (flutter-team-archive/engine#3164)

    bb90af8
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