Fix argument type in FlutterDesktopEngineGetTextureRegistrar #27522

knopp · 2021-07-18T09:39:10Z

Fixes flutter/flutter#86617

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stuartmorgan-g · 2021-07-18T10:28:22Z

Why are the unit tests compiling? It seems like this should have been caught immediately by the compiler.

knopp · 2021-07-18T10:30:28Z

They are both opaque pointers.

stuartmorgan-g · 2021-07-18T10:52:01Z

Opaque pointers should be typesafe though; that's the whole point of the struct pointer construct over just making them typedefs for void*. Are they mis-declared somehow?

knopp · 2021-07-18T10:59:42Z

I checked, they are declared correctly. But I don't think that FlutterDesktopEngineGetTextureRegistrar is called anywhere in the tests, is it? It builds correctly because FlutterDesktopEngineGetTextureRegistrar is extern "C" so there's no mangling, it's just a pointer. As far as I can tell it's not called from anywhere and it's not exposed in the client wrapper, which is probably why the compiler doesn't complain.

knopp · 2021-07-18T11:14:58Z

Actually, I was wrong. Because the extern "C" declaration has wrong type, the implementation inside flutter_windows.cc is not extern "C" anymore, so it is mangled. I guess nobody has tried calling it yet.

stuartmorgan-g · 2021-07-18T15:05:16Z

As far as I can tell it's not called from anywhere and it's not exposed in the client wrapper

Looks like I missed that this part wasn't tested when approving the PR, and I forgot that it wasn't exposed there. We should include testing in this PR, either directly of the C API, or by exposing it, so there's code compiled against it that would have caught this.

knopp · 2021-07-18T17:44:59Z

@stuartmorgan, I added FlutterEngine::GetTextureRegistrar so the compiler can now check the type.

stuartmorgan-g · 2021-07-18T18:24:48Z

shell/platform/windows/client_wrapper/include/flutter/flutter_engine.h

@@ -62,6 +62,9 @@ class FlutterEngine : public PluginRegistry {
  FlutterDesktopPluginRegistrarRef GetRegistrarForPlugin(
      const std::string& plugin_name) override;

+  // Returns the texture registrar for this engine.
+  FlutterDesktopTextureRegistrarRef GetTextureRegistrar();


We should expose a wrapper, not the raw type. The only reason the plugin registrar is the raw type is that the use case for it is to pass to a plugin registration function, which is a C API (as it's a dll interface). This should be like the messenger or the view, where the wrapper vends a wrapper.

I don't currently have time to write a wrapper for FlutterDesktopTextureRegistrar, nor do I think that should that be in scope of this PR. I can remove this from FlutterEngine and just call FlutterDesktopEngineGetTextureRegistrar somewhere, but I'm really not sure what the proper place for that would be. Any suggestion is appreciated.

A direct test would a test written against the C API directly. It doesn't look like there are any at the moment, but I don't remember if there's a reason doing that is problematic, or it was just never backfilled. It may just need some build plumbing to make it possible to launch the engine from a test (IIRC that was done for macOS, but I'm not sure if Linux and Windows have it.)

@cbracken I know you have a plan around doing some more testing of the desktop embeddings; is that part of that plan?

The C api is currently tested indirectly through the client wrapper. Since there's no wrapper for texture registrar yet I added a test that just calls the C API. (TEST(FlutterEngineTest, GetTextureRegistrar))

@cbracken I know you have a plan around doing some more testing of the desktop embeddings; is that part of that plan?

That is indeed part of the plan. The person working on it has put that work on hold for the moment. You're correct that some progress was made on the macOS side of things. Filed flutter/flutter#87299 for this.

@cbracken, is that something that should block this PR? It just fixes the method signature (otherwise it can't be called as the underlying implementation is not exported)

This reverts commit 014c539.

chinmaygarde · 2021-07-29T20:23:19Z

This should be good for another review pass.

chinmaygarde · 2021-08-05T20:29:13Z

cc @stuartmorgan @cbracken Thoughts on another review?

stuartmorgan-g · 2021-08-13T17:52:34Z

shell/platform/windows/client_wrapper/flutter_engine_unittests.cc

+  FlutterDesktopEngineProperties properties;
+  memset(&properties, 0, sizeof(FlutterDesktopEngineProperties));
+  auto engine = FlutterDesktopEngineCreate(&properties);
+  auto texture_registrar = FlutterDesktopEngineGetTextureRegistrar(engine);


It doesn't make sense for this test to be in client_wrapper. The purpose of the unit tests for client_wrapper are specifically to unit test the client_wrapper code, and this isn't doing that. We shouldn't put tests in places they don't belong as a workaround for not yet having the harness we should have for testing the C API surface.

Can't you write this test in the right place (a new unit test target that's part of the C API layer) by using the embedding API mock support that I added a while back to make it not need complex setup (stubbing out the underlying engine calls that would try to spin everything up)?

chinmaygarde · 2021-08-26T20:17:12Z

@knopp Any updates to Stuart's comments?

knopp · 2021-08-26T20:19:26Z

@knopp Any updates to Stuart's comments?

Sorry, not yet, we talked about this on discord but I haven't had time yet to update the PR.

flutter-dashboard · 2022-01-12T18:30:36Z

This pull request executed golden file tests, but it has not been updated in a while (20+ days). Test results from Gold expire after as many days, so this pull request will need to be updated with a fresh commit in order to get results from Gold.

Hixie · 2022-03-15T23:26:47Z

@knopp should we close this PR for now?

knopp · 2022-03-16T16:00:50Z

@Hixie, I currently don't have time to write the unit tests that @stuartmorgan requested, but the declaration is still wrong (and the symbol not exported). This is a trivial fix and it seems weird to block this on account of a missing unit test (which other parts of the API don't have either).

Hixie · 2022-03-18T06:19:37Z

We shouldn't have landed the other parts of the API that don't have tests either.

stuartmorgan-g · 2022-03-18T15:01:33Z

We shouldn't have landed the other parts of the API that don't have tests either.

Agreed, as noted above

To add a bit more context about the history of testing in the Windows embedding: originally the desktop embeddings had ~no testing (for historical reasons; they were not originally part of Flutter). As they matured, we started filling in testing—although I certainly admit that I did not prioritize that as much as I should have. For Windows in particular, we reached a point where where:

As I refactored the prototype (originally pretty much one big file) into maintainable classes, I made sure those had unit test coverage
- The goal was to have what was left in the C API layer implementation be a very thin wrapper around those implementation classes.
As we added new C++ wrappers, we ensured that they had unit test coverage.

That left a testing gap for the thin C layer, but because it was a thin layer, there wasn't a lot to test there, so the priority of setting up testing coverage of that specific was relatively low. (Especially since in almost all cases we did have compilation coverage that would have caught this issue, since we usually added the wrapper as part of the same PR that added the C API).

This PR demonstrates the problem with having no direct testing of that layer, and so—as with any other bug that we find that indicates a testing gap—we need to close that gap as part of the fix.

chinmaygarde · 2022-05-05T20:27:22Z

Is any progress on this PR likely? Can we close it?

stuartmorgan-g · 2022-05-05T20:49:10Z

@cbracken Could someone on the desktop team add the test here? It's a testing gap we already wanted to close, and this API is clearly broken, so it seems worth some investment on wiring up the test.

cbracken · 2022-05-05T23:46:38Z

I'll take a look at adding the test. Agreed the change itself looks absolutely fine.

cbracken · 2022-07-27T20:30:46Z

Picking this up now.

@knopp

FlutterDesktopEngineGetTextureRegistrar is used to get the texture registrar associated with an engine object and therefore should take a FlutterDesktopEngineRef parameter. This also adds an initial unit test for the public Windows C API used to implement the C++ client wrapper. In order to fully test this API, we'll want to support test fixtures similar to what we do in the embedder API tests. See: https://github.com/flutter/engine/blob/4cc5ad0b7e3c1fe9d19d2621559786ceac9302b7/shell/platform/embedder/BUILD.gn#L187-L319 This was initially identified and fixed by @knopp in: flutter#27522 This patch replaces that one and adds the simplest possible unit test to get it landed. Fixes: flutter/flutter#86617

@knopp

FlutterDesktopEngineGetTextureRegistrar is used to get the texture registrar associated with an engine object and therefore should take a FlutterDesktopEngineRef parameter. This bug was initially identified and fixed by @knopp in: flutter#27522 This patch replaces that one and adds the simplest possible unit test to get it landed. This also adds an initial unit test for the public Windows C API used to implement the C++ client wrapper. In order to fully test this API, we'll want to support test fixtures similar to what we do in the embedder API tests. See: flutter/flutter#87299 Fixes: flutter/flutter#86617

@knopp

FlutterDesktopEngineGetTextureRegistrar is used to get the texture registrar associated with an engine object and therefore should take a FlutterDesktopEngineRef parameter. This bug was initially identified and fixed by @knopp in: flutter#27522 This patch replaces that one and adds the simplest possible unit test to get it landed. This also adds an initial unit test for the public Windows C API used to implement the C++ client wrapper. In order to fully test this API, we'll want to support test fixtures similar to what we do in the embedder API tests. See: flutter/flutter#87299 Fixes: flutter/flutter#86617

@knopp

FlutterDesktopEngineGetTextureRegistrar is used to get the texture registrar associated with an engine object and therefore should take a FlutterDesktopEngineRef parameter. This bug was initially identified and fixed by @knopp in: flutter#27522 This patch replaces that one and adds the simplest possible unit test to get it landed. This also adds an initial unit test for the public Windows C API used to implement the C++ client wrapper. In order to fully test this API, we'll want to support test fixtures similar to what we do in the embedder API tests. See: flutter/flutter#87299 Fixes: flutter/flutter#86617

@knopp

FlutterDesktopEngineGetTextureRegistrar is used to get the texture registrar associated with an engine object and therefore should take a FlutterDesktopEngineRef parameter. This bug was initially identified and fixed by @knopp in: #27522 This patch replaces that one and adds the simplest possible unit test to get it landed. This also adds an initial unit test for the public Windows C API used to implement the C++ client wrapper. In order to fully test this API, we'll want to support test fixtures similar to what we do in the embedder API tests. See: flutter/flutter#87299 Fixes: flutter/flutter#86617

cbracken · 2022-08-03T00:10:41Z

Replaced by #27522; sorry for the delay in getting a test written. Was behind a few other things on my list :/

@knopp

FlutterDesktopEngineGetTextureRegistrar is used to get the texture registrar associated with an engine object and therefore should take a FlutterDesktopEngineRef parameter. This bug was initially identified and fixed by @knopp in: flutter#27522 This patch replaces that one and adds the simplest possible unit test to get it landed. This also adds an initial unit test for the public Windows C API used to implement the C++ client wrapper. In order to fully test this API, we'll want to support test fixtures similar to what we do in the embedder API tests. See: flutter/flutter#87299 Fixes: flutter/flutter#86617

@knopp

FlutterDesktopEngineGetTextureRegistrar is used to get the texture registrar associated with an engine object and therefore should take a FlutterDesktopEngineRef parameter. This bug was initially identified and fixed by @knopp in: flutter#27522 This patch replaces that one and adds the simplest possible unit test to get it landed. This also adds an initial unit test for the public Windows C API used to implement the C++ client wrapper. In order to fully test this API, we'll want to support test fixtures similar to what we do in the embedder API tests. See: flutter/flutter#87299 Fixes: flutter/flutter#86617

Fix argument type in FlutterDesktopEngineGetTextureRegistrar

0a6aa7f

flutter-dashboard bot added the platform-windows label Jul 18, 2021

knopp requested a review from stuartmorgan-g July 18, 2021 09:39

google-cla bot added the cla: yes label Jul 18, 2021

knopp mentioned this pull request Jul 18, 2021

WIP: Add support for external textures nativeshell/nativeshell#47

Closed

Add GetTextureRegistar to FlutterEngine wrapper

014c539

stuartmorgan-g reviewed Jul 18, 2021

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knopp added 2 commits July 20, 2021 01:10

Revert "Add GetTextureRegistar to FlutterEngine wrapper"

8f8036b

This reverts commit 014c539.

Add unit test for FlutterDesktopEngineGetTextureRegistrar

bd5237c

knopp force-pushed the win_engine_argument branch from efc8608 to bd5237c Compare July 19, 2021 23:27

stuartmorgan-g reviewed Aug 13, 2021

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chinmaygarde added the Work in progress (WIP) Not ready (yet) for review! label Sep 9, 2021

CaseyHillers changed the base branch from master to main November 15, 2021 18:16

fluttergithubbot force-pushed the master branch from b1a8771 to 2962099 Compare November 15, 2021 18:30

godofredoc changed the base branch from master to main November 24, 2021 07:25

cbracken mentioned this pull request Aug 2, 2022

[Windows] Fix incorrect public C API argument type #35106

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cbracken closed this Aug 3, 2022

Fix argument type in FlutterDesktopEngineGetTextureRegistrar #27522

Fix argument type in FlutterDesktopEngineGetTextureRegistrar #27522

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knopp commented Jul 18, 2021

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