219 Commits

Author SHA1 Message Date
Kaushik Iska
ede658e2d1
[profiling] CPU Profiling support for iOS (#18087)
See flutter.dev/go/engine-cpu-profiling for details
2020-05-07 08:11:07 -07:00
Chris Yang
2622cb9c33
Introduce TaskRunnerChecker, TaskRunnerAffineWeakPtr (#17649) 2020-05-01 11:28:20 -07:00
liyuqian
a8af96da66
Read SkSLs from asset (#17601)
Fixes https://github.com/flutter/flutter/issues/53117

Test added:
- ShellTest.CanLoadSkSLsFromAsset
2020-04-10 00:16:33 -07:00
gaaclarke
8f6590cbbc
Added "unrecognized-selector" errors to match g3 builds (#17566)
Added "unrecognized-selector" errors to match g3 builds, added
"overriding-method-mismatch" to catch a common error.
2020-04-07 13:28:42 -07:00
Chris Bracken
b2cc00f078
Revert "Added errors to match g3 builds and simple errors (#17536)" (#17564)
Test failure:

    [ RUN      ] FlutterStringCodec.CanEncodeAndDecodeNil
    2020-04-07 10:21:25.091 flutter_channels_unittests[26965:163315] *** Assertion failure in -[FlutterStringCodec encode:], ../../flutter/shell/platform/darwin/common/framework/Source/FlutterCodecs.mm:36
    2020-04-07 10:21:25.118 flutter_channels_unittests[26965:163315] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: ''
    *** First throw call stack:
    (
    	0   CoreFoundation                      0x00007fff2ccabcf9 __exceptionPreprocess + 256
    	1   libobjc.A.dylib                     0x00007fff5785ea17 objc_exception_throw + 48
    	2   CoreFoundation                      0x00007fff2ccc6a16 +[NSException raise:format:arguments:] + 98
    	3   Foundation                          0x00007fff2ef58e11 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 194
    	4   flutter_channels_unittests          0x0000000105f1cce2 -[FlutterStringCodec encode:] + 290
    	5   flutter_channels_unittests          0x0000000105f01bbb _ZN45FlutterStringCodec_CanEncodeAndDecodeNil_Test8TestBodyEv + 107
    	6   flutter_channels_unittests          0x00000001081d1732 _ZN7testing8internal38HandleSehExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc + 146
    	7   flutter_channels_unittests          0x00000001081a76b0 _ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc + 128
    	8   flutter_channels_unittests          0x00000001081a75c1 _ZN7testing4Test3RunEv + 209
    	9   flutter_channels_unittests          0x00000001081a8415 _ZN7testing8TestInfo3RunEv + 229
    	10  flutter_channels_unittests          0x00000001081a95aa _ZN7testing9TestSuite3RunEv + 266
    	11  flutter_channels_unittests          0x00000001081b4e43 _ZN7testing8internal12UnitTestImpl11RunAllTestsEv + 995
    	12  flutter_channels_unittests          0x00000001081d8572 _ZN7testing8internal38HandleSehExceptionsInMethodIfSupportedINS0_12UnitTestImplEbEET0_PT_MS4_FS3_vEPKc + 146
    	13  flutter_channels_unittests          0x00000001081b49b3 _ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS0_12UnitTestImplEbEET0_PT_MS4_FS3_vEPKc + 131
    	14  flutter_channels_unittests          0x00000001081b4835 _ZN7testing8UnitTest3RunEv + 197
    	15  flutter_channels_unittests          0x0000000105f22e73 _Z13RUN_ALL_TESTSv + 35
    	16  flutter_channels_unittests          0x0000000105f22d79 main + 553
    	17  libdyld.dylib                       0x00007fff5908c3d5 start + 1
    )
    libc++abi.dylib: terminating with uncaught exception of type NSException
    [ERROR:flutter/fml/backtrace.cc(110)] Caught signal SIGABRT during program execution.
    Frame 0: 0x7fff591316a6 abort
    Frame 1: 0x7fff560ea641 __cxa_bad_cast
    Frame 2: 0x7fff560ea7df default_unexpected_handler()�
    Frame 3: 0x7fff57860ee3 _objc_terminate()�
    Frame 4: 0x7fff560f619e std::__terminate(void (*)())�
    Frame 5: 0x7fff560f5f86 __cxa_get_exception_ptr
    Frame 6: 0x7fff560e8f99 __cxa_get_globals
    Frame 7: 0x7fff5785eb51 objc_exception_throw
    Frame 8: 0x7fff2ccc6a16 +[NSException raise:format:arguments:]
    Frame 9: 0x7fff2ef58e11 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:]
    Frame 10: 0x105f1cce2 -[FlutterStringCodec encode:]
    Frame 11: 0x105f01bbb FlutterStringCodec_CanEncodeAndDecodeNil_Test::TestBody()�
    Frame 12: 0x1081d1732 void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)�
    Frame 13: 0x1081a76b0 void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)�
    Frame 14: 0x1081a75c1 testing::Test::Run()�
    Frame 15: 0x1081a8415 testing::TestInfo::Run()�
    Frame 16: 0x1081a95aa testing::TestSuite::Run()�
    Frame 17: 0x1081b4e43 testing::internal::UnitTestImpl::RunAllTests()�
    Frame 18: 0x1081d8572 bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*)�
    Frame 19: 0x1081b49b3 bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*)�
    Frame 20: 0x1081b4835 testing::UnitTest::Run()�
    Frame 21: 0x105f22e73 RUN_ALL_TESTS()�
    Frame 22: 0x105f22d79 main
    Frame 23: 0x7fff5908c3d5 start

This reverts commit d1c90b4284282f9745ecd7c65aa72c612df671c1.
2020-04-07 10:32:38 -07:00
gaaclarke
d1c90b4284
Added errors to match g3 builds and simple errors (#17536)
"unrecognized-selector" and "overriding-method-mismatch" added as errors.
2020-04-07 10:03:49 -07:00
Kaushik Iska
abc72933e7
[pipeline] Add trace event for lag between target and display times (#17384)
This change also adds TimeRecorder which records time at the start
of each frame to capture the latest vsync target display time and
wires it in to the rasterizer to add trace events when there is a lag.
2020-04-02 17:15:45 -07:00
liyuqian
f003d9b41a
GPU to raster rename, patch 2 (#17428) 2020-03-31 15:16:11 -07:00
liyuqian
807ca8543c
More rename from GPU thread to raster thread (#17408)
This PR touches variable names, class names, and file names so it's significantly more risky than its predecessor https://github.com/flutter/engine/pull/17329

Due to file name changes, this PR is expected to change the license files.

We haven't rename `shell/gpu` to `shell/raster` yet. It should be optional but I think it's better to have `raster_surface_software.cc` than `gpu_surface_software.cc`.
2020-03-31 14:05:28 -07:00
liyuqian
b3075b3091
Rename GPU thread to raster thread in code comments (#17329)
1. Simple "GPU thread" to "raster thread" replacement.

2. Regex replace "GPU([\n\r\s]+//+ thread)" with "raster$1".

3. Regex replace "// gpu$" with "// raster".

4. Simple test change.

5. Run ci/format.sh
2020-03-25 22:49:59 -07:00
Chinmay Garde
518c9e09cc
Remove checks for the always true using_fuchsia_sdk flag in all GN files. (#17261) 2020-03-23 18:31:02 -07:00
Chinmay Garde
e56b335ade
Allow external texture sources when using the Metal backend. (#17154) 2020-03-22 22:36:03 -07:00
gaaclarke
fddb0c272e
Made it so you can whitelist what events you want to listen to (#17108) 2020-03-16 11:00:03 -07:00
Chinmay Garde
2844d4480b
Remove unused or unnecessary compiler specific marcos in FML. (#17101)
Macros to control inlining are not used and we explicitly recommending against
playing with compiler inlining. The macros for alignment became part of the
standard in C++11 and we already use the standard variants over these macros
(see `PointerData`). The formatters are unused as well and we use the stream
based variants for formatting.
2020-03-11 16:31:50 -07:00
Chinmay Garde
a37560a074
Use the standard [[nodiscard]] attribute instead of an FML macro. (#17100) 2020-03-11 13:36:01 -07:00
Chinmay Garde
7c2d975b55
Gather demangled stack traces and report the same to console on crashes. (#16450)
These should only be used on host binaries for more detailed crash reports.
Installing the handler on targets (iOS/Android) may cause use to break existing
crash reporting mechanisms users may have installed themselves in the process.

This should work on Darwin & Linux for now.

Doing something like int* a = nullptr; *a = 12; or abort or tripping an
assertion should print something the following before program termination. We
can tweak the report further if necessary.

```
[ERROR:flutter/fml/backtrace.cc(110)] Caught signal SIGSEGV during program execution.
Frame 0: 0x10658342c void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)
Frame 1: 0x106555070 void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)
Frame 2: 0x106554f81 testing::Test::Run()
Frame 3: 0x106555dc3 testing::TestInfo::Run()
Frame 4: 0x1065570a1 testing::TestSuite::Run()
Frame 5: 0x106562a55 testing::internal::UnitTestImpl::RunAllTests()
Frame 6: 0x10658c22c bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*)
Frame 7: 0x1065625c3 bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*)
Frame 8: 0x106562445 testing::UnitTest::Run()
Frame 9: 0x105c8dc33 RUN_ALL_TESTS()
Frame 10: 0x105c8dbe6 main
Frame 11: 0x7fff7c2dc3d5 start
```

Known issue: This routines that generate the stack trace are not signal safe.
But since we only use the same before the process is terminating, this ought to
be fine. I’ll work in a separate patch to convert all the internals to be signal
safe. In the meantime, this will help us better identify the causes of flakes on
our bots.

Fixes https://github.com/flutter/flutter/issues/50244
2020-03-10 16:31:06 -07:00
Chinmay Garde
92abb22c64
Reland "Lift restriction that embedders may not trample the render thread OpenGL context in composition callbacks." (#16711)
This reverts commit ef9e7b1a1365c07ab0df2e2016c4442c3963c2c7 with the following changes to accommodate an embedder for whom the original optimizations caused issues:

* Ensure stable order in the backing stores presented to the embedder. This is a pessimization that will be reverted when the embedder migrates. Tracked in  https://github.com/flutter/flutter/issues/51228
* Forego the optimization where the unused layers would be collected before allocation of new layers needs to happen. This is a pessimization that will be reverted when the embedder migrates. Tracked in  https://github.com/flutter/flutter/issues/51229

More context in b/146142979.
2020-02-24 11:48:32 -08:00
Chinmay Garde
ef9e7b1a13
Revert "Lift restriction that embedders may not trample the render thread OpenGL context in composition callbacks. (#16653)" (#16674)
This reverts commit 110c1c9adf0f580d16c8252e3b37992af93e9cea.
2020-02-18 18:59:21 -08:00
Chinmay Garde
110c1c9adf
Lift restriction that embedders may not trample the render thread OpenGL context in composition callbacks. (#16653)
During the implementation of custom compositor integration, the embedder gets
callbacks on the render thread to prepare render targets (framebuffers,
textures, etc) for the engine to render into, callbacks to present these render
targets along with platform managed contents, and, callbacks to collect render
targets once they can no longer be recycled by the engine in subsequent frames.
During these callbacks, the engine mandates the OpenGL state on the render
thread be preserved. This restriction has been the source of hard to isolate
issues where the embedder trampled on the OpenGL bindings state in the callback
but failed to restore state before control went back to the engine. Due to the
nature of the OpenGL API, such errors are easy to make and overlook. This patch
lifts the restriction from the embedder. Embedders may now freely work with the
OpenGL state in custom compositor callbacks and the engine will make sure to
disregard OpenGL bindings when control flows back to it.

Disregarding current OpenGL state has a certain performance penalty and the
majority of this patch handles refactoring various engine embedder components
such that this happens only once per frame. The most trivial version of this
patch would reset context bindings on every transition of control flow from the
embedder to the engine. However, that naive approach would have necessitated
more than 50 binding resets in existing unit-test cases (depending on the number
of platform view interleaving levels and render target recycling hit rates). In
this implementation, bindings will be reset only once per frame and this does
not depend on the number of platform views in the scene.

The majority of this patch is a refactoring of engine subsystems used in
`ExternalViewEmbedder::SubmitFrame` which is thoroughly documented with each
opportunity for the embedder to invalidate OpenGL state tagged.

The refactoring also enables the implementation of the following optimizations
to engine behavior which should aid in reducing the memory needed for the
creation of render targets. These optimization include:
* The engine will only ask the embedder for render targets in which it expects
  to render into. This was a quirk in the way in which root and non-root render
  targets were handled. The engine could require the embedder to create a render
  target but then realize it didn’t have anything to render into it. In the
  presentation callback, it would skip that render target. But the embedder
  still had to allocate that extra render target. This will no longer be the
  case and should reduce memory use.
* The engine may now skip always realizing (via the embedder render target
  creation callback) and presenting the root render target. This was also a side
  effect of the same quirk. Previously, the engine would always ask the embedder
  to present the root render target even if it was empty. Since this is no
  longer the case, few render targets should be allocated which will reduce
  memory consumption.
* The engine will now ask the embedder to collect unused render targets before
  it asks it to create new ones. The previous behavior was to ask the embedder
  for new targets and then collect old ones. This would cause spikes in memory
  use when the size of the render targets would change. These memory use spikes
  should now be troughs.
* The previous render target cache also considered the platform view ID in cache
  viability considerations (instead of just the size of the render target). This
  was a bug which has been fixed. This should lead to better cache utilization
  in some situations.

These optimizations are now codified in unit-tests and the updated test
expectations are a result of these optimizations now being in place.

* Fixes https://github.com/flutter/flutter/issues/50751
* Fixes https://github.com/flutter/flutter/issues/46911
* Fixes https://github.com/flutter/flutter/issues/43778
* Fixes b/146142979
2020-02-18 12:51:49 -08:00
George Wright
15062ca7a2
Revert "Re-arm timer as necessary in MessageLoopFuchsia" (#16568)
This reverts commit 8ec994b4d6addbe730a0f1044ee63593e5f842c3.
2020-02-12 17:22:02 -08:00
Francisco Magdaleno
e0ebaea590
Revert "Re-land: Use os_log instead of syslog on Apple platforms (#16549)" (#16558)
This reverts commit 6aacf5e76755feb8e0f791fa619cbd99a3bd5885.
2020-02-12 12:40:31 -08:00
Chris Bracken
6aacf5e767
Re-land: Use os_log instead of syslog on Apple platforms (#16549)
Migrates to using os_log for app logging on iOS 13 and above, macOS
10.11 and above. On older platform, fall back to syslog(), which is what
we used previously.

This re-lands commit 78a8909725bbaeec80870f498d01ea6e56932a3a with a fix.
That commit was reverted in a61dbf2f66b97e85f4d8bf0cfb29a8b3c2640c09.
2020-02-11 15:11:46 -08:00
Chris Bracken
a61dbf2f66
Revert "Use os_log instead of syslog on Apple platforms (#13487)" (#16546)
Looks like somehow the fix to move to static_cast didn't get merged.

This reverts commit 78a8909725bbaeec80870f498d01ea6e56932a3a.
2020-02-11 13:20:52 -08:00
Jenn Magder
78a8909725
Use os_log instead of syslog on Apple platforms (#13487)
Migrates to using os_log for app logging on iOS 13 and above, macOS
10.11 and above. On older platform, fall back to syslog(), which is what
we used previously.
2020-02-11 10:23:44 -08:00
Dan Field
826b2d46ef
Apply lints from internal roll (#16509) 2020-02-10 13:53:04 -08:00
Dan Field
d589ddea68
Fix text range logic for a11y (#16496)
Make sure that a text range at the end of the string is still valid.
2020-02-07 12:20:30 -08:00
Kaushik Iska
5c70356a98
Simplify task queues locking mechanism (#16477)
We now have one mutex guarding all accesses to
the underlying task heaps. This simplifies the more granular
but bug prone mechanism of having striped locks.

This also re-enables GPUThreadMerger tests that are currently
disabled due to their flaky nature. The scenario that gets fixed by this
change is as follows:

1. Thread-1: We lock `queue_meta_mutex_` and grab locks on `queue_1` and release the meta mutex.
2. Thread-1: We add an Observer on `queues` object.
3. Thread-2: We lock `queue_meta_mutex_` and grab locks on `queue_2`.
4. Thread-2: We try to dispose all the pending tasks on `queue_2` which calls `erase` on `queues`.

The above situation is not thread safe without having 1 lock.

Note: This increases the contention on one lock and could potentially be bad for perf. We are
explicitly making this trade-off towards reducing the complexity.

Fixes: https://github.com/flutter/flutter/issues/49007
2020-02-07 10:24:05 -08:00
George Wright
3ac1e6d8b5
Disable unit tests using --gtest-filter instead of at compile time (#16472) 2020-02-06 13:01:14 -08:00
Chinmay Garde
71ec0a1817
Relax timing restrictions on WakeUpTimersAreSingletons. (#16446)
We don’t run this test on bots because we don’t want timeouts on any tests. This
only runs locally as a sanity check for timers.
2020-02-06 12:35:36 -08:00
stuartmorgan
9ad81dae16
Wrap strdup to use compliant name on Windows (#16372)
A number of POSIX methods were renamed on Windows to match standards
requirements, giving deprecation warnings when calling strdup on Windows.
This adds a wrapper, to allow calling _strdup on Windows instead.

Part of #16256
2020-02-05 22:32:56 -08:00
stuartmorgan
473f55940f
Suppress some deprecation warnings on Windows (#16416)
Targeted suppression of some deprecation warnings that are build errors under
clang:
- Ignore the deprecation of codecvt's unicode conversion until we decide on
  a replacement strategy.
- Allow the deprecated posix names of functions in third_party/txt.

Part of https://github.com/flutter/flutter/issues/16256
2020-02-05 21:10:25 -08:00
stuartmorgan
1cd8f3b1aa
Fix and consolidate wstring conversion utils (#16342)
There were two variants of string/wstring conversion utils, one using
codecvt_utf8 and the other using codecvt_utf8_utf16. We want the latter,
since we want to be using UTF-16, not UCS2.
2020-02-04 13:33:07 -08:00
Chinmay Garde
f8d31baf5b
Disable flaky MessageLoop tests on Fuchsia. (#16340)
Investigation is being tracked in https://github.com/flutter/flutter/issues/50032.
2020-02-03 12:49:50 -08:00
Chinmay Garde
f7b78e001d
Remove all uses of the redundant flutter_root variable. (#16311)
This was only necessary when the Engine had to build in multiple buildroots
where the sources where checked out at different paths relative to the
buildroot. This is no longer the case and there are already cases GN rules
have been written that mix and match variable usage with the direct
specification of the path to the Flutter sources relative to the sole buildroot.
2020-01-31 21:49:48 -08:00
George Wright
f5de1acf94
Revert "Migrate flutter_runner from flutter_runner::{Thread,Loop} to fml::{Thread,MessageLoop} (#15118)" (#16277)
This reverts commit 41e8ed071454cfd9ae02e34198250dea0edab9c4.
2020-01-30 17:19:13 -08:00
stuartmorgan
465529531b
Fix Windows file checks of unicode paths (#16105) 2020-01-30 15:43:02 -08:00
Chinmay Garde
532fdc4f9d
Add test to ensure that concurrent message loops have at least one workers. (#16074)
The current count is determined from std:🧵:hardware_concurrency which can
return zero. Even in such cases, the implementation may not return a loop with
no workers. There are numerous components that depend on having non-zero workers
in the queue.
2020-01-28 11:29:42 -08:00
Chinmay Garde
c5329ef5c4
Allow embedders to schedule a callback on all engine managed threads. (#15980)
`FlutterEnginePostCallbackOnAllNativeThreads` schedule a callback to be run on
all engine managed threads. The engine will attempt to service this callback the
next time the message loops for each managed thread is idle. Since the engine
manages the entire lifecycle of multiple threads, there is no opportunity for
the embedders to finely tune the priorities of threads directly, or, perform
other thread specific configuration (for example, setting thread names for
tracing). This callback gives embedders a chance to affect such tuning.

Fixes flutter/flutter#49551
Fixes b/143774406
Fixes b/148278215
Fixes b/148278931
2020-01-27 13:49:39 -08:00
Chinmay Garde
276481c4d3
Move tonic into //flutter/third_party. (#15895)
Tonic used to be used by multiple consumers outside of Flutter Engine. Due to
this, it has an unnecessary abstraction layer as well as utilities duplicated in
FML and other engine subsystems. The sole user of Tonic is now the Flutter
Engine. It is intended that the Flutter Engine team now owns this subsystem,
remove unnecessary utilities and document the headers. This is the first step in
the transition. No history is being imported as the initial history was already
lost in the transition of this component to fuchsia.googlesource. As this
component was unmaintained there, I could see no additional value in importing
the history of the patches there.

No functional change. Just moved the repo from //third_party to
//flutter/third_party and updates GN refs.
2020-01-25 17:01:56 -08:00
George Wright
1e7a9debc6
Disable flakey CountDownLatchTest.CanWait unit test on Fuchsia (#15982) 2020-01-24 19:21:20 -08:00
Dan Field
89f3471fa7
the the fix (#15973) 2020-01-24 12:43:32 -08:00
George Wright
41e8ed0714 Migrate flutter_runner from flutter_runner::{Thread,Loop} to fml::{Thread,MessageLoop} (#15118) 2020-01-23 18:54:49 -08:00
George Wright
8ec994b4d6 Re-arm timer as necessary in MessageLoopFuchsia 2020-01-23 18:54:49 -08:00
Jason Simmons
51919ed38e
Do not produce timeline events in release mode (#15894)
Calling Dart_TimelineEvent has a performance cost, and the APIs for collecting
timeline events are not available in release mode.
2020-01-23 15:05:00 -08:00
George Wright
69bc783016
Revert "Migrate flutter_runner from flutter_runner::{Thread,Loop} to fml::{Thread,MessageLoop} (#15118)" (#15903)
This reverts commit a50f1ef56a05999bfa97a777cca14fd7a00e8454.
2020-01-22 20:35:41 -08:00
Nathan Rogers
c561e610b1
[fuchsia] Support Skia tracing arguments (#15745)
When running on Fuchsia, respect the argument values that Skia passes
into the Flutter implementation of the |SkEventTracer| interface.

Bug: https://github.com/flutter/flutter/issues/48864
2020-01-21 10:00:11 -08:00
Chinmay Garde
2c64a06d4a
Disable GPUThreadMerger tests inline instead of via harness flags. (#15706) 2020-01-16 17:11:54 -08:00
George Wright
a50f1ef56a
Migrate flutter_runner from flutter_runner::{Thread,Loop} to fml::{Thread,MessageLoop} (#15118) 2020-01-07 19:24:45 -08:00
George Wright
1d3bb8c271
Fix message_loop_fuchsia and thus enable fml_tests and flow_tests for Fuchsia (#14583) 2019-12-19 17:25:06 -05:00
Chinmay Garde
f05832153b
Allow embedders to post Dart objects on send ports from the native side. (#14477)
This is a non-breaking addition to the stable Flutter Embedder API and exposes a
subset of the functionality provided by Dart_PostCObject API in a stable and
tested manner to custom embedder implementations.

Send port acquisition can currently be done as described in the unit-test but
there may be opportunities to extend this API in the future to access ports more
easily or create ports from the native side.

The following capabilities of the the Dart_PostCObject API are explicitly NOT
exposed:
* Object arrays: This allows callers to create complex object graphs but only
  using the primitives specified in the native API. I could find no current use
  case for this and would have made the implementation a lot more complex. This
  is something we can add in the future if necessary however.
* Capabilities and ports: Again no use cases and I honestly I didn’t understand
  how to use capabilities. If needed, these can be added at a later point by
  appending to the union.

Fixes https://github.com/flutter/flutter/issues/46624
Fixes b/145982720
2019-12-13 17:28:21 -08:00