@Transaction query returning deferred/async type - Flow in particular [190075899]

Fixed

Bug

Status Update

No update yet.

Description

ma...@justpinch.com

created issue #1

Jun 7, 2021 10:15AM

Component used:androidx.room:room-*
Version used: 2.3.0, 2.4.0-alpha02
Devices/Android versions reproduced on: N/A -> code-gen error (kapt)

The documentation on @Transaction states:

If the query is asynchronous (e.g. returns a LiveData or RxJava Flowable), the transaction is properly handled when the query is run, not when the method is called.

But unless I'm misunderstanding what this is trying to communicate, reality seems to be different.

Given the following dao:

@Dao
interface ExampleDao {

    @Query("SELECT * FROM table_example")
    fun allFlow(): Flow<List<ExampleEntity>>

    @Query("SELECT * FROM table_example")
    fun allLiveData(): LiveData<List<ExampleEntity>>

    @Query("SELECT * FROM table_example")
    fun allRx(): Flowable<List<ExampleEntity>>

    @Transaction
    fun transactionFlow() = allFlow()

    @Transaction
    fun transactionLiveData() = allLiveData()    // <-- Nope

    @Transaction
    fun transactionRx() = allRx()                // <-- Nope
}

Although implementations are generated, errors are thrown for the @Transaction annotated functions returning LiveData and Flowable:

error: Method annotated with @Transaction must not return deferred/async return type <type>. Since transactions are thread confined and Room cannot guarantee that all queries in the method implementation are performed on the same thread, only synchronous @Transaction implemented methods are allowed. If a transaction is started and a change of thread is done and waited upon then a database deadlock can occur if the additional thread attempts to perform a query. This restrictions prevents such situation from occurring.

This seems to contradict the earlier statement from the documentation on @Transaction? Is there another way to use @Transaction with a deferred/async return type?

What's also interesting is that the @Transaction annotated function returning a Flow does not yield any errors. Isn't Flow also a deferred/async return type? Does this mean that Room can in fact guarantee that all queries in the method are performed on the same thread? If so, how?

The generated code looks like this:

@Override
public Flow<List<ExampleEntity>> transactionFlow() {
  __db.beginTransaction();
  try {
    Flow<List<ExampleEntity>> _result = ExampleDao.DefaultImpls.transactionFlow(ExampleDao_Impl.this);
    __db.setTransactionSuccessful();
    return _result;
  } finally {
    __db.endTransaction();
  }
}

This function is no longer deferred, because the transactional operations involve blocking I/O, and there are assertions in place that will fail if this is called from the main thread. And even if we were to make this function suspendable (we would then have a suspendable function returning a Flow?🤨), it would still not be main-safe.

In conclusion, I suspect:

the documentation for @Transaction is no longer accurate?
a function with @Transaction annotation returning a Flow should also yield a code-gen error?

Comments

da...@google.com <da...@google.com> #2Jun 7, 2021 03:33PM

Reassigned to el...@google.com.

Project: platform/frameworks/support
Branch: androidx-main

commit 0154910724cdc44253af1d2f8cede76264783226
Author: Aurimas Liutikas <aurimas@google.com>
Date: Thu Jun 27 15:25:02 2024

Expand native target support for annotation and collection libraries

- Enable watchos and tvos download in importMaven
- Add support for watchos and tvos targets in AndroidXMultiplatformExtension
- Enable watchos and tvos in :annotation:annotation
- Enable linuxArm64, watchos, and tvos in :collection:collection

This work is required as we work towards setting up native stubs for
compose projects.

Test: ./gradlew collection:collection:publish
Bug: 349894318
Change-Id: Idfd1faa3a826bb91ee14722f7437bdcf99cf0018

M annotation/annotation/build.gradle
M buildSrc/private/src/main/kotlin/androidx/build/AndroidXMultiplatformExtension.kt
M buildSrc/public/src/main/kotlin/androidx/build/KmpPlatforms.kt
M collection/collection/build.gradle
M development/build_log_simplifier/messages.ignore
M development/importMaven/src/main/kotlin/androidx/build/importMaven/KmpConfig.kt

https://android-review.googlesource.com/3151736

ap...@google.com <ap...@google.com> #3Jun 7, 2021 09:44PM

Project: platform/frameworks/support
Branch: androidx-main

commit 39cd1e9f7579513bde139c17f9c51f9012d56152
Author: Aurimas Liutikas <aurimas@google.com>
Date: Thu Jun 27 15:25:02 2024

Expand native target support for annotation and collection libraries

Reland

r.android.com/3151736 now with workaround for

https://youtrack.jetbrains.com/issue/KT-62653

- Enable watchos and tvos download in importMaven
- Add support for watchos and tvos targets in AndroidXMultiplatformExtension
- Enable watchos and tvos in :annotation:annotation
- Enable linuxArm64, watchos, and tvos in :collection:collection

This work is required as we work towards setting up native stubs for
compose projects.

Test: ./gradlew collection:collection:publish
Bug: 349894318
Change-Id: Ic795af8486db48b31633799e06665717d08398db

M annotation/annotation/build.gradle
M buildSrc/private/src/main/kotlin/androidx/build/AndroidXMultiplatformExtension.kt
M buildSrc/public/src/main/kotlin/androidx/build/KmpPlatforms.kt
M collection/collection/build.gradle
M development/build_log_simplifier/messages.ignore
M development/importMaven/src/main/kotlin/androidx/build/importMaven/KmpConfig.kt

https://android-review.googlesource.com/3156121

el...@google.com <el...@google.com> Jun 7, 2021 09:45PM

Marked as fixed.

ma...@justpinch.com <ma...@justpinch.com> #4Jun 8, 2021 08:20AM

Project: platform/frameworks/support
Branch: androidx-main

commit c3a06e79cf427aef1cf0ede1bacb463eb89472be
Author: Aurimas Liutikas <aurimas@google.com>
Date: Thu Jun 27 15:25:02 2024

Expand native target support for annotation and collection libraries

Reland

r.android.com/3151736 /

r.android.com/3156121 but now with
moving to project(":annotation:annotation") in commonMain as due to

https://youtrack.jetbrains.com/issue/KT-62653 we cannot depend on
project in one source set and prebuilt in the other.

- Enable watchos and tvos download in importMaven
- Add support for watchos and tvos targets in AndroidXMultiplatformExtension
- Enable watchos and tvos in :annotation:annotation
- Enable linuxArm64, watchos, and tvos in :collection:collection

This work is required as we work towards setting up native stubs for
compose projects.

Test: ./gradlew collection:collection:publish
Bug: 349894318
Change-Id: I7f2a1bddbe79ab5e920cdb01ca6a428950a8c2c3

M annotation/annotation/build.gradle
M buildSrc/private/src/main/kotlin/androidx/build/AndroidXMultiplatformExtension.kt
M buildSrc/public/src/main/kotlin/androidx/build/KmpPlatforms.kt
M busytown/androidx_multiplatform_mac_host_tests_arm64.sh
M camera/integration-tests/avsynctestapp/build.gradle
M collection/collection/build.gradle
M development/build_log_simplifier/messages.ignore
M development/importMaven/src/main/kotlin/androidx/build/importMaven/KmpConfig.kt
M test/uiautomator/integration-tests/testapp/build.gradle
M wear/compose/integration-tests/navigation/build.gradle

https://android-review.googlesource.com/3156423

da...@google.com <da...@google.com> #5Jun 8, 2021 05:32PM

Project: platform/frameworks/support
Branch: androidx-main

commit c56a2faf24c82bf961cb10440156745bf3cf30bd
Author: Aurimas Liutikas <aurimas@google.com>
Date: Wed Jul 03 11:10:40 2024

Add linuxX64Stubs for compose runtime libraries

- Add support for linuxX64Stubs
- Add these linuxX64Stubs to compose runtime projects
- Move OperationsTest from commonTest to jvmTest as it has
jvm-reflection usages

Bug: 349894318
Test: ./gradlew -p compose/runtime build
Change-Id: Ia600fafb174b585cf5a0d7a7f3c3726d10b4cc92

M buildSrc/private/src/main/kotlin/androidx/build/AndroidXMultiplatformExtension.kt
M buildSrc/public/src/main/kotlin/androidx/build/KmpPlatforms.kt
M compose/runtime/runtime-saveable/build.gradle
M compose/runtime/runtime-test-utils/build.gradle
A compose/runtime/runtime-test-utils/src/commonMain/kotlin/androidx/compose/runtime/mock/SynchronizedObject.kt
M compose/runtime/runtime-test-utils/src/commonMain/kotlin/androidx/compose/runtime/mock/TestMonotonicFrameClock.kt
A compose/runtime/runtime-test-utils/src/jvmMain/kotlin/androidx/compose/runtime/mock/SynchronizedObject.jvm.kt
A compose/runtime/runtime-test-utils/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/mock/SynchronizedObject.linuxx64Stubs.kt
M compose/runtime/runtime/build.gradle
M compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/Stack.kt
M compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/collection/ScopeMap.kt
M compose/runtime/runtime/src/commonMain/kotlin/androidx/compose/runtime/snapshots/SnapshotStateSet.kt
M compose/runtime/runtime/src/commonTest/kotlin/androidx/compose/runtime/CompositionTestExtensions.kt
M compose/runtime/runtime/src/jvmTest/kotlin/androidx/compose/runtime/changelist/OperationsTest.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/MonotonicFrameClock.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/NotImplemented.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/SynchronizedObject.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/TestOnly.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/internal/Atomic.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/internal/ComposableLambda.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/internal/JvmDefaultWithCompatibility.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/internal/Thread.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/internal/Utils.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/internal/WeakReference.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsMain/kotlin/androidx/compose/runtime/snapshots/SnapshotContextElement.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsTest/kotlin/kotlinx/test/IgnoreAndroidUnitTestTarget.linuxx64Stubs.kt
A compose/runtime/runtime/src/linuxx64StubsTest/kotlin/kotlinx/test/IgnoreJsTarget.linuxx64Stubs.kt

https://android-review.googlesource.com/3159861

ma...@justpinch.com <ma...@justpinch.com> #6Jun 11, 2021 12:29PM

Project: platform/frameworks/support
Branch: androidx-main

commit 2363176cf646e7eb7647fcda7186746757fa9353
Author: Aurimas Liutikas <aurimas@google.com>
Date: Mon Jul 08 10:48:51 2024

Convert first batch of compose ui projects to add linuxX64Stubs target

- Disable running linuxx64StubsTest, as they are not representative
of a real environment
- Add all needed stub actuals

Bug: 349894318
Test: ./gradlew -p compose/ui build
Change-Id: I6abbf8d425714a1c6c492e5ea25897fe6f226584

M buildSrc/private/src/main/kotlin/androidx/build/AndroidXImplPlugin.kt
M buildSrc/private/src/main/kotlin/androidx/build/AndroidXMultiplatformExtension.kt
M compose/ui/ui-geometry/build.gradle
M compose/ui/ui-graphics/build.gradle
M compose/ui/ui-graphics/src/androidMain/kotlin/androidx/compose/ui/graphics/internal/JvmDefaultWithCompatibility.android.kt
M compose/ui/ui-graphics/src/commonMain/kotlin/androidx/compose/ui/graphics/Bezier.kt
M compose/ui/ui-graphics/src/commonMain/kotlin/androidx/compose/ui/graphics/Float16.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/BlendMode.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/Canvas.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/ColorFilter.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/ImageBitmap.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/NotImplemented.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/Paint.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/Path.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/PathEffect.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/PathIterator.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/PathMeasure.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/RenderEffect.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/Shader.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/TileMode.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/internal/JvmDefaultWithCompatibility.commonStubs.kt
M compose/ui/ui-graphics/src/commonStubsMain/kotlin/androidx/compose/ui/graphics/layer/GraphicsLayer.commonStubs.kt
M compose/ui/ui-graphics/src/commonTest/kotlin/androidx/compose/ui/graphics/vector/FastFloatParserTest.kt
M compose/ui/ui-unit/build.gradle
M compose/ui/ui-unit/src/commonMain/kotlin/androidx/compose/ui/unit/Constraints.kt
M compose/ui/ui-unit/src/commonMain/kotlin/androidx/compose/ui/unit/Dp.kt
M compose/ui/ui-unit/src/commonMain/kotlin/androidx/compose/ui/unit/IntOffset.kt
M compose/ui/ui-unit/src/linuxx64StubsMain/kotlin/androidx/compose/ui/unit/FontScaling.linuxx64Stubs.kt
M compose/ui/ui-unit/src/linuxx64StubsMain/kotlin/androidx/compose/ui/unit/internal/JvmDefaultWithCompatibility.linuxx64Stubs.kt
M compose/ui/ui-util/build.gradle
M compose/ui/ui-util/src/commonStubsMain/kotlin/androidx/compose/ui/util/NotImplemented.commonStubs.kt
M compose/ui/ui-util/src/commonStubsMain/kotlin/androidx/compose/ui/util/Trace.commonStubs.kt
M compose/ui/ui-util/src/linuxx64StubsMain/kotlin/androidx/compose/ui/util/InlineClassHelper.linuxx64Stubs.kt

https://android-review.googlesource.com/3163196

Issue 190075899