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Commit 576b95bf authored by Nicolo' Mazzucato's avatar Nicolo' Mazzucato
Browse files

Prevent initial empty state to be propagated in DisplayRepository 

Depending on timings, it was possible for the `scan` to propagate the initial state first before calculating the next state based on available display ids.
In this cl the initial state is filtered out, and a log.wtf is added in the case enabledDisplays is empty (which should never happen)

Bug: 361989878
Test: DisplayRepositoryTest#displayFlow_onlyDefaultDisplayAvailable_neverEmitsEmptySet
Flag: NONE small bugfix
Change-Id: I7b7ee6883ca5b5fd95304a0a5f1168d8b5ce2e4e
parent c30ba623

packages/SystemUI/src/com/android/systemui/display/data/repository/DisplayRepository.kt

+9 −4
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ import kotlinx.coroutines.flow.filter 
import kotlinx.coroutines.flow.filterIsInstance

import kotlinx.coroutines.flow.flowOn

import kotlinx.coroutines.flow.map

import kotlinx.coroutines.flow.onEach

import kotlinx.coroutines.flow.onStart

import kotlinx.coroutines.flow.scan

import kotlinx.coroutines.flow.shareIn
@@ -184,6 +185,9 @@ constructor( 
        if (Flags.enableEfficientDisplayRepository()) {

            enabledDisplayIds

                .mapElementsLazily { displayId -> getDisplay(displayId) }

                .onEach {

                    if (it.isEmpty()) Log.wtf(TAG, "No enabled displays. This should never happen.")

                }

                .flowOn(backgroundCoroutineDispatcher)

                .debugLog("enabledDisplays")

                .stateIn(
@@ -194,7 +198,8 @@ constructor( 
                    // performance concerns.

                    // Ultimately, this is a trade-off between a one-time UI thread binder call and

                    // the constant overhead of sharedFlows.

                    initialValue = getDisplays())

                    initialValue = getDisplays()

                )

        } else {

            oldEnabledDisplays

        }
@@ -380,9 +385,8 @@ constructor( 
            val resultSet: Set<V>

        )



        val initialState = State(emptySet<T>(), emptyMap(), emptySet<V>())



        return this.scan(initialState) { state, currentSet ->

        val emptyInitialState = State(emptySet<T>(), emptyMap(), emptySet<V>())

        return this.scan(emptyInitialState) { state, currentSet ->

                if (currentSet == state.previousSet) {

                    state

                } else {
@@ -397,6 +401,7 @@ constructor( 
                    State(currentSet, newMap, resultSet)

                }

            }

            .filter { it != emptyInitialState }

            .map { it.resultSet }

    }

packages/SystemUI/tests/src/com/android/systemui/display/data/repository/DisplayRepositoryTest.kt

+10 −0
Original line number Diff line number Diff line
@@ -467,6 +467,16 @@ class DisplayRepositoryTest : SysuiTestCase() { 
            assertThat(values.toIdSets()).containsExactly(setOf(0, 1, 2))

        }



    @Test

    fun displayFlow_onlyDefaultDisplayAvailable_neverEmitsEmptySet() =

        testScope.runTest {

            setDisplays(0)



            val values: List<Set<Display>> by collectValues(displayRepository.displays)



            assertThat(values.toIdSets()).containsExactly(setOf(0))

        }



    private fun Iterable<Display>.ids(): List<Int> = map { it.displayId }



    private fun Iterable<Set<Display>>.toIdSets(): List<Set<Int>> = map { it.ids().toSet() }