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RoomList: use same logic than Timeline for caching built items. (#1013)

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* RoomList: use same logic than Timeline for caching built items. Extract into reusable components.

* RoomList: fix tests

* Fix `DiffCacheUpdater` docs

---------

Co-authored-by: ganfra <francoisg@element.io>
Co-authored-by: Jorge Martín <jorgem@element.io>
This commit is contained in:
ganfra 2023-08-01 10:53:41 +02:00 • committed by GitHub
parent b14c741422
commit 62a367520e
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 373 additions and 142 deletions
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1
features/messages/impl/build.gradle.kts
View file

@ -52,7 +52,6 @@ dependencies {
implementation(libs.coil.compose)
implementation(libs.datetime)
implementation(libs.accompanist.flowlayout)
implementation(libs.androidx.recyclerview)
implementation(libs.jsoup)
implementation(libs.androidx.constraintlayout)
implementation(libs.androidx.constraintlayout.compose)

56
features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/diff/CacheInvalidator.kt
View file

@ -1,56 +0,0 @@
/*
* Copyright (c) 2023 New Vector Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.element.android.features.messages.impl.timeline.diff
import androidx.recyclerview.widget.ListUpdateCallback
import io.element.android.features.messages.impl.timeline.model.TimelineItem
import io.element.android.features.messages.impl.timeline.util.invalidateLast
import timber.log.Timber
internal class CacheInvalidator(private val itemStatesCache: MutableList<TimelineItem?>) :
ListUpdateCallback {
override fun onChanged(position: Int, count: Int, payload: Any?) {
Timber.d("onChanged(position= $position, count= $count)")
(position until position + count).forEach {
// Invalidate cache
itemStatesCache[it] = null
}
}
override fun onMoved(fromPosition: Int, toPosition: Int) {
Timber.d("onMoved(fromPosition= $fromPosition, toPosition= $toPosition)")
val model = itemStatesCache.removeAt(fromPosition)
itemStatesCache.add(toPosition, model)
}
override fun onInserted(position: Int, count: Int) {
Timber.d("onInserted(position= $position, count= $count)")
itemStatesCache.invalidateLast()
repeat(count) {
itemStatesCache.add(position, null)
}
}
override fun onRemoved(position: Int, count: Int) {
Timber.d("onRemoved(position= $position, count= $count)")
itemStatesCache.invalidateLast()
repeat(count) {
itemStatesCache.removeAt(position)
}
}
}

63
features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/diff/TimelineItemsCacheInvalidator.kt Normal file
View file

@ -0,0 +1,63 @@
/*
* Copyright (c) 2023 New Vector Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.element.android.features.messages.impl.timeline.diff
import io.element.android.features.messages.impl.timeline.model.TimelineItem
import io.element.android.libraries.androidutils.diff.DefaultDiffCacheInvalidator
import io.element.android.libraries.androidutils.diff.DiffCacheInvalidator
import io.element.android.libraries.androidutils.diff.MutableDiffCache
/**
* [DiffCacheInvalidator] implementation for [TimelineItem].
* It uses [DefaultDiffCacheInvalidator] and invalidate the cache around the updated item so that those items are computed again.
* This is needed because a timeline item is computed based on the previous and next items.
*/
internal class TimelineItemsCacheInvalidator : DiffCacheInvalidator<TimelineItem> {
private val delegate = DefaultDiffCacheInvalidator<TimelineItem>()
override fun onChanged(position: Int, count: Int, cache: MutableDiffCache<TimelineItem>) {
delegate.onChanged(position, count, cache)
}
override fun onMoved(fromPosition: Int, toPosition: Int, cache: MutableDiffCache<TimelineItem>) {
delegate.onMoved(fromPosition, toPosition, cache)
}
override fun onInserted(position: Int, count: Int, cache: MutableDiffCache<TimelineItem>) {
cache.invalidateAround(position)
delegate.onInserted(position, count, cache)
}
override fun onRemoved(position: Int, count: Int, cache: MutableDiffCache<TimelineItem>) {
cache.invalidateAround(position)
delegate.onRemoved(position, count, cache)
}
}
/**
* Invalidate the cache around the given position.
* It invalidates the previous and next items.
*/
private fun MutableDiffCache<*>.invalidateAround(position: Int) {
if (position > 0) {
set(position - 1, null)
}
if (position < indices().last) {
set(position + 1, null)
}
}

47
features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/factories/TimelineItemsFactory.kt
View file

@ -19,13 +19,13 @@ package io.element.android.features.messages.impl.timeline.factories
import androidx.compose.runtime.Composable
import androidx.compose.runtime.State
import androidx.compose.runtime.collectAsState
import androidx.recyclerview.widget.DiffUtil
import io.element.android.features.messages.impl.timeline.diff.CacheInvalidator
import io.element.android.features.messages.impl.timeline.diff.MatrixTimelineItemsDiffCallback
import io.element.android.features.messages.impl.timeline.diff.TimelineItemsCacheInvalidator
import io.element.android.features.messages.impl.timeline.factories.event.TimelineItemEventFactory
import io.element.android.features.messages.impl.timeline.factories.virtual.TimelineItemVirtualFactory
import io.element.android.features.messages.impl.timeline.groups.TimelineItemGrouper
import io.element.android.features.messages.impl.timeline.model.TimelineItem
import io.element.android.libraries.androidutils.diff.DiffCacheUpdater
import io.element.android.libraries.androidutils.diff.MutableListDiffCache
import io.element.android.libraries.core.coroutine.CoroutineDispatchers
import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
import kotlinx.collections.immutable.ImmutableList
@ -35,9 +35,7 @@ import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.sync.Mutex
import kotlinx.coroutines.sync.withLock
import kotlinx.coroutines.withContext
import timber.log.Timber
import javax.inject.Inject
import kotlin.system.measureTimeMillis
class TimelineItemsFactory @Inject constructor(
private val dispatchers: CoroutineDispatchers,
@ -46,13 +44,20 @@ class TimelineItemsFactory @Inject constructor(
private val timelineItemGrouper: TimelineItemGrouper,
) {
private val timelineItems = MutableStateFlow(persistentListOf<TimelineItem>())
private val timelineItemsCache = arrayListOf<TimelineItem?>()
// Items from rust sdk, used for diffing
private var matrixTimelineItems: List<MatrixTimelineItem> = emptyList()
private val lock = Mutex()
private val cacheInvalidator = CacheInvalidator(timelineItemsCache)
private val diffCache = MutableListDiffCache<TimelineItem>()
private val diffCacheUpdater = DiffCacheUpdater<MatrixTimelineItem, TimelineItem>(
diffCache = diffCache,
detectMoves = false,
cacheInvalidator = TimelineItemsCacheInvalidator()
) { old, new ->
if (old is MatrixTimelineItem.Event && new is MatrixTimelineItem.Event) {
old.uniqueId == new.uniqueId
} else {
false
}
}
@Composable
fun collectItemsAsState(): State<ImmutableList<TimelineItem>> {
@ -63,15 +68,15 @@ class TimelineItemsFactory @Inject constructor(
timelineItems: List<MatrixTimelineItem>,
) = withContext(dispatchers.computation) {
lock.withLock {
calculateAndApplyDiff(timelineItems)
diffCacheUpdater.updateWith(timelineItems)
buildAndEmitTimelineItemStates(timelineItems)
}
}
private suspend fun buildAndEmitTimelineItemStates(timelineItems: List<MatrixTimelineItem>) {
val newTimelineItemStates = ArrayList<TimelineItem>()
for (index in timelineItemsCache.indices.reversed()) {
val cacheItem = timelineItemsCache[index]
for (index in diffCache.indices().reversed()) {
val cacheItem = diffCache.get(index)
if (cacheItem == null) {
buildAndCacheItem(timelineItems, index)?.also { timelineItemState ->
newTimelineItemStates.add(timelineItemState)
@ -84,20 +89,6 @@ class TimelineItemsFactory @Inject constructor(
this.timelineItems.emit(result)
}
private fun calculateAndApplyDiff(newTimelineItems: List<MatrixTimelineItem>) {
val timeToDiff = measureTimeMillis {
val diffCallback =
MatrixTimelineItemsDiffCallback(
oldList = matrixTimelineItems,
newList = newTimelineItems
)
val diffResult = DiffUtil.calculateDiff(diffCallback, false)
matrixTimelineItems = newTimelineItems
diffResult.dispatchUpdatesTo(cacheInvalidator)
}
Timber.v("Time to apply diff on new list of ${newTimelineItems.size} items: $timeToDiff ms")
}
private fun buildAndCacheItem(
timelineItems: List<MatrixTimelineItem>,
index: Int
@ -108,7 +99,7 @@ class TimelineItemsFactory @Inject constructor(
is MatrixTimelineItem.Virtual -> virtualItemFactory.create(currentTimelineItem)
MatrixTimelineItem.Other -> null
}
timelineItemsCache[index] = timelineItemState
diffCache[index] = timelineItemState
return timelineItemState
}
}

100
features/roomlist/impl/src/main/kotlin/io/element/android/features/roomlist/impl/datasource/RoomListDataSource.kt
View file

@ -18,6 +18,8 @@ package io.element.android.features.roomlist.impl.datasource
import io.element.android.features.roomlist.impl.model.RoomListRoomSummary
import io.element.android.features.roomlist.impl.model.RoomListRoomSummaryPlaceholders
import io.element.android.libraries.androidutils.diff.DiffCacheUpdater
import io.element.android.libraries.androidutils.diff.MutableListDiffCache
import io.element.android.libraries.core.coroutine.CoroutineDispatchers
import io.element.android.libraries.core.extensions.orEmpty
import io.element.android.libraries.dateformatter.api.LastMessageTimestampFormatter
@ -36,6 +38,8 @@ import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.combine
import kotlinx.coroutines.flow.launchIn
import kotlinx.coroutines.flow.onEach
import kotlinx.coroutines.sync.Mutex
import kotlinx.coroutines.sync.withLock
import kotlinx.coroutines.withContext
import javax.inject.Inject
@ -50,15 +54,17 @@ class RoomListDataSource @Inject constructor(
private val _allRooms = MutableStateFlow<ImmutableList<RoomListRoomSummary>>(persistentListOf())
private val _filteredRooms = MutableStateFlow<ImmutableList<RoomListRoomSummary>>(persistentListOf())
private val lock = Mutex()
private val diffCache = MutableListDiffCache<RoomListRoomSummary>()
private val diffCacheUpdater = DiffCacheUpdater<RoomSummary, RoomListRoomSummary>(diffCache = diffCache, detectMoves = true) { old, new ->
old?.identifier() == new?.identifier()
}
fun launchIn(coroutineScope: CoroutineScope) {
roomSummaryDataSource
.allRooms()
.onEach { roomSummaries ->
_allRooms.value = if (roomSummaries.isEmpty()) {
RoomListRoomSummaryPlaceholders.createFakeList(16)
} else {
mapRoomSummaries(roomSummaries)
}.toImmutableList()
replaceWith(roomSummaries)
}
.launchIn(coroutineScope)
@ -85,33 +91,63 @@ class RoomListDataSource @Inject constructor(
val allRooms: StateFlow<ImmutableList<RoomListRoomSummary>> = _allRooms
val filteredRooms: StateFlow<ImmutableList<RoomListRoomSummary>> = _filteredRooms
private suspend fun mapRoomSummaries(
roomSummaries: List<RoomSummary>
): List<RoomListRoomSummary> = withContext(coroutineDispatchers.computation) {
roomSummaries.map { roomSummary ->
when (roomSummary) {
is RoomSummary.Empty -> RoomListRoomSummaryPlaceholders.create(roomSummary.identifier)
is RoomSummary.Filled -> {
val avatarData = AvatarData(
id = roomSummary.identifier(),
name = roomSummary.details.name,
url = roomSummary.details.avatarURLString,
size = AvatarSize.RoomListItem,
)
val roomIdentifier = roomSummary.identifier()
RoomListRoomSummary(
id = roomSummary.identifier(),
roomId = RoomId(roomIdentifier),
name = roomSummary.details.name,
hasUnread = roomSummary.details.unreadNotificationCount > 0,
timestamp = lastMessageTimestampFormatter.format(roomSummary.details.lastMessageTimestamp),
lastMessage = roomSummary.details.lastMessage?.let { message ->
roomLastMessageFormatter.format(message.event, roomSummary.details.isDirect)
}.orEmpty(),
avatarData = avatarData,
)
}
}
private suspend fun replaceWith(roomSummaries: List<RoomSummary>) = withContext(coroutineDispatchers.computation) {
lock.withLock {
diffCacheUpdater.updateWith(roomSummaries)
buildAndEmitAllRooms(roomSummaries)
}
}
private suspend fun buildAndEmitAllRooms(roomSummaries: List<RoomSummary>) {
if (diffCache.isEmpty()) {
_allRooms.emit(
RoomListRoomSummaryPlaceholders.createFakeList(16).toImmutableList()
)
} else {
val roomListRoomSummaries = ArrayList<RoomListRoomSummary>()
for (index in diffCache.indices()) {
val cacheItem = diffCache.get(index)
if (cacheItem == null) {
buildAndCacheItem(roomSummaries, index)?.also { timelineItemState ->
roomListRoomSummaries.add(timelineItemState)
}
} else {
roomListRoomSummaries.add(cacheItem)
}
}
_allRooms.emit(roomListRoomSummaries.toImmutableList())
}
}
private fun buildAndCacheItem(
roomSummaries: List<RoomSummary>,
index: Int
): RoomListRoomSummary? {
val roomListRoomSummary = when (val roomSummary = roomSummaries.getOrNull(index)) {
is RoomSummary.Empty -> RoomListRoomSummaryPlaceholders.create(roomSummary.identifier)
is RoomSummary.Filled -> {
val avatarData = AvatarData(
id = roomSummary.identifier(),
name = roomSummary.details.name,
url = roomSummary.details.avatarURLString,
size = AvatarSize.RoomListItem,
)
val roomIdentifier = roomSummary.identifier()
RoomListRoomSummary(
id = roomSummary.identifier(),
roomId = RoomId(roomIdentifier),
name = roomSummary.details.name,
hasUnread = roomSummary.details.unreadNotificationCount > 0,
timestamp = lastMessageTimestampFormatter.format(roomSummary.details.lastMessageTimestamp),
lastMessage = roomSummary.details.lastMessage?.let { message ->
roomLastMessageFormatter.format(message.event, roomSummary.details.isDirect)
}.orEmpty(),
avatarData = avatarData,
)
}
null -> null
}
diffCache[index] = roomListRoomSummary
return roomListRoomSummary
}
}

26
features/roomlist/impl/src/test/kotlin/io/element/android/features/roomlist/impl/RoomListPresenterTests.kt
View file

@ -50,6 +50,7 @@ import io.element.android.libraries.matrix.test.FakeMatrixClient
import io.element.android.libraries.matrix.test.room.FakeRoomSummaryDataSource
import io.element.android.libraries.matrix.test.room.aRoomSummaryFilled
import io.element.android.libraries.matrix.test.verification.FakeSessionVerificationService
import io.element.android.tests.testutils.consumeItemsUntilPredicate
import io.element.android.tests.testutils.testCoroutineDispatchers
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.test.TestScope
@ -118,13 +119,12 @@ class RoomListPresenterTests {
moleculeFlow(RecompositionMode.Immediate) {
presenter.present()
}.test {
skipItems(1)
val initialState = awaitItem()
val initialState = consumeItemsUntilPredicate { state -> state.roomList.size == 16 }.last()
// Room list is loaded with 16 placeholders
Truth.assertThat(initialState.roomList.size).isEqualTo(16)
Truth.assertThat(initialState.roomList.all { it.isPlaceholder }).isTrue()
roomSummaryDataSource.postAllRooms(listOf(aRoomSummaryFilled()))
val withRoomState = awaitItem()
val withRoomState = consumeItemsUntilPredicate { state -> state.roomList.size == 1 }.last()
Truth.assertThat(withRoomState.roomList.size).isEqualTo(1)
Truth.assertThat(withRoomState.roomList.first())
.isEqualTo(aRoomListRoomSummary)
@ -142,21 +142,19 @@ class RoomListPresenterTests {
presenter.present()
}.test {
roomSummaryDataSource.postAllRooms(listOf(aRoomSummaryFilled()))
skipItems(1)
val loadedState = awaitItem()
val loadedState = consumeItemsUntilPredicate { state -> state.roomList.size == 1 }.last()
// Test filtering with result
loadedState.eventSink.invoke(RoomListEvents.UpdateFilter(A_ROOM_NAME.substring(0, 3)))
skipItems(1) // Filter update
val withNotFilteredRoomState = awaitItem()
Truth.assertThat(withNotFilteredRoomState.filter).isEqualTo(A_ROOM_NAME.substring(0, 3))
Truth.assertThat(withNotFilteredRoomState.filteredRoomList.size).isEqualTo(1)
Truth.assertThat(withNotFilteredRoomState.filteredRoomList.first())
val withFilteredRoomState = consumeItemsUntilPredicate { state -> state.filteredRoomList.size == 1 }.last()
Truth.assertThat(withFilteredRoomState.filter).isEqualTo(A_ROOM_NAME.substring(0, 3))
Truth.assertThat(withFilteredRoomState.filteredRoomList.size).isEqualTo(1)
Truth.assertThat(withFilteredRoomState.filteredRoomList.first())
.isEqualTo(aRoomListRoomSummary)
// Test filtering without result
withNotFilteredRoomState.eventSink.invoke(RoomListEvents.UpdateFilter("tada"))
skipItems(1) // Filter update
Truth.assertThat(awaitItem().filter).isEqualTo("tada")
Truth.assertThat(awaitItem().filteredRoomList).isEmpty()
withFilteredRoomState.eventSink.invoke(RoomListEvents.UpdateFilter("tada"))
val withNotFilteredRoomState = consumeItemsUntilPredicate { state -> state.filteredRoomList.size == 0 }.last()
Truth.assertThat(withNotFilteredRoomState.filter).isEqualTo("tada")
Truth.assertThat(withNotFilteredRoomState.filteredRoomList).isEmpty()
}
}

1
libraries/androidutils/build.gradle.kts
View file

@ -37,6 +37,7 @@ dependencies {
implementation(libs.timber)
implementation(libs.androidx.corektx)
implementation(libs.androidx.activity.activity)
implementation(libs.androidx.recyclerview)
implementation(libs.androidx.exifinterface)
implementation(libs.androidx.security.crypto)
implementation(libs.androidx.browser)

21
features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/diff/MatrixTimelineItemsDiffCallback.kt → libraries/androidutils/src/main/kotlin/io/element/android/libraries/androidutils/diff/DefaultDiffCallback.kt
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2022 New Vector Ltd
* Copyright (c) 2023 New Vector Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@ -14,14 +14,17 @@
* limitations under the License.
*/
package io.element.android.features.messages.impl.timeline.diff
package io.element.android.libraries.androidutils.diff
import androidx.recyclerview.widget.DiffUtil
import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
internal class MatrixTimelineItemsDiffCallback(
private val oldList: List<MatrixTimelineItem>,
private val newList: List<MatrixTimelineItem>
/**
* Default implementation of [DiffUtil.Callback] that uses [areItemsTheSame] to compare items.
*/
internal class DefaultDiffCallback<T>(
private val oldList: List<T>,
private val newList: List<T>,
private val areItemsTheSame: (oldItem: T?, newItem: T?) -> Boolean,
) : DiffUtil.Callback() {
override fun getOldListSize(): Int {
@ -35,11 +38,7 @@ internal class MatrixTimelineItemsDiffCallback(
override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
val oldItem = oldList.getOrNull(oldItemPosition)
val newItem = newList.getOrNull(newItemPosition)
return if (oldItem is MatrixTimelineItem.Event && newItem is MatrixTimelineItem.Event) {
oldItem.uniqueId == newItem.uniqueId
} else {
false
}
return areItemsTheSame(oldItem, newItem)
}
override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {

67
libraries/androidutils/src/main/kotlin/io/element/android/libraries/androidutils/diff/DiffCache.kt Normal file
View file

@ -0,0 +1,67 @@
/*
* Copyright (c) 2023 New Vector Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.element.android.libraries.androidutils.diff
/**
* A cache that can be used to store some data that can be invalidated when a diff is applied.
* The cache is invalidated by the [DiffCacheInvalidator].
*/
interface DiffCache<E> {
fun get(index: Int): E?
fun indices(): IntRange
fun isEmpty(): Boolean
}
/**
* A [DiffCache] that can be mutated by adding, removing or updating elements.
*/
interface MutableDiffCache<E> : DiffCache<E> {
fun removeAt(index: Int): E?
fun add(index: Int, element: E?)
operator fun set(index: Int, element: E?)
}
/**
* A [MutableDiffCache] backed by a [MutableList].
*
*/
class MutableListDiffCache<E>(private val mutableList: MutableList<E?> = ArrayList()) : MutableDiffCache<E> {
override fun removeAt(index: Int): E? {
return mutableList.removeAt(index)
}
override fun get(index: Int): E? {
return mutableList.getOrNull(index)
}
override fun indices(): IntRange {
return mutableList.indices
}
override fun isEmpty(): Boolean {
return mutableList.isEmpty()
}
override operator fun set(index: Int, element: E?) {
mutableList[index] = element
}
override fun add(index: Int, element: E?) {
mutableList.add(index, element)
}
}

63
libraries/androidutils/src/main/kotlin/io/element/android/libraries/androidutils/diff/DiffCacheInvalidator.kt Normal file
View file

@ -0,0 +1,63 @@
/*
* Copyright (c) 2023 New Vector Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.element.android.libraries.androidutils.diff
/**
* [DiffCacheInvalidator] is used to invalidate the cache when the list is updated.
* It is used by [DiffCacheUpdater].
* Check the default implementation [DefaultDiffCacheInvalidator].
*/
interface DiffCacheInvalidator<T> {
fun onChanged(position: Int, count: Int, cache: MutableDiffCache<T>)
fun onMoved(fromPosition: Int, toPosition: Int, cache: MutableDiffCache<T>)
fun onInserted(position: Int, count: Int, cache: MutableDiffCache<T>)
fun onRemoved(position: Int, count: Int, cache: MutableDiffCache<T>)
}
/**
* Default implementation of [DiffCacheInvalidator].
* It invalidates the cache by setting values to null.
*/
class DefaultDiffCacheInvalidator<T> : DiffCacheInvalidator<T> {
override fun onChanged(position: Int, count: Int, cache: MutableDiffCache<T>) {
(position until position + count).forEach {
// Invalidate cache
cache[it] = null
}
}
override fun onMoved(fromPosition: Int, toPosition: Int, cache: MutableDiffCache<T>) {
val model = cache.removeAt(fromPosition)
cache.add(toPosition, model)
}
override fun onInserted(position: Int, count: Int, cache: MutableDiffCache<T>) {
repeat(count) {
cache.add(position, null)
}
}
override fun onRemoved(position: Int, count: Int, cache: MutableDiffCache<T>) {
repeat(count) {
cache.removeAt(position)
}
}
}

70
libraries/androidutils/src/main/kotlin/io/element/android/libraries/androidutils/diff/DiffCacheUpdater.kt Normal file
View file

@ -0,0 +1,70 @@
/*
* Copyright (c) 2023 New Vector Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.element.android.libraries.androidutils.diff
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.ListUpdateCallback
import timber.log.Timber
import kotlin.system.measureTimeMillis
/**
* Class in charge of updating a [MutableDiffCache] according to the cache invalidation rules provided by the [DiffCacheInvalidator].
* @param ListItem the type of the items in the list
* @param CachedItem the type of the items in the cache
* @param diffCache the cache to update
* @param detectMoves true if DiffUtil should try to detect moved items, false otherwise
* @param cacheInvalidator the invalidator to use to update the cache
* @param areItemsTheSame the function to use to compare items
*/
class DiffCacheUpdater<ListItem, CachedItem>(
private val diffCache: MutableDiffCache<CachedItem>,
private val detectMoves: Boolean = false,
private val cacheInvalidator: DiffCacheInvalidator<CachedItem> = DefaultDiffCacheInvalidator(),
private val areItemsTheSame: (oldItem: ListItem?, newItem: ListItem?) -> Boolean,
) {
private val lock = Object()
private var prevOriginalList: List<ListItem> = emptyList()
private val listUpdateCallback = object : ListUpdateCallback {
override fun onInserted(position: Int, count: Int) {
cacheInvalidator.onInserted(position, count, diffCache)
}
override fun onRemoved(position: Int, count: Int) {
cacheInvalidator.onRemoved(position, count, diffCache)
}
override fun onMoved(fromPosition: Int, toPosition: Int) {
cacheInvalidator.onMoved(fromPosition, toPosition, diffCache)
}
override fun onChanged(position: Int, count: Int, payload: Any?) {
cacheInvalidator.onChanged(position, count, diffCache)
}
}
fun updateWith(newOriginalList: List<ListItem>) = synchronized(lock) {
val timeToDiff = measureTimeMillis {
val diffCallback = DefaultDiffCallback(prevOriginalList, newOriginalList, areItemsTheSame)
val diffResult = DiffUtil.calculateDiff(diffCallback, detectMoves)
prevOriginalList = newOriginalList
diffResult.dispatchUpdatesTo(listUpdateCallback)
}
Timber.v("Time to apply diff on new list of ${newOriginalList.size} items: $timeToDiff ms")
}
}