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/*
* Copyright 2019 The Android Open Source Project
*
* 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 androidx.paging
import androidx.arch.core.executor.ArchTaskExecutor
import androidx.lifecycle.LiveData
import androidx.paging.LoadState.Error
import androidx.paging.LoadState.Loading
import androidx.paging.LoadType.REFRESH
import kotlinx.coroutines.CoroutineDispatcher
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.Job
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
import java.util.concurrent.Executor
@Suppress("DEPRECATION")
internal class LivePagedList<Key : Any, Value : Any>(
private val coroutineScope: CoroutineScope,
initialKey: Key?,
private val config: PagedList.Config,
private val boundaryCallback: PagedList.BoundaryCallback<Value>?,
private val pagingSourceFactory: () -> PagingSource<Key, Value>,
private val notifyDispatcher: CoroutineDispatcher,
private val fetchDispatcher: CoroutineDispatcher
) : LiveData<PagedList<Value>>() {
private var currentData: PagedList<Value>
private var currentJob: Job? = null
private val callback = { invalidate(true) }
private val refreshRetryCallback = Runnable { invalidate(true) }
init {
currentData = InitialPagedList(
pagingSourceFactory(),
coroutineScope,
config,
initialKey
)
currentData.setRetryCallback(refreshRetryCallback)
value = currentData
}
override fun onActive() {
super.onActive()
invalidate(false)
}
private fun invalidate(force: Boolean) {
// work is already ongoing, not forcing, so skip invalidate
if (currentJob != null && !force) return
currentJob?.cancel()
currentJob = coroutineScope.launch(fetchDispatcher) {
currentData.pagingSource.unregisterInvalidatedCallback(callback)
val pagingSource = pagingSourceFactory()
pagingSource.registerInvalidatedCallback(callback)
withContext(notifyDispatcher) {
currentData.setInitialLoadState(REFRESH, Loading)
}
@Suppress("UNCHECKED_CAST")
val lastKey = currentData.lastKey as Key?
val params = config.toRefreshLoadParams(lastKey)
when (val initialResult = pagingSource.load(params)) {
is PagingSource.LoadResult.Error -> {
currentData.setInitialLoadState(REFRESH, Error(initialResult.throwable))
}
is PagingSource.LoadResult.Page -> {
val pagedList = PagedList.create(
pagingSource,
initialResult,
coroutineScope,
notifyDispatcher,
fetchDispatcher,
boundaryCallback,
config,
lastKey
)
onItemUpdate(currentData, pagedList)
currentData = pagedList
postValue(pagedList)
}
}
}
}
private fun onItemUpdate(previous: PagedList<Value>, next: PagedList<Value>) {
previous.setRetryCallback(null)
next.setRetryCallback(refreshRetryCallback)
}
}
/**
* Constructs a `LiveData<PagedList>`, from this [DataSource.Factory], convenience for
* [LivePagedListBuilder].
*
* No work (such as loading) is done immediately, the creation of the first [PagedList] is deferred
* until the [LiveData] is observed.
*
* @param config Paging configuration.
* @param initialLoadKey Initial load key passed to the first [PagedList] / [PagingSource].
* @param boundaryCallback The boundary callback for listening to [PagedList] load state.
* @param fetchExecutor [Executor] for fetching data from [PagingSource]s.
*
* @see LivePagedListBuilder
*/
@Suppress("DEPRECATION")
@Deprecated(
message = "PagedList is deprecated and has been replaced by PagingData",
replaceWith = ReplaceWith(
"""LivePagingData(
PagingConfig(
config.pageSize,
config.prefetchDistance,
config.enablePlaceholders,
config.initialLoadSizeHint,
config.maxSize
),
initialLoadKey,
this.asPagingSourceFactory(fetchExecutor.asCoroutineDispatcher())
)""",
"androidx.paging.LivePagingData",
"androidx.paging.PagingConfig",
"kotlinx.coroutines.asCoroutineDispatcher"
)
)
fun <Key : Any, Value : Any> DataSource.Factory<Key, Value>.toLiveData(
config: PagedList.Config,
initialLoadKey: Key? = null,
boundaryCallback: PagedList.BoundaryCallback<Value>? = null,
fetchExecutor: Executor = ArchTaskExecutor.getIOThreadExecutor()
): LiveData<PagedList<Value>> {
return LivePagedListBuilder(this, config)
.setInitialLoadKey(initialLoadKey)
.setBoundaryCallback(boundaryCallback)
.setFetchExecutor(fetchExecutor)
.build()
}
/**
* Constructs a `LiveData<PagedList>`, from this `DataSource.Factory`, convenience for
* [LivePagedListBuilder].
*
* No work (such as loading) is done immediately, the creation of the first [PagedList] is deferred
* until the [LiveData] is observed.
*
* @param pageSize Page size.
* @param initialLoadKey Initial load key passed to the first [PagedList] / [PagingSource].
* @param boundaryCallback The boundary callback for listening to [PagedList] load state.
* @param fetchExecutor Executor for fetching data from DataSources.
*
* @see LivePagedListBuilder
*/
@Suppress("DEPRECATION")
@Deprecated(
message = "PagedList is deprecated and has been replaced by PagingData",
replaceWith = ReplaceWith(
"""LivePagingData(
PagingConfig(pageSize),
initialLoadKey,
this.asPagingSourceFactory(fetchExecutor.asCoroutineDispatcher())
)""",
"androidx.paging.LivePagingData",
"androidx.paging.PagingConfig",
"kotlinx.coroutines.asCoroutineDispatcher"
)
)
fun <Key : Any, Value : Any> DataSource.Factory<Key, Value>.toLiveData(
pageSize: Int,
initialLoadKey: Key? = null,
boundaryCallback: PagedList.BoundaryCallback<Value>? = null,
fetchExecutor: Executor = ArchTaskExecutor.getIOThreadExecutor()
): LiveData<PagedList<Value>> {
return LivePagedListBuilder(this, Config(pageSize))
.setInitialLoadKey(initialLoadKey)
.setBoundaryCallback(boundaryCallback)
.setFetchExecutor(fetchExecutor)
.build()
}
/**
* Constructs a `LiveData<PagedList>`, from this PagingSource factory, convenience for
* [LivePagedListBuilder].
*
* No work (such as loading) is done immediately, the creation of the first [PagedList] is deferred
* until the [LiveData] is observed.
*
* @param config Paging configuration.
* @param initialLoadKey Initial load key passed to the first [PagedList] / [PagingSource].
* @param boundaryCallback The boundary callback for listening to [PagedList] load state.
* @param coroutineScope Set the [CoroutineScope] that page loads should be launched within. The
* set [coroutineScope] allows a [PagingSource] to cancel running load operations when the results
* are no longer needed - for example, when the containing activity is destroyed.
*
* Defaults to [GlobalScope].
* @param fetchDispatcher [CoroutineDispatcher] for fetching data from [PagingSource]s.
*
* @see LivePagedListBuilder
*/
@Suppress("DEPRECATION")
@Deprecated(
message = "PagedList is deprecated and has been replaced by PagingData",
replaceWith = ReplaceWith(
"""LivePagingData(
PagingConfig(
config.pageSize,
config.prefetchDistance,
config.enablePlaceholders,
config.initialLoadSizeHint,
config.maxSize
),
initialLoadKey,
this
)""",
"androidx.paging.LivePagingData",
"androidx.paging.PagingConfig"
)
)
fun <Key : Any, Value : Any> (() -> PagingSource<Key, Value>).toLiveData(
config: PagedList.Config,
initialLoadKey: Key? = null,
boundaryCallback: PagedList.BoundaryCallback<Value>? = null,
coroutineScope: CoroutineScope = GlobalScope,
fetchDispatcher: CoroutineDispatcher = Dispatchers.IO
): LiveData<PagedList<Value>> {
return LivePagedList(
coroutineScope,
initialLoadKey,
config,
boundaryCallback,
this,
Dispatchers.Main.immediate,
fetchDispatcher
)
}
/**
* Constructs a `LiveData<PagedList>`, from this PagingSource factory, convenience for
* [LivePagedListBuilder].
*
* No work (such as loading) is done immediately, the creation of the first [PagedList] is deferred
* until the [LiveData] is observed.
*
* @param pageSize Page size.
* @param initialLoadKey Initial load key passed to the first [PagedList] / [PagingSource].
* @param boundaryCallback The boundary callback for listening to [PagedList] load state.
* @param coroutineScope Set the [CoroutineScope] that page loads should be launched within. The
* set [coroutineScope] allows a [PagingSource] to cancel running load operations when the results
* are no longer needed - for example, when the containing activity is destroyed.
*
* Defaults to [GlobalScope].
* @param fetchDispatcher [CoroutineDispatcher] for fetching data from [PagingSource]s.
*
* @see LivePagedListBuilder
*/
@Suppress("DEPRECATION")
@Deprecated(
message = "PagedList is deprecated and has been replaced by PagingData",
replaceWith = ReplaceWith(
"""LivePagingData(
PagingConfig(pageSize),
initialLoadKey,
this
)""",
"androidx.paging.LivePagingData",
"androidx.paging.PagingConfig"
)
)
fun <Key : Any, Value : Any> (() -> PagingSource<Key, Value>).toLiveData(
pageSize: Int,
initialLoadKey: Key? = null,
boundaryCallback: PagedList.BoundaryCallback<Value>? = null,
coroutineScope: CoroutineScope = GlobalScope,
fetchDispatcher: CoroutineDispatcher = Dispatchers.IO
): LiveData<PagedList<Value>> {
return LivePagedList(
coroutineScope,
initialLoadKey,
PagedList.Config.Builder().setPageSize(pageSize).build(),
boundaryCallback,
this,
Dispatchers.Main.immediate,
fetchDispatcher
)
}