| /* |
| * 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 kotlinx.coroutines.CoroutineScope |
| import kotlinx.coroutines.Job |
| import kotlinx.coroutines.asCoroutineDispatcher |
| import kotlinx.coroutines.launch |
| import kotlinx.coroutines.withContext |
| import java.util.concurrent.Executor |
| |
| 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 pagedSourceFactory: PagedSourceFactory<Key, Value>, |
| private val notifyExecutor: Executor, |
| private val fetchExecutor: Executor |
| ) : 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( |
| pagedSourceFactory(), |
| coroutineScope, |
| config, |
| initialKey |
| ) |
| onSuccess(currentData) |
| } |
| |
| override fun onActive() { |
| super.onActive() |
| invalidate(false) |
| } |
| |
| private fun onError(throwable: Throwable) { |
| val loadState = if (currentData.pagedSource.isRetryableError(throwable)) { |
| PagedList.LoadState.RETRYABLE_ERROR |
| } else { |
| PagedList.LoadState.ERROR |
| } |
| |
| currentData.setInitialLoadState(loadState, throwable) |
| } |
| |
| private fun onSuccess(value: PagedList<Value>) { |
| onItemUpdate(currentData, value) |
| currentData = value |
| setValue(value) |
| } |
| |
| private fun invalidate(force: Boolean) { |
| // work is already ongoing, not forcing, so skip invalidate |
| if (currentJob != null && !force) return |
| |
| currentJob?.cancel() |
| currentJob = coroutineScope.launch(fetchExecutor.asCoroutineDispatcher()) { |
| try { |
| val pagedList = createPagedList() |
| withContext(notifyExecutor.asCoroutineDispatcher()) { |
| onSuccess(pagedList) |
| } |
| } catch (throwable: Throwable) { |
| withContext(notifyExecutor.asCoroutineDispatcher()) { |
| onError(throwable) |
| } |
| } |
| } |
| } |
| |
| private fun onItemUpdate(previous: PagedList<Value>, next: PagedList<Value>) { |
| previous.setRetryCallback(null) |
| next.setRetryCallback(refreshRetryCallback) |
| } |
| |
| private suspend fun createPagedList(): PagedList<Value> { |
| val pagedSource = pagedSourceFactory() |
| currentData.pagedSource.unregisterInvalidatedCallback(callback) |
| pagedSource.registerInvalidatedCallback(callback) |
| currentData.setInitialLoadState(PagedList.LoadState.LOADING, null) |
| |
| @Suppress("UNCHECKED_CAST") // getLastKey guaranteed to be of 'Key' type |
| val lastKey = currentData.lastKey as Key? |
| return PagedList.create( |
| pagedSource, |
| coroutineScope, |
| notifyExecutor, |
| fetchExecutor, |
| fetchExecutor, |
| boundaryCallback, |
| config, |
| lastKey |
| ) |
| } |
| } |
| |
| /** |
| * 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 is |
| * deferred until the LiveData is observed. |
| * |
| * @param config Paging configuration. |
| * @param initialLoadKey Initial load key passed to the first PagedList/DataSource. |
| * @param boundaryCallback The boundary callback for listening to PagedList load state. |
| * @param fetchExecutor Executor for fetching data from DataSources. |
| * |
| * @see LivePagedListBuilder |
| */ |
| @Deprecated("DataSource is deprecated and has been replaced by PagedSource") |
| 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>> { |
| @Suppress("DEPRECATION") |
| 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 is |
| * deferred until the LiveData is observed. |
| * |
| * @param pageSize Page size. |
| * @param initialLoadKey Initial load key passed to the first PagedList/DataSource. |
| * @param boundaryCallback The boundary callback for listening to PagedList load state. |
| * @param fetchExecutor Executor for fetching data from DataSources. |
| * |
| * @see LivePagedListBuilder |
| */ |
| @Deprecated("DataSource is deprecated and has been replaced by PagedSource") |
| 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>> { |
| @Suppress("DEPRECATION") |
| return LivePagedListBuilder(this, Config(pageSize)) |
| .setInitialLoadKey(initialLoadKey) |
| .setBoundaryCallback(boundaryCallback) |
| .setFetchExecutor(fetchExecutor) |
| .build() |
| } |
| |
| /** |
| * Constructs a `LiveData<PagedList>`, from this [PagedSourceFactory], convenience for |
| * [LivePagedListBuilder]. |
| * |
| * No work (such as loading) is done immediately, the creation of the first PagedList is is |
| * deferred until the LiveData is observed. |
| * |
| * @param config Paging configuration. |
| * @param initialLoadKey Initial load key passed to the first PagedList/PagedSource. |
| * @param boundaryCallback The boundary callback for listening to PagedList load state. |
| * @param fetchExecutor Executor for fetching data from PagedSources. |
| * |
| * @see LivePagedListBuilder |
| */ |
| fun <Key : Any, Value : Any> PagedSourceFactory<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 [PagedSourceFactory], convenience for |
| * [LivePagedListBuilder]. |
| * |
| * No work (such as loading) is done immediately, the creation of the first PagedList is is |
| * deferred until the LiveData is observed. |
| * |
| * @param pageSize Page size. |
| * @param initialLoadKey Initial load key passed to the first PagedList/PagedSource. |
| * @param boundaryCallback The boundary callback for listening to PagedList load state. |
| * @param fetchExecutor Executor for fetching data from PagedSources. |
| * |
| * @see LivePagedListBuilder |
| */ |
| fun <Key : Any, Value : Any> PagedSourceFactory<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() |
| } |
