Andrew
1 month ago
committed by
GitHub
commit
b757691334
@ -1,71 +1,88 @@
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package org.thoughtcrime.securesms.home
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import android.content.ContentResolver
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import android.content.Context
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import androidx.lifecycle.LiveData
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import androidx.lifecycle.MutableLiveData
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import androidx.lifecycle.ViewModel
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import androidx.lifecycle.asFlow
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import androidx.lifecycle.viewModelScope
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import app.cash.copper.flow.observeQuery
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import dagger.hilt.android.lifecycle.HiltViewModel
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import kotlinx.coroutines.*
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import kotlinx.coroutines.channels.Channel
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import kotlinx.coroutines.flow.collect
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import kotlinx.coroutines.flow.onEach
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import kotlinx.coroutines.Dispatchers
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import kotlinx.coroutines.channels.BufferOverflow
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import kotlinx.coroutines.flow.Flow
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import kotlinx.coroutines.flow.MutableSharedFlow
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import kotlinx.coroutines.flow.SharingStarted
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import kotlinx.coroutines.flow.StateFlow
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import kotlinx.coroutines.flow.combine
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import kotlinx.coroutines.flow.debounce
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import kotlinx.coroutines.flow.distinctUntilChanged
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import kotlinx.coroutines.flow.mapLatest
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import kotlinx.coroutines.flow.merge
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import kotlinx.coroutines.flow.onStart
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import kotlinx.coroutines.flow.stateIn
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import kotlinx.coroutines.withContext
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import org.thoughtcrime.securesms.ApplicationContext
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import org.thoughtcrime.securesms.database.DatabaseContentProviders
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import org.thoughtcrime.securesms.database.ThreadDatabase
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import org.thoughtcrime.securesms.database.model.ThreadRecord
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import java.lang.ref.WeakReference
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import org.thoughtcrime.securesms.util.observeChanges
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import javax.inject.Inject
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import dagger.hilt.android.qualifiers.ApplicationContext as ApplicationContextQualifier
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@HiltViewModel
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class HomeViewModel @Inject constructor(private val threadDb: ThreadDatabase): ViewModel() {
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class HomeViewModel @Inject constructor(
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private val threadDb: ThreadDatabase,
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private val contentResolver: ContentResolver,
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@ApplicationContextQualifier private val context: Context,
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) : ViewModel() {
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// SharedFlow that emits whenever the user asks us to reload the conversation
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private val manualReloadTrigger = MutableSharedFlow<Unit>(
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extraBufferCapacity = 1,
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onBufferOverflow = BufferOverflow.DROP_OLDEST
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)
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private val executor = viewModelScope + SupervisorJob()
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private var lastContext: WeakReference<Context>? = null
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private var updateJobs: MutableList<Job> = mutableListOf()
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/**
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* A [StateFlow] that emits the list of threads and the typing status of each thread.
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*
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* This flow will emit whenever the user asks us to reload the conversation list or
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* whenever the conversation list changes.
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*/
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val threads: StateFlow<Data?> = combine(observeConversationList(), observeTypingStatus(), ::Data)
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.stateIn(viewModelScope, SharingStarted.Eagerly, null)
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private val _conversations = MutableLiveData<List<ThreadRecord>>()
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val conversations: LiveData<List<ThreadRecord>> = _conversations
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private fun observeTypingStatus(): Flow<Set<Long>> =
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ApplicationContext.getInstance(context).typingStatusRepository
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.typingThreads
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.asFlow()
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.onStart { emit(emptySet()) }
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.distinctUntilChanged()
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private val listUpdateChannel = Channel<Unit>(capacity = Channel.CONFLATED)
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fun tryUpdateChannel() = listUpdateChannel.trySend(Unit)
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fun getObservable(context: Context): LiveData<List<ThreadRecord>> {
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// If the context has changed (eg. the activity gets recreated) then
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// we need to cancel the old executors and recreate them to prevent
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// the app from triggering extra updates when data changes
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if (context != lastContext?.get()) {
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lastContext = WeakReference(context)
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updateJobs.forEach { it.cancel() }
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updateJobs.clear()
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updateJobs.add(
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executor.launch(Dispatchers.IO) {
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context.contentResolver
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.observeQuery(DatabaseContentProviders.ConversationList.CONTENT_URI)
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.onEach { listUpdateChannel.trySend(Unit) }
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.collect()
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}
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)
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updateJobs.add(
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executor.launch(Dispatchers.IO) {
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for (update in listUpdateChannel) {
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threadDb.approvedConversationList.use { openCursor ->
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val reader = threadDb.readerFor(openCursor)
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val threads = mutableListOf<ThreadRecord>()
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@Suppress("OPT_IN_USAGE")
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private fun observeConversationList(): Flow<List<ThreadRecord>> = merge(
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manualReloadTrigger,
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contentResolver.observeChanges(DatabaseContentProviders.ConversationList.CONTENT_URI))
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.debounce(CHANGE_NOTIFICATION_DEBOUNCE_MILLS)
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.onStart { emit(Unit) }
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.mapLatest { _ ->
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withContext(Dispatchers.IO) {
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threadDb.approvedConversationList.use { openCursor ->
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val reader = threadDb.readerFor(openCursor)
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buildList(reader.count) {
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while (true) {
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threads += reader.next ?: break
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}
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withContext(Dispatchers.Main) {
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_conversations.value = threads
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add(reader.next ?: break)
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}
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}
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}
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}
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)
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}
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return conversations
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}
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}
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fun tryReload() = manualReloadTrigger.tryEmit(Unit)
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}
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data class Data(
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val threads: List<ThreadRecord>,
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val typingThreadIDs: Set<Long>
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)
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companion object {
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private const val CHANGE_NOTIFICATION_DEBOUNCE_MILLS = 100L
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}
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}
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@ -0,0 +1,31 @@
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package org.thoughtcrime.securesms.util
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import android.content.ContentResolver
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import android.database.ContentObserver
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import android.net.Uri
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import android.os.Handler
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import android.os.Looper
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import androidx.annotation.CheckResult
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import kotlinx.coroutines.channels.awaitClose
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import kotlinx.coroutines.flow.Flow
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import kotlinx.coroutines.flow.callbackFlow
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/**
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* Observe changes to a content Uri. This function will emit the Uri whenever the content or
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* its descendants change, according to the parameter [notifyForDescendants].
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*/
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@CheckResult
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fun ContentResolver.observeChanges(uri: Uri, notifyForDescendants: Boolean = false): Flow<Uri> {
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return callbackFlow {
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val observer = object : ContentObserver(Handler(Looper.getMainLooper())) {
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override fun onChange(selfChange: Boolean) {
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trySend(uri)
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}
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}
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registerContentObserver(uri, notifyForDescendants, observer)
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awaitClose {
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unregisterContentObserver(observer)
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}
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}
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}
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