Use coroutines for drag and drop differ

app/build.gradle.kts

@@ -184,7 +184,6 @@ dependencies {
     implementation("androidx.room:room-ktx:${Versions.room}")
     kapt("androidx.room:room-compiler:${Versions.room}")
     implementation("androidx.appcompat:appcompat:1.3.1")
-    implementation("io.reactivex.rxjava2:rxandroid:2.1.1")
     implementation("androidx.paging:paging-runtime:2.1.2")
     implementation("io.noties.markwon:core:${Versions.markwon}")
     implementation("io.noties.markwon:editor:${Versions.markwon}")

app/licenses.yml

@@ -189,12 +189,6 @@
   license: The Apache Software License, Version 2.0
   licenseUrl: http://www.apache.org/licenses/LICENSE-2.0.txt
   url: http://developer.android.com/tools/extras/support-library.html
-- artifact: io.reactivex.rxjava2:rxandroid:+
-  name: RxAndroid
-  copyrightHolder: The RxAndroid authors
-  license: The Apache Software License, Version 2.0
-  licenseUrl: http://www.apache.org/licenses/LICENSE-2.0.txt
-  url: https://github.com/ReactiveX/RxAndroid
 - artifact: androidx.swiperefreshlayout:swiperefreshlayout:+
   name: Android Support Library Custom View
   copyrightHolder: Android Open Source Project
@@ -274,12 +268,6 @@
   license: The Apache Software License, Version 2.0
   licenseUrl: http://www.apache.org/licenses/LICENSE-2.0.txt
   url: http://developer.android.com/tools/extras/support-library.html
-- artifact: org.reactivestreams:reactive-streams:+
-  name: reactive-streams
-  copyrightHolder: Public domain
-  license: CC0
-  licenseUrl: http://creativecommons.org/publicdomain/zero/1.0/
-  url: http://www.reactive-streams.org/
 - artifact: androidx.work:work-runtime:+
   name: Android WorkManager Runtime
   copyrightHolder: Android Open Source Project
@@ -333,12 +321,6 @@
   license: The Apache Software License, Version 2.0
   licenseUrl: http://www.apache.org/licenses/LICENSE-2.0.txt
   url: http://developer.android.com/tools/extras/support-library.html
-- artifact: io.reactivex.rxjava2:rxjava:+
-  name: RxJava
-  copyrightHolder: RxJava Contributors
-  license: The Apache Software License, Version 2.0
-  licenseUrl: http://www.apache.org/licenses/LICENSE-2.0.txt
-  url: https://github.com/ReactiveX/RxJava
 - artifact: com.google.apis:google-api-services-tasks:+
   name: Tasks API v1-rev55-1.25.0
   copyrightHolder: Google Inc.

app/src/main/assets/licenses.json

@@ -455,20 +455,6 @@
       "url": "http://developer.android.com/tools/extras/support-library.html",
       "libraryName": "Android Support Library Custom View"
     },
-    {
-      "artifactId": {
-        "name": "rxandroid",
-        "group": "io.reactivex.rxjava2",
-        "version": "+"
-      },
-      "copyrightHolder": "The RxAndroid authors",
-      "copyrightStatement": "Copyright © The RxAndroid authors. All rights reserved.",
-      "license": "The Apache Software License, Version 2.0",
-      "licenseUrl": "http://www.apache.org/licenses/LICENSE-2.0.txt",
-      "normalizedLicense": "apache2",
-      "url": "https://github.com/ReactiveX/RxAndroid",
-      "libraryName": "RxAndroid"
-    },
     {
       "artifactId": {
         "name": "swiperefreshlayout",
@@ -651,20 +637,6 @@
       "url": "http://developer.android.com/tools/extras/support-library.html",
       "libraryName": "Android Support VectorDrawable"
     },
-    {
-      "artifactId": {
-        "name": "reactive-streams",
-        "group": "org.reactivestreams",
-        "version": "+"
-      },
-      "copyrightHolder": "Public domain",
-      "copyrightStatement": "Copyright © Public domain. All rights reserved.",
-      "license": "CC0",
-      "licenseUrl": "http://creativecommons.org/publicdomain/zero/1.0/",
-      "normalizedLicense": "cc0",
-      "url": "http://www.reactive-streams.org/",
-      "libraryName": "reactive-streams"
-    },
     {
       "artifactId": {
         "name": "work-runtime",
@@ -790,20 +762,6 @@
       "url": "http://developer.android.com/tools/extras/support-library.html",
       "libraryName": "Android Support Library Drawer Layout"
     },
-    {
-      "artifactId": {
-        "name": "rxjava",
-        "group": "io.reactivex.rxjava2",
-        "version": "+"
-      },
-      "copyrightHolder": "RxJava Contributors",
-      "copyrightStatement": "Copyright © RxJava Contributors. All rights reserved.",
-      "license": "The Apache Software License, Version 2.0",
-      "licenseUrl": "http://www.apache.org/licenses/LICENSE-2.0.txt",
-      "normalizedLicense": "apache2",
-      "url": "https://github.com/ReactiveX/RxJava",
-      "libraryName": "RxJava"
-    },
     {
       "artifactId": {
         "name": "google-api-services-tasks",

app/src/main/java/com/todoroo/astrid/adapter/NavigationDrawerAdapter.kt

@@ -14,11 +14,10 @@ import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.RecyclerView
 import com.todoroo.astrid.api.Filter
 import com.todoroo.astrid.api.FilterListItem
-import io.reactivex.disposables.CompositeDisposable
-import io.reactivex.subjects.PublishSubject
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.asCoroutineDispatcher
+import kotlinx.coroutines.flow.MutableSharedFlow
 import org.tasks.LocalBroadcastManager
 import org.tasks.activities.DragAndDropDiffer
 import org.tasks.billing.Inventory
@@ -46,13 +45,12 @@ class NavigationDrawerAdapter @Inject constructor(
 
     private lateinit var onClick: (FilterListItem?) -> Unit
     private var selected: Filter? = null
-    override val disposables = CompositeDisposable()
-    override val publishSubject = PublishSubject.create<MutableList<FilterListItem>>()
+    override val flow = MutableSharedFlow<MutableList<FilterListItem>>()
     override val updates: Queue<Pair<MutableList<FilterListItem>, DiffUtil.DiffResult?>> = LinkedList()
+    override val scope: CoroutineScope =
+        CoroutineScope(Executors.newSingleThreadExecutor().asCoroutineDispatcher() + Job())
     override var items = initializeDiffer(ArrayList())
     override var dragging = false
-    override val scope: CoroutineScope =
-            CoroutineScope(Executors.newSingleThreadExecutor().asCoroutineDispatcher() + Job())
 
     fun setOnClick(onClick: (FilterListItem?) -> Unit) {
         this.onClick = onClick

app/src/main/java/org/tasks/activities/DragAndDropDiffer.kt

@@ -3,19 +3,14 @@ package org.tasks.activities
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ListUpdateCallback
 import com.todoroo.andlib.utility.AndroidUtilities
-import io.reactivex.android.schedulers.AndroidSchedulers
-import io.reactivex.disposables.CompositeDisposable
-import io.reactivex.schedulers.Schedulers
-import io.reactivex.subjects.PublishSubject
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.cancel
-import kotlinx.coroutines.launch
+import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.*
 import java.util.*
+import java.util.concurrent.Executors
 
 interface DragAndDropDiffer<T, R> : ListUpdateCallback {
-    val publishSubject: PublishSubject<R>
+    val flow: MutableSharedFlow<R>
     val updates: Queue<Pair<R, DiffUtil.DiffResult?>>
-    val disposables: CompositeDisposable
     var items: R
     var dragging: Boolean
     val scope: CoroutineScope
@@ -23,7 +18,7 @@ interface DragAndDropDiffer<T, R> : ListUpdateCallback {
     fun submitList(list: List<T>) {
         scope.launch {
             val transform = transform(list)
-            publishSubject.onNext(transform)
+            flow.emit(transform)
         }
     }
 
@@ -50,16 +45,18 @@ interface DragAndDropDiffer<T, R> : ListUpdateCallback {
         }
     }
 
+    @ExperimentalCoroutinesApi
     fun initializeDiffer(list: List<T>): R {
         val initial = transform(list)
-        disposables.add(publishSubject
-                .observeOn(Schedulers.single())
+        scope.launch(Dispatchers.Main) {
+            flow
                 .scan(Pair(initial, null), { last: Pair<R, DiffUtil.DiffResult?>, next: R ->
                     calculateDiff(last, next)
                 })
-                .skip(1)
-                .observeOn(AndroidSchedulers.mainThread())
-                .subscribe(this::applyDiff))
+                .drop(1)
+                .flowOn(Executors.newSingleThreadExecutor().asCoroutineDispatcher())
+                .collect { applyDiff(it) }
+        }
         return initial
     }
 
@@ -68,7 +65,6 @@ interface DragAndDropDiffer<T, R> : ListUpdateCallback {
     fun diff(last: R, next: R): DiffUtil.DiffResult
 
     fun dispose() {
-        disposables.dispose()
         scope.cancel()
     }
 }

app/src/main/java/org/tasks/tasklist/DragAndDropRecyclerAdapter.kt

@@ -10,11 +10,10 @@ import androidx.recyclerview.widget.RecyclerView
 import com.todoroo.astrid.activity.TaskListFragment
 import com.todoroo.astrid.adapter.TaskAdapter
 import com.todoroo.astrid.utility.Flags
-import io.reactivex.disposables.CompositeDisposable
-import io.reactivex.subjects.PublishSubject
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.asCoroutineDispatcher
+import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.runBlocking
 import org.tasks.activities.DragAndDropDiffer
 import org.tasks.data.TaskContainer
@@ -40,13 +39,12 @@ class DragAndDropRecyclerAdapter(
     private val itemTouchHelper = ItemTouchHelper(ItemTouchHelperCallback()).apply {
         attachToRecyclerView(recyclerView)
     }
-    override val publishSubject = PublishSubject.create<SectionedDataSource>()
-    override val disposables = CompositeDisposable()
+    override val flow = MutableSharedFlow<SectionedDataSource>()
     override val updates: Queue<Pair<SectionedDataSource, DiffUtil.DiffResult?>> = LinkedList()
     override var dragging = false
-    override var items = initializeDiffer(tasks)
     override val scope: CoroutineScope =
             CoroutineScope(Executors.newSingleThreadExecutor().asCoroutineDispatcher() + Job())
+    override var items = initializeDiffer(tasks)
 
     override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
         val viewType = getItemViewType(position)