Add better instantiation and synchronization of scope

doublesymmetry · Apr 19, 2022 · 4bb4c72 · 4bb4c72
1 parent ef89a28
commit 4bb4c72
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Showing 3 changed files with 24 additions and 28 deletions.
diff --git a/api/multiplatform-viewmodel.api b/api/multiplatform-viewmodel.api
@@ -5,8 +5,9 @@ public final class com/doublesymmetry/viewmodel/BuildConfig {
 	public fun <init> ()V
 }
 
-public class com/doublesymmetry/viewmodel/ViewModel : androidx/lifecycle/ViewModel {
+public abstract class com/doublesymmetry/viewmodel/ViewModel : androidx/lifecycle/ViewModel {
 	public fun <init> ()V
-	public final fun getScope ()Lkotlinx/coroutines/CoroutineScope;
+	public final fun getViewModelScope ()Lkotlinx/coroutines/CoroutineScope;
+	protected fun onCleared ()V
 }
 
diff --git a/src/commonMain/kotlin/com/doublesymmetry/viewmodel/ViewModel.kt b/src/commonMain/kotlin/com/doublesymmetry/viewmodel/ViewModel.kt
@@ -3,6 +3,11 @@ package com.doublesymmetry.viewmodel
 import kotlinx.coroutines.CoroutineScope
 
 expect abstract class ViewModel() {
+    /**
+     * [CoroutineScope] tied to this [ViewModel]. This scope will be canceled when ViewModel will be cleared, i.e [ViewModel.onCleared] is called
+     *
+     * This scope is bound to [Dispatchers.Main.immediate]
+     */
     val viewModelScope: CoroutineScope
 
     /**

diff --git a/src/darwinMain/kotlin/com/doublesymmetry/viewmodel/ViewModel.kt b/src/darwinMain/kotlin/com/doublesymmetry/viewmodel/ViewModel.kt
@@ -1,39 +1,29 @@
 package com.doublesymmetry.viewmodel
 
-import kotlinx.atomicfu.locks.reentrantLock
-import kotlinx.atomicfu.locks.withLock
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.*
 
 actual abstract class ViewModel {
-    private val lock = reentrantLock()
-    private var backingScope: CoroutineScope? = null
+    private var hasCleared = false
 
-    actual val viewModelScope: CoroutineScope
-        get() {
-            return this.getScopeInstance() ?: this.createScopeInstance()
-        }
-
-    protected actual open fun onCleared() {}
+    actual val viewModelScope: CoroutineScope by lazy {
+        val result = CloseableCoroutineScope(SupervisorJob() + Dispatchers.Main.immediate)
 
-    fun clear() {
-        lock.withLock {
-            closeWithRuntimeException(backingScope)
-            backingScope = null
-        }
+        if (hasCleared)
+            closeWithRuntimeException(result)
 
-        onCleared()
+        return@lazy result
     }
 
-    private fun getScopeInstance(): CoroutineScope? {
-        lock.withLock { return backingScope }
-    }
+    protected actual open fun onCleared() {}
 
-    private fun createScopeInstance(): CoroutineScope {
-        val scope = CloseableCoroutineScope(SupervisorJob() + Dispatchers.Main.immediate)
-        backingScope = scope
-        return scope
+    /**
+     * Closes the [viewModelScope] and cancels all its coroutines.
+     * Should be called from main thread.
+     */
+    fun clear() {
+        hasCleared = true
+        closeWithRuntimeException(viewModelScope)
+        onCleared()
     }
 
     companion object {