Create `DispatchingHandler` helper class

1 files changed, 48 insertions, 0 deletions

diff --git a/android/src/main/kotlin/net/mullvad/mullvadvpn/ipc/DispatchingHandler.kt b/android/src/main/kotlin/net/mullvad/mullvadvpn/ipc/DispatchingHandler.kt
new file mode 100644
index 0000000000..0f3820ff48
--- /dev/null
+++ b/android/src/main/kotlin/net/mullvad/mullvadvpn/ipc/DispatchingHandler.kt
@@ -0,0 +1,48 @@
+package net.mullvad.mullvadvpn.ipc
+
+import android.os.Handler
+import android.os.Looper
+import android.os.Message
+import android.util.Log
+import java.util.concurrent.locks.ReentrantReadWriteLock
+import kotlin.concurrent.withLock
+import kotlin.reflect.KClass
+
+class DispatchingHandler<T : Any>(
+    looper: Looper,
+    private val extractor: (Message) -> T?
+) : Handler(looper) {
+    private val handlers = HashMap<KClass<out T>, (T) -> Unit>()
+    private val lock = ReentrantReadWriteLock()
+
+    fun <V : T> registerHandler(variant: KClass<V>, handler: (V) -> Unit) {
+        lock.writeLock().withLock {
+            handlers.put(variant) { instance ->
+                @Suppress("UNCHECKED_CAST")
+                handler(instance as V)
+            }
+        }
+    }
+
+    override fun handleMessage(message: Message) {
+        lock.readLock().withLock {
+            val instance = extractor(message)
+
+            if (instance != null) {
+                val handler = handlers.get(instance::class)
+
+                handler?.invoke(instance)
+            } else {
+                Log.e("mullvad", "Dispatching handler received an unexpected message")
+            }
+        }
+    }
+
+    fun onDestroy() {
+        lock.writeLock().withLock {
+            handlers.clear()
+        }
+
+        removeCallbacksAndMessages(null)
+    }
+}