Make IInputMethodManager to oneway (8/N)

Add IVoidResultCallback mechanism to emulate
current behavior.

Bug: 163453493
Test: Manual test with keyboard
Test: atest CtsInputMethodTestCases
Change-Id: I009d3a6e09c98166c08e8b9b318d821be36c42a7

core/java/com/android/internal/inputmethod/CallbackUtils.java

@@ -200,4 +200,29 @@ public final class CallbackUtils {
             callback.onResult(result);
         } catch (RemoteException ignored) { }
     }
+
+    /**
+     * A utility method using given {@link IVoidResultCallback} to callback the result.
+     *
+     * @param callback {@link IVoidResultCallback} to be called back.
+     * @param resultSupplier the supplier from which the result is provided.
+     */
+    public static void onResult(@NonNull IVoidResultCallback callback,
+            @NonNull Supplier<Void> resultSupplier) {
+        Throwable exception = null;
+
+        try {
+            resultSupplier.get();
+        } catch (Throwable throwable) {
+            exception = throwable;
+        }
+
+        try {
+            if (exception != null) {
+                callback.onError(ThrowableHolder.of(exception));
+                return;
+            }
+            callback.onResult();
+        } catch (RemoteException ignored) { }
+    }
 }

core/java/com/android/internal/inputmethod/Completable.java

@@ -285,6 +285,42 @@ public final class Completable {
         }
     }
 
+    /**
+     * Completable object of {@link java.lang.Void}.
+     */
+    public static final class Void extends ValueBase {
+        /**
+         * Notify when this completable object callback.
+         */
+        @AnyThread
+        @Override
+        protected void onComplete() {
+            synchronized (mStateLock) {
+                switch (mState) {
+                    case CompletionState.NOT_COMPLETED:
+                        mState = CompletionState.COMPLETED_WITH_VALUE;
+                        break;
+                    default:
+                        throw new UnsupportedOperationException(
+                                "onComplete() is not allowed on state=" + stateToString(mState));
+                }
+            }
+            super.onComplete();
+        }
+
+        /**
+         * @throws RuntimeException when called while {@link #onError} happened.
+         * @throws UnsupportedOperationException when called while {@link #hasValue()} returns
+         *                                       {@code false}.
+         */
+        @AnyThread
+        public void getValue() {
+            synchronized (mStateLock) {
+                enforceGetValueLocked();
+            }
+        }
+    }
+
     /**
      * Base class of completable object types.
      *
@@ -395,6 +431,13 @@ public final class Completable {
         return new Completable.InputMethodInfoList();
     }
 
+    /**
+     * @return an instance of {@link Completable.Void}.
+     */
+    public static Completable.Void createVoid() {
+        return new Completable.Void();
+    }
+
     /**
      * Completable object of {@link java.lang.Boolean}.
      */
@@ -464,6 +507,17 @@ public final class Completable {
         return value.getValue();
     }
 
+    /**
+     * Await the result by the {@link Completable.Void}.
+     *
+     * Check the result once {@link ValueBase#onComplete()}
+     */
+    @AnyThread
+    public static void getResult(@NonNull Completable.Void value) {
+        value.await();
+        value.getValue();
+    }
+
     /**
      * Await the result by the {@link Completable.Int}, and log it if there is no result after
      * given timeout.

core/java/com/android/internal/inputmethod/IVoidResultCallback.aidl

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2020 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 com.android.internal.inputmethod;
+
+import com.android.internal.inputmethod.ThrowableHolder;
+
+oneway interface IVoidResultCallback {
+    void onResult();
+    void onError(in ThrowableHolder exception);
+}

core/java/com/android/internal/inputmethod/ResultCallbacks.java

@@ -352,4 +352,39 @@ public final class ResultCallbacks {
             }
         };
     }
+
+    /**
+     * Creates {@link IVoidResultCallback.Stub} that is to set {@link Completable.Void} when
+     * receiving the result.
+     *
+     * @param value {@link Completable.Void} to be set when receiving the result.
+     * @return {@link IVoidResultCallback.Stub} that can be passed as a binder IPC parameter.
+     */
+    @AnyThread
+    public static IVoidResultCallback.Stub of(@NonNull Completable.Void value) {
+        final AtomicReference<WeakReference<Completable.Void>> atomicRef =
+                new AtomicReference<>(new WeakReference<>(value));
+
+        return new IVoidResultCallback.Stub() {
+            @BinderThread
+            @Override
+            public void onResult() {
+                final Completable.Void value = unwrap(atomicRef);
+                if (value == null) {
+                    return;
+                }
+                value.onComplete();
+            }
+
+            @BinderThread
+            @Override
+            public void onError(ThrowableHolder throwableHolder) {
+                final Completable.Void value = unwrap(atomicRef);
+                if (value == null) {
+                    return;
+                }
+                value.onError(throwableHolder);
+            }
+        };
+    }
 }