Merge "Add TimingLogger."
diff --git a/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/Reflect.java b/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/Reflect.java
new file mode 100644
index 0000000..a2603b5
--- /dev/null
+++ b/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/Reflect.java
@@ -0,0 +1,103 @@
+/*
+ * Copyright 2021 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.server.nearby.common.bluetooth.fastpair;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+/**
+ * Utilities for calling methods using reflection. The main benefit of using this helper is to avoid
+ * complications around exception handling when calling methods reflectively. It's not safe to use
+ * Java 8's multicatch on such exceptions, because the java compiler converts multicatch into
+ * ReflectiveOperationException in some instances, which doesn't work on older sdk versions.
+ * Instead, use these utilities and catch ReflectionException.
+ *
+ * <p>Example usage:
+ *
+ * <pre>{@code
+ * try {
+ *   Reflect.on(btAdapter)
+ *       .withMethod("setScanMode", int.class)
+ *       .invoke(BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE)
+ * } catch (ReflectionException e) { }
+ * }</pre>
+ */
+// TODO(b/202549655): remove existing Reflect usage. New usage is not allowed! No exception!
+public final class Reflect {
+    private final Object mTargetObject;
+
+    private Reflect(Object targetObject) {
+        this.mTargetObject = targetObject;
+    }
+
+    /** Creates an instance of this helper to invoke methods on the given target object. */
+    public static Reflect on(Object targetObject) {
+        return new Reflect(targetObject);
+    }
+
+    /** Finds a method with the given name and parameter types. */
+    public ReflectionMethod withMethod(String methodName, Class<?>... paramTypes)
+            throws ReflectionException {
+        try {
+            return new ReflectionMethod(mTargetObject.getClass().getMethod(methodName, paramTypes));
+        } catch (NoSuchMethodException e) {
+            throw new ReflectionException(e);
+        }
+    }
+
+    /** Represents an invokable method found reflectively. */
+    public final class ReflectionMethod {
+        private final Method mMethod;
+
+        private ReflectionMethod(Method method) {
+            this.mMethod = method;
+        }
+
+        /**
+         * Invokes this instance method with the given parameters. The called method does not return
+         * a value.
+         */
+        public void invoke(Object... parameters) throws ReflectionException {
+            try {
+                mMethod.invoke(mTargetObject, parameters);
+            } catch (IllegalAccessException e) {
+                throw new ReflectionException(e);
+            } catch (InvocationTargetException e) {
+                throw new ReflectionException(e);
+            }
+        }
+
+        /**
+         * Invokes this instance method with the given parameters. The called method returns a non
+         * null value.
+         */
+        public Object get(Object... parameters) throws ReflectionException {
+            Object value;
+            try {
+                value = mMethod.invoke(mTargetObject, parameters);
+            } catch (IllegalAccessException e) {
+                throw new ReflectionException(e);
+            } catch (InvocationTargetException e) {
+                throw new ReflectionException(e);
+            }
+            if (value == null) {
+                throw new ReflectionException(new NullPointerException());
+            }
+            return value;
+        }
+    }
+}
diff --git a/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/ReflectionException.java b/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/ReflectionException.java
new file mode 100644
index 0000000..1c20c55
--- /dev/null
+++ b/nearby/service/java/com/android/server/nearby/common/bluetooth/fastpair/ReflectionException.java
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2021 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.server.nearby.common.bluetooth.fastpair;
+
+/**
+ * An exception thrown during a reflection operation. Like ReflectiveOperationException, except
+ * compatible on older API versions.
+ */
+public final class ReflectionException extends Exception {
+    ReflectionException(Throwable cause) {
+        super(cause.getMessage(), cause);
+    }
+}