neuralnetworks/1.0/IEvent.hal

/*
 * Copyright (C) 2017 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.
 */

/* This HAL is a work in progress */

package android.hardware.neuralnetworks@1.0;

/**
 * The IEvent interface is a callback object passed by the
 * Neuralnetworks runtime to the vendor service. It is used as a
 * synchronization primitive between one or more runtime threads and a
 * single asynchronous vendor thread.  An event object is passed as an
 * argument to a HIDL call that is expected to take a non-trivial
 * amount of time. When the asynchronous execution thread has
 * completed its computation, it must call "notify" on the event to
 * indicate to the Neuralnetworks runtime whether the computation was
 * successful or not, and that the corresponding output is ready to be
 * consumed if the execution was successful.
 *
 * TODO: Mention that "notify" is also called by a runtime thread
 * during CPU fallback execution? Depends on whether the HIDL comments
 * are strictly for vendors or not.
 */
interface IEvent {

    /**
     * IEvent::notify is called by the server thread (i.e. the thread doing the
     * work) to mark the event as completed so that any threads requiring the
     * corresponding resources can continue executing.
     *
     * @param status Status of the execution associated with the Event.
     *               Should be SUCCESS or ERROR.
     */
    oneway notify(ErrorStatus status);

};