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/*
* 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
*/
package com.android.dialer.common.concurrent;
import android.support.annotation.NonNull;
import android.support.v4.app.FragmentManager;
import com.android.dialer.common.Assert;
import com.android.dialer.common.concurrent.DialerExecutor.Worker;
/**
* Factory methods for creating {@link DialerExecutor} objects for doing background work.
*
* <p>You may create an executor from a UI component (activity or fragment) or a non-UI component.
* Using this class provides a number of benefits:
*
* <ul>
* <li>Ensures that UI tasks keep running across configuration changes by using a headless
* fragment.
* <li>Forces exceptions to crash the application, unless the user implements their own onFailure
* method.
* <li>Checks for dead UI components which can be encountered if a UI task runs longer than its
* UI. If a dead UI component is encountered, onSuccess/onFailure are not called (because they
* can't be) but a message is logged.
* <li>Helps prevents memory leaks in UI tasks by ensuring that callbacks are nulled out when the
* headless fragment is detached.
* <li>UI and non-UI threads are shared across the application and run at reasonable priorities
* </ul>
*
* <p>Executors accept a single input and output parameter which should be immutable data objects.
* If you don't require an input or output, use Void and null as needed.
*
* <p>You may optionally specify onSuccess and onFailure listeners; the default behavior on success
* is a no-op and the default behavior on failure is to crash the application.
*
* <p>To use an executor from a UI component, you must create it in your onCreate method and then
* use it from anywhere:
*
* <pre><code>
*
* public class MyActivity extends Activity {
*
* private final DialerExecutor<MyInputType> myExecutor;
*
* public void onCreate(Bundle state) {
* super.onCreate(bundle);
*
* // Must be called in onCreate; don't use non-static or anonymous inner classes for worker!
* myExecutor = DialerExecutors.createUiTaskBuilder(fragmentManager, taskId, worker)
* .onSuccess(this::onSuccess) // Lambdas, anonymous, or non-static inner classes all fine
* .onFailure(this::onFailure) // Lambdas, anonymous, or non-static inner classes all fine
* .build();
* );
* }
*
* private static class MyWorker implements Worker<MyInputType, MyOutputType> {
* MyOutputType doInBackground(MyInputType input) { ... }
* }
* private void onSuccess(MyOutputType output) { ... }
* private void onFailure(Throwable throwable) { ... }
*
* private void userDidSomething() { myExecutor.executeParallel(input); }
* }
* </code></pre>
*
* <p>Usage for non-UI tasks is the same, except that tasks can be created from anywhere instead of
* in onCreate. Non-UI tasks use low-priority threads separate from the UI task threads so as not to
* compete with more critical UI tasks.
*
* <pre><code>
*
* public class MyManager {
*
* private final DialerExecutor<MyInputType> myExecutor;
*
* public void init() {
* // Don't use non-static or anonymous inner classes for worker!
* myExecutor = DialerExecutors.createNonUiTaskBuilder(worker)
* .onSuccess(this::onSuccess) // Lambdas, anonymous, or non-static inner classes all fine
* .onFailure(this::onFailure) // Lambdas, anonymous, or non-static inner classes all fine
* .build();
* );
* }
*
* private static class MyWorker implements Worker<MyInputType, MyOutputType> {
* MyOutputType doInBackground(MyInputType input) { ... }
* }
* private void onSuccess(MyOutputType output) { ... }
* private void onFailure(Throwable throwable) { ... }
*
* private void userDidSomething() { myExecutor.executeParallel(input); }
* }
* </code></pre>
*
* Note that non-UI tasks are intended to be relatively quick; for example reading/writing shared
* preferences or doing simple database work. If you submit long running non-UI tasks you may
* saturate the shared application threads and block other tasks. Also, this class does not create
* any wakelocks, so a long running task could be killed if the device goes to sleep while your task
* is still running. If you have to do long running or periodic work, consider using a job
* scheduler.
*/
public final class DialerExecutors {
/** @see DialerExecutorFactory#createUiTaskBuilder(FragmentManager, String, Worker) */
@NonNull
public static <InputT, OutputT> DialerExecutor.Builder<InputT, OutputT> createUiTaskBuilder(
@NonNull FragmentManager fragmentManager,
@NonNull String taskId,
@NonNull Worker<InputT, OutputT> worker) {
return new DefaultDialerExecutorFactory()
.createUiTaskBuilder(
Assert.isNotNull(fragmentManager), Assert.isNotNull(taskId), Assert.isNotNull(worker));
}
/** @see DialerExecutorFactory#createNonUiTaskBuilder(Worker) */
@NonNull
public static <InputT, OutputT> DialerExecutor.Builder<InputT, OutputT> createNonUiTaskBuilder(
@NonNull Worker<InputT, OutputT> worker) {
return new DefaultDialerExecutorFactory().createNonUiTaskBuilder(Assert.isNotNull(worker));
}
}
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