RecurringRunner.java revision 633eb826b8c97731dfc5ef12c7bf78a63734275d 
1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License
15 */
16
17package com.android.tv.util;
18
19import android.content.Context;
20import android.content.SharedPreferences;
21import android.os.AsyncTask;
22import android.os.Handler;
23import android.support.annotation.WorkerThread;
24import android.util.Log;
25
26import com.android.tv.common.SharedPreferencesUtils;
27import com.android.tv.common.SoftPreconditions;
28
29import java.util.Date;
30
31/**
32 * Repeatedly executes a {@link Runnable}.
33 *
34 * <p>The next execution time is saved to a {@link SharedPreferences}, and used on the next start.
35 * The given {@link Runnable} will run in the main thread.
36 */
37public final class RecurringRunner {
38    private static final String TAG = "RecurringRunner";
39    private static final boolean DEBUG = false;
40
41    private final Handler mHandler;
42    private final long mIntervalMs;
43    private final Runnable mRunnable;
44    private final Runnable mOnStopRunnable;
45    private final Context mContext;
46    private final String mName;
47    private boolean mRunning;
48
49    public RecurringRunner(Context context, long intervalMs, Runnable runnable,
50            Runnable onStopRunnable) {
51        mContext = context.getApplicationContext();
52        mRunnable = runnable;
53        mOnStopRunnable = onStopRunnable;
54        mIntervalMs = intervalMs;
55        mName = runnable.getClass().getCanonicalName();
56        if (DEBUG) Log.i(TAG, " Delaying " + mName + " " + (intervalMs / 1000.0) + " seconds");
57        mHandler = new Handler(mContext.getMainLooper());
58    }
59
60    public void start(boolean resetNextRunTime) {
61        SoftPreconditions.checkState(!mRunning, TAG, mName + " start is called twice.");
62        if (mRunning) {
63            return;
64        }
65        mRunning = true;
66        if (resetNextRunTime) {
67            resetNextRunTime();
68        }
69        new AsyncTask<Void, Void, Long>() {
70            @Override
71            protected Long doInBackground(Void... params) {
72                return getNextRunTime();
73            }
74
75            @Override
76            protected void onPostExecute(Long nextRunTime) {
77                postAt(nextRunTime);
78            }
79        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
80    }
81
82    public void start() {
83        start(false);
84    }
85
86    public void stop() {
87        mRunning = false;
88        mHandler.removeCallbacksAndMessages(null);
89        if (mOnStopRunnable != null) {
90            mOnStopRunnable.run();
91        }
92    }
93
94    private void postAt(long next) {
95        if (!mRunning) {
96            return;
97        }
98        long now = System.currentTimeMillis();
99        // Run it anyways even if it is in the past
100        if (DEBUG) Log.i(TAG, "Next run of " + mName + " at " + new Date(next));
101        long delay = Math.max(next - now, 0);
102        boolean posted = mHandler.postDelayed(new Runnable() {
103            @Override
104            public void run() {
105                try {
106                    if (DEBUG) Log.i(TAG, "Starting " + mName);
107                    mRunnable.run();
108                } catch (Exception e) {
109                    Log.w(TAG, "Error running " + mName, e);
110                }
111                postAt(resetNextRunTime());
112            }
113        }, delay);
114        if (!posted) {
115            Log.w(TAG, "Scheduling a future run of " + mName + " at " + new Date(next) + "failed");
116        }
117        if (DEBUG) Log.i(TAG, "Actual delay of " + mName + " is " + (delay / 1000.0) + " seconds.");
118    }
119
120    private SharedPreferences getSharedPreferences() {
121        return mContext.getSharedPreferences(SharedPreferencesUtils.SHARED_PREF_RECURRING_RUNNER,
122                Context.MODE_PRIVATE);
123    }
124
125    @WorkerThread
126    private long getNextRunTime() {
127        // The access to SharedPreferences is done by an AsyncTask thread because
128        // SharedPreferences reads to disk at first time.
129        long next = getSharedPreferences().getLong(mName, System.currentTimeMillis());
130        if (next > System.currentTimeMillis() + mIntervalMs) {
131            next = resetNextRunTime();
132        }
133        return next;
134    }
135
136    private long resetNextRunTime() {
137        long next = System.currentTimeMillis() + mIntervalMs;
138        getSharedPreferences().edit().putLong(mName, next).apply();
139        return next;
140    }
141}
142