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      1 /*
      2  * Copyright (C) 2017 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 
     17 package com.android.dialer.persistentlog;
     18 
     19 import android.content.Context;
     20 import android.os.Handler;
     21 import android.os.HandlerThread;
     22 import android.support.annotation.AnyThread;
     23 import android.support.annotation.NonNull;
     24 import android.support.annotation.VisibleForTesting;
     25 import android.support.annotation.WorkerThread;
     26 import android.support.v4.os.UserManagerCompat;
     27 import com.android.dialer.common.Assert;
     28 import com.android.dialer.common.LogUtil;
     29 import java.io.IOException;
     30 import java.nio.charset.StandardCharsets;
     31 import java.util.ArrayList;
     32 import java.util.Calendar;
     33 import java.util.List;
     34 import java.util.concurrent.CountDownLatch;
     35 import java.util.concurrent.LinkedBlockingQueue;
     36 
     37 /**
     38  * Logs data that is persisted across app termination and device reboot. The logs are stored as
     39  * rolling files in cache with a limit of {@link #LOG_FILE_SIZE_LIMIT} * {@link
     40  * #LOG_FILE_COUNT_LIMIT}. The log writing is batched and there is a {@link #FLUSH_DELAY_MILLIS}
     41  * delay before the logs are committed to disk to avoid excessive IO. If the app is terminated
     42  * before the logs are committed it will be lost. {@link
     43  * com.google.android.apps.dialer.crashreporter.SilentCrashReporter} is expected to handle such
     44  * cases.
     45  *
     46  * <p>{@link #logText(String, String)} should be used to log ad-hoc text logs. TODO: switch
     47  * to structured logging
     48  */
     49 public final class PersistentLogger {
     50 
     51   private static final int FLUSH_DELAY_MILLIS = 200;
     52   private static final String LOG_FOLDER = "plain_text";
     53   private static final int MESSAGE_FLUSH = 1;
     54 
     55   @VisibleForTesting static final int LOG_FILE_SIZE_LIMIT = 64 * 1024;
     56   @VisibleForTesting static final int LOG_FILE_COUNT_LIMIT = 8;
     57 
     58   private static PersistentLogFileHandler fileHandler;
     59 
     60   private static HandlerThread loggerThread;
     61   private static Handler loggerThreadHandler;
     62 
     63   private static final LinkedBlockingQueue<byte[]> messageQueue = new LinkedBlockingQueue<>();
     64 
     65   private PersistentLogger() {}
     66 
     67   public static void initialize(Context context) {
     68     fileHandler =
     69         new PersistentLogFileHandler(LOG_FOLDER, LOG_FILE_SIZE_LIMIT, LOG_FILE_COUNT_LIMIT);
     70     loggerThread = new HandlerThread("PersistentLogger");
     71     loggerThread.start();
     72     loggerThreadHandler =
     73         new Handler(
     74             loggerThread.getLooper(),
     75             (message) -> {
     76               if (message.what == MESSAGE_FLUSH) {
     77                 if (messageQueue.isEmpty()) {
     78                   return true;
     79                 }
     80                 loggerThreadHandler.removeMessages(MESSAGE_FLUSH);
     81                 List<byte[]> messages = new ArrayList<>();
     82                 messageQueue.drainTo(messages);
     83                 if (!UserManagerCompat.isUserUnlocked(context)) {
     84                   return true;
     85                 }
     86                 try {
     87                   fileHandler.writeLogs(messages);
     88                 } catch (IOException e) {
     89                   LogUtil.e("PersistentLogger.MESSAGE_FLUSH", "error writing message", e);
     90                 }
     91               }
     92               return true;
     93             });
     94     loggerThreadHandler.post(() -> fileHandler.initialize(context));
     95   }
     96 
     97   static HandlerThread getLoggerThread() {
     98     return loggerThread;
     99   }
    100 
    101   @AnyThread
    102   public static void logText(String tag, String string) {
    103     log(buildTextLog(tag, string));
    104   }
    105 
    106   @VisibleForTesting
    107   @AnyThread
    108   static void log(byte[] data) {
    109     messageQueue.add(data);
    110     loggerThreadHandler.sendEmptyMessageDelayed(MESSAGE_FLUSH, FLUSH_DELAY_MILLIS);
    111   }
    112 
    113   /** Dump the log as human readable string. Blocks until the dump is finished. */
    114   @NonNull
    115   @WorkerThread
    116   public static String dumpLogToString() {
    117     Assert.isWorkerThread();
    118     DumpStringRunnable dumpStringRunnable = new DumpStringRunnable();
    119     loggerThreadHandler.post(dumpStringRunnable);
    120     try {
    121       return dumpStringRunnable.get();
    122     } catch (InterruptedException e) {
    123       Thread.currentThread().interrupt();
    124       return "Cannot dump logText: " + e;
    125     }
    126   }
    127 
    128   private static class DumpStringRunnable implements Runnable {
    129     private String result;
    130     private final CountDownLatch latch = new CountDownLatch(1);
    131 
    132     @Override
    133     public void run() {
    134       result = dumpLogToStringInternal();
    135       latch.countDown();
    136     }
    137 
    138     public String get() throws InterruptedException {
    139       latch.await();
    140       return result;
    141     }
    142   }
    143 
    144   @NonNull
    145   @WorkerThread
    146   private static String dumpLogToStringInternal() {
    147     StringBuilder result = new StringBuilder();
    148     List<byte[]> logs;
    149     try {
    150       logs = readLogs();
    151     } catch (IOException e) {
    152       return "Cannot dump logText: " + e;
    153     }
    154 
    155     for (byte[] log : logs) {
    156       result.append(new String(log, StandardCharsets.UTF_8)).append("\n");
    157     }
    158     return result.toString();
    159   }
    160 
    161   @NonNull
    162   @WorkerThread
    163   @VisibleForTesting
    164   static List<byte[]> readLogs() throws IOException {
    165     Assert.isWorkerThread();
    166     return fileHandler.getLogs();
    167   }
    168 
    169   private static byte[] buildTextLog(String tag, String string) {
    170     Calendar c = Calendar.getInstance();
    171     return String.format("%tm-%td %tH:%tM:%tS.%tL - %s - %s", c, c, c, c, c, c, tag, string)
    172         .getBytes(StandardCharsets.UTF_8);
    173   }
    174 }
    175