MetricsReader.java revision b62371434c9b63560c78a85123fe9386edac1205
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 */ 16package android.metrics; 17 18import android.annotation.SystemApi; 19 20import com.android.internal.logging.legacy.LegacyConversionLogger; 21import com.android.internal.logging.legacy.EventLogCollector; 22 23import java.util.Queue; 24 25/** 26 * Read platform logs. 27 * @hide 28 */ 29@SystemApi 30public class MetricsReader { 31 private EventLogCollector mReader; 32 private Queue<LogMaker> mEventQueue; 33 private long mLastEventMs; 34 private long mCheckpointMs; 35 36 /** Open a new session and start reading logs. 37 * 38 * Starts reading from the oldest log not already read by this reader object. 39 * On first invocation starts from the oldest available log ion the system. 40 */ 41 public void read(long startMs) { 42 EventLogCollector reader = EventLogCollector.getInstance(); 43 LegacyConversionLogger logger = new LegacyConversionLogger(); 44 mLastEventMs = reader.collect(logger, startMs); 45 mEventQueue = logger.getEvents(); 46 } 47 48 public void checkpoint() { 49 read(0L); 50 mCheckpointMs = mLastEventMs; 51 mEventQueue = null; 52 } 53 54 public void reset() { 55 read(mCheckpointMs); 56 } 57 58 /* Does the current log session have another entry? */ 59 public boolean hasNext() { 60 return mEventQueue == null ? false : !mEventQueue.isEmpty(); 61 } 62 63 /* Next entry in the current log session. */ 64 public LogMaker next() { 65 return mEventQueue == null ? null : mEventQueue.remove(); 66 } 67 68} 69