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.internal.os;
18 
19 import android.annotation.Nullable;
20 import android.os.SystemClock;
21 import android.util.Slog;
22 
23 /**
24  * The base class of all KernelUidCpuTimeReaders.
25  *
26  * This class is NOT designed to be thread-safe or accessed by more than one caller (due to
27  * the nature of {@link #readDelta(Callback)}).
28  */
29 public abstract class KernelUidCpuTimeReaderBase<T extends KernelUidCpuTimeReaderBase.Callback> {
30     protected static final boolean DEBUG = false;
31     // Throttle interval in milliseconds
32     private static final long DEFAULT_THROTTLE_INTERVAL = 10_000L;
33 
34     private final String TAG = this.getClass().getSimpleName();
35     private long mLastTimeReadMs = Long.MIN_VALUE;
36     private long mThrottleInterval = DEFAULT_THROTTLE_INTERVAL;
37 
38     // A generic Callback interface (used by readDelta) to be extended by subclasses.
39     public interface Callback {
40     }
41 
readDelta(@ullable T cb)42     public void readDelta(@Nullable T cb) {
43         if (SystemClock.elapsedRealtime() < mLastTimeReadMs + mThrottleInterval) {
44             if (DEBUG) {
45                 Slog.d(TAG, "Throttle");
46             }
47             return;
48         }
49         readDeltaImpl(cb);
50         mLastTimeReadMs = SystemClock.elapsedRealtime();
51     }
52 
readDeltaImpl(@ullable T cb)53     protected abstract void readDeltaImpl(@Nullable T cb);
54 
setThrottleInterval(long throttleInterval)55     public void setThrottleInterval(long throttleInterval) {
56         if (throttleInterval >= 0) {
57             mThrottleInterval = throttleInterval;
58         }
59     }
60 }
61