1/*
2 * Copyright (C) 2012 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.internal.util;
18
19import java.io.PrintWriter;
20import java.util.ArrayList;
21
22import android.util.Slog;
23
24/**
25 * Helper class for logging serious issues, which also keeps a small
26 * snapshot of the logged events that can be printed later, such as part
27 * of a system service's dumpsys output.
28 * @hide
29 */
30public class LocalLog {
31    private final String mTag;
32    private final int mMaxLines = 20;
33    private final ArrayList<String> mLines = new ArrayList<String>(mMaxLines);
34
35    public LocalLog(String tag) {
36        mTag = tag;
37    }
38
39    public void w(String msg) {
40        synchronized (mLines) {
41            Slog.w(mTag, msg);
42            if (mLines.size() >= mMaxLines) {
43                mLines.remove(0);
44            }
45            mLines.add(msg);
46        }
47    }
48
49    public boolean dump(PrintWriter pw, String header, String prefix) {
50        synchronized (mLines) {
51            if (mLines.size() <= 0) {
52                return false;
53            }
54            if (header != null) {
55                pw.println(header);
56            }
57            for (int i=0; i<mLines.size(); i++) {
58                if (prefix != null) {
59                    pw.print(prefix);
60                }
61                pw.println(mLines.get(i));
62            }
63            return true;
64        }
65    }
66}
67