1/*
2 * Copyright (C) 2006 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 android.util;
18
19import java.io.FileDescriptor;
20import java.io.PrintWriter;
21import java.util.Calendar;
22import java.util.Iterator;
23import java.util.Deque;
24import java.util.ArrayDeque;
25
26/**
27 * @hide
28 */
29public final class LocalLog {
30
31    private final Deque<String> mLog;
32    private final int mMaxLines;
33
34    public LocalLog(int maxLines) {
35        mMaxLines = Math.max(0, maxLines);
36        mLog = new ArrayDeque<>(mMaxLines);
37    }
38
39    public void log(String msg) {
40        if (mMaxLines <= 0) {
41            return;
42        }
43        Calendar c = Calendar.getInstance();
44        c.setTimeInMillis(System.currentTimeMillis());
45        append(String.format("%tm-%td %tH:%tM:%tS.%tL - %s", c, c, c, c, c, c, msg));
46    }
47
48    private synchronized void append(String logLine) {
49        while (mLog.size() >= mMaxLines) {
50            mLog.remove();
51        }
52        mLog.add(logLine);
53    }
54
55    public synchronized void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
56        Iterator<String> itr = mLog.iterator();
57        while (itr.hasNext()) {
58            pw.println(itr.next());
59        }
60    }
61
62    public synchronized void reverseDump(FileDescriptor fd, PrintWriter pw, String[] args) {
63        Iterator<String> itr = mLog.descendingIterator();
64        while (itr.hasNext()) {
65            pw.println(itr.next());
66        }
67    }
68
69    public static class ReadOnlyLocalLog {
70        private final LocalLog mLog;
71        ReadOnlyLocalLog(LocalLog log) {
72            mLog = log;
73        }
74        public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
75            mLog.dump(fd, pw, args);
76        }
77        public void reverseDump(FileDescriptor fd, PrintWriter pw, String[] args) {
78            mLog.reverseDump(fd, pw, args);
79        }
80    }
81
82    public ReadOnlyLocalLog readOnlyLocalLog() {
83        return new ReadOnlyLocalLog(this);
84    }
85}
86