HdmiLogger.java revision a7221ce87683fab16603290378408ce92f02e88a 
1/*
2 * Copyright (C) 2014 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.server.hdmi;
18
19import android.annotation.Nullable;
20import android.os.SystemClock;
21import android.util.Pair;
22import android.util.Slog;
23
24import java.util.HashMap;
25
26/**
27 * A logger that prevents spammy log. For the same log message, it logs once every 20seconds.
28 * This class is not thread-safe.
29 */
30final class HdmiLogger {
31    // Logging duration for same error message.
32    private static final long ERROR_LOG_DURATTION_MILLIS = 20 * 1000;  // 20s
33
34    private static final boolean DEBUG = false;
35
36    // Key (String): log message.
37    // Value (Pair(Long, Integer)): a pair of last log time millis and the number of logMessage.
38    // Cache for warning.
39    private final HashMap<String, Pair<Long, Integer>> mWarningTimingCache = new HashMap<>();
40    // Cache for error.
41    private final HashMap<String, Pair<Long, Integer>> mErrorTimingCache = new HashMap<>();
42    private final String mTag;
43
44    HdmiLogger(String tag) {
45        mTag = "HDMI:" + tag;
46    }
47
48    void warning(String logMessage) {
49        String log = updateLog(mWarningTimingCache, logMessage);
50        if (!log.isEmpty()) {
51            Slog.w(mTag, log);
52        }
53    }
54
55    void error(String logMessage) {
56        String log = updateLog(mErrorTimingCache, logMessage);
57        if (!log.isEmpty()) {
58            Slog.e(mTag, log);
59        }
60    }
61
62    void debug(String logMessage) {
63        if (!DEBUG) {
64            return;
65        }
66        Slog.d(mTag, logMessage);
67    }
68
69    private static String updateLog(HashMap<String, Pair<Long, Integer>> cache, String logMessage) {
70        long curTime = SystemClock.uptimeMillis();
71        Pair<Long, Integer> timing = cache.get(logMessage);
72        if (shouldLogNow(timing, curTime)) {
73            String log = buildMessage(logMessage, timing);
74            cache.put(logMessage, new Pair<>(curTime, 1));
75            return log;
76        } else {
77            increaseLogCount(cache, logMessage);
78        }
79        return "";
80    }
81
82    private static String buildMessage(String message, @Nullable Pair<Long, Integer> timing) {
83        return new StringBuilder()
84                .append("[").append(timing == null ? 1 : timing.second).append("]:")
85                .append(message).toString();
86    }
87
88    private static void increaseLogCount(HashMap<String, Pair<Long, Integer>> cache,
89            String message) {
90        Pair<Long, Integer> timing = cache.get(message);
91        if (timing != null) {
92            cache.put(message, new Pair<>(timing.first, timing.second + 1));
93        }
94    }
95
96    private static boolean shouldLogNow(@Nullable Pair<Long, Integer> timing, long curTime) {
97        return timing == null || curTime - timing.first > ERROR_LOG_DURATTION_MILLIS;
98    }
99}
100