src/com/android/mail/analytics/AnalyticsTimer.java

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.mail.analytics;

import android.os.SystemClock;

import com.google.common.collect.Maps;

import java.util.Map;

/**
 * Generic static singleton timer that keeps track of start time of various events. It  logs the
 * event's duration into Analytics using the provided naming information.
 * This timer class supports multiple data points per event ("lapping").
 *
 * This class also holds some defaults constant IDs that we log. This provides an easy way to check
 * what data we are logging as well as ensuring that the IDs are consistent when accessed by
 * different classes.
 */
public class AnalyticsTimer {
    public static final String OPEN_CONV_VIEW_FROM_LIST = "open_conv_from_list";

    private final Map<String, Long> mStartTimes = Maps.newConcurrentMap();

    // Static singleton class to ensure that you can access the timer from anywhere in the code
    private static final AnalyticsTimer mInstance = new AnalyticsTimer();

    private AnalyticsTimer() {}

    public static AnalyticsTimer getInstance() {
        return mInstance;
    }

    public void trackStart(String id) {
        mStartTimes.put(id, SystemClock.uptimeMillis());
    }

    /**
     * Logs the duration of the event with the provided category, name, and label.
     * This method can be destructive, meaning that any additional calls without calling
     * {@link AnalyticsTimer#trackStart(String)} will do nothing
     * We allow the method to be destructive to prevent the following cases from happening:
     *   - recurring methods that call this with irrelevant mapped start times.
     *   - multiple entry ways to the method that calls this, thus misusing the
     *     start time.
     * With destructive read, we ensure that we only log the event that we care about and only once.
     * @param id id of the event
     * @param isDestructive if you are done with this tag (used for multiple data points per tag)
     * @param category category for analytics logging
     * @param name name for analytics logging
     * @param label label for analytics logging
     */
    public void logDuration(String id, boolean isDestructive, String category, String name,
            String label) {
        Long value = isDestructive ? mStartTimes.remove(id) : mStartTimes.get(id);
        if (value != null) {
            Analytics.getInstance().sendTiming(category, SystemClock.uptimeMillis() - value, name,
                    label);
        }
    }
}