SoundTrigger Event logging

/*

 * Copyright (C) 2019 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.server.soundtrigger;

import android.util.Log;

import java.io.PrintWriter;

import java.text.SimpleDateFormat;

import java.util.Date;

import java.util.LinkedList;

/**

* Constructor SoundTriggerLogger class

*/

public class SoundTriggerLogger {

    // ring buffer of events to log.

    private final LinkedList<Event> mEvents;

    private final String mTitle;

    // the maximum number of events to keep in log

    private final int mMemSize;

    /**

     * Constructor for Event class.

     */

    public abstract static class Event {

        // formatter for timestamps

        private static final SimpleDateFormat sFormat = new SimpleDateFormat("MM-dd HH:mm:ss:SSS");

        private final long mTimestamp;

        Event() {

            mTimestamp = System.currentTimeMillis();

        }

    /**

     * Convert event to String

     * @return StringBuilder

     */

        public String toString() {

            return (new StringBuilder(sFormat.format(new Date(mTimestamp))))

                    .append(" ").append(eventToString()).toString();

        }

        /**

         * Causes the string message for the event to appear in the logcat.

         * Here is an example of how to create a new event (a StringEvent), adding it to the logger

         * (an instance of SoundTriggerLogger) while also making it show in the logcat:

         * <pre>

         *     myLogger.log(

         *         (new StringEvent("something for logcat and logger")).printLog(MyClass.TAG) );

         * </pre>

         * @param tag the tag for the android.util.Log.v

         * @return the same instance of the event

         */

        public Event printLog(String tag) {

            Log.i(tag, eventToString());

            return this;

        }

        /**

         * Convert event to String.

         * This method is only called when the logger history is about to the dumped,

         * so this method is where expensive String conversions should be made, not when the Event

         * subclass is created.

         * Timestamp information will be automatically added, do not include it.

         * @return a string representation of the event that occurred.

         */

        public abstract String eventToString();

    }

    /**

    * Constructor StringEvent class

    */

    public static class StringEvent extends Event {

        private final String mMsg;

        public StringEvent(String msg) {

            mMsg = msg;

        }

        @Override

        public String eventToString() {

            return mMsg;

        }

    }

    /**

     * Constructor for logger.

     * @param size the maximum number of events to keep in log

     * @param title the string displayed before the recorded log

     */

    public SoundTriggerLogger(int size, String title) {

        mEvents = new LinkedList<Event>();

        mMemSize = size;

        mTitle = title;

    }

    /**

     * Constructor for logger.

     * @param evt the maximum number of events to keep in log

     */

    public synchronized void log(Event evt) {

        if (mEvents.size() >= mMemSize) {

            mEvents.removeFirst();

        }

        mEvents.add(evt);

    }

    /**

     * Constructor for logger.

     * @param pw the maximum number of events to keep in log

     */

    public synchronized void dump(PrintWriter pw) {

        pw.println("ST Event log: " + mTitle);

        for (Event evt : mEvents) {

            pw.println(evt.toString());

        }

    }

}