1/*
2 * Copyright 2018 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.display.utils;
18
19
20import java.lang.StringBuilder;
21import java.lang.System;
22
23import android.util.Slog;
24
25/**
26 * A utility to log multiple points and curves in a structured way so they can be easily consumed
27 * by external tooling
28 *
29 * To start a plot, call {@link Plog.start} with the plot's title; to add a point to it, call
30 * {@link Plog.logPoint} with the point name (that will appear in the legend) and coordinates; and
31 * to log a curve, call {@link Plog.logCurve} with its name and points.
32 */
33public abstract class Plog {
34    // A unique identifier used to group points and curves that belong on the same plot.
35    private long mId;
36
37    /**
38     * Returns a Plog instance that emits messages to the system log.
39     *
40     * @param tag The tag of the emitted messages in the system log.
41     * @return A plog instance that emits messages to the system log.
42     */
43    public static Plog createSystemPlog(String tag) {
44        return new SystemPlog(tag);
45    }
46
47    /**
48     * Start a new plot.
49     *
50     * @param title The plot title.
51     * @return The Plog instance (for chaining).
52     */
53    public Plog start(String title) {
54        mId = System.currentTimeMillis();
55        write(formatTitle(title));
56        return this;
57    }
58
59    /**
60     * Adds a point to the current plot.
61     *
62     * @param name The point name (that will appear in the legend).
63     * @param x The point x coordinate.
64     * @param y The point y coordinate.
65     * @return The Plog instance (for chaining).
66     */
67    public Plog logPoint(String name, float x, float y) {
68        write(formatPoint(name, x, y));
69        return this;
70    }
71
72    /**
73     * Adds a curve to the current plot.
74     *
75     * @param name The curve name (that will appear in the legend).
76     * @param xs The curve x coordinates.
77     * @param ys The curve y coordinates.
78     * @return The Plog instance (for chaining).
79     */
80    public Plog logCurve(String name, float[] xs, float[] ys) {
81        write(formatCurve(name, xs, ys));
82        return this;
83    }
84
85    private String formatTitle(String title) {
86        return "title: " + title;
87    }
88
89    private String formatPoint(String name, float x, float y) {
90        return "point: " + name + ": (" + x + "," + y + ")";
91    }
92
93    private String formatCurve(String name, float[] xs, float[] ys) {
94        StringBuilder sb = new StringBuilder();
95        sb.append("curve: " + name + ": [");
96        int n = xs.length <= ys.length ? xs.length : ys.length;
97        for (int i = 0; i < n; i++) {
98            sb.append("(" + xs[i] + "," + ys[i] + "),");
99        }
100        sb.append("]");
101        return sb.toString();
102    }
103
104    private void write(String message) {
105        emit("[PLOG " + mId + "] " + message);
106    }
107
108    /**
109     * Emits a message (depending on the concrete Plog implementation).
110     *
111     * @param message The message.
112     */
113    protected abstract void emit(String message);
114
115    /**
116     * A Plog that emits messages to the system log.
117     */
118    public static class SystemPlog extends Plog {
119        // The tag of the emitted messages in the system log.
120        private final String mTag;
121
122        /**
123         * Returns a Plog instance that emits messages to the system log.
124         *
125         * @param tag The tag of the emitted messages in the system log.
126         * @return A Plog instance that emits messages to the system log.
127         */
128        public SystemPlog(String tag) {
129            mTag = tag;
130        }
131
132        /**
133         * Emits a message to the system log.
134         *
135         * @param message The message.
136         */
137        protected void emit(String message) {
138            Slog.d(mTag, message);
139        }
140    }
141}
142