ematrix/js/logger.js

/*******************************************************************************

    ηMatrix - a browser extension to black/white list requests.
    Copyright (C) 2015-2019 Raymond Hill
    Copyright (C) 2019-2022 Alessio Vanni

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see {http://www.gnu.org/licenses/}.

    Home: https://gitlab.com/vannilla/ematrix
    uMatrix Home: https://github.com/gorhill/uBlock
*/

'use strict';

ηMatrix.logger = (function () {
    let LogEntry = function (args) {
        this.init(args);
    };

    LogEntry.prototype.init = function (args) {
        this.tstamp = Date.now();
        this.tab = args[0] || '';
        this.cat = args[1] || '';
        this.d0 = args[2];
        this.d1 = args[3];
        this.d2 = args[4];
        this.d3 = args[5];
    };

    var buffer = null;
    var lastReadTime = 0;
    var writePtr = 0;

    // After 60 seconds without being read, a buffer will be considered
    // unused, and thus removed from memory.
    var logBufferObsoleteAfter = 30 * 1000;

    var janitor = function () {
        if (buffer !== null
	    && lastReadTime < (Date.now() - logBufferObsoleteAfter)) {
            buffer = null;
            writePtr = 0;
            api.ownerId = undefined;
        }
        if (buffer !== null) {
            vAPI.setTimeout(janitor, logBufferObsoleteAfter);
        }
    };

    var api = {
        ownerId: undefined,

        writeOne: function () {
            if (buffer === null) {
		return;
	    }

            if (writePtr === buffer.length) {
                buffer.push(new LogEntry(arguments));
            } else {
                buffer[writePtr].init(arguments);
            }

            writePtr += 1;
        },
        readAll: function (ownerId) {
            this.ownerId = ownerId;

            if (buffer === null) {
                buffer = [];
                vAPI.setTimeout(janitor, logBufferObsoleteAfter);
            }

            var out = buffer.slice(0, writePtr);
            writePtr = 0;
            lastReadTime = Date.now();

            return out;
        }
    };

    return api;
})();