1st step of refactoring request logger

src/js/logger.js

@@ -0,0 +1,201 @@
+/*******************************************************************************
+
+    uMatrix - a browser extension to block requests.
+    Copyright (C) 2015 Raymond Hill
+
+    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://github.com/gorhill/uBlock
+*/
+
+/* global µMatrix */
+
+/******************************************************************************/
+/******************************************************************************/
+
+µMatrix.logger = (function() {
+
+'use strict';
+
+/******************************************************************************/
+/******************************************************************************/
+
+var LogEntry = function(tabId, details, result) {
+    this.init(tabId, details, result);
+};
+
+/******************************************************************************/
+
+var logEntryFactory = function(tabId, details, result) {
+    var entry = logEntryJunkyard.pop();
+    if ( entry ) {
+        return entry.init(tabId, details, result);
+    }
+    return new LogEntry(tabId, details, result);
+};
+
+var logEntryJunkyard = [];
+var logEntryJunkyardMax = 100;
+
+/******************************************************************************/
+
+LogEntry.prototype.init = function(tabId, details, result) {
+    this.tstamp = Date.now();
+    this.tabId = tabId;
+    this.url = details.requestURL;
+    this.hostname = details.requestHostname;
+    this.type = details.requestType;
+    this.result = result;
+    return this;
+};
+
+/******************************************************************************/
+
+LogEntry.prototype.dispose = function() {
+    this.url = this.hostname = this.type = this.result = '';
+    if ( logEntryJunkyard.length < logEntryJunkyardMax ) {
+        logEntryJunkyard.push(this);
+    }
+};
+
+/******************************************************************************/
+/******************************************************************************/
+
+var LogBuffer = function() {
+    this.lastReadTime = 0;
+    this.size = 50;
+    this.buffer = new Array(this.size);
+    this.readPtr = 0;
+    this.writePtr = 0;
+};
+
+/******************************************************************************/
+
+LogBuffer.prototype.dispose = function() {
+    var entry;
+    var i = this.buffer.length;
+    while ( i-- ) {
+        entry = this.buffer[i];
+        if ( entry instanceof LogEntry ) {
+            entry.dispose();
+        }
+    }
+    this.buffer = null;
+    return null;
+};
+
+/******************************************************************************/
+
+LogBuffer.prototype.writeOne = function(tabId, details, result) {
+    // Reusing log entry = less memory churning
+    var entry = this.buffer[this.writePtr];
+    if ( entry instanceof LogEntry === false ) {
+        this.buffer[this.writePtr] = logEntryFactory(tabId, details, result);
+    } else {
+        entry.init(tabId, details, result);
+    }
+    this.writePtr += 1;
+    if ( this.writePtr === this.size ) {
+        this.writePtr = 0;
+    }
+    // Grow the buffer between 1.5x-2x the current size
+    if ( this.writePtr === this.readPtr ) {
+        var toMove = this.buffer.slice(0, this.writePtr);
+        var minSize = Math.ceil(this.size * 1.5);
+        this.size += toMove.length;
+        if ( this.size < minSize ) {
+            this.buffer = this.buffer.concat(toMove, new Array(minSize - this.size));
+            this.writePtr = this.size;
+        } else {
+            this.buffer = this.buffer.concat(toMove);
+            this.writePtr = 0;
+        }
+        this.size = this.buffer.length;
+    }
+};
+
+/******************************************************************************/
+
+LogBuffer.prototype.readAll = function() {
+    var out;
+    if ( this.readPtr < this.writePtr ) {
+        out = this.buffer.slice(this.readPtr, this.writePtr);
+    } else if ( this.writePtr < this.readPtr ) {
+        out = this.buffer.slice(this.readPtr).concat(this.buffer.slice(0, this.writePtr));
+    } else {
+        out = [];
+    }
+    this.readPtr = this.writePtr;
+    this.lastReadTime = Date.now();
+    return out;
+};
+
+/******************************************************************************/
+/******************************************************************************/
+
+// Tab id to log buffer instances
+var logBuffer = null;
+
+// After 60 seconds without being read, a buffer will be considered unused, and
+// thus removed from memory.
+var logBufferObsoleteAfter = 60 * 1000;
+
+// The janitor will look for stale log buffer every 2 minutes.
+var loggerJanitorPeriod = 2 * 60 * 1000;
+
+/******************************************************************************/
+
+var writeOne = function(tabId, details, result) {
+    if ( logBuffer === null ) {
+        return;
+    }
+    logBuffer.writeOne(tabId, details, result);
+};
+
+/******************************************************************************/
+
+var readAll = function(tabId) {
+    if ( logBuffer === null ) {
+        logBuffer = new LogBuffer();
+    }
+    return logBuffer.readAll();
+};
+
+/******************************************************************************/
+
+var loggerJanitor = function() {
+    if (
+        logBuffer !== null &&
+        logBuffer.lastReadTime < (Date.now() - logBufferObsoleteAfter)
+    ) {
+        logBuffer = logBuffer.dispose();
+    }
+    setTimeout(loggerJanitor, loggerJanitorPeriod);
+};
+
+setTimeout(loggerJanitor, loggerJanitorPeriod);
+
+/******************************************************************************/
+
+return {
+    writeOne: writeOne,
+    readAll: readAll
+};
+
+/******************************************************************************/
+/******************************************************************************/
+
+})();
+
+/******************************************************************************/