lz4.js (6379B) - View raw
/******************************************************************************* uBlock Origin - a comprehensive, efficient content blocker Copyright (C) 2018-present 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 lz4BlockCodec */ import µb from './background.js'; /******************************************************************************* Experimental support for storage compression. For background information on the topic, see: https://github.com/uBlockOrigin/uBlock-issues/issues/141#issuecomment-407737186 **/ /******************************************************************************/ let promisedInstance; let textEncoder, textDecoder; let ttlCount = 0; let ttlDelay = 60000; const init = function() { ttlDelay = µb.hiddenSettings.autoUpdateAssetFetchPeriod * 2 * 1000; if ( promisedInstance === undefined ) { let flavor; if ( µb.hiddenSettings.disableWebAssembly === true ) { flavor = 'js'; } promisedInstance = lz4BlockCodec.createInstance(flavor); } return promisedInstance; }; // We can't shrink memory usage of lz4 codec instances, and in the // current case memory usage can grow to a significant amount given // that a single contiguous memory buffer is required to accommodate // both input and output data. Thus a time-to-live implementation // which will cause the wasm instance to be forgotten after enough // time elapse without the instance being used. const destroy = function() { //if ( lz4CodecInstance !== undefined ) { // console.info( // 'uBO: freeing lz4-block-codec instance (%s KB)', // lz4CodecInstance.bytesInUse() >>> 10 // ); //} promisedInstance = undefined; textEncoder = textDecoder = undefined; ttlCount = 0; }; const ttlTimer = vAPI.defer.create(destroy); const ttlManage = function(count) { ttlTimer.off(); ttlCount += count; if ( ttlCount > 0 ) { return; } ttlTimer.on(ttlDelay); }; const encodeValue = function(lz4CodecInstance, dataIn) { if ( !lz4CodecInstance ) { return; } //let t0 = window.performance.now(); if ( textEncoder === undefined ) { textEncoder = new TextEncoder(); } const inputArray = textEncoder.encode(dataIn); const inputSize = inputArray.byteLength; const outputArray = lz4CodecInstance.encodeBlock(inputArray, 8); if ( outputArray instanceof Uint8Array === false ) { return; } outputArray[0] = 0x18; outputArray[1] = 0x4D; outputArray[2] = 0x22; outputArray[3] = 0x04; outputArray[4] = (inputSize >>> 0) & 0xFF; outputArray[5] = (inputSize >>> 8) & 0xFF; outputArray[6] = (inputSize >>> 16) & 0xFF; outputArray[7] = (inputSize >>> 24) & 0xFF; //console.info( // 'uBO: [%s] compressed %d KB => %d KB (%s%%) in %s ms', // inputArray.byteLength >> 10, // outputArray.byteLength >> 10, // (outputArray.byteLength / inputArray.byteLength * 100).toFixed(0), // (window.performance.now() - t0).toFixed(1) //); return outputArray; }; const decodeValue = function(lz4CodecInstance, inputArray) { if ( !lz4CodecInstance ) { return; } //let t0 = window.performance.now(); if ( inputArray[0] !== 0x18 || inputArray[1] !== 0x4D || inputArray[2] !== 0x22 || inputArray[3] !== 0x04 ) { console.error('decodeValue: invalid input array'); return; } const outputSize = (inputArray[4] << 0) | (inputArray[5] << 8) | (inputArray[6] << 16) | (inputArray[7] << 24); const outputArray = lz4CodecInstance.decodeBlock(inputArray, 8, outputSize); if ( outputArray instanceof Uint8Array === false ) { return; } if ( textDecoder === undefined ) { textDecoder = new TextDecoder(); } const s = textDecoder.decode(outputArray); //console.info( // 'uBO: [%s] decompressed %d KB => %d KB (%s%%) in %s ms', // inputArray.byteLength >>> 10, // outputSize >>> 10, // (inputArray.byteLength / outputSize * 100).toFixed(0), // (window.performance.now() - t0).toFixed(1) //); return s; }; const lz4Codec = { // Arguments: // dataIn: must be a string // Returns: // A Uint8Array, or the input string as is if compression is not // possible. encode: async function(dataIn, serialize = undefined) { if ( typeof dataIn !== 'string' || dataIn.length < 4096 ) { return dataIn; } ttlManage(1); const lz4CodecInstance = await init(); let dataOut = encodeValue(lz4CodecInstance, dataIn); ttlManage(-1); if ( serialize instanceof Function ) { dataOut = await serialize(dataOut); } return dataOut || dataIn; }, // Arguments: // dataIn: must be a Uint8Array // Returns: // A string, or the input argument as is if decompression is not // possible. decode: async function(dataIn, deserialize = undefined) { if ( deserialize instanceof Function ) { dataIn = await deserialize(dataIn); } if ( dataIn instanceof Uint8Array === false ) { return dataIn; } ttlManage(1); const lz4CodecInstance = await init(); const dataOut = decodeValue(lz4CodecInstance, dataIn); ttlManage(-1); return dataOut || dataIn; }, relinquish: function() { ttlDelay = 1; ttlManage(0); }, }; /******************************************************************************/ export default lz4Codec; /******************************************************************************/