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/*******************************************************************************
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 */
'use strict';
/******************************************************************************/
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;
/******************************************************************************/
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