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uBlock/src/js/hntrie.js
Manish Jethani 5d2c295600
Remove globals usage from hntrie.js (#3842)
2021-08-21 07:33:53 -04:00

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/*******************************************************************************
uBlock Origin - a browser extension to block requests.
Copyright (C) 2017-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
*/
/* globals WebAssembly */
'use strict';
/*******************************************************************************
The original prototype was to develop an idea I had about using jump indices
in a TypedArray for quickly matching hostnames (or more generally strings)[1].
Once I had a working, un-optimized prototype, I realized I had ended up
with something formally named a "trie": <https://en.wikipedia.org/wiki/Trie>,
hence the name. I have no idea whether the implementation here or one
resembling it has been done elsewhere.
"HN" in HNTrieContainer stands for "HostName", because the trie is
specialized to deal with matching hostnames -- which is a bit more
complicated than matching plain strings.
For example, `www.abc.com` is deemed matching `abc.com`, because the former
is a subdomain of the latter. The opposite is of course not true.
The resulting read-only tries created as a result of using HNTrieContainer
are simply just typed arrays filled with integers. The matching algorithm is
just a matter of reading/comparing these integers, and further using them as
indices in the array as a way to move around in the trie.
[1] To solve <https://github.com/gorhill/uBlock/issues/3193>
Since this trie is specialized for matching hostnames, the stored
strings are reversed internally, because of hostname comparison logic:
Correct matching:
index 0123456
abc.com
|
www.abc.com
index 01234567890
Incorrect matching (typically used for plain strings):
index 0123456
abc.com
|
www.abc.com
index 01234567890
------------------------------------------------------------------------------
1st iteration:
- https://github.com/gorhill/uBlock/blob/ff58107dac3a32607f8113e39ed5015584506813/src/js/hntrie.js
- Suitable for small to medium set of hostnames
- One buffer per trie
2nd iteration: goal was to make matches() method wasm-able
- https://github.com/gorhill/uBlock/blob/c3b0fd31f64bd7ffecdd282fb1208fe07aac3eb0/src/js/hntrie.js
- Suitable for small to medium set of hostnames
- Distinct tries all share same buffer:
- Reduced memory footprint
- https://stackoverflow.com/questions/45803829/memory-overhead-of-typed-arrays-vs-strings/45808835#45808835
- Reusing needle character lookups for all tries
- This significantly reduce the number of String.charCodeAt() calls
- Slightly improved creation time
This is the 3rd iteration: goal was to make add() method wasm-able and
further improve memory/CPU efficiency.
This 3rd iteration has the following new traits:
- Suitable for small to large set of hostnames
- Support multiple trie containers (instanciable)
- Designed to hold large number of hostnames
- Hostnames can be added at any time (instead of all at once)
- This means pre-sorting is no longer a requirement
- The trie is always compact
- There is no longer a need for a `vacuum` method
- This makes the add() method wasm-able
- It can return the exact hostname which caused the match
- serializable/unserializable available for fast loading
- Distinct trie reference support the iteration protocol, thus allowing
to extract all the hostnames in the trie
Its primary purpose is to replace the use of Set() as a mean to hold
large number of hostnames (ex. FilterHostnameDict in static filtering
engine).
A HNTrieContainer is mostly a large buffer in which distinct but related
tries are stored. The memory layout of the buffer is as follow:
0-254: needle being processed
255: length of needle
256-259: offset to start of trie data section (=> trie0)
260-263: offset to end of trie data section (=> trie1)
264-267: offset to start of character data section (=> char0)
268-271: offset to end of character data section (=> char1)
272: start of trie data section
*/
const PAGE_SIZE = 65536;
// i32 / i8
const TRIE0_SLOT = 256 >>> 2; // 64 / 256
const TRIE1_SLOT = TRIE0_SLOT + 1; // 65 / 260
const CHAR0_SLOT = TRIE0_SLOT + 2; // 66 / 264
const CHAR1_SLOT = TRIE0_SLOT + 3; // 67 / 268
const TRIE0_START = TRIE0_SLOT + 4 << 2; // 272
const roundToPageSize = v => (v + PAGE_SIZE-1) & ~(PAGE_SIZE-1);
const HNTrieContainer = class {
constructor() {
const len = PAGE_SIZE * 2;
this.buf = new Uint8Array(len);
this.buf32 = new Uint32Array(this.buf.buffer);
this.needle = '';
this.buf32[TRIE0_SLOT] = TRIE0_START;
this.buf32[TRIE1_SLOT] = this.buf32[TRIE0_SLOT];
this.buf32[CHAR0_SLOT] = len >>> 1;
this.buf32[CHAR1_SLOT] = this.buf32[CHAR0_SLOT];
this.wasmMemory = null;
this.lastStored = '';
this.lastStoredLen = this.lastStoredIndex = 0;
}
//--------------------------------------------------------------------------
// Public methods
//--------------------------------------------------------------------------
reset(details) {
if (
details instanceof Object &&
typeof details.byteLength === 'number' &&
typeof details.char0 === 'number'
) {
if ( details.byteLength > this.buf.byteLength ) {
this.reallocateBuf(details.byteLength);
}
this.buf32[CHAR0_SLOT] = details.char0;
}
this.buf32[TRIE1_SLOT] = this.buf32[TRIE0_SLOT];
this.buf32[CHAR1_SLOT] = this.buf32[CHAR0_SLOT];
this.lastStored = '';
this.lastStoredLen = this.lastStoredIndex = 0;
}
setNeedle(needle) {
if ( needle !== this.needle ) {
const buf = this.buf;
let i = needle.length;
if ( i > 255 ) { i = 255; }
buf[255] = i;
while ( i-- ) {
buf[i] = needle.charCodeAt(i);
}
this.needle = needle;
}
return this;
}
matchesJS(iroot) {
const buf32 = this.buf32;
const buf8 = this.buf;
const char0 = buf32[CHAR0_SLOT];
let ineedle = buf8[255];
let icell = buf32[iroot+0];
if ( icell === 0 ) { return -1; }
let c = 0, v = 0, i0 = 0, n = 0;
for (;;) {
if ( ineedle === 0 ) { return -1; }
ineedle -= 1;
c = buf8[ineedle];
// find first segment with a first-character match
for (;;) {
v = buf32[icell+2];
i0 = char0 + (v >>> 8);
if ( buf8[i0] === c ) { break; }
icell = buf32[icell+0];
if ( icell === 0 ) { return -1; }
}
// all characters in segment must match
n = v & 0x7F;
if ( n > 1 ) {
n -= 1;
if ( n > ineedle ) { return -1; }
i0 += 1;
const i1 = i0 + n;
do {
ineedle -= 1;
if ( buf8[i0] !== buf8[ineedle] ) { return -1; }
i0 += 1;
} while ( i0 < i1 );
}
// boundary at end of segment?
if ( (v & 0x80) !== 0 ) {
if ( ineedle === 0 || buf8[ineedle-1] === 0x2E /* '.' */ ) {
return ineedle;
}
}
// next segment
icell = buf32[icell+1];
if ( icell === 0 ) { break; }
}
return -1;
}
createOne(args) {
if ( Array.isArray(args) ) {
return new this.HNTrieRef(this, args[0], args[1]);
}
// grow buffer if needed
if ( (this.buf32[CHAR0_SLOT] - this.buf32[TRIE1_SLOT]) < 12 ) {
this.growBuf(12, 0);
}
const iroot = this.buf32[TRIE1_SLOT] >>> 2;
this.buf32[TRIE1_SLOT] += 12;
this.buf32[iroot+0] = 0;
this.buf32[iroot+1] = 0;
this.buf32[iroot+2] = 0;
return new this.HNTrieRef(this, iroot, 0);
}
compileOne(trieRef) {
return [ trieRef.iroot, trieRef.size ];
}
addJS(iroot) {
let lhnchar = this.buf[255];
if ( lhnchar === 0 ) { return 0; }
// grow buffer if needed
if (
(this.buf32[CHAR0_SLOT] - this.buf32[TRIE1_SLOT]) < 24 ||
(this.buf.length - this.buf32[CHAR1_SLOT]) < 256
) {
this.growBuf(24, 256);
}
let icell = this.buf32[iroot+0];
// special case: first node in trie
if ( icell === 0 ) {
this.buf32[iroot+0] = this.addLeafCell(lhnchar);
return 1;
}
//
const char0 = this.buf32[CHAR0_SLOT];
let isegchar, lsegchar, boundaryBit, inext;
// find a matching cell: move down
for (;;) {
const v = this.buf32[icell+2];
let isegchar0 = char0 + (v >>> 8);
// if first character is no match, move to next descendant
if ( this.buf[isegchar0] !== this.buf[lhnchar-1] ) {
inext = this.buf32[icell+0];
if ( inext === 0 ) {
this.buf32[icell+0] = this.addLeafCell(lhnchar);
return 1;
}
icell = inext;
continue;
}
// 1st character was tested
isegchar = 1;
lhnchar -= 1;
// find 1st mismatch in rest of segment
lsegchar = v & 0x7F;
if ( lsegchar !== 1 ) {
for (;;) {
if ( isegchar === lsegchar ) { break; }
if ( lhnchar === 0 ) { break; }
if ( this.buf[isegchar0+isegchar] !== this.buf[lhnchar-1] ) { break; }
isegchar += 1;
lhnchar -= 1;
}
}
boundaryBit = v & 0x80;
// all segment characters matched
if ( isegchar === lsegchar ) {
// needle remainder: no
if ( lhnchar === 0 ) {
// boundary: yes, already present
if ( boundaryBit !== 0 ) { return 0; }
// boundary: no, mark as boundary
this.buf32[icell+2] = v | 0x80;
}
// needle remainder: yes
else {
// remainder is at label boundary? if yes, no need to add
// the rest since the shortest match is always reported
if ( boundaryBit !== 0 ) {
if ( this.buf[lhnchar-1] === 0x2E /* '.' */ ) { return -1; }
}
inext = this.buf32[icell+1];
if ( inext !== 0 ) {
icell = inext;
continue;
}
// add needle remainder
this.buf32[icell+1] = this.addLeafCell(lhnchar);
}
}
// some segment characters matched
else {
// split current cell
isegchar0 -= char0;
this.buf32[icell+2] = isegchar0 << 8 | isegchar;
inext = this.addCell(
0,
this.buf32[icell+1],
isegchar0 + isegchar << 8 | boundaryBit | lsegchar - isegchar
);
this.buf32[icell+1] = inext;
// needle remainder: yes, need new cell for remaining characters
if ( lhnchar !== 0 ) {
this.buf32[inext+0] = this.addLeafCell(lhnchar);
}
// needle remainder: no, need boundary cell
else {
this.buf32[icell+2] |= 0x80;
}
}
return 1;
}
}
optimize() {
this.shrinkBuf();
return {
byteLength: this.buf.byteLength,
char0: this.buf32[CHAR0_SLOT],
};
}
fromIterable(hostnames, add) {
if ( add === undefined ) { add = 'add'; }
const trieRef = this.createOne();
for ( const hn of hostnames ) {
trieRef[add](hn);
}
return trieRef;
}
serialize(encoder) {
if ( encoder instanceof Object ) {
return encoder.encode(
this.buf32.buffer,
this.buf32[CHAR1_SLOT]
);
}
return Array.from(
new Uint32Array(
this.buf32.buffer,
0,
this.buf32[CHAR1_SLOT] + 3 >>> 2
)
);
}
unserialize(selfie, decoder) {
this.needle = '';
const shouldDecode = typeof selfie === 'string';
let byteLength = shouldDecode
? decoder.decodeSize(selfie)
: selfie.length << 2;
if ( byteLength === 0 ) { return false; }
byteLength = roundToPageSize(byteLength);
if ( this.wasmMemory !== null ) {
const pageCountBefore = this.buf.length >>> 16;
const pageCountAfter = byteLength >>> 16;
if ( pageCountAfter > pageCountBefore ) {
this.wasmMemory.grow(pageCountAfter - pageCountBefore);
this.buf = new Uint8Array(this.wasmMemory.buffer);
this.buf32 = new Uint32Array(this.buf.buffer);
}
} else if ( byteLength > this.buf.length ) {
this.buf = new Uint8Array(byteLength);
this.buf32 = new Uint32Array(this.buf.buffer);
}
if ( shouldDecode ) {
decoder.decode(selfie, this.buf.buffer);
} else {
this.buf32.set(selfie);
}
return true;
}
// The following *Hostname() methods can be used to store hostname strings
// outside the trie. This is useful to store/match hostnames which are
// not part of a collection, and yet still benefit from storing the strings
// into a trie container's character buffer.
// TODO: WASM version of matchesHostname()
storeHostname(hn) {
let n = hn.length;
if ( n > 255 ) {
hn = hn.slice(-255);
n = 255;
}
if ( n === this.lastStoredLen && hn === this.lastStored ) {
return this.lastStoredIndex;
}
this.lastStored = hn;
this.lastStoredLen = n;
if ( (this.buf.length - this.buf32[CHAR1_SLOT]) < n ) {
this.growBuf(0, n);
}
const offset = this.buf32[CHAR1_SLOT];
this.buf32[CHAR1_SLOT] = offset + n;
const buf8 = this.buf;
for ( let i = 0; i < n; i++ ) {
buf8[offset+i] = hn.charCodeAt(i);
}
return (this.lastStoredIndex = offset - this.buf32[CHAR0_SLOT]);
}
extractHostname(i, n) {
const textDecoder = new TextDecoder();
const offset = this.buf32[CHAR0_SLOT] + i;
return textDecoder.decode(this.buf.subarray(offset, offset + n));
}
matchesHostname(hn, i, n) {
this.setNeedle(hn);
const buf8 = this.buf;
const hr = buf8[255];
if ( n > hr ) { return false; }
const hl = hr - n;
const nl = this.buf32[CHAR0_SLOT] + i;
for ( let j = 0; j < n; j++ ) {
if ( buf8[nl+j] !== buf8[hl+j] ) { return false; }
}
return n === hr || hn.charCodeAt(hl-1) === 0x2E /* '.' */;
}
async enableWASM(wasmModuleFetcher, path) {
if ( typeof WebAssembly === 'undefined' ) { return false; }
if ( this.wasmMemory instanceof WebAssembly.Memory ) { return true; }
const module = await getWasmModule(wasmModuleFetcher, path);
if ( module instanceof WebAssembly.Module === false ) { return false; }
const memory = new WebAssembly.Memory({ initial: 2 });
const instance = await WebAssembly.instantiate(module, {
imports: {
memory,
growBuf: this.growBuf.bind(this, 24, 256)
}
});
if ( instance instanceof WebAssembly.Instance === false ) { return false; }
this.wasmMemory = memory;
const curPageCount = memory.buffer.byteLength >>> 16;
const newPageCount = roundToPageSize(this.buf.byteLength) >>> 16;
if ( newPageCount > curPageCount ) {
memory.grow(newPageCount - curPageCount);
}
const buf = new Uint8Array(memory.buffer);
buf.set(this.buf);
this.buf = buf;
this.buf32 = new Uint32Array(this.buf.buffer);
this.matches = this.matchesWASM = instance.exports.matches;
this.add = this.addWASM = instance.exports.add;
return true;
}
//--------------------------------------------------------------------------
// Private methods
//--------------------------------------------------------------------------
addCell(idown, iright, v) {
let icell = this.buf32[TRIE1_SLOT];
this.buf32[TRIE1_SLOT] = icell + 12;
icell >>>= 2;
this.buf32[icell+0] = idown;
this.buf32[icell+1] = iright;
this.buf32[icell+2] = v;
return icell;
}
addLeafCell(lsegchar) {
const r = this.buf32[TRIE1_SLOT] >>> 2;
let i = r;
while ( lsegchar > 127 ) {
this.buf32[i+0] = 0;
this.buf32[i+1] = i + 3;
this.buf32[i+2] = this.addSegment(lsegchar, lsegchar - 127);
lsegchar -= 127;
i += 3;
}
this.buf32[i+0] = 0;
this.buf32[i+1] = 0;
this.buf32[i+2] = this.addSegment(lsegchar, 0) | 0x80;
this.buf32[TRIE1_SLOT] = i + 3 << 2;
return r;
}
addSegment(lsegchar, lsegend) {
if ( lsegchar === 0 ) { return 0; }
let char1 = this.buf32[CHAR1_SLOT];
const isegchar = char1 - this.buf32[CHAR0_SLOT];
let i = lsegchar;
do {
this.buf[char1++] = this.buf[--i];
} while ( i !== lsegend );
this.buf32[CHAR1_SLOT] = char1;
return isegchar << 8 | lsegchar - lsegend;
}
growBuf(trieGrow, charGrow) {
const char0 = Math.max(
roundToPageSize(this.buf32[TRIE1_SLOT] + trieGrow),
this.buf32[CHAR0_SLOT]
);
const char1 = char0 + this.buf32[CHAR1_SLOT] - this.buf32[CHAR0_SLOT];
const bufLen = Math.max(
roundToPageSize(char1 + charGrow),
this.buf.length
);
this.resizeBuf(bufLen, char0);
}
shrinkBuf() {
// Can't shrink WebAssembly.Memory
if ( this.wasmMemory !== null ) { return; }
const char0 = this.buf32[TRIE1_SLOT] + 24;
const char1 = char0 + this.buf32[CHAR1_SLOT] - this.buf32[CHAR0_SLOT];
const bufLen = char1 + 256;
this.resizeBuf(bufLen, char0);
}
resizeBuf(bufLen, char0) {
bufLen = roundToPageSize(bufLen);
if ( bufLen === this.buf.length && char0 === this.buf32[CHAR0_SLOT] ) {
return;
}
const charDataLen = this.buf32[CHAR1_SLOT] - this.buf32[CHAR0_SLOT];
if ( this.wasmMemory !== null ) {
const pageCount = (bufLen >>> 16) - (this.buf.byteLength >>> 16);
if ( pageCount > 0 ) {
this.wasmMemory.grow(pageCount);
this.buf = new Uint8Array(this.wasmMemory.buffer);
this.buf32 = new Uint32Array(this.wasmMemory.buffer);
}
} else if ( bufLen !== this.buf.length ) {
const newBuf = new Uint8Array(bufLen);
newBuf.set(
new Uint8Array(
this.buf.buffer,
0,
this.buf32[TRIE1_SLOT]
),
0
);
newBuf.set(
new Uint8Array(
this.buf.buffer,
this.buf32[CHAR0_SLOT],
charDataLen
),
char0
);
this.buf = newBuf;
this.buf32 = new Uint32Array(this.buf.buffer);
this.buf32[CHAR0_SLOT] = char0;
this.buf32[CHAR1_SLOT] = char0 + charDataLen;
}
if ( char0 !== this.buf32[CHAR0_SLOT] ) {
this.buf.set(
new Uint8Array(
this.buf.buffer,
this.buf32[CHAR0_SLOT],
charDataLen
),
char0
);
this.buf32[CHAR0_SLOT] = char0;
this.buf32[CHAR1_SLOT] = char0 + charDataLen;
}
}
reallocateBuf(newSize) {
newSize = roundToPageSize(newSize);
if ( newSize === this.buf.length ) { return; }
if ( this.wasmMemory === null ) {
const newBuf = new Uint8Array(newSize);
newBuf.set(
newBuf.length < this.buf.length
? this.buf.subarray(0, newBuf.length)
: this.buf
);
this.buf = newBuf;
} else {
const growBy =
((newSize + 0xFFFF) >>> 16) - (this.buf.length >>> 16);
if ( growBy <= 0 ) { return; }
this.wasmMemory.grow(growBy);
this.buf = new Uint8Array(this.wasmMemory.buffer);
}
this.buf32 = new Uint32Array(this.buf.buffer);
}
};
HNTrieContainer.prototype.matches = HNTrieContainer.prototype.matchesJS;
HNTrieContainer.prototype.matchesWASM = null;
HNTrieContainer.prototype.add = HNTrieContainer.prototype.addJS;
HNTrieContainer.prototype.addWASM = null;
/*******************************************************************************
Class to hold reference to a specific trie
*/
HNTrieContainer.prototype.HNTrieRef = class {
constructor(container, iroot, size) {
this.container = container;
this.iroot = iroot;
this.size = size;
this.needle = '';
this.last = -1;
}
add(hn) {
if ( this.container.setNeedle(hn).add(this.iroot) > 0 ) {
this.last = -1;
this.needle = '';
this.size += 1;
return true;
}
return false;
}
addJS(hn) {
if ( this.container.setNeedle(hn).addJS(this.iroot) > 0 ) {
this.last = -1;
this.needle = '';
this.size += 1;
return true;
}
return false;
}
addWASM(hn) {
if ( this.container.setNeedle(hn).addWASM(this.iroot) > 0 ) {
this.last = -1;
this.needle = '';
this.size += 1;
return true;
}
return false;
}
matches(needle) {
if ( needle !== this.needle ) {
this.needle = needle;
this.last = this.container.setNeedle(needle).matches(this.iroot);
}
return this.last;
}
matchesJS(needle) {
if ( needle !== this.needle ) {
this.needle = needle;
this.last = this.container.setNeedle(needle).matchesJS(this.iroot);
}
return this.last;
}
matchesWASM(needle) {
if ( needle !== this.needle ) {
this.needle = needle;
this.last = this.container.setNeedle(needle).matchesWASM(this.iroot);
}
return this.last;
}
dump() {
let hostnames = Array.from(this);
if ( String.prototype.padStart instanceof Function ) {
const maxlen = Math.min(
hostnames.reduce((maxlen, hn) => Math.max(maxlen, hn.length), 0),
64
);
hostnames = hostnames.map(hn => hn.padStart(maxlen));
}
for ( const hn of hostnames ) {
console.log(hn);
}
}
[Symbol.iterator]() {
return {
value: undefined,
done: false,
next: function() {
if ( this.icell === 0 ) {
if ( this.forks.length === 0 ) {
this.value = undefined;
this.done = true;
return this;
}
this.charPtr = this.forks.pop();
this.icell = this.forks.pop();
}
for (;;) {
const idown = this.container.buf32[this.icell+0];
if ( idown !== 0 ) {
this.forks.push(idown, this.charPtr);
}
const v = this.container.buf32[this.icell+2];
let i0 = this.container.buf32[CHAR0_SLOT] + (v >>> 8);
const i1 = i0 + (v & 0x7F);
while ( i0 < i1 ) {
this.charPtr -= 1;
this.charBuf[this.charPtr] = this.container.buf[i0];
i0 += 1;
}
this.icell = this.container.buf32[this.icell+1];
if ( this.icell === 0 ) {
return this.toHostname();
}
if ( this.container.buf32[this.icell+2] === 0 ) {
this.icell = this.container.buf32[this.icell+1];
return this.toHostname();
}
}
},
toHostname: function() {
this.value = this.textDecoder.decode(
new Uint8Array(this.charBuf.buffer, this.charPtr)
);
return this;
},
container: this.container,
icell: this.iroot,
charBuf: new Uint8Array(256),
charPtr: 256,
forks: [],
textDecoder: new TextDecoder()
};
}
};
HNTrieContainer.prototype.HNTrieRef.prototype.last = -1;
HNTrieContainer.prototype.HNTrieRef.prototype.needle = '';
/******************************************************************************/
// Code below is to attempt to load a WASM module which implements:
//
// - HNTrieContainer.add()
// - HNTrieContainer.matches()
//
// The WASM module is entirely optional, the JS implementations will be
// used should the WASM module be unavailable for whatever reason.
const getWasmModule = (( ) => {
let wasmModulePromise;
return async function(wasmModuleFetcher, path) {
if ( wasmModulePromise instanceof Promise ) {
return wasmModulePromise;
}
// The wasm module will work only if CPU is natively little-endian,
// as we use native uint32 array in our js code.
const uint32s = new Uint32Array(1);
const uint8s = new Uint8Array(uint32s.buffer);
uint32s[0] = 1;
if ( uint8s[0] !== 1 ) { return; }
wasmModulePromise = wasmModuleFetcher(`${path}hntrie`).catch(reason => {
console.info(reason);
});
return wasmModulePromise;
};
})();
/******************************************************************************/
export default HNTrieContainer;
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