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implement diffUpdates with tests - #263

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This commit is contained in:
Kevin Jahns
2021-01-29 18:18:09 +01:00
parent 7edbb2485f
commit 275d52b19d
6 changed files with 144 additions and 45 deletions
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71
src/utils/updates.js
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@@ -3,6 +3,7 @@ import * as binary from 'lib0/binary.js'
import * as decoding from 'lib0/decoding.js'
import * as encoding from 'lib0/encoding.js'
import * as logging from 'lib0/logging.js'
import * as math from 'lib0/math.js'
import {
createID,
readItemContent,
@@ -12,6 +13,7 @@ import {
mergeDeleteSets,
DSEncoderV1,
DSEncoderV2,
decodeStateVector,
Item, GC, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2 // eslint-disable-line
} from '../internals.js'
@@ -28,7 +30,7 @@ function * lazyStructReaderGenerator (decoder) {
const info = decoder.readInfo()
// @todo use switch instead of ifs
if (info === 10) {
const len = decoder.readLen()
const len = decoding.readVarUint(decoder.restDecoder)
yield new Skip(createID(client, clock), len)
clock += len
} else if ((binary.BITS5 & info) !== 0) {
@@ -62,25 +64,27 @@ function * lazyStructReaderGenerator (decoder) {
export class LazyStructReader {
/**
* @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
* @param {boolean} filterSkips
*/
constructor (decoder) {
constructor (decoder, filterSkips) {
this.gen = lazyStructReaderGenerator(decoder)
/**
* @type {null | Item | GC}
* @type {null | Item | Skip | GC}
*/
this.curr = null
this.done = false
this.filterSkips = filterSkips
this.next()
}
/**
* @return {Item | GC | null}
* @return {Item | GC | Skip |null}
*/
next () {
// ignore "Skip" structs
do {
this.curr = this.gen.next().value || null
} while (this.curr !== null && this.curr.constructor === Skip)
} while (this.filterSkips && this.curr !== null && this.curr.constructor === Skip)
return this.curr
}
}
@@ -99,7 +103,7 @@ export const logUpdate = update => logUpdateV2(update, UpdateDecoderV1)
export const logUpdateV2 = (update, YDecoder = UpdateDecoderV2) => {
const structs = []
const updateDecoder = new YDecoder(decoding.createDecoder(update))
const lazyDecoder = new LazyStructReader(updateDecoder)
const lazyDecoder = new LazyStructReader(updateDecoder, false)
for (let curr = lazyDecoder.curr; curr !== null; curr = lazyDecoder.next()) {
structs.push(curr)
}
@@ -145,7 +149,7 @@ export const mergeUpdates = updates => mergeUpdatesV2(updates, UpdateDecoderV1,
*/
export const encodeStateVectorFromUpdateV2 = (update, YEncoder = DSEncoderV2, YDecoder = UpdateDecoderV2) => {
const encoder = new YEncoder()
const updateDecoder = new LazyStructReader(new YDecoder(decoding.createDecoder(update)))
const updateDecoder = new LazyStructReader(new YDecoder(decoding.createDecoder(update)), true)
let curr = updateDecoder.curr
if (curr !== null) {
let size = 1
@@ -204,7 +208,7 @@ export const parseUpdateMetaV2 = (update, YDecoder = UpdateDecoderV2) => {
* @type {Map<number, number>}
*/
const to = new Map()
const updateDecoder = new LazyStructReader(new YDecoder(decoding.createDecoder(update)))
const updateDecoder = new LazyStructReader(new YDecoder(decoding.createDecoder(update)), false)
let curr = updateDecoder.curr
if (curr !== null) {
let currClient = curr.id.client
@@ -277,7 +281,7 @@ const sliceStruct = (left, diff) => {
*/
export const mergeUpdatesV2 = (updates, YDecoder = UpdateDecoderV2, YEncoder = UpdateEncoderV2) => {
const updateDecoders = updates.map(update => new YDecoder(decoding.createDecoder(update)))
let lazyStructDecoders = updateDecoders.map(decoder => new LazyStructReader(decoder))
let lazyStructDecoders = updateDecoders.map(decoder => new LazyStructReader(decoder, true))
/**
* @todo we don't need offset because we always slice before
@@ -395,13 +399,52 @@ export const mergeUpdatesV2 = (updates, YDecoder = UpdateDecoderV2, YEncoder = U
/**
* @param {Uint8Array} update
* @param {Uint8Array} [sv]
* @param {Uint8Array} sv
* @param {typeof UpdateDecoderV1 | typeof UpdateDecoderV2} [YDecoder]
* @param {typeof UpdateEncoderV1 | typeof UpdateEncoderV2} [YEncoder]
*/
export const diffUpdate = (update, sv = new Uint8Array([0])) => {
// @todo!!!
return update
export const diffUpdateV2 = (update, sv, YDecoder = UpdateDecoderV2, YEncoder = UpdateEncoderV2) => {
const state = decodeStateVector(sv)
const encoder = new YEncoder()
const lazyStructWriter = new LazyStructWriter(encoder)
const decoder = new YDecoder(decoding.createDecoder(update))
const reader = new LazyStructReader(decoder, false)
while (reader.curr) {
const curr = reader.curr
const currClient = curr.id.client
const svClock = state.get(currClient) || 0
if (reader.curr.constructor === Skip) {
// the first written struct shouldn't be a skip
reader.next()
continue
}
if (curr.id.clock + curr.length > svClock) {
writeStructToLazyStructWriter(lazyStructWriter, curr, math.max(svClock - curr.id.clock, 0))
reader.next()
while (reader.curr && reader.curr.id.client === currClient) {
writeStructToLazyStructWriter(lazyStructWriter, reader.curr, 0)
reader.next()
}
} else {
// read until something new comes up
while (reader.curr && reader.curr.id.client === currClient && reader.curr.id.clock + reader.curr.length <= svClock) {
reader.next()
}
}
}
finishLazyStructWriting(lazyStructWriter)
// write ds
const ds = readDeleteSet(decoder)
writeDeleteSet(encoder, ds)
return encoder.toUint8Array()
}
/**
* @param {Uint8Array} update
* @param {Uint8Array} sv
*/
export const diffUpdate = (update, sv) => diffUpdateV2(update, sv, UpdateDecoderV1, UpdateEncoderV1)
/**
* @param {LazyStructWriter} lazyWriter
*/
@@ -428,7 +471,7 @@ const writeStructToLazyStructWriter = (lazyWriter, struct, offset) => {
// write next client
lazyWriter.encoder.writeClient(struct.id.client)
// write startClock
encoding.writeVarUint(lazyWriter.encoder.restEncoder, struct.id.clock)
encoding.writeVarUint(lazyWriter.encoder.restEncoder, struct.id.clock + offset)
}
struct.write(lazyWriter.encoder, offset)
lazyWriter.written++