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first working version that also considers holes in document updates - #263

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This commit is contained in:
Kevin Jahns
2020-12-15 15:39:08 +01:00
parent 004a781a56
commit f8341220c3
5 changed files with 65 additions and 21 deletions
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68
src/utils/updates.js
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@@ -7,6 +7,7 @@ import {
readItemContent,
readDeleteSet,
writeDeleteSet,
Skip,
mergeDeleteSets,
Item, GC, AbstractUpdateDecoder, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2 // eslint-disable-line
} from '../internals.js'
@@ -22,7 +23,12 @@ function * lazyStructReaderGenerator (decoder) {
let clock = decoding.readVarUint(decoder.restDecoder)
for (let i = 0; i < numberOfStructs; i++) {
const info = decoder.readInfo()
if ((binary.BITS5 & info) !== 0) {
// @todo use switch instead of ifs
if (info === 10) {
const len = decoder.readLen()
yield new Skip(createID(client, clock), len)
clock += len
} else if ((binary.BITS5 & info) !== 0) {
const cantCopyParentInfo = (info & (binary.BIT7 | binary.BIT8)) === 0
// If parent = null and neither left nor right are defined, then we know that `parent` is child of `y`
// and we read the next string as parentYKey.
@@ -68,7 +74,11 @@ export class LazyStructReader {
* @return {Item | GC | null}
*/
next () {
return (this.curr = this.gen.next().value || null)
// ignore "Skip" structs
do {
this.curr = this.gen.next().value || null
} while (this.curr !== null && this.curr.constructor === Skip)
return this.curr
}
}
@@ -77,13 +87,6 @@ export class LazyStructWriter {
* @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
*/
constructor (encoder) {
/**
* We keep the last written struct around in case we want to
* merge it with the next written struct.
* When a new struct is received: if mergeable ⇒ merge; otherwise ⇒ write curr and keep new struct around.
* @type {null | Item | GC}
*/
this.curr = null
this.currClient = 0
this.startClock = 0
this.written = 0
@@ -112,7 +115,7 @@ export const mergeUpdates = updates => mergeUpdatesV2(updates, UpdateDecoderV1,
* This method is intended to slice any kind of struct and retrieve the right part.
* It does not handle side-effects, so it should only be used by the lazy-encoder.
*
* @param {Item | GC} left
* @param {Item | GC | Skip} left
* @param {number} diff
* @return {Item | GC}
*/
@@ -120,6 +123,9 @@ const sliceStruct = (left, diff) => {
if (left.constructor === GC) {
const { client, clock } = left.id
return new GC(createID(client, clock + diff), left.length - diff)
} else if (left.constructor === Skip) {
const { client, clock } = left.id
return new Skip(createID(client, clock + diff), left.length - diff)
} else {
const leftItem = /** @type {Item} */ (left)
const { client, clock } = leftItem.id
@@ -151,7 +157,7 @@ export const mergeUpdatesV2 = (updates, YDecoder = UpdateDecoderV2, YEncoder = U
/**
* @todo we don't need offset because we always slice before
* @type {null | { struct: Item | GC, offset: number }}
* @type {null | { struct: Item | GC | Skip, offset: number }}
*/
let currWrite = null
@@ -167,10 +173,20 @@ export const mergeUpdatesV2 = (updates, YDecoder = UpdateDecoderV2, YEncoder = U
// Write higher clients first ⇒ sort by clientID & clock and remove decoders without content
lazyStructDecoders = lazyStructDecoders.filter(dec => dec.curr !== null)
lazyStructDecoders.sort(
/** @type {function(any,any):number} */ (dec1, dec2) =>
dec1.curr.id.client === dec2.curr.id.client
? dec1.curr.id.clock - dec2.curr.id.clock
: dec1.curr.id.client - dec2.curr.id.client
/** @type {function(any,any):number} */ (dec1, dec2) => {
if (dec1.curr.id.client === dec2.curr.id.client) {
const clockDiff = dec1.curr.id.clock - dec2.curr.id.clock
if (clockDiff === 0) {
return dec1.curr.constructor === dec2.curr.constructor ? 0 : (
dec1.curr.constructor === Skip ? 1 : -1
)
} else {
return clockDiff
}
} else {
return dec2.curr.id.client - dec1.curr.id.client
}
}
)
if (lazyStructDecoders.length === 0) {
break
@@ -187,11 +203,27 @@ export const mergeUpdatesV2 = (updates, YDecoder = UpdateDecoderV2, YEncoder = U
currDecoder.next()
} else if (currWrite.struct.id.clock + currWrite.struct.length < curr.id.clock) {
// @todo write currStruct & set currStruct = Skip(clock = currStruct.id.clock + currStruct.length, length = curr.id.clock - self.clock)
throw new Error('unhandled case') // @Todo !
if (currWrite.struct.constructor === Skip) {
// extend existing skip
currWrite.struct.length = curr.id.clock + curr.length - currWrite.struct.id.clock
} else {
writeStructToLazyStructWriter(lazyStructEncoder, currWrite.struct, currWrite.offset)
const diff = curr.id.clock - currWrite.struct.id.clock - currWrite.struct.length
/**
* @type {Skip}
*/
const struct = new Skip(createID(firstClient, currWrite.struct.id.clock + currWrite.struct.length), diff)
currWrite = { struct, offset: 0 }
}
} else if (currWrite.struct.id.clock + currWrite.struct.length >= curr.id.clock) {
const diff = currWrite.struct.id.clock + currWrite.struct.length - curr.id.clock
if (diff > 0) {
curr = sliceStruct(curr, diff)
if (currWrite.struct.constructor === Skip) {
// prefer to slice Skip because the other struct might contain more information
currWrite.struct.length -= diff
} else {
curr = sliceStruct(curr, diff)
}
}
if (!currWrite.struct.mergeWith(/** @type {any} */ (curr))) {
writeStructToLazyStructWriter(lazyStructEncoder, currWrite.struct, currWrite.offset)
@@ -205,7 +237,7 @@ export const mergeUpdatesV2 = (updates, YDecoder = UpdateDecoderV2, YEncoder = U
}
for (
let next = currDecoder.curr;
next !== null && next.id.client === firstClient && next.id.clock === currWrite.struct.id.clock + currWrite.struct.length; // @Todo && next.constructor !== skippable
next !== null && next.id.client === firstClient && next.id.clock === currWrite.struct.id.clock + currWrite.struct.length && next.constructor !== Skip;
next = currDecoder.next()
) {
writeStructToLazyStructWriter(lazyStructEncoder, currWrite.struct, currWrite.offset)