From f8341220c3e51d01e81987bc029d0e9ae5cca0fc Mon Sep 17 00:00:00 2001
From: Kevin Jahns <kevin.jahns@pm.me>
Date: Tue, 15 Dec 2020 15:39:08 +0100
Subject: [PATCH] first working version that also considers holes in document
updates - #263
---
src/internals.js | 1 +
src/structs/GC.js | 3 ++
src/structs/Item.js | 6 ++--
src/utils/updates.js | 68 +++++++++++++++++++++++++++++++-----------
tests/updates.tests.js | 8 ++++-
5 files changed, 65 insertions(+), 21 deletions(-)
diff --git a/src/internals.js b/src/internals.js
index 5d32f0ad..bc386f0a 100644
--- a/src/internals.js
+++ b/src/internals.js
@@ -40,3 +40,4 @@ export * from './structs/ContentAny.js'
export * from './structs/ContentString.js'
export * from './structs/ContentType.js'
export * from './structs/Item.js'
+export * from './structs/Skip.js'
diff --git a/src/structs/GC.js b/src/structs/GC.js
index 0b9e4244..110f68b6 100644
--- a/src/structs/GC.js
+++ b/src/structs/GC.js
@@ -22,6 +22,9 @@ export class GC extends AbstractStruct {
* @return {boolean}
*/
mergeWith (right) {
+ if (this.constructor !== right.constructor) {
+ return false
+ }
this.length += right.length
return true
}
diff --git a/src/structs/Item.js b/src/structs/Item.js
index b4c10074..c63dff84 100644
--- a/src/structs/Item.js
+++ b/src/structs/Item.js
@@ -554,6 +554,7 @@ export class Item extends AbstractStruct {
*/
mergeWith (right) {
if (
+ this.constructor === right.constructor &&
compareIDs(right.origin, this.lastId) &&
this.right === right &&
compareIDs(this.rightOrigin, right.rightOrigin) &&
@@ -675,7 +676,7 @@ export const readItemContent = (decoder, info) => contentRefs[info & binary.BITS
* @type {Array<function(AbstractUpdateDecoder):AbstractContent>}
*/
export const contentRefs = [
- () => { throw error.unexpectedCase() }, // GC is not ItemContent
+ () => { error.unexpectedCase() }, // GC is not ItemContent
readContentDeleted, // 1
readContentJSON, // 2
readContentBinary, // 3
@@ -684,7 +685,8 @@ export const contentRefs = [
readContentFormat, // 6
readContentType, // 7
readContentAny, // 8
- readContentDoc // 9
+ readContentDoc, // 9
+ () => { error.unexpectedCase() } // 10 - Skip is not ItemContent
]
/**
diff --git a/src/utils/updates.js b/src/utils/updates.js
index c2285cce..e0b6733c 100644
--- a/src/utils/updates.js
+++ b/src/utils/updates.js
@@ -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)
diff --git a/tests/updates.tests.js b/tests/updates.tests.js
index 70084273..108c5535 100644
--- a/tests/updates.tests.js
+++ b/tests/updates.tests.js
@@ -56,9 +56,15 @@ export const testMergeUpdatesWrongOrder = tc => {
Y.mergeUpdates([updates[1], updates[3]])
])
- ;[wrongOrder, overlapping, separated].forEach(updates => {
+ const targetState = Y.encodeStateAsUpdate(ydoc)
+ ;[wrongOrder, overlapping, separated].forEach((updates, i) => {
const merged = new Y.Doc()
Y.applyUpdate(merged, updates)
t.compareArrays(merged.getArray().toArray(), array.toArray())
+ t.compare(updates, targetState)
})
}
+
+/**
+ * @todo be able to apply Skip structs to Yjs docs
+ */