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micro optimizations in struct reader

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This commit is contained in:
Kevin Jahns 2020-07-13 15:47:51 +02:00
parent 3406247a3e
commit 3449687280
2 changed files with 100 additions and 37 deletions
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101
src/utils/encoding.js
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@ -130,47 +130,68 @@ export const readClientsStructRefs = (decoder, clientRefs, doc) => {
/**
* @type {Array<GC|Item>}
*/
const refs = []
const refs = new Array(numberOfStructs)
const client = decoder.readClient()
let clock = decoding.readVarUint(decoder.restDecoder)
// const start = performance.now()
clientRefs.set(client, refs)
for (let i = 0; i < numberOfStructs; i++) {
const info = decoder.readInfo()
if ((binary.BITS5 & info) !== 0) {
/**
* The item that was originally to the left of this item.
* @type {ID | null}
* The optimized implementation doesn't use any variables because inlining variables is faster.
* Below a non-optimized version is shown that implements the basic algorithm with
* a few comments
*/
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.
// It indicates how we store/retrieve parent from `y.share`
// @type {string|null}
const struct = new Item(
createID(client, clock),
null, // leftd
(info & binary.BIT8) === binary.BIT8 ? decoder.readLeftID() : null, // origin
null, // right
(info & binary.BIT7) === binary.BIT7 ? decoder.readRightID() : null, // right origin
cantCopyParentInfo ? (decoder.readParentInfo() ? doc.get(decoder.readString()) : decoder.readLeftID()) : null, // parent
cantCopyParentInfo && (info & binary.BIT6) === binary.BIT6 ? decoder.readString() : null, // parentSub
readItemContent(decoder, info) // item content
)
/* A non-optimized implementation of the above algorithm:
// The item that was originally to the left of this item.
const origin = (info & binary.BIT8) === binary.BIT8 ? decoder.readLeftID() : null
/**
* The item that was originally to the right of this item.
* @type {ID | null}
*/
// The item that was originally to the right of this item.
const rightOrigin = (info & binary.BIT7) === binary.BIT7 ? decoder.readRightID() : null
const canCopyParentInfo = (info & (binary.BIT7 | binary.BIT8)) === 0
const hasParentYKey = canCopyParentInfo ? decoder.readParentInfo() : false
/**
* 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.
* It indicates how we store/retrieve parent from `y.share`
* @type {string|null}
*/
const parentYKey = canCopyParentInfo && hasParentYKey ? decoder.readString() : null
const cantCopyParentInfo = (info & (binary.BIT7 | binary.BIT8)) === 0
const hasParentYKey = cantCopyParentInfo ? decoder.readParentInfo() : false
// 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.
// It indicates how we store/retrieve parent from `y.share`
// @type {string|null}
const parentYKey = cantCopyParentInfo && hasParentYKey ? decoder.readString() : null
const struct = new Item(
createID(client, clock), null, origin, null, rightOrigin,
canCopyParentInfo && !hasParentYKey ? decoder.readLeftID() : (parentYKey !== null ? doc.get(parentYKey) : null), // parent
canCopyParentInfo && (info & binary.BIT6) === binary.BIT6 ? decoder.readString() : null, // parentSub
/** @type {AbstractContent} */ (readItemContent(decoder, info)) // item content
createID(client, clock),
null, // leftd
origin, // origin
null, // right
rightOrigin, // right origin
cantCopyParentInfo && !hasParentYKey ? decoder.readLeftID() : (parentYKey !== null ? doc.get(parentYKey) : null), // parent
cantCopyParentInfo && (info & binary.BIT6) === binary.BIT6 ? decoder.readString() : null, // parentSub
readItemContent(decoder, info) // item content
)
refs.push(struct)
*/
refs[i] = struct
clock += struct.length
} else {
const len = decoder.readLen()
refs.push(new GC(createID(client, clock), len))
refs[i] = new GC(createID(client, clock), len)
clock += len
}
}
// console.log('time to read: ', performance.now() - start) // @todo remove
}
return clientRefs
}
@ -221,18 +242,15 @@ const resumeStructIntegration = (transaction, store) => {
}
}
const ref = stack[stack.length - 1]
const refID = ref.id
const client = refID.client
const refClock = refID.clock
const localClock = getState(store, client)
const offset = refClock < localClock ? localClock - refClock : 0
if (refClock + offset !== localClock) {
const localClock = getState(store, ref.id.client)
const offset = ref.id.clock < localClock ? localClock - ref.id.clock : 0
if (ref.id.clock + offset !== localClock) {
// A previous message from this client is missing
// check if there is a pending structRef with a smaller clock and switch them
const structRefs = clientsStructRefs.get(client) || { refs: [], i: 0 }
const structRefs = clientsStructRefs.get(ref.id.client) || { refs: [], i: 0 }
if (structRefs.refs.length !== structRefs.i) {
const r = structRefs.refs[structRefs.i]
if (r.id.clock < refClock) {
if (r.id.clock < ref.id.clock) {
// put ref with smaller clock on stack instead and continue
structRefs.refs[structRefs.i] = ref
stack[stack.length - 1] = r
@ -246,7 +264,12 @@ const resumeStructIntegration = (transaction, store) => {
return
}
const missing = ref.getMissing(transaction, store)
if (missing !== null) {
if (missing === null) {
if (offset < ref.length) {
ref.integrate(transaction, offset)
}
stack.pop()
} else {
// get the struct reader that has the missing struct
const structRefs = clientsStructRefs.get(missing) || { refs: [], i: 0 }
if (structRefs.refs.length === structRefs.i) {
@ -254,11 +277,6 @@ const resumeStructIntegration = (transaction, store) => {
return
}
stack.push(structRefs.refs[structRefs.i++])
} else {
if (offset < ref.length) {
ref.integrate(transaction, offset)
}
stack.pop()
}
}
store.pendingClientsStructRefs.clear()
@ -342,11 +360,22 @@ const cleanupPendingStructs = pendingClientsStructRefs => {
*/
export const readStructs = (decoder, transaction, store) => {
const clientsStructRefs = new Map()
let start = performance.now()
readClientsStructRefs(decoder, clientsStructRefs, transaction.doc)
console.log('time to read structs: ', performance.now() - start) // @todo remove
start = performance.now()
mergeReadStructsIntoPendingReads(store, clientsStructRefs)
console.log('time to merge: ', performance.now() - start) // @todo remove
start = performance.now()
resumeStructIntegration(transaction, store)
console.log('time to integrate: ', performance.now() - start) // @todo remove
start = performance.now()
cleanupPendingStructs(store.pendingClientsStructRefs)
console.log('time to cleanup: ', performance.now() - start) // @todo remove
start = performance.now()
tryResumePendingDeleteReaders(transaction, store)
console.log('time to resume delete readers: ', performance.now() - start) // @todo remove
start = performance.now()
}
/**

36
tests/y-text.tests.js
View File

@ -205,6 +205,40 @@ export const testFormattingRemovedInMidText = tc => {
t.assert(Y.getTypeChildren(text0).length === 3)
}
const id = Y.createID(0, 0)
const c = new Y.ContentString('a')
/**
* @param {t.TestCase} tc
*/
export const testBestCase = tc => {
const N = 2000000
const items = new Array(N)
t.measureTime('time to create two million items in the best case', () => {
const parent = /** @type {any} */ ({})
let prevItem = null
for (let i = 0; i < N; i++) {
/**
* @type {Y.Item}
*/
const n = new Y.Item(Y.createID(0, 0), null, null, null, null, null, null, c)
// items.push(n)
items[i] = n
n.right = prevItem
n.rightOrigin = prevItem ? id : null
n.content = c
n.parent = parent
prevItem = n
}
})
const newArray = new Array(N)
t.measureTime('time to copy two million items to new Array', () => {
for (let i = 0; i < N; i++) {
newArray[i] = items[i]
}
})
}
const tryGc = () => {
if (typeof global !== 'undefined' && global.gc) {
global.gc()
@ -215,7 +249,7 @@ const tryGc = () => {
* @param {t.TestCase} tc
*/
export const testLargeFragmentedDocument = tc => {
const itemsToInsert = 1000000
const itemsToInsert = 2000000
let update = /** @type {any} */ (null)
;(() => {
const doc1 = new Y.Doc()