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Separate the hot path from the cold path in prisms

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This commit is contained in:
Aria Minaei 2022-11-28 13:38:18 +01:00
parent c81fe11e52
commit ed322b66de
2 changed files with 326 additions and 219 deletions
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4
packages/dataverse/src/derivations/prism/prism.test.ts
View file

@ -36,7 +36,9 @@ describe('prism', () => {
return bD.getValue()
})
expect(cD.getValue()).toEqual(2)
expect((cD as $IntentionalAny)._dependencies.size).toEqual(1)
const untap = cD.keepHot()
expect((cD as $IntentionalAny)._state.handle._dependencies.size).toEqual(1)
untap()
})
describe('prism.ref()', () => {

541
packages/dataverse/src/derivations/prism/prism.ts
View file

@ -20,25 +20,21 @@ type IDependent = (msgComingFrom: IDerivation<$IntentionalAny>) => void
const voidFn = () => {}
class PrismDerivation<V> implements IDerivation<V> {
class HotHandle<V> {
get hasDependents(): boolean {
return this._dependents.size > 0
}
removeDependent(d: IDependent) {
this._dependents.delete(d)
}
addDependent(d: IDependent) {
// having no dependents means the prism is currently cold
this._dependents.add(d)
}
private _didMarkDependentsAsStale: boolean = false
private _isFresh: boolean = false
protected _cacheOfDendencyValues: Map<IDerivation<unknown>, unknown> =
new Map()
protected _possiblyStaleDeps = new Set<IDerivation<unknown>>()
private _prismScope = new PrismScope()
/**
* Whether the object is a derivation.
*/
readonly isDerivation: true = true
private _didMarkDependentsAsStale: boolean = false
private _isHot: boolean = false
private _isFresh: boolean = false
/**
* @internal
*/
protected _lastValue: undefined | V = undefined
/**
* @internal
@ -50,13 +46,123 @@ class PrismDerivation<V> implements IDerivation<V> {
*/
protected _dependencies: Set<IDerivation<$IntentionalAny>> = new Set()
constructor(readonly _fn: () => V) {}
protected _possiblyStaleDeps = new Set<IDerivation<unknown>>()
private _scope = new HotScope()
/**
* Whether the derivation is hot.
* @internal
*/
get isHot(): boolean {
return this._isHot
protected _lastValue: undefined | V = undefined
constructor(
private readonly _fn: () => V,
private readonly _prismInstance: PrismDerivation<V>,
) {
for (const d of this._dependencies) {
d.addDependent(this._markAsStale)
}
this._scope = new HotScope()
startIgnoringDependencies()
this.getValue()
stopIgnoringDependencies()
}
destroy() {
for (const d of this._dependencies) {
d.removeDependent(this._markAsStale)
}
cleanupScopeStack(this._scope)
}
getValue(): V {
if (!this._isFresh) {
const newValue = this._recalculate()
this._lastValue = newValue
this._isFresh = true
this._didMarkDependentsAsStale = false
}
return this._lastValue!
}
_recalculate() {
let value: V
if (this._possiblyStaleDeps.size > 0) {
let anActuallyStaleDepWasFound = false
startIgnoringDependencies()
for (const dep of this._possiblyStaleDeps) {
if (this._cacheOfDendencyValues.get(dep) !== dep.getValue()) {
anActuallyStaleDepWasFound = true
break
}
}
stopIgnoringDependencies()
this._possiblyStaleDeps.clear()
if (!anActuallyStaleDepWasFound) {
return this._lastValue!
}
}
const newDeps: Set<IDerivation<unknown>> = new Set()
this._cacheOfDendencyValues.clear()
const collector = (observedDep: IDerivation<unknown>): void => {
newDeps.add(observedDep)
this._addDependency(observedDep)
}
pushCollector(collector)
hookScopeStack.push(this._scope)
try {
value = this._fn()
} catch (error) {
console.error(error)
} finally {
const topOfTheStack = hookScopeStack.pop()
if (topOfTheStack !== this._scope) {
console.warn(
// @todo guide the user to report the bug in an issue
`The Prism hook stack has slipped. This is a bug.`,
)
}
}
popCollector(collector)
for (const dep of this._dependencies) {
if (!newDeps.has(dep)) {
this._removeDependency(dep)
}
}
this._dependencies = newDeps
startIgnoringDependencies()
for (const dep of newDeps) {
this._cacheOfDendencyValues.set(dep, dep.getValue())
}
stopIgnoringDependencies()
return value!
}
protected _markAsStale = (which: IDerivation<$IntentionalAny>) => {
this._reactToDependencyBecomingStale(which)
if (this._didMarkDependentsAsStale) return
this._didMarkDependentsAsStale = true
this._isFresh = false
for (const dependent of this._dependents) {
dependent(this._prismInstance)
}
}
_reactToDependencyBecomingStale(msgComingFrom: IDerivation<unknown>) {
this._possiblyStaleDeps.add(msgComingFrom)
}
/**
@ -65,7 +171,7 @@ class PrismDerivation<V> implements IDerivation<V> {
protected _addDependency(d: IDerivation<$IntentionalAny>) {
if (this._dependencies.has(d)) return
this._dependencies.add(d)
if (this._isHot) d.addDependent(this._markAsStale)
d.addDependent(this._markAsStale)
}
/**
@ -74,7 +180,30 @@ class PrismDerivation<V> implements IDerivation<V> {
protected _removeDependency(d: IDerivation<$IntentionalAny>) {
if (!this._dependencies.has(d)) return
this._dependencies.delete(d)
if (this._isHot) d.removeDependent(this._markAsStale)
d.removeDependent(this._markAsStale)
}
}
class PrismDerivation<V> implements IDerivation<V> {
/**
* Whether the object is a derivation.
*/
readonly isDerivation: true = true
private _state:
| {hot: false; handle: undefined}
| {hot: true; handle: HotHandle<V>} = {
hot: false,
handle: undefined,
}
constructor(private readonly _fn: () => V) {}
/**
* Whether the derivation is hot.
*/
get isHot(): boolean {
return this._state.hot
}
/**
@ -128,11 +257,17 @@ class PrismDerivation<V> implements IDerivation<V> {
* @see removeDependent
*/
addDependent(d: IDependent) {
const hadDepsBefore = this._dependents.size > 0
this._dependents.add(d)
const hasDepsNow = this._dependents.size > 0
if (hadDepsBefore !== hasDepsNow) {
this._reactToNumberOfDependentsChange()
if (!this._state.hot) {
this._goHot()
}
this._state.handle!.addDependent(d)
}
private _goHot() {
const hotHandle = new HotHandle(this._fn, this)
this._state = {
hot: true,
handle: hotHandle,
}
}
@ -144,24 +279,15 @@ class PrismDerivation<V> implements IDerivation<V> {
* @see addDependent
*/
removeDependent(d: IDependent) {
const hadDepsBefore = this._dependents.size > 0
this._dependents.delete(d)
const hasDepsNow = this._dependents.size > 0
if (hadDepsBefore !== hasDepsNow) {
this._reactToNumberOfDependentsChange()
const state = this._state
if (!state.hot) {
return
}
}
protected _markAsStale = (which: IDerivation<$IntentionalAny>) => {
this._reactToDependencyBecomingStale(which)
if (this._didMarkDependentsAsStale) return
this._didMarkDependentsAsStale = true
this._isFresh = false
for (const dependent of this._dependents) {
dependent(this)
const handle = state.handle
handle.removeDependent(d)
if (!handle.hasDependents) {
this._state = {hot: false, handle: undefined}
handle.destroy()
}
}
@ -196,38 +322,17 @@ class PrismDerivation<V> implements IDerivation<V> {
*/
reportResolutionStart(this)
if (!this._isFresh) {
const newValue = this._recalculate()
this._lastValue = newValue
if (this._isHot) {
this._isFresh = true
this._didMarkDependentsAsStale = false
}
const state = this._state
let val: V
if (state.hot) {
val = state.handle.getValue()
} else {
val = ColdStuff.calculateColdPrism(this._fn)
}
reportResolutionEnd(this)
return this._lastValue!
}
private _reactToNumberOfDependentsChange() {
const shouldBecomeHot = this._dependents.size > 0
if (shouldBecomeHot === this._isHot) return
this._isHot = shouldBecomeHot
this._didMarkDependentsAsStale = false
this._isFresh = false
if (shouldBecomeHot) {
for (const d of this._dependencies) {
d.addDependent(this._markAsStale)
}
this._keepHot()
} else {
for (const d of this._dependencies) {
d.removeDependent(this._markAsStale)
}
this._becomeCold()
}
return val
}
/**
@ -266,103 +371,107 @@ class PrismDerivation<V> implements IDerivation<V> {
return possibleDerivationToValue(fn(this.getValue()))
})
}
_recalculate() {
let value: V
if (this._possiblyStaleDeps.size > 0) {
let anActuallyStaleDepWasFound = false
startIgnoringDependencies()
for (const dep of this._possiblyStaleDeps) {
if (this._cacheOfDendencyValues.get(dep) !== dep.getValue()) {
anActuallyStaleDepWasFound = true
break
}
}
stopIgnoringDependencies()
this._possiblyStaleDeps.clear()
if (!anActuallyStaleDepWasFound) {
// console.log('ok')
return this._lastValue!
}
}
const newDeps: Set<IDerivation<unknown>> = new Set()
this._cacheOfDendencyValues.clear()
const collector = (observedDep: IDerivation<unknown>): void => {
newDeps.add(observedDep)
this._addDependency(observedDep)
}
pushCollector(collector)
hookScopeStack.push(this._prismScope)
try {
value = this._fn()
} catch (error) {
console.error(error)
} finally {
const topOfTheStack = hookScopeStack.pop()
if (topOfTheStack !== this._prismScope) {
console.warn(
// @todo guide the user to report the bug in an issue
`The Prism hook stack has slipped. This is a bug.`,
)
}
}
popCollector(collector)
for (const dep of this._dependencies) {
if (!newDeps.has(dep)) {
this._removeDependency(dep)
}
}
this._dependencies = newDeps
startIgnoringDependencies()
for (const dep of newDeps) {
this._cacheOfDendencyValues.set(dep, dep.getValue())
}
stopIgnoringDependencies()
return value!
}
_reactToDependencyBecomingStale(msgComingFrom: IDerivation<unknown>) {
this._possiblyStaleDeps.add(msgComingFrom)
}
_keepHot() {
this._prismScope = new PrismScope()
startIgnoringDependencies()
this.getValue()
stopIgnoringDependencies()
}
_becomeCold() {
cleanupScopeStack(this._prismScope)
this._prismScope = new PrismScope()
}
}
class PrismScope {
interface PrismScope {
effect(key: string, cb: () => () => void, deps?: unknown[]): void
memo<T>(
key: string,
fn: () => T,
deps: undefined | $IntentionalAny[] | ReadonlyArray<$IntentionalAny>,
): T
state<T>(key: string, initialValue: T): [T, (val: T) => void]
ref<T>(key: string, initialValue: T): IRef<T>
sub(key: string): PrismScope
}
class HotScope implements PrismScope {
protected readonly _refs: Map<string, IRef<unknown>> = new Map()
ref<T>(key: string, initialValue: T): IRef<T> {
let ref = this._refs.get(key)
if (ref !== undefined) {
return ref as $IntentionalAny as IRef<T>
} else {
const ref = {
current: initialValue,
}
this._refs.set(key, ref)
return ref
}
}
isPrismScope = true
// NOTE probably not a great idea to eager-allocate all of these objects/maps for every scope,
// especially because most wouldn't get used in the majority of cases. However, back when these
// were stored on weakmaps, they were uncomfortable to inspect in the debugger.
readonly subs: Record<string, PrismScope> = {}
readonly subs: Record<string, HotScope> = {}
readonly effects: Map<string, IEffect> = new Map()
readonly memos: Map<string, IMemo> = new Map()
readonly refs: Map<string, IRef<unknown>> = new Map()
sub(key: string) {
effect(key: string, cb: () => () => void, deps?: unknown[]): void {
let effect = this.effects.get(key)
if (effect === undefined) {
effect = {
cleanup: voidFn,
deps: undefined,
}
this.effects.set(key, effect)
}
if (depsHaveChanged(effect.deps, deps)) {
effect.cleanup()
startIgnoringDependencies()
effect.cleanup = safelyRun(cb, voidFn).value
stopIgnoringDependencies()
effect.deps = deps
}
}
readonly memos: Map<string, IMemo> = new Map()
memo<T>(
key: string,
fn: () => T,
deps: undefined | $IntentionalAny[] | ReadonlyArray<$IntentionalAny>,
): T {
let memo = this.memos.get(key)
if (memo === undefined) {
memo = {
cachedValue: null,
// undefined will always indicate "deps have changed", so we set its initial value as such
deps: undefined,
}
this.memos.set(key, memo)
}
if (depsHaveChanged(memo.deps, deps)) {
startIgnoringDependencies()
memo.cachedValue = safelyRun(fn, undefined).value
stopIgnoringDependencies()
memo.deps = deps
}
return memo.cachedValue as $IntentionalAny as T
}
state<T>(key: string, initialValue: T): [T, (val: T) => void] {
const {b, setValue} = this.memo(
'state/' + key,
() => {
const b = new Box<T>(initialValue)
const setValue = (val: T) => b.set(val)
return {b, setValue}
},
[],
)
return [b.derivation.getValue(), setValue]
}
sub(key: string): HotScope {
if (!this.subs[key]) {
this.subs[key] = new PrismScope()
this.subs[key] = new HotScope()
}
return this.subs[key]
}
@ -375,7 +484,7 @@ class PrismScope {
}
}
function cleanupScopeStack(scope: PrismScope) {
function cleanupScopeStack(scope: HotScope) {
for (const sub of Object.values(scope.subs)) {
cleanupScopeStack(sub)
}
@ -420,16 +529,7 @@ function ref<T>(key: string, initialValue: T): IRef<T> {
throw new Error(`prism.ref() is called outside of a prism() call.`)
}
let ref = scope.refs.get(key)
if (ref !== undefined) {
return ref as $IntentionalAny as IRef<T>
} else {
const ref = {
current: initialValue,
}
scope.refs.set(key, ref)
return ref
}
return scope.ref(key, initialValue)
}
/**
@ -445,23 +545,7 @@ function effect(key: string, cb: () => () => void, deps?: unknown[]): void {
throw new Error(`prism.effect() is called outside of a prism() call.`)
}
let effect = scope.effects.get(key)
if (effect === undefined) {
effect = {
cleanup: voidFn,
deps: undefined,
}
scope.effects.set(key, effect)
}
if (depsHaveChanged(effect.deps, deps)) {
effect.cleanup()
startIgnoringDependencies()
effect.cleanup = safelyRun(cb, voidFn).value
stopIgnoringDependencies()
effect.deps = deps
}
return scope.effect(key, cb, deps)
}
function depsHaveChanged(
@ -500,25 +584,7 @@ function memo<T>(
throw new Error(`prism.memo() is called outside of a prism() call.`)
}
let memo = scope.memos.get(key)
if (memo === undefined) {
memo = {
cachedValue: null,
// undefined will always indicate "deps have changed", so we set it's initial value as such
deps: undefined,
}
scope.memos.set(key, memo)
}
if (depsHaveChanged(memo.deps, deps)) {
startIgnoringDependencies()
memo.cachedValue = safelyRun(fn, undefined).value
stopIgnoringDependencies()
memo.deps = deps
}
return memo.cachedValue as $IntentionalAny as T
return scope.memo(key, fn, deps)
}
/**
@ -556,17 +622,12 @@ function memo<T>(
* ```
*/
function state<T>(key: string, initialValue: T): [T, (val: T) => void] {
const {b, setValue} = prism.memo(
'state/' + key,
() => {
const b = new Box<T>(initialValue)
const setValue = (val: T) => b.set(val)
return {b, setValue}
},
[],
)
const scope = hookScopeStack.peek()
if (!scope) {
throw new Error(`prism.state() is called outside of a prism() call.`)
}
return [b.derivation.getValue(), setValue]
return scope.state(key, initialValue)
}
/**
@ -655,6 +716,50 @@ const prism: IPrismFn = (fn) => {
return new PrismDerivation(fn)
}
class ColdScope implements PrismScope {
effect(key: string, cb: () => () => void, deps?: unknown[]): void {
console.warn(`prism.effect() does not run in cold prisms`)
}
memo<T>(
key: string,
fn: () => T,
deps: any[] | readonly any[] | undefined,
): T {
return fn()
}
state<T>(key: string, initialValue: T): [T, (val: T) => void] {
return [initialValue, () => {}]
}
ref<T>(key: string, initialValue: T): IRef<T> {
return {current: initialValue}
}
sub(key: string): ColdScope {
return new ColdScope()
}
}
namespace ColdStuff {
export function calculateColdPrism<V>(fn: () => V): V {
const scope = new ColdScope()
hookScopeStack.push(scope)
let value: V
try {
value = fn()
} catch (error) {
console.error(error)
} finally {
const topOfTheStack = hookScopeStack.pop()
if (topOfTheStack !== scope) {
console.warn(
// @todo guide the user to report the bug in an issue
`The Prism hook stack has slipped. This is a bug.`,
)
}
}
return value!
}
}
prism.ref = ref
prism.effect = effect
prism.memo = memo