Skip to content

Optimize unchanged FiberRefs updates #6453

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
coyaSONG wants to merge 1 commit into
base: v3
Choose a base branch
from
+55 −12
Draft

Optimize unchanged FiberRefs updates #6453

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions .changeset/fuzzy-spiders-smile.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
"effect": patch
---

Avoid copying all FiberRefs when an update keeps the current fiber's value unchanged.
36 changes: 24 additions & 12 deletions packages/effect/src/internal/fiberRefs.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -210,45 +210,57 @@ export const updateAs = dual<
readonly fiberRef: FiberRef.FiberRef<A>
readonly value: A
}) => {
const newStack = updatedStack(self.locals, fiberId, fiberRef, value)
if (newStack === undefined) {
return self
}
if (self.locals.size === 0) {
return new FiberRefsImpl(new Map([[fiberRef, [[fiberId, value] as const]]]))
return new FiberRefsImpl(new Map([[fiberRef, newStack]]))
}
const locals = new Map(self.locals)
unsafeUpdateAs(locals, fiberId, fiberRef, value)
locals.set(fiberRef, newStack)
return new FiberRefsImpl(locals)
})

const unsafeUpdateAs = (
const updatedStack = (
locals: Map<FiberRef.FiberRef<any>, Arr.NonEmptyReadonlyArray<readonly [FiberId.Single, any]>>,
fiberId: FiberId.Single,
fiberRef: FiberRef.FiberRef<any>,
value: any
) => {
): Arr.NonEmptyReadonlyArray<readonly [FiberId.Single, any]> | undefined => {
const oldStack: ReadonlyArray<readonly [FiberId.Single, any]> = locals.get(fiberRef) ?? []
let newStack: Arr.NonEmptyReadonlyArray<readonly [FiberId.Single, any]> | undefined

if (Arr.isNonEmptyReadonlyArray(oldStack)) {
const [currentId, currentValue] = Arr.headNonEmpty(oldStack)
if (currentId[Equal.symbol](fiberId)) {
if (Equal.equals(currentValue, value)) {
return
return undefined
} else {
newStack = [
return [
[fiberId, value] as const,
...oldStack.slice(1)
]
}
} else {
newStack = [
return [
[fiberId, value] as const,
...oldStack
]
}
} else {
newStack = [[fiberId, value] as const]
}

locals.set(fiberRef, newStack)
return [[fiberId, value] as const]
}

const unsafeUpdateAs = (
locals: Map<FiberRef.FiberRef<any>, Arr.NonEmptyReadonlyArray<readonly [FiberId.Single, any]>>,
fiberId: FiberId.Single,
fiberRef: FiberRef.FiberRef<any>,
value: any
) => {
const newStack = updatedStack(locals, fiberId, fiberRef, value)
if (newStack !== undefined) {
locals.set(fiberRef, newStack)
}
}

/** @internal */
Expand Down
26 changes: 26 additions & 0 deletions packages/effect/test/FiberRefs.test.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,32 @@ describe("FiberRefs", () => {
deepStrictEqual(FiberRefs.get(newParentFiberRefs, FiberRef.interruptedCause), Option.some(Cause.empty))
})

it("updateAs reuses unchanged FiberRefs for the same fiber", () => {
const fiberId = FiberId.make(1, 0) as FiberId.Runtime
const childId = FiberId.make(2, 1) as FiberId.Runtime
const fiberRef = FiberRef.unsafeMake(0)
const fiberRefs = FiberRefs.updateAs(FiberRefs.empty(), {
fiberId,
fiberRef,
value: 1
})

const unchanged = FiberRefs.updateAs(fiberRefs, {
fiberId,
fiberRef,
value: 1
})
strictEqual(unchanged, fiberRefs)

const childFiberRefs = FiberRefs.updateAs(fiberRefs, {
fiberId: childId,
fiberRef,
value: 1
})
assertTrue(childFiberRefs !== fiberRefs)
strictEqual(childFiberRefs.locals.get(fiberRef)?.length, 2)
Comment on lines +51 to +59

@coderabbitai coderabbitai Bot Jul 19, 2026

Copy link
Copy Markdown

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

printf '\n== FiberRefs.test.ts ==\n'
cat -n packages/effect/test/FiberRefs.test.ts | sed -n '1,220p'

printf '\n== Search assert imports/usages in package tests ==\n'
rg -n "from '`@effect/vitest`'|from \"`@effect/vitest`\"|assertTrue\\(|strictEqual\\(|assert\\." packages/effect/test packages/effect -g '*.ts' -g '*.tsx'

printf '\n== Nearby test files using `@effect/vitest` assert ==\n'
rg -n "from '`@effect/vitest`'|from \"`@effect/vitest`\"" packages/effect/test -g '*.ts' -g '*.tsx'

Repository: Effect-TS/effect

Length of output: 50373

🏁 Script executed:

#!/bin/bash
set -euo pipefail

sed -n '1,120p' packages/effect/test/FiberRefs.test.ts | nl -ba

printf '\n--- assert-related imports in FiberRefs.test.ts ---\n'
rg -n "assert|strictEqual|assertTrue" packages/effect/test/FiberRefs.test.ts

printf '\n--- package-local test convention sample ---\n'
fd -a 'test.ts' packages/effect/test | head -n 10 | while read -r f; do
  echo "FILE: $f"
  rg -n "from '`@effect/vitest`'|from \"`@effect/vitest`\"|assert\\." "$f" || true
  echo
done

Repository: Effect-TS/effect

Length of output: 194

🏁 Script executed:

#!/bin/bash
set -euo pipefail

printf '== FiberRefs.test.ts (top) ==\n'
sed -n '1,90p' packages/effect/test/FiberRefs.test.ts

printf '\n== FiberRefs.test.ts assertion/import lines ==\n'
grep -nE 'from "`@effect/vitest`"|from '\''`@effect/vitest`'\''|assertTrue\\(|strictEqual\\(|assert\\.' packages/effect/test/FiberRefs.test.ts || true

printf '\n== Nearby tests that import assert from `@effect/vitest` ==\n'
grep -R -nE 'from "`@effect/vitest`"|from '\''`@effect/vitest`'\''' packages/effect/test/FiberRefs.test.ts packages/effect/test/Fiber.test.ts packages/effect/test/FiberMap.test.ts packages/effect/test/PartitionedSemaphore.test.ts | head -n 80

Repository: Effect-TS/effect

Length of output: 3841

Use assert for these new checks. packages/effect/test/FiberRefs.test.ts:51-59 should import assert from @effect/vitest and use assert.strictEqual / assert.notStrictEqual here instead of the strictEqual / assertTrue helpers from @effect/vitest/utils.

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/effect/test/FiberRefs.test.ts` around lines 51 - 59, Update the
FiberRefs test checks around FiberRefs.updateAs to import assert from
`@effect/vitest` and replace the standalone strictEqual and assertTrue helpers
with assert.strictEqual and assert.notStrictEqual, preserving the existing
equality and identity assertions.

Source: Coding guidelines

})

describe("currentLogAnnotations", () => {
it("doesnt leak", () => {
Effect.void.pipe(Effect.annotateLogs("test", "abc"), Effect.runSync)
Expand Down