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bench: add buffers() benchmarks
Covers the new Source.prototype.buffers() method across the cases where it matters: - concat-source: flat (10 raw) and nested (4x10 raw) — isolates the Buffer.concat avoided by buffers(). - cached-source: cold and warm paths against a CachedSource wrapping a ConcatSource, so both "first call" and "hit the cache" are observable. - compat-source: delegated vs super-fallback to mirror the buffer() benchmarks. - realistic-source-map-pipeline: reproduces the CachedSource -> ConcatSource -> CachedSource -> ConcatSource layering from issue #157 and measures cold + warm buffer() vs buffers(). Local wall-clock sample (not CodSpeed) shows ~3x on the flat ConcatSource and ~2.4x on the nested ConcatSource; warm paths are unchanged (CachedSource returns the cached array/buffer either way), which is the expected shape.
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Lines changed: 174 additions & 1 deletion

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‎benchmark/README.md‎

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@@ -112,7 +112,7 @@ stable than per-call timing for sub-microsecond work.
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| Case | What it measures |
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| --------------------------------- | ----------------------------------------------------------------------------- |
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| `realistic-source-map-pipeline` | OriginalSource -> ReplaceSource -> ConcatSource -> CachedSource (cold + warm) |
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| `realistic-source-map-pipeline` | OriginalSource -> ReplaceSource -> ConcatSource -> CachedSource (cold + warm); also `buffer()` vs `buffers()` over the `CachedSource -> ConcatSource -> CachedSource -> ConcatSource` layering from issue #157 |
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## Adding a new case
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‎benchmark/cases/cached-source/index.bench.mjs‎

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@@ -36,6 +36,18 @@ const warmed = (() => {
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return cached;
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})();
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/**
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* A CachedSource wrapping a ConcatSource of 10 RawSources with buffers()
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* already populated. Used to measure warm buffers()/buffer() delegation.
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*/
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const warmedConcat = (() => {
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const parts = [];
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for (let i = 0; i < 10; i++) parts.push(new sources.RawSource(fixtureCode));
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const cached = new sources.CachedSource(new sources.ConcatSource(...parts));
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cached.buffers();
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return cached;
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})();
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/**
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* @param {import("tinybench").Bench} bench bench
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*/
@@ -60,6 +72,38 @@ export default function register(bench) {
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for (let i = 0; i < 500; i++) warmed.buffer();
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});
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bench.add("cached-source: buffers() (cached)", () => {
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for (let i = 0; i < 500; i++) warmed.buffers();
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});
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bench.add("cached-source: buffer() (cold, wraps ConcatSource x10)", () => {
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for (let i = 0; i < 10; i++) {
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const parts = [];
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for (let j = 0; j < 10; j++) {
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parts.push(new sources.RawSource(fixtureCode));
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}
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new sources.CachedSource(new sources.ConcatSource(...parts)).buffer();
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}
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});
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bench.add("cached-source: buffers() (cold, wraps ConcatSource x10)", () => {
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for (let i = 0; i < 10; i++) {
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const parts = [];
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for (let j = 0; j < 10; j++) {
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parts.push(new sources.RawSource(fixtureCode));
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}
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new sources.CachedSource(new sources.ConcatSource(...parts)).buffers();
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}
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});
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bench.add("cached-source: buffer() (warm, wraps ConcatSource x10)", () => {
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for (let i = 0; i < 500; i++) warmedConcat.buffer();
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});
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bench.add("cached-source: buffers() (warm, wraps ConcatSource x10)", () => {
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for (let i = 0; i < 500; i++) warmedConcat.buffers();
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});
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bench.add("cached-source: size() (cached)", () => {
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for (let i = 0; i < 500; i++) warmed.size();
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});

‎benchmark/cases/compat-source/index.bench.mjs‎

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@@ -11,12 +11,19 @@ import sources from "../../../lib/index.js";
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import { fixtureCode } from "../../fixtures.mjs";
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const fixtureBuffer = Buffer.from(fixtureCode, "utf8");
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const fixtureBufferArray = [fixtureBuffer];
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const sourceLike = {
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source: () => fixtureCode,
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buffer: () => fixtureBuffer,
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};
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const sourceLikeWithBuffers = {
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source: () => fixtureCode,
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buffer: () => fixtureBuffer,
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buffers: () => fixtureBufferArray,
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};
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const richSourceLike = {
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source: () => fixtureCode,
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buffer: () => fixtureBuffer,
@@ -56,6 +63,16 @@ export default function register(bench) {
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for (let i = 0; i < 500; i++) cs.buffer();
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});
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bench.add("compat-source: buffers() (fallback via super)", () => {
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const cs = new sources.CompatSource({ source: () => fixtureCode });
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for (let i = 0; i < 50; i++) cs.buffers();
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});
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bench.add("compat-source: buffers() (delegated)", () => {
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const cs = new sources.CompatSource(sourceLikeWithBuffers);
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for (let i = 0; i < 500; i++) cs.buffers();
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});
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bench.add("compat-source: size() (fallback via super)", () => {
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const cs = new sources.CompatSource({ source: () => fixtureCode });
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for (let i = 0; i < 50; i++) cs.size();

‎benchmark/cases/concat-source/index.bench.mjs‎

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@@ -74,6 +74,47 @@ export default function register(bench) {
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for (let i = 0; i < 10; i++) cs.buffer();
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});
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bench.add("concat-source: buffers() (10 raw)", () => {
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const parts = [];
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for (let i = 0; i < 10; i++) parts.push(new sources.RawSource(fixtureCode));
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const cs = new sources.ConcatSource(...parts);
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for (let i = 0; i < 10; i++) cs.buffers();
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});
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bench.add("concat-source: buffer() (nested 4x10 raw)", () => {
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const makeInner = () => {
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const parts = [];
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for (let i = 0; i < 10; i++) {
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parts.push(new sources.RawSource(fixtureCode));
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}
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return new sources.ConcatSource(...parts);
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};
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const cs = new sources.ConcatSource(
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makeInner(),
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makeInner(),
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makeInner(),
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makeInner(),
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);
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for (let i = 0; i < 5; i++) cs.buffer();
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});
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bench.add("concat-source: buffers() (nested 4x10 raw)", () => {
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const makeInner = () => {
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const parts = [];
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for (let i = 0; i < 10; i++) {
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parts.push(new sources.RawSource(fixtureCode));
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}
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return new sources.ConcatSource(...parts);
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};
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const cs = new sources.ConcatSource(
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makeInner(),
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makeInner(),
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makeInner(),
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makeInner(),
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);
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for (let i = 0; i < 5; i++) cs.buffers();
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});
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bench.add("concat-source: size()", () => {
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const cs = buildMixed();
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for (let i = 0; i < 10; i++) cs.size();

‎benchmark/cases/realistic-source-map-pipeline/index.bench.mjs‎

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@@ -46,6 +46,49 @@ const warmChunk = (() => {
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return cached;
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})();
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/*
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* Reproduces the layering pattern called out in
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* https://github.com/webpack/webpack-sources/issues/157:
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*
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* CachedSource -> ConcatSource -> CachedSource -> ConcatSource
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*
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* At every ConcatSource boundary, the legacy `buffer()` path calls
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* Buffer.concat on the children's buffers, which copies all of the bytes
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* through each layer. `buffers()` returns Buffer[] without concatenating,
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* so the wrapping CachedSource can pass the chunks through to the consumer
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* (e.g. fs.createWriteStream / writev) without ever materializing a single
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* contiguous Buffer.
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*
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* Each inner chunk is ~5 raw sources of fixtureCode, the outer chunk stitches
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* 4 of them together, mirroring "chunk-of-modules" nesting depth.
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*/
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/**
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* @returns {CachedSource} cached source
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*/
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function buildLayeredChunk() {
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const inner = [];
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for (let i = 0; i < 4; i++) {
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const parts = [];
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for (let j = 0; j < 5; j++) {
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parts.push(new sources.RawSource(fixtureCode));
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}
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inner.push(new sources.CachedSource(new sources.ConcatSource(...parts)));
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}
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return new sources.CachedSource(
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new sources.ConcatSource(
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new sources.RawSource("/* outer header */\n"),
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...inner,
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new sources.RawSource("/* outer footer */\n"),
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),
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);
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}
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const warmLayeredChunk = (() => {
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const chunk = buildLayeredChunk();
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chunk.buffers();
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return chunk;
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})();
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/**
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* @param {import("tinybench").Bench} bench bench
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*/
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);
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},
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);
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bench.add(
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"realistic-source-map-pipeline: cold buffer() (Cached->Concat->Cached->Concat)",
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() => {
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buildLayeredChunk().buffer();
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},
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);
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bench.add(
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"realistic-source-map-pipeline: cold buffers() (Cached->Concat->Cached->Concat)",
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() => {
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buildLayeredChunk().buffers();
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},
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);
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bench.add(
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"realistic-source-map-pipeline: warm buffer() (Cached->Concat->Cached->Concat)",
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() => {
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for (let i = 0; i < 50; i++) warmLayeredChunk.buffer();
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},
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);
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bench.add(
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"realistic-source-map-pipeline: warm buffers() (Cached->Concat->Cached->Concat)",
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() => {
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for (let i = 0; i < 50; i++) warmLayeredChunk.buffers();
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},
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);
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}

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