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Add a per-importer cache for loads that aren't cacheable en masse
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Inspired by comments on #2215
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@nex3
nex3 committed Apr 12, 2024
1 parent 821b98e commit 015856c
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Showing 2 changed files with 77 additions and 69 deletions.
72 changes: 38 additions & 34 deletions lib/src/async_import_cache.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -43,30 +43,20 @@ final class AsyncImportCache {
/// The `forImport` in each key is true when this canonicalization is for an
/// `@import` rule. Otherwise, it's for a `@use` or `@forward` rule.
///
/// This cache isn't used for relative imports, because they depend on the
/// specific base importer. That's stored separately in
/// [_relativeCanonicalizeCache].
/// This cache covers loads that go through the entire chain of [_importers],
/// but it doesn't cover individual loads or loads in which any importer
/// accesses `containingUrl`. See also [_perImporterCanonicalizeCache].
final _canonicalizeCache =
<(Uri, {bool forImport}), AsyncCanonicalizeResult?>{};

/// The canonicalized URLs for each non-canonical URL that's resolved using a
/// relative importer.
/// Like [_canonicalizeCache] but also includes the specific importer in the
/// key.
///
/// The map's keys have four parts:
///
/// 1. The URL passed to [canonicalize] (the same as in [_canonicalizeCache]).
/// 2. Whether the canonicalization is for an `@import` rule.
/// 3. The `baseImporter` passed to [canonicalize].
/// 4. The `baseUrl` passed to [canonicalize].
///
/// The map's values are the same as the return value of [canonicalize].
final _relativeCanonicalizeCache = <(
Uri, {
bool forImport,
AsyncImporter baseImporter,
Uri? baseUrl
}),
AsyncCanonicalizeResult?>{};
/// This is used to cache both relative imports from the base importer and
/// individual importer results in the case where some other component of the
/// importer chain isn't cacheable.
final _perImporterCanonicalizeCache =
<(AsyncImporter, Uri, {bool forImport}), AsyncCanonicalizeResult?>{};

/// The parsed stylesheets for each canonicalized import URL.
final _importCache = <Uri, Stylesheet?>{};
Expand Down Expand Up @@ -154,14 +144,11 @@ final class AsyncImportCache {
}

if (baseImporter != null && url.scheme == '') {
var relativeResult = await putIfAbsentAsync(_relativeCanonicalizeCache, (
url,
forImport: forImport,
baseImporter: baseImporter,
baseUrl: baseUrl
), () async {
var (result, cacheable) = await _canonicalize(
baseImporter, baseUrl?.resolveUri(url) ?? url, baseUrl, forImport);
var resolvedUrl = baseUrl?.resolveUri(url) ?? url;
var relativeResult = await putIfAbsentAsync(_perImporterCanonicalizeCache,
(baseImporter, resolvedUrl, forImport: forImport), () async {
var (result, cacheable) =
await _canonicalize(baseImporter, resolvedUrl, baseUrl, forImport);
assert(
cacheable,
"Relative loads should always be cacheable because they never "
Expand All @@ -181,17 +168,34 @@ final class AsyncImportCache {
// `canonicalize()` calls we've attempted are cacheable. Only if they are do
// we store the result in the cache.
var cacheable = true;
for (var importer in _importers) {
for (var i = 0; i < _importers.length; i++) {
var importer = _importers[i];
switch (await _canonicalize(importer, url, baseUrl, forImport)) {
case (var result?, true) when cacheable:
_canonicalizeCache[key] = result;
return result;

case (var result?, _):
return result;

case (_, false):
cacheable = false;
case (var result, true) when !cacheable:
_perImporterCanonicalizeCache[(
importer,
url,
{forImport: forImport}
)] = result;
if (result != null) return result;

case (var result, false):
if (cacheable) {
// If this is the first uncacheable result, add all previous results
// to the per-importer cache so we don't have to re-run them for
// future uses of this importer.
var perImporterKey = (_importers[j], url, {forImport: forImport});
for (var j = 0; i < j; j++) {
_perImporterCanonicalizeCache[perImporterKey] = null;
}
cacheable = false;
}

if (result != null) return result;
}
}

Expand Down
74 changes: 39 additions & 35 deletions lib/src/import_cache.dart
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
// DO NOT EDIT. This file was generated from async_import_cache.dart.
// See tool/grind/synchronize.dart for details.
//
// Checksum: 37dd173d676ec6cf201a25b3cca9ac81d92b1433
// Checksum: cee1a9f159b153663ae361b862e66fe15b38518a
//
// ignore_for_file: unused_import

Expand Down Expand Up @@ -46,29 +46,19 @@ final class ImportCache {
/// The `forImport` in each key is true when this canonicalization is for an
/// `@import` rule. Otherwise, it's for a `@use` or `@forward` rule.
///
/// This cache isn't used for relative imports, because they depend on the
/// specific base importer. That's stored separately in
/// [_relativeCanonicalizeCache].
/// This cache covers loads that go through the entire chain of [_importers],
/// but it doesn't cover individual loads or loads in which any importer
/// accesses `containingUrl`. See also [_perImporterCanonicalizeCache].
final _canonicalizeCache = <(Uri, {bool forImport}), CanonicalizeResult?>{};

/// The canonicalized URLs for each non-canonical URL that's resolved using a
/// relative importer.
/// Like [_canonicalizeCache] but also includes the specific importer in the
/// key.
///
/// The map's keys have four parts:
///
/// 1. The URL passed to [canonicalize] (the same as in [_canonicalizeCache]).
/// 2. Whether the canonicalization is for an `@import` rule.
/// 3. The `baseImporter` passed to [canonicalize].
/// 4. The `baseUrl` passed to [canonicalize].
///
/// The map's values are the same as the return value of [canonicalize].
final _relativeCanonicalizeCache = <(
Uri, {
bool forImport,
Importer baseImporter,
Uri? baseUrl
}),
CanonicalizeResult?>{};
/// This is used to cache both relative imports from the base importer and
/// individual importer results in the case where some other component of the
/// importer chain isn't cacheable.
final _perImporterCanonicalizeCache =
<(Importer, Uri, {bool forImport}), CanonicalizeResult?>{};

/// The parsed stylesheets for each canonicalized import URL.
final _importCache = <Uri, Stylesheet?>{};
Expand Down Expand Up @@ -154,14 +144,11 @@ final class ImportCache {
}

if (baseImporter != null && url.scheme == '') {
var relativeResult = _relativeCanonicalizeCache.putIfAbsent((
url,
forImport: forImport,
baseImporter: baseImporter,
baseUrl: baseUrl
), () {
var (result, cacheable) = _canonicalize(
baseImporter, baseUrl?.resolveUri(url) ?? url, baseUrl, forImport);
var resolvedUrl = baseUrl?.resolveUri(url) ?? url;
var relativeResult = _perImporterCanonicalizeCache
.putIfAbsent((baseImporter, resolvedUrl, forImport: forImport), () {
var (result, cacheable) =
_canonicalize(baseImporter, resolvedUrl, baseUrl, forImport);
assert(
cacheable,
"Relative loads should always be cacheable because they never "
Expand All @@ -181,17 +168,34 @@ final class ImportCache {
// `canonicalize()` calls we've attempted are cacheable. Only if they are do
// we store the result in the cache.
var cacheable = true;
for (var importer in _importers) {
for (var i = 0; i < _importers.length; i++) {
var importer = _importers[i];
switch (_canonicalize(importer, url, baseUrl, forImport)) {
case (var result?, true) when cacheable:
_canonicalizeCache[key] = result;
return result;

case (var result?, _):
return result;

case (_, false):
cacheable = false;
case (var result, true) when !cacheable:
_perImporterCanonicalizeCache[(
importer,
url,
{forImport: forImport}
)] = result;
if (result != null) return result;

case (var result, false):
if (cacheable) {
// If this is the first uncacheable result, add all previous results
// to the per-importer cache so we don't have to re-run them for
// future uses of this importer.
var perImporterKey = (_importers[j], url, {forImport: forImport});
for (var j = 0; i < j; j++) {
_perImporterCanonicalizeCache[perImporterKey] = null;
}
cacheable = false;
}

if (result != null) return result;
}
}

Expand Down

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