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perf(compiler-cli): cache results of absoluteFromSourceFile (#41475)

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The compiler frequently translates TypeScript source file `fileName` strings
into absolute paths, via a `fs.resolve()` operation. This is often done via
the helper function `absoluteFromSourceFile`.

This commit adds a caching mechanism whereby the `AbsoluteFsPath` of a
source file is patched onto the object under an Angular-specific symbol
property, allowing the compiler to avoid resolving the path on subsequent
calls.

PR Close #41475
This commit is contained in:
Alex Rickabaugh 2021-04-06 08:54:35 -04:00 committed by Zach Arend
parent 71b8c9ab29
commit fab1a6468e
1 changed files with 13 additions and 3 deletions
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16
packages/compiler-cli/src/ngtsc/file_system/src/helpers.ts
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@ -29,11 +29,21 @@ export function absoluteFrom(path: string): AbsoluteFsPath {
return fs.resolve(path); return fs.resolve(path);
} }
const ABSOLUTE_PATH = Symbol('AbsolutePath');
/** /**
* Extract an `AbsoluteFsPath` from a `ts.SourceFile`. * Extract an `AbsoluteFsPath` from a `ts.SourceFile`-like object.
*/ */
export function absoluteFromSourceFile(sf: ts.SourceFile): AbsoluteFsPath { export function absoluteFromSourceFile(sf: {fileName: string}): AbsoluteFsPath {
return fs.resolve(sf.fileName); const sfWithPatch = sf as {fileName: string, [ABSOLUTE_PATH]?: AbsoluteFsPath};
if (sfWithPatch[ABSOLUTE_PATH] === undefined) {
sfWithPatch[ABSOLUTE_PATH] = fs.resolve(sfWithPatch.fileName);
}
// Non-null assertion needed since TS doesn't narrow the type of fields that use a symbol as a key
// apparently.
return sfWithPatch[ABSOLUTE_PATH]!;
} }
/** /**