caches.md

Lots of caching in ts-node.

Caches

FS cache:

caches results of primitive ts.sys.readFile, etc operations Shared across compiler and config loader

fileContents (and fileVersions) cache:

sits in front of fs cache. Node.js module loading mechanism reads file contents from disk. That's put into this cache.

Output cache:

Caches the emitted JS syntax from compilation. Has appended //# sourcemap comments. source-map-support reads from here before fallback to filesystem.

source-map-support cache:

caches fs.readFile calls overlayed by output cache above overlayed by sourcesContents from parsed sourcemaps

SourceFile cache: (does not exist today)

for Compiler API codepath to avoid re-parsing SourceFile repeatedly

Questions

If both:

• source-map-support caches a sourcesContents string of a .ts file
• cachedFsReader caches the same .ts file from disk ...which is used by source-map-support? Does it matter since they should be identical?