This patch implements automatic on-disk code caching that can be enabled
via an environment variable NODE_COMPILE_CACHE.
When set, whenever Node.js compiles a CommonJS or a ECMAScript Module,
it will use on-disk [V8 code cache][] persisted in the specified
directory to speed up the compilation. This may slow down the first
load of a module graph, but subsequent loads of the same module graph
may get a significant speedup if the contents of the modules do not
change. Locally, this speeds up loading of
test/fixtures/snapshot/typescript.js from ~130ms to ~80ms.
To clean up the generated code cache, simply remove the directory.
It will be recreated the next time the same directory is used for
`NODE_COMPILE_CACHE`.
Compilation cache generated by one version of Node.js may not be used
by a different version of Node.js. Cache generated by different versions
of Node.js will be stored separately if the same directory is used
to persist the cache, so they can co-exist.
Caveat: currently when using this with V8 JavaScript code coverage, the
coverage being collected by V8 may be less precise in functions that are
deserialized from the code cache. It's recommended to turn this off when
running tests to generate precise coverage.
Implementation details:
There is one cache file per module on disk. The directory layout
is:
- Compile cache directory (from NODE_COMPILE_CACHE)
- 8b23c8fe: CRC32 hash of CachedDataVersionTag + NODE_VERESION
- 2ea3424d:
- 10860e5a: CRC32 hash of filename + module type
- 431e9adc: ...
- ...
Inside the cache file, there is a header followed by the actual
cache content:
```
[uint32_t] code size
[uint32_t] code hash
[uint32_t] cache size
[uint32_t] cache hash
... compile cache content ...
```
When reading the cache file, we'll also check if the code size
and code hash match the code that the module loader is loading
and whether the cache size and cache hash match the file content
read. If they don't match, or if V8 rejects the cache passed,
we'll ignore the mismatch cache, and regenerate the cache after
compilation succeeds and rewrite it to disk.
PR-URL: https://github.com/nodejs/node/pull/52535
Refs: https://github.com/nodejs/node/issues/47472
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz.nizipli@sentry.io>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Documentation style guide
This style guide helps us create organized and easy-to-read documentation. It provides guidelines for organization, spelling, formatting, and more.
These are guidelines rather than strict rules. Content is more important than formatting. You do not need to learn the entire style guide before contributing to documentation. Someone can always edit your material later to conform with this guide.
- Documentation is in markdown files with names formatted as
lowercase-with-dashes.md.- Use an underscore in the filename only if the underscore is part of the
topic name (e.g.,
child_process). - Some files, such as top-level markdown files, are exceptions.
- Use an underscore in the filename only if the underscore is part of the
topic name (e.g.,
- Documents should be word-wrapped at 80 characters.
.editorconfigdescribes the preferred formatting.- A plugin is available for some editors to apply these rules.
- Check changes to documentation with
make test-doc -jorvcbuild test-doc. - Use US spelling.
- Use serial commas.
- Avoid first-person pronouns (I, we).
- Exception: we recommend foo is preferable to foo is recommended.
- Use gender-neutral pronouns and gender-neutral plural nouns.
- OK: they, their, them, folks, people, developers
- NOT OK: his, hers, him, her, guys, dudes
- When combining wrapping elements (parentheses and quotes), place terminal
punctuation:
- Inside the wrapping element if the wrapping element contains a complete clause.
- Outside of the wrapping element if the wrapping element contains only a fragment of a clause.
- Documents must start with a level-one heading.
- Prefer affixing links (
[a link][]) to inlining links ([a link](http://example.com)). - When documenting APIs, update the YAML comment associated with the API as appropriate. This is especially true when introducing or deprecating an API.
- When documenting APIs, every function should have a usage example or link to an example that uses the function.
- For code blocks:
-
Use language-aware fences. (
```js) -
For the info string, use one of the following.
Meaning Info string Bash bashC cC++ cppCoffeeScript coffeeDiff diffHTTP httpJavaScript jsJSON jsonMarkdown markdownPlaintext textPowershell powershellR rShell Session consoleIf one of your language-aware fences needs an info string that is not already on this list, you may use
textuntil the grammar gets added toremark-preset-lint-node. -
Code need not be complete. Treat code blocks as an illustration or aid to your point, not as complete running programs. If a complete running program is necessary, include it as an asset in
assets/code-examplesand link to it.
-
- When using underscores, asterisks, and backticks, please use
backslash-escaping:
\_,\*, and\`. - Constructors should use PascalCase.
- Instances should use camelCase.
- Denote methods with parentheses:
socket.end()instead ofsocket.end. - Function arguments or object properties should use the following format:
* `name` {type|type2} Optional description. **Default:** `value`.
- For example:
*byteOffset{integer} Index of first byte to expose. Default:0.
- The
typeshould refer to a Node.js type or a JavaScript type.
- Function returns should use the following format:
* Returns: {type|type2} Optional description.- E.g.
* Returns: {AsyncHook} A reference toasyncHook.
- Use official styling for capitalization in products and projects.
- OK: JavaScript, Google's V8
- NOT OK: Javascript, Google's v8
- Use Node.js and not Node, NodeJS, or similar variants.
- When referring to the executable,
nodeis acceptable.
- When referring to the executable,
- Be direct.
- When referring to a version of Node.js in prose, use Node.js and the version
number. Do not prefix the version number with v in prose. This is to avoid
confusion about whether v8 refers to Node.js 8.x or the V8 JavaScript
engine.
- OK: Node.js 14.x, Node.js 14.3.1
- NOT OK: Node.js v14
- Use sentence-style capitalization for headings.
See also API documentation structure overview in doctools README.
For topics not covered here, refer to the Microsoft Writing Style Guide.