717 lines
22 KiB
Markdown
717 lines
22 KiB
Markdown
# cacache [](https://npm.im/cacache) [](https://npm.im/cacache) [](https://travis-ci.org/npm/cacache) [](https://ci.appveyor.com/project/npm/cacache) [](https://coveralls.io/github/npm/cacache?branch=latest)
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[`cacache`](https://github.com/npm/cacache) is a Node.js library for managing
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local key and content address caches. It's really fast, really good at
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concurrency, and it will never give you corrupted data, even if cache files
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get corrupted or manipulated.
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On systems that support user and group settings on files, cacache will
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match the `uid` and `gid` values to the folder where the cache lives, even
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when running as `root`.
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It was written to be used as [npm](https://npm.im)'s local cache, but can
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just as easily be used on its own.
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## Install
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`$ npm install --save cacache`
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## Table of Contents
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* [Example](#example)
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* [Features](#features)
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* [Contributing](#contributing)
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* [API](#api)
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* [Using localized APIs](#localized-api)
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* Reading
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* [`ls`](#ls)
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* [`ls.stream`](#ls-stream)
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* [`get`](#get-data)
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* [`get.stream`](#get-stream)
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* [`get.info`](#get-info)
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* [`get.hasContent`](#get-hasContent)
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* Writing
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* [`put`](#put-data)
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* [`put.stream`](#put-stream)
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* [`rm.all`](#rm-all)
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* [`rm.entry`](#rm-entry)
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* [`rm.content`](#rm-content)
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* [`index.compact`](#index-compact)
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* [`index.insert`](#index-insert)
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* Utilities
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* [`clearMemoized`](#clear-memoized)
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* [`tmp.mkdir`](#tmp-mkdir)
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* [`tmp.withTmp`](#with-tmp)
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* Integrity
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* [Subresource Integrity](#integrity)
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* [`verify`](#verify)
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* [`verify.lastRun`](#verify-last-run)
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### Example
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```javascript
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const cacache = require('cacache')
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const fs = require('fs')
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const tarball = '/path/to/mytar.tgz'
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const cachePath = '/tmp/my-toy-cache'
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const key = 'my-unique-key-1234'
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// Cache it! Use `cachePath` as the root of the content cache
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cacache.put(cachePath, key, '10293801983029384').then(integrity => {
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console.log(`Saved content to ${cachePath}.`)
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})
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const destination = '/tmp/mytar.tgz'
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// Copy the contents out of the cache and into their destination!
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// But this time, use stream instead!
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cacache.get.stream(
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cachePath, key
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).pipe(
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fs.createWriteStream(destination)
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).on('finish', () => {
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console.log('done extracting!')
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})
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// The same thing, but skip the key index.
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cacache.get.byDigest(cachePath, integrityHash).then(data => {
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fs.writeFile(destination, data, err => {
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console.log('tarball data fetched based on its sha512sum and written out!')
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})
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})
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```
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### Features
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* Extraction by key or by content address (shasum, etc)
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* [Subresource Integrity](#integrity) web standard support
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* Multi-hash support - safely host sha1, sha512, etc, in a single cache
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* Automatic content deduplication
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* Fault tolerance (immune to corruption, partial writes, process races, etc)
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* Consistency guarantees on read and write (full data verification)
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* Lockless, high-concurrency cache access
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* Streaming support
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* Promise support
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* Fast -- sub-millisecond reads and writes including verification
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* Arbitrary metadata storage
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* Garbage collection and additional offline verification
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* Thorough test coverage
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* There's probably a bloom filter in there somewhere. Those are cool, right? 🤔
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### Contributing
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The cacache team enthusiastically welcomes contributions and project participation! There's a bunch of things you can do if you want to contribute! Please don't hesitate to jump in if you'd like to, or even ask us questions if something isn't clear.
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All participants and maintainers in this project are expected to follow [Code of Conduct](CODE_OF_CONDUCT.md), and just generally be excellent to each other.
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Please refer to the [Changelog](CHANGELOG.md) for project history details, too.
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Happy hacking!
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### API
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#### <a name="ls"></a> `> cacache.ls(cache) -> Promise<Object>`
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Lists info for all entries currently in the cache as a single large object. Each
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entry in the object will be keyed by the unique index key, with corresponding
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[`get.info`](#get-info) objects as the values.
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##### Example
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```javascript
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cacache.ls(cachePath).then(console.log)
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// Output
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{
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'my-thing': {
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key: 'my-thing',
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integrity: 'sha512-BaSe64/EnCoDED+HAsh=='
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path: '.testcache/content/deadbeef', // joined with `cachePath`
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time: 12345698490,
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size: 4023948,
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metadata: {
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name: 'blah',
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version: '1.2.3',
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description: 'this was once a package but now it is my-thing'
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}
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},
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'other-thing': {
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key: 'other-thing',
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integrity: 'sha1-ANothER+hasH=',
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path: '.testcache/content/bada55',
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time: 11992309289,
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size: 111112
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}
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}
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```
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#### <a name="ls-stream"></a> `> cacache.ls.stream(cache) -> Readable`
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Lists info for all entries currently in the cache as a single large object.
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This works just like [`ls`](#ls), except [`get.info`](#get-info) entries are
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returned as `'data'` events on the returned stream.
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##### Example
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```javascript
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cacache.ls.stream(cachePath).on('data', console.log)
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// Output
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{
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key: 'my-thing',
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integrity: 'sha512-BaSe64HaSh',
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path: '.testcache/content/deadbeef', // joined with `cachePath`
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time: 12345698490,
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size: 13423,
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metadata: {
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name: 'blah',
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version: '1.2.3',
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description: 'this was once a package but now it is my-thing'
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}
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}
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{
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key: 'other-thing',
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integrity: 'whirlpool-WoWSoMuchSupport',
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path: '.testcache/content/bada55',
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time: 11992309289,
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size: 498023984029
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}
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{
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...
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}
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```
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#### <a name="get-data"></a> `> cacache.get(cache, key, [opts]) -> Promise({data, metadata, integrity})`
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Returns an object with the cached data, digest, and metadata identified by
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`key`. The `data` property of this object will be a `Buffer` instance that
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presumably holds some data that means something to you. I'm sure you know what
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to do with it! cacache just won't care.
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`integrity` is a [Subresource
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Integrity](#integrity)
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string. That is, a string that can be used to verify `data`, which looks like
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`<hash-algorithm>-<base64-integrity-hash>`.
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If there is no content identified by `key`, or if the locally-stored data does
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not pass the validity checksum, the promise will be rejected.
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A sub-function, `get.byDigest` may be used for identical behavior, except lookup
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will happen by integrity hash, bypassing the index entirely. This version of the
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function *only* returns `data` itself, without any wrapper.
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See: [options](#get-options)
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##### Note
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This function loads the entire cache entry into memory before returning it. If
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you're dealing with Very Large data, consider using [`get.stream`](#get-stream)
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instead.
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##### Example
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```javascript
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// Look up by key
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cache.get(cachePath, 'my-thing').then(console.log)
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// Output:
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{
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metadata: {
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thingName: 'my'
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},
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integrity: 'sha512-BaSe64HaSh',
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data: Buffer#<deadbeef>,
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size: 9320
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}
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// Look up by digest
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cache.get.byDigest(cachePath, 'sha512-BaSe64HaSh').then(console.log)
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// Output:
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Buffer#<deadbeef>
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```
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#### <a name="get-stream"></a> `> cacache.get.stream(cache, key, [opts]) -> Readable`
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Returns a [Readable Stream](https://nodejs.org/api/stream.html#stream_readable_streams) of the cached data identified by `key`.
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If there is no content identified by `key`, or if the locally-stored data does
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not pass the validity checksum, an error will be emitted.
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`metadata` and `integrity` events will be emitted before the stream closes, if
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you need to collect that extra data about the cached entry.
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A sub-function, `get.stream.byDigest` may be used for identical behavior,
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except lookup will happen by integrity hash, bypassing the index entirely. This
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version does not emit the `metadata` and `integrity` events at all.
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See: [options](#get-options)
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##### Example
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```javascript
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// Look up by key
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cache.get.stream(
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cachePath, 'my-thing'
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).on('metadata', metadata => {
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console.log('metadata:', metadata)
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}).on('integrity', integrity => {
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console.log('integrity:', integrity)
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}).pipe(
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fs.createWriteStream('./x.tgz')
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)
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// Outputs:
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metadata: { ... }
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integrity: 'sha512-SoMeDIGest+64=='
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// Look up by digest
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cache.get.stream.byDigest(
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cachePath, 'sha512-SoMeDIGest+64=='
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).pipe(
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fs.createWriteStream('./x.tgz')
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)
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```
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#### <a name="get-info"></a> `> cacache.get.info(cache, key) -> Promise`
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Looks up `key` in the cache index, returning information about the entry if
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one exists.
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##### Fields
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* `key` - Key the entry was looked up under. Matches the `key` argument.
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* `integrity` - [Subresource Integrity hash](#integrity) for the content this entry refers to.
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* `path` - Filesystem path where content is stored, joined with `cache` argument.
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* `time` - Timestamp the entry was first added on.
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* `metadata` - User-assigned metadata associated with the entry/content.
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##### Example
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```javascript
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cacache.get.info(cachePath, 'my-thing').then(console.log)
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// Output
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{
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key: 'my-thing',
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integrity: 'sha256-MUSTVERIFY+ALL/THINGS=='
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path: '.testcache/content/deadbeef',
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time: 12345698490,
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size: 849234,
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metadata: {
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name: 'blah',
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version: '1.2.3',
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description: 'this was once a package but now it is my-thing'
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}
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}
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```
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#### <a name="get-hasContent"></a> `> cacache.get.hasContent(cache, integrity) -> Promise`
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Looks up a [Subresource Integrity hash](#integrity) in the cache. If content
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exists for this `integrity`, it will return an object, with the specific single integrity hash
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that was found in `sri` key, and the size of the found content as `size`. If no content exists for this integrity, it will return `false`.
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##### Example
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```javascript
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cacache.get.hasContent(cachePath, 'sha256-MUSTVERIFY+ALL/THINGS==').then(console.log)
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// Output
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{
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sri: {
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source: 'sha256-MUSTVERIFY+ALL/THINGS==',
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algorithm: 'sha256',
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digest: 'MUSTVERIFY+ALL/THINGS==',
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options: []
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},
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size: 9001
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}
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cacache.get.hasContent(cachePath, 'sha521-NOT+IN/CACHE==').then(console.log)
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// Output
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false
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```
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##### <a name="get-options"></a> Options
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##### `opts.integrity`
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If present, the pre-calculated digest for the inserted content. If this option
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is provided and does not match the post-insertion digest, insertion will fail
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with an `EINTEGRITY` error.
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##### `opts.memoize`
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Default: null
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If explicitly truthy, cacache will read from memory and memoize data on bulk read. If `false`, cacache will read from disk data. Reader functions by default read from in-memory cache.
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##### `opts.size`
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If provided, the data stream will be verified to check that enough data was
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passed through. If there's more or less data than expected, insertion will fail
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with an `EBADSIZE` error.
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#### <a name="put-data"></a> `> cacache.put(cache, key, data, [opts]) -> Promise`
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Inserts data passed to it into the cache. The returned Promise resolves with a
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digest (generated according to [`opts.algorithms`](#optsalgorithms)) after the
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cache entry has been successfully written.
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See: [options](#put-options)
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##### Example
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```javascript
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fetch(
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'https://registry.npmjs.org/cacache/-/cacache-1.0.0.tgz'
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).then(data => {
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return cacache.put(cachePath, 'registry.npmjs.org|cacache@1.0.0', data)
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}).then(integrity => {
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console.log('integrity hash is', integrity)
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})
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```
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#### <a name="put-stream"></a> `> cacache.put.stream(cache, key, [opts]) -> Writable`
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Returns a [Writable
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Stream](https://nodejs.org/api/stream.html#stream_writable_streams) that inserts
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data written to it into the cache. Emits an `integrity` event with the digest of
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written contents when it succeeds.
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See: [options](#put-options)
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##### Example
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```javascript
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request.get(
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'https://registry.npmjs.org/cacache/-/cacache-1.0.0.tgz'
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).pipe(
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cacache.put.stream(
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cachePath, 'registry.npmjs.org|cacache@1.0.0'
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).on('integrity', d => console.log(`integrity digest is ${d}`))
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)
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```
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##### <a name="put-options"></a> Options
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##### `opts.metadata`
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Arbitrary metadata to be attached to the inserted key.
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##### `opts.size`
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If provided, the data stream will be verified to check that enough data was
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passed through. If there's more or less data than expected, insertion will fail
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with an `EBADSIZE` error.
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##### `opts.integrity`
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If present, the pre-calculated digest for the inserted content. If this option
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is provided and does not match the post-insertion digest, insertion will fail
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with an `EINTEGRITY` error.
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`algorithms` has no effect if this option is present.
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##### `opts.integrityEmitter`
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*Streaming only* If present, uses the provided event emitter as a source of
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truth for both integrity and size. This allows use cases where integrity is
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already being calculated outside of cacache to reuse that data instead of
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calculating it a second time.
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The emitter must emit both the `'integrity'` and `'size'` events.
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NOTE: If this option is provided, you must verify that you receive the correct
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integrity value yourself and emit an `'error'` event if there is a mismatch.
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[ssri Integrity Streams](https://github.com/npm/ssri#integrity-stream) do this for you when given an expected integrity.
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##### `opts.algorithms`
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Default: ['sha512']
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Hashing algorithms to use when calculating the [subresource integrity
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digest](#integrity)
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for inserted data. Can use any algorithm listed in `crypto.getHashes()` or
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`'omakase'`/`'お任せします'` to pick a random hash algorithm on each insertion. You
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may also use any anagram of `'modnar'` to use this feature.
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Currently only supports one algorithm at a time (i.e., an array length of
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exactly `1`). Has no effect if `opts.integrity` is present.
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##### `opts.memoize`
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Default: null
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If provided, cacache will memoize the given cache insertion in memory, bypassing
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any filesystem checks for that key or digest in future cache fetches. Nothing
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will be written to the in-memory cache unless this option is explicitly truthy.
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If `opts.memoize` is an object or a `Map`-like (that is, an object with `get`
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and `set` methods), it will be written to instead of the global memoization
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cache.
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Reading from disk data can be forced by explicitly passing `memoize: false` to
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the reader functions, but their default will be to read from memory.
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##### `opts.tmpPrefix`
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Default: null
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Prefix to append on the temporary directory name inside the cache's tmp dir.
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#### <a name="rm-all"></a> `> cacache.rm.all(cache) -> Promise`
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Clears the entire cache. Mainly by blowing away the cache directory itself.
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##### Example
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```javascript
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cacache.rm.all(cachePath).then(() => {
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console.log('THE APOCALYPSE IS UPON US 😱')
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})
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```
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#### <a name="rm-entry"></a> `> cacache.rm.entry(cache, key, [opts]) -> Promise`
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Alias: `cacache.rm`
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Removes the index entry for `key`. Content will still be accessible if
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requested directly by content address ([`get.stream.byDigest`](#get-stream)).
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By default, this appends a new entry to the index with an integrity of `null`.
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If `opts.removeFully` is set to `true` then the index file itself will be
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physically deleted rather than appending a `null`.
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To remove the content itself (which might still be used by other entries), use
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[`rm.content`](#rm-content). Or, to safely vacuum any unused content, use
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[`verify`](#verify).
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##### Example
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```javascript
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cacache.rm.entry(cachePath, 'my-thing').then(() => {
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console.log('I did not like it anyway')
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})
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```
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#### <a name="rm-content"></a> `> cacache.rm.content(cache, integrity) -> Promise`
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Removes the content identified by `integrity`. Any index entries referring to it
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will not be usable again until the content is re-added to the cache with an
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identical digest.
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##### Example
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```javascript
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cacache.rm.content(cachePath, 'sha512-SoMeDIGest/IN+BaSE64==').then(() => {
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console.log('data for my-thing is gone!')
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})
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```
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#### <a name="index-compact"></a> `> cacache.index.compact(cache, key, matchFn, [opts]) -> Promise`
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Uses `matchFn`, which must be a synchronous function that accepts two entries
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and returns a boolean indicating whether or not the two entries match, to
|
|
deduplicate all entries in the cache for the given `key`.
|
|
|
|
If `opts.validateEntry` is provided, it will be called as a function with the
|
|
only parameter being a single index entry. The function must return a Boolean,
|
|
if it returns `true` the entry is considered valid and will be kept in the index,
|
|
if it returns `false` the entry will be removed from the index.
|
|
|
|
If `opts.validateEntry` is not provided, however, every entry in the index will
|
|
be deduplicated and kept until the first `null` integrity is reached, removing
|
|
all entries that were written before the `null`.
|
|
|
|
The deduplicated list of entries is both written to the index, replacing the
|
|
existing content, and returned in the Promise.
|
|
|
|
#### <a name="index-insert"></a> `> cacache.index.insert(cache, key, integrity, opts) -> Promise`
|
|
|
|
Writes an index entry to the cache for the given `key` without writing content.
|
|
|
|
It is assumed if you are using this method, you have already stored the content
|
|
some other way and you only wish to add a new index to that content. The `metadata`
|
|
and `size` properties are read from `opts` and used as part of the index entry.
|
|
|
|
Returns a Promise resolving to the newly added entry.
|
|
|
|
#### <a name="clear-memoized"></a> `> cacache.clearMemoized()`
|
|
|
|
Completely resets the in-memory entry cache.
|
|
|
|
#### <a name="tmp-mkdir"></a> `> tmp.mkdir(cache, opts) -> Promise<Path>`
|
|
|
|
Returns a unique temporary directory inside the cache's `tmp` dir. This
|
|
directory will use the same safe user assignment that all the other stuff use.
|
|
|
|
Once the directory is made, it's the user's responsibility that all files
|
|
within are given the appropriate `gid`/`uid` ownership settings to match
|
|
the rest of the cache. If not, you can ask cacache to do it for you by
|
|
calling [`tmp.fix()`](#tmp-fix), which will fix all tmp directory
|
|
permissions.
|
|
|
|
If you want automatic cleanup of this directory, use
|
|
[`tmp.withTmp()`](#with-tpm)
|
|
|
|
See: [options](#tmp-options)
|
|
|
|
##### Example
|
|
|
|
```javascript
|
|
cacache.tmp.mkdir(cache).then(dir => {
|
|
fs.writeFile(path.join(dir, 'blablabla'), Buffer#<1234>, ...)
|
|
})
|
|
```
|
|
|
|
#### <a name="tmp-fix"></a> `> tmp.fix(cache) -> Promise`
|
|
|
|
Sets the `uid` and `gid` properties on all files and folders within the tmp
|
|
folder to match the rest of the cache.
|
|
|
|
Use this after manually writing files into [`tmp.mkdir`](#tmp-mkdir) or
|
|
[`tmp.withTmp`](#with-tmp).
|
|
|
|
##### Example
|
|
|
|
```javascript
|
|
cacache.tmp.mkdir(cache).then(dir => {
|
|
writeFile(path.join(dir, 'file'), someData).then(() => {
|
|
// make sure we didn't just put a root-owned file in the cache
|
|
cacache.tmp.fix().then(() => {
|
|
// all uids and gids match now
|
|
})
|
|
})
|
|
})
|
|
```
|
|
|
|
#### <a name="with-tmp"></a> `> tmp.withTmp(cache, opts, cb) -> Promise`
|
|
|
|
Creates a temporary directory with [`tmp.mkdir()`](#tmp-mkdir) and calls `cb`
|
|
with it. The created temporary directory will be removed when the return value
|
|
of `cb()` resolves, the tmp directory will be automatically deleted once that
|
|
promise completes.
|
|
|
|
The same caveats apply when it comes to managing permissions for the tmp dir's
|
|
contents.
|
|
|
|
See: [options](#tmp-options)
|
|
|
|
##### Example
|
|
|
|
```javascript
|
|
cacache.tmp.withTmp(cache, dir => {
|
|
return fs.writeFile(path.join(dir, 'blablabla'), 'blabla contents', { encoding: 'utf8' })
|
|
}).then(() => {
|
|
// `dir` no longer exists
|
|
})
|
|
```
|
|
|
|
##### <a name="tmp-options"></a> Options
|
|
|
|
##### `opts.tmpPrefix`
|
|
Default: null
|
|
|
|
Prefix to append on the temporary directory name inside the cache's tmp dir.
|
|
|
|
#### <a name="integrity"></a> Subresource Integrity Digests
|
|
|
|
For content verification and addressing, cacache uses strings following the
|
|
[Subresource
|
|
Integrity spec](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity).
|
|
That is, any time cacache expects an `integrity` argument or option, it
|
|
should be in the format `<hashAlgorithm>-<base64-hash>`.
|
|
|
|
One deviation from the current spec is that cacache will support any hash
|
|
algorithms supported by the underlying Node.js process. You can use
|
|
`crypto.getHashes()` to see which ones you can use.
|
|
|
|
##### Generating Digests Yourself
|
|
|
|
If you have an existing content shasum, they are generally formatted as a
|
|
hexadecimal string (that is, a sha1 would look like:
|
|
`5f5513f8822fdbe5145af33b64d8d970dcf95c6e`). In order to be compatible with
|
|
cacache, you'll need to convert this to an equivalent subresource integrity
|
|
string. For this example, the corresponding hash would be:
|
|
`sha1-X1UT+IIv2+UUWvM7ZNjZcNz5XG4=`.
|
|
|
|
If you want to generate an integrity string yourself for existing data, you can
|
|
use something like this:
|
|
|
|
```javascript
|
|
const crypto = require('crypto')
|
|
const hashAlgorithm = 'sha512'
|
|
const data = 'foobarbaz'
|
|
|
|
const integrity = (
|
|
hashAlgorithm +
|
|
'-' +
|
|
crypto.createHash(hashAlgorithm).update(data).digest('base64')
|
|
)
|
|
```
|
|
|
|
You can also use [`ssri`](https://npm.im/ssri) to have a richer set of functionality
|
|
around SRI strings, including generation, parsing, and translating from existing
|
|
hex-formatted strings.
|
|
|
|
#### <a name="verify"></a> `> cacache.verify(cache, opts) -> Promise`
|
|
|
|
Checks out and fixes up your cache:
|
|
|
|
* Cleans up corrupted or invalid index entries.
|
|
* Custom entry filtering options.
|
|
* Garbage collects any content entries not referenced by the index.
|
|
* Checks integrity for all content entries and removes invalid content.
|
|
* Fixes cache ownership.
|
|
* Removes the `tmp` directory in the cache and all its contents.
|
|
|
|
When it's done, it'll return an object with various stats about the verification
|
|
process, including amount of storage reclaimed, number of valid entries, number
|
|
of entries removed, etc.
|
|
|
|
##### <a name="verify-options"></a> Options
|
|
|
|
##### `opts.concurrency`
|
|
|
|
Default: 20
|
|
|
|
Number of concurrently read files in the filesystem while doing clean up.
|
|
|
|
##### `opts.filter`
|
|
Receives a formatted entry. Return false to remove it.
|
|
Note: might be called more than once on the same entry.
|
|
|
|
##### `opts.log`
|
|
Custom logger function:
|
|
```
|
|
log: { silly () {} }
|
|
log.silly('verify', 'verifying cache at', cache)
|
|
```
|
|
|
|
##### Example
|
|
|
|
```sh
|
|
echo somegarbage >> $CACHEPATH/content/deadbeef
|
|
```
|
|
|
|
```javascript
|
|
cacache.verify(cachePath).then(stats => {
|
|
// deadbeef collected, because of invalid checksum.
|
|
console.log('cache is much nicer now! stats:', stats)
|
|
})
|
|
```
|
|
|
|
#### <a name="verify-last-run"></a> `> cacache.verify.lastRun(cache) -> Promise`
|
|
|
|
Returns a `Date` representing the last time `cacache.verify` was run on `cache`.
|
|
|
|
##### Example
|
|
|
|
```javascript
|
|
cacache.verify(cachePath).then(() => {
|
|
cacache.verify.lastRun(cachePath).then(lastTime => {
|
|
console.log('cacache.verify was last called on' + lastTime)
|
|
})
|
|
})
|
|
```
|