carbites
v2.0.0
Published
Chunking for CAR files. Split a single CAR into multiple CARs.
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carbites
Chunking for CAR files. Split a single CAR into multiple CARs.
Install
npm install carbites
Usage
Carbites supports 3 different strategies:
- Simple (default) - fast but naive, only the first CAR output has a root CID, subsequent CARs have a placeholder "empty" CID.
- Rooted - like simple, but creates a custom root node to ensure all blocks in a CAR are referenced.
- Treewalk - walks the DAG to pack sub-graphs into each CAR file that is output. Every CAR has the same root CID, but contains a different portion of the DAG.
Simple
import { CarSplitter } from 'carbites'
import { CarReader } from '@ipld/car'
import fs from 'fs'
const bigCar = await CarReader.fromIterable(fs.createReadStream('/path/to/big.car'))
const targetSize = 1024 * 1024 * 100 // chunk to ~100MB CARs
const splitter = new CarSplitter(bigCar, targetSize) // (simple strategy)
for await (const car of splitter.cars()) {
// Each `car` is an AsyncIterable<Uint8Array>
}
⚠️ Note: The first CAR output has roots in the header, subsequent CARs have an empty root CID bafkqaaa
as recommended.
Rooted
Instead of an empty CID, carbites can generate a special root node for each split CAR that references all the blocks and the original roots (only in the first CAR). To do this, use the RootedCarSplitter
constructor. When reading/extracting data from the CARs, the root node should be discarded.
import { RootedCarSplitter } from 'carbites/rooted'
import { CarReader } from '@ipld/car/reader'
import * as dagCbor from '@ipld/dag-cbor'
import fs from 'fs'
const bigCar = await CarReader.fromIterable(fs.createReadStream('/path/to/big.car'))
const targetSize = 1024 * 1024 * 100 // chunk to ~100MB CARs
const splitter = new RootedCarSplitter(bigCar, targetSize)
const cars = splitter.cars()
// Every CAR has a single root - a CBOR node that is an tuple of `/carbites/1`,
// an array of root CIDs and an array of block CIDs.
// e.g. ['/carbites/1', ['bafkroot'], ['bafy1', 'bafy2']]
const { done, value: car } = await cars.next()
const reader = await CarReader.fromIterable(car)
const rootCids = await reader.getRoots()
const rootNode = dagCbor.decode(await reader.get(rootCids[0]))
console.log(rootNode[0]) // /carbites/1
console.log(rootNode[1]) // Root CIDs (only in first CAR)
/*
[
CID(bafybeictvyf6polqzgop3jt32owubfmsg3kl226omqrfte4eyidubc4rpq)
]
*/
console.log(rootNode[2]) // Block CIDs (all blocks in this CAR)
/*
[
CID(bafybeictvyf6polqzgop3jt32owubfmsg3kl226omqrfte4eyidubc4rpq),
CID(bafyreihcsxqhd6agqpboc3wrlvpy5bwuxctv5upicdnt3u2wojv4exxl24),
CID(bafyreiasq7d2ihbqm5xvhjjzlmzsensuadrpmpt2tkjsuwq42xpa34qevu)
]
*/
The root node is limited to 4MB in size (the largest message IPFS will bitswap). Depending on the settings used to construct the DAG in the CAR, this may mean a split CAR size limit of around 30GiB.
Treewalk
Every CAR file has the same root CID but a different portion of the DAG. The DAG is traversed from the root node and each block is decoded and links extracted in order to determine which sub-graph to include in each CAR.
import { TreewalkCarSplitter } from 'carbites/treewalk'
import { CarReader } from '@ipld/car/reader'
import * as dagCbor from '@ipld/dag-cbor'
import fs from 'fs'
const bigCar = await CarReader.fromIterable(fs.createReadStream('/path/to/big.car'))
const [rootCid] = await bigCar.getRoots()
const targetSize = 1024 * 1024 * 100 // chunk to ~100MB CARs
const splitter = new TreewalkCarSplitter(bigCar, targetSize)
for await (const car of splitter.cars()) {
// Each `car` is an AsyncIterable<Uint8Array>
const reader = await CarReader.fromIterable(car)
const [splitCarRootCid] = await reader.getRoots()
console.assert(rootCid.equals(splitCarRootCid)) // all cars will have the same root
}
CLI
Install the CLI tool to use Carbites from the comfort of your terminal:
npm i -g carbites-cli
# Split a big CAR into many smaller CARs
carbites split big.car --size 100MB --strategy simple # (default size & strategy)
# Join many split CARs back into a single CAR.
carbites join big-0.car big-1.car ...
# Note: not a tool for joining arbitrary CARs together! The split CARs MUST
# belong to the same CAR and big-0.car should be the first argument.
API
class CarSplitter
class CarJoiner
class RootedCarSplitter
class RootedCarJoiner
class TreewalkCarSplitter
class TreewalkCarJoiner
class CarSplitter
Split a CAR file into several smaller CAR files.
Import in the browser:
import { CarSplitter } from 'https://cdn.skypack.dev/carbites'
Import in Node.js:
import { CarSplitter } from 'carbites'
Note: This is an alias of SimpleCarSplitter
- the default strategy for splitting CARs.
constructor(car: CarReader, targetSize: number)
Create a new CarSplitter
for the passed CAR file, aiming to generate CARs of around targetSize
bytes in size.
cars(): AsyncGenerator<AsyncIterable<Uint8Array> & RootsReader>
Split the CAR file and create multiple smaller CAR files. Returns an AsyncGenerator
that yields the split CAR files (of type AsyncIterable<Uint8Array>
).
The CAR files output also implement the RootsReader
interface from @ipld/car
which means you can call getRoots(): Promise<CID[]>
to obtain the root CIDs.
static async fromBlob(blob: Blob, targetSize: number): CarSplitter
Convenience function to create a new CarSplitter
from a blob of CAR file data.
static async fromIterable(iterable: AsyncIterable<Uint8Array>, targetSize: number): CarSplitter
Convenience function to create a new CarSplitter
from an AsyncIterable<Uint8Array>
of CAR file data.
class CarJoiner
Join together split CAR files into a single big CAR.
Import in the browser:
import { CarJoiner } from 'https://cdn.skypack.dev/carbites'
Import in Node.js:
import { CarJoiner } from 'carbites'
Note: This is an alias of SimpleCarJoiner
- a joiner for the the default CAR splitting strategy.
constructor(cars: Iterable<CarReader>)
Create a new CarJoiner
for joining the passed CAR files together.
car(): AsyncGenerator<Uint8Array>
Join the CAR files together and return the joined CAR.
class RootedCarSplitter
Split a CAR file into several smaller CAR files ensuring every CAR file contains a single root node that references all the blocks and the original roots (only in the first CAR). When reading/extracting data from the CARs, the root node should be discarded.
Import in the browser:
import { RootedCarSplitter } from 'https://cdn.skypack.dev/carbites/rooted'
Import in Node.js:
import { RootedCarSplitter } from 'carbites/rooted'
The API is the same as for CarSplitter
.
Root Node Format
The root node is a dag-cbor
node that is a tuple of the string /carbites/1
, an array of root CIDs (only seen in first CAR) and an array of block CIDs (all the blocks in the CAR). e.g. ['/carbites/1', ['bafkroot'], ['bafy1', 'bafy2']]
.
Note: The root node is limited to 4MB in size (the largest message IPFS will bitswap). Depending on the settings used to construct the DAG in the CAR, this may mean a split CAR size limit of around 30GiB.
class RootedCarJoiner
Join together CAR files that were split using RootedCarSplitter
.
The API is the same as for CarJoiner
.
class TreewalkCarSplitter
Split a CAR file into several smaller CAR files. Every CAR file has the same root CID but a different portion of the DAG. The DAG is traversed from the root node and each block is decoded and links extracted in order to determine which sub-graph to include in each CAR.
Import in the browser:
import { TreewalkCarSplitter } from 'https://cdn.skypack.dev/carbites/treewalk'
Import in Node.js:
import { TreewalkCarSplitter } from 'carbites/treewalk'
The API is the same as for CarSplitter
.
class TreewalkCarJoiner
Join together CAR files that were split using TreewalkCarSplitter
.
The API is the same as for CarJoiner
.
Releasing
You can publish by either running npm publish
in the dist
directory or using npx ipjs publish
.
Related
Contribute
Feel free to dive in! Open an issue or submit PRs.
License
Dual-licensed under MIT + Apache 2.0