@hash-stream/index-pipeline v1.2.0

Install

npm install @hash-stream/index-pipeline

Overview

@hash-stream/index-pipeline provides a modular pipeline for indexing files in a content-addressable way. It consists of interfaces and implementations for reading files from a store, scheduling indexing tasks, and processing files into indexes.

This package is ideal for cloud or local workflows that:

• need to scan large object stores or filesystems
• schedule files for processing (e.g., via a queue)
• generate content-addressed indexes (e.g., UnixFS link indexes) without data transformation

Usage

import {
  scheduleStoreFilesForIndexing,
  processFileForIndexing
} from '@hash-stream/index-pipeline/index'
import all from 'it-all'

// Example implementations
import { MemoryFileStore } from '@hash-stream/index-pipeline/file-store/memory'
import { MemoryIndexScheduler } from '@hash-stream/index-pipeline/index-scheduler/memory'
import { MemoryPackStore } from '@hash-stream/pack/store/memory'

const fileStore = new MemoryFileStore([...])
const scheduler = new MemoryIndexScheduler([])
const packStoreWriter = new MemoryPackStore()
// See @hash-stream/index package to select a writer
const indexWriters = [...]

// Schedule all files for indexing
await all(scheduleStoreFilesForIndexing(fileStore, scheduler))

// Consume and process tasks
for await (const task of scheduler.drain()) {
  await processFileForIndexing(fileStore, packStoreWriter, indexWriters, 'unixfs', task.fileReference)
}

It is worth noting that @hash-stream/utils package exports a UnixFsPackReader implementation, which MAY be the desired implementation of a HashStream server after running this pipeline. This is useful for keeping original raw files in a separate store and UnixFS Dag files in another store.

API

scheduleStoreFilesForIndexing(fileStore, indexScheduler, options?)

Lists all files from a FileStore and schedules them via an IndexScheduler.

• fileStore: an object implementing FileStore
• indexScheduler: an object implementing IndexScheduler
• options.format: index format (defaults to 'unixfs')

Returns:

• AsyncIterable<string> with files scheduled for indexing

processFileForIndexing(fileStore, indexWriters, indexFormat, fileReference, options?)

Scheduler consumer function where a file reference is fetched from the store, processed, and then written to the index store. Depending on the index format (for example the DAG in UnixFS) more information may be stored using the packStoreWriter.

• fileStore: an object implementing FileStore
• packStoreWriter: an object implementing PackStoreWriter
• indexWriters: an array of objects implementing IndexWriter
• indexFormat: string (e.g., 'unixfs')
• fileReference: string reference to the file in the file store
• options: optional ProcessFileForIndexingOptions

Returns:

• Promise<MultihashDigest> containing multihash of the indexed data

Interfaces

FileStore

interface FileStore {
  list(): AsyncIterable<FileMetadata>
  get(fileReference: string): Promise<BlobLike | null>
}

IndexScheduler

interface IndexScheduler {
  add(fileReference: string, options?: IndexSchedulerAddOptions): Promise<void>
}

IndexWriter

The IndexWriter interface is defined in @hash-stream/index/types. It is used to write generated index data.

Provided Implementations

FileStore

IndexScheduler

You can mix and match any implementation of FileStore and IndexScheduler.

Testing Utilities

The package exports reusable test suites to validate your own FileStore or IndexScheduler implementations:

import { runFileStoreTests, runIndexSchedulerTests } from '@hash-stream/index-pipeline/test'

You can use these to ensure your custom implementations behave correctly.

Custom Implementations

You can provide your own implementations by adhering to the exported interfaces. Here is an example:

Example: Implementing a Custom File Store

import { FileStore } from '@hash-stream/index-pipeline/types'

class MyCustomStore implements FileStore {
  async *list() {
    yield { key: 'file1.txt', size: 1234 }
  }

  async get(fileReference) {
    return new Blob(['hello world'])
  }
}

Contributing

Feel free to join in. All welcome. Please open an issue!

License

Dual-licensed under MIT + Apache 2.0