bloscZarrDecompress.js

import { runPipeline, InterfaceTypes, WorkerPool } from 'itk-wasm'
import { getSize } from '../IO/dtypeUtils'

const cores = navigator.hardwareConcurrency ? navigator.hardwareConcurrency : 4
const numberOfWorkers = cores + Math.floor(Math.sqrt(cores))
const workerPool = new WorkerPool(numberOfWorkers, runPipeline)
workerPool.terminateWorkers()

/**
 * Input:
 *
 *   chunkData: An Array of
 *
 *     {
 *       data: chunkArrayBuffer,
 *       metadata: zarrayMetadata
 *     }
 *
 *   objects.
 *
 *
 * Output:
 *
 *   An Array of decompressed ArrayBuffer chunks.
 */
async function bloscZarrDecompress(chunkData) {
  const desiredOutputs = [{ type: InterfaceTypes.BinaryStream }]
  const taskArgsArray = []
  let dtype = null
  for (let index = 0; index < chunkData.length; index++) {
    const zarrayMetadata = chunkData[index].metadata
    const compressedChunk = chunkData[index].data
    dtype = zarrayMetadata.dtype
    const nElements = zarrayMetadata.chunks.reduce((a, b) => a * b)
    const elementSize = getSize(dtype)
    if (!elementSize) throw Error('Unknown dtype in .zarray metadata')
    const outputSize = nElements * elementSize
    const inputs = [
      {
        type: InterfaceTypes.BinaryStream,
        data: { data: new Uint8Array(compressedChunk) },
      },
    ]
    const args = [
      '0',
      '0',
      zarrayMetadata.compressor.cname,
      compressedChunk.byteLength.toString(),
      '--output-size',
      outputSize.toString(),
      '--decompress',
      '--memory-io',
    ]
    taskArgsArray.push(['BloscZarr', args, desiredOutputs, inputs])
  }
  const results = await workerPool.runTasks(taskArgsArray).promise
  workerPool.terminateWorkers()
  const decompressedChunks = []
  for (let index = 0; index < results.length; index++) {
    // console.log(results[index].stdout)
    // console.error(results[index].stderr)
    decompressedChunks.push(results[index].outputs[0].data.data.buffer)
  }
  return decompressedChunks
}

export default bloscZarrDecompress