js-libp2p/src/content-routing.js

'use strict'

const errCode = require('err-code')
const { messages, codes } = require('./errors')

const all = require('it-all')
const pAny = require('p-any')

module.exports = (node) => {
  const routers = node._modules.contentRouting || []
  const dht = node._dht

  // If we have the dht, make it first
  if (dht) {
    routers.unshift(dht)
  }

  return {
    /**
     * Iterates over all content routers in series to find providers of the given key.
     * Once a content router succeeds, iteration will stop.
     *
     * @param {CID} key The CID key of the content to find
     * @param {object} [options]
     * @param {number} [options.timeout] How long the query should run
     * @param {number} [options.maxNumProviders] - maximum number of providers to find
     * @returns {AsyncIterable<PeerInfo>}
     */
    async * findProviders (key, options) {
      if (!routers.length) {
        throw errCode(new Error('No content routers available'), 'NO_ROUTERS_AVAILABLE')
      }

      const result = await pAny(
        routers.map(async (router) => {
          const provs = await all(router.findProviders(key, options))

          if (!provs || !provs.length) {
            throw errCode(new Error('not found'), 'NOT_FOUND')
          }
          return provs
        })
      )

      for (const pInfo of result) {
        yield pInfo
      }
    },

    /**
     * Iterates over all content routers in parallel to notify it is
     * a provider of the given key.
     *
     * @param {CID} key The CID key of the content to find
     * @returns {Promise<void>}
     */
    async provide (key) { // eslint-disable-line require-await
      if (!routers.length) {
        throw errCode(new Error('No content routers available'), 'NO_ROUTERS_AVAILABLE')
      }

      return Promise.all(routers.map((router) => router.provide(key)))
    },

    /**
     * Store the given key/value pair in the DHT.
     * @param {Buffer} key
     * @param {Buffer} value
     * @param {Object} [options] - put options
     * @param {number} [options.minPeers] - minimum number of peers required to successfully put
     * @returns {Promise<void>}
     */
    async put (key, value, options) { // eslint-disable-line require-await
      if (!node.isStarted() || !dht.isStarted) {
        throw errCode(new Error(messages.NOT_STARTED_YET), codes.DHT_NOT_STARTED)
      }

      return dht.put(key, value, options)
    },

    /**
     * Get the value to the given key.
     * Times out after 1 minute by default.
     * @param {Buffer} key
     * @param {Object} [options] - get options
     * @param {number} [options.timeout] - optional timeout (default: 60000)
     * @returns {Promise<{from: PeerId, val: Buffer}>}
     */
    async get (key, options) { // eslint-disable-line require-await
      if (!node.isStarted() || !dht.isStarted) {
        throw errCode(new Error(messages.NOT_STARTED_YET), codes.DHT_NOT_STARTED)
      }

      return dht.get(key, options)
    },

    /**
     * Get the `n` values to the given key without sorting.
     * @param {Buffer} key
     * @param {number} nVals
     * @param {Object} [options] - get options
     * @param {number} [options.timeout] - optional timeout (default: 60000)
     * @returns {Promise<Array<{from: PeerId, val: Buffer}>>}
     */
    async getMany (key, nVals, options) { // eslint-disable-line require-await
      if (!node.isStarted() || !dht.isStarted) {
        throw errCode(new Error(messages.NOT_STARTED_YET), codes.DHT_NOT_STARTED)
      }

      return dht.getMany(key, nVals, options)
    }
  }
}