autobase-discovery/lib/db.js

Automatic service discovery with self-registering services, using autobase

const HyperDB = require('hyperdb')
const ReadyResource = require('ready-resource')
const DBLock = require('db-lock')
const IdEnc = require('hypercore-id-encoding')

const spec = require('../spec/hyperdb')

class RpcDiscoveryDb extends ReadyResource {
  constructor(core, { maxParallel = 256, extension = true } = {}) {
    super()

    const db = HyperDB.bee(core, spec, { extension, autoUpdate: true })
    this.db = db
    this._lock = new DBLock({
      // Sanity check so we always flush at some point,
      // even with a continuous stream of put requests
      maxParallel,
      enter() {
        return db.transaction()
      },
      async exit(tx) {
        await tx.flush()
      }
    })
  }

  get key() {
    return this.db.core.key
  }

  get discoveryKey() {
    return this.db.core.discoveryKey
  }

  async _open() {
    await this.db.ready()
  }

  async _close() {
    await this.db.close()
  }

  async insert(publicKey, service) {
    publicKey = IdEnc.decode(publicKey)
    if (!this.opened) await this.ready()

    const tx = await this._lock.enter()
    try {
      await tx.insert('@autodiscovery/service-entry', { publicKey, service })
    } finally {
      await this._lock.exit(tx)
    }
  }

  async get(publicKey) {
    publicKey = IdEnc.decode(publicKey)
    if (!this.opened) await this.ready()

    const entry = await this.db.get('@autodiscovery/service-entry', {
      publicKey
    })
    return entry
  }

  async has(publicKey) {
    return (await this.get(publicKey)) !== null
  }

  async delete(publicKey) {
    publicKey = IdEnc.decode(publicKey)
    if (!this.opened) await this.ready()

    const tx = await this._lock.enter()
    try {
      await tx.delete('@autodiscovery/service-entry', { publicKey })
    } finally {
      await this._lock.exit(tx)
    }
  }

  list(service, { limit = 100 } = {}) {
    const query = { gte: { service }, lte: { service } }
    return this.db.find('@autodiscovery/services', query, { limit })
  }
}

module.exports = RpcDiscoveryDb