v12.0.0 - initial commit

packages/server/lib/machine-settings.js

@@ -0,0 +1,145 @@
+const NodeCache = require('node-cache')
+
+const {
+  db: { default: kdb, inTransaction },
+  machines: { getMachinesGroups },
+  machineGroups: { getMachineGroupsComplianceTriggerSets },
+  complianceTriggers: { getAllComplianceTriggers },
+} = require('typesafe-db')
+
+const db = require('./db')
+const logger = require('./logger')
+
+db.connect({ direct: true }).then(sco => {
+  sco.client.on('notification', () => reloadAll())
+  return sco.none('LISTEN updated_machine_groups')
+})
+
+db.connect({ direct: true }).then(sco => {
+  sco.client.on('notification', () => reloadAll())
+  return sco.none('LISTEN updated_compliance_trigger_sets')
+})
+
+db.connect({ direct: true }).then(sco => {
+  sco.client.on('notification', () => reloadAll())
+  return sco.none('LISTEN updated_compliance_triggers')
+})
+
+// Make any given psudo real time clock strictly monotonic
+const StrictlyMonotonicPseudoRealTimeClock = opts => {
+  let last = opts?.last ?? 0
+  const now = opts?.now ?? Date.now
+  return () => (last = Math.max(last + 1, now()))
+}
+
+const timestamp = StrictlyMonotonicPseudoRealTimeClock()
+
+const TTL = 3600 // 1h in seconds
+const CACHE = new NodeCache({
+  stdTTL: TTL,
+  checkperiod: TTL / 3,
+})
+
+const KEY = 0
+
+const get = () => CACHE.get(KEY)
+const set = val => CACHE.set(KEY, val)
+
+CACHE.on('expired', (key, value) => {
+  reloadAll(value)
+})
+
+const oneAtATime = func => {
+  let running = null
+
+  // Wait for the function to finish, resolve with its result, and clear the
+  // running promise. Resolving a reject results in a reject.
+  const stop = res => resolve =>
+    Promise.resolve(res)
+      .then(resolve)
+      .finally(() => {
+        running = null
+      })
+
+  // If the function is running, return the current promise. Otherwise, create
+  // a new promise and run the function.
+  return (...args) => running || (running = new Promise(stop(func(...args))))
+}
+
+const getTriggersByMachine = (machines, machineGroups, complianceTriggers) => {
+  const triggersBySet = Object.groupBy(
+    complianceTriggers,
+    t => t.complianceTriggerSetId,
+  )
+
+  const triggersByGroup = Object.fromEntries(
+    machineGroups.map(({ id, complianceTriggerSetId }) => [
+      id,
+      // Machine groups with no compliance trigger set have no compliance triggers.
+      triggersBySet[complianceTriggerSetId] ?? [],
+    ]),
+  )
+
+  return Object.fromEntries(
+    machines.map(({ deviceId, machineGroupId }) => [
+      deviceId,
+      triggersByGroup[machineGroupId],
+    ]),
+  )
+}
+
+const reloadAll = oneAtATime(oldCache => {
+  const ts = timestamp()
+  oldCache ??= get() // oldCache is given only on `expired`
+  oldCache ??= [null, {}] // the cache is empty on the first reload
+
+  const ret = inTransaction(
+    async tx => [
+      await getMachinesGroups(tx),
+      await getMachineGroupsComplianceTriggerSets(tx),
+      await getAllComplianceTriggers(tx),
+    ],
+    kdb,
+  )
+    .then(([machines, machineGroups, complianceTriggers]) => [
+      ts,
+      getTriggersByMachine(machines, machineGroups, complianceTriggers),
+    ])
+    .catch(err => {
+      logger.error(err)
+      logger.info(
+        'Reloading machine settings cache failed; using previous cache',
+      )
+      return oldCache
+    })
+
+  set(ret)
+  return ret
+})
+
+const getFromPromise = async (cachePromise, deviceId) => {
+  if (!cachePromise) return null
+  const [settingsVersion, cache] = await cachePromise
+  const complianceTriggers = cache[deviceId]
+  if (!complianceTriggers) return null
+  return { settingsVersion, complianceTriggers }
+}
+
+const getOrUpdate = async (deviceId, machineVersion) => {
+  let settings =
+    (await getFromPromise(get(), deviceId)) ??
+    (await getFromPromise(reloadAll(), deviceId))
+
+  if (!settings)
+    throw new Error(`Compliance triggers cache has no entry for ${deviceId}`)
+
+  if (machineVersion && settings.settingsVersion < machineVersion)
+    throw new Error(`Compliance triggers cache is older than ${deviceId}`)
+
+  return settings
+}
+
+module.exports = {
+  reloadAll,
+  getOrUpdate,
+}