Merge branch '215-admins-can-undo-recycle' into 'main'

Resolve "admins can undo recycle"

Closes #215

See merge request !384

app/api/routes.js

@@ -69,9 +69,7 @@ const routesOf = async router => {
 
   router.post('/phoneNumbers/recycle', async ctx => {
     const { phoneNumbers } = ctx.request.body
-    const result = await phoneNumberService.recycle({
-      phoneNumbers,
-    })
+    const result = await phoneNumberService.requestToRecycle(phoneNumbers.split(','))
     merge(ctx, { status: httpStatusOfMany(result), body: result })
   })
 

app/config/job.js

 const defaults = {
+  healthcheckInterval: 1000 * 60 * 15, // 15 min
+  hotlineMessageExpiryInMillis: 1000 * 60 * 60 * 24 * 28, // 4 weeks
   inviteDeletionInterval: 1000 * 60 * 60, // 1 hour
   inviteExpiryInMillis: 1000 * 60 * 60 * 24 * 14, // 2 weeks
-  hotlineMessageExpiryInMillis: 1000 * 60 * 60 * 24 * 28, // 4 weeks
+  recycleInterval: 1000 * 60 * 60, // 1 hr
+  recycleGracePeriod: 1000 * 60 * 60 * 24, // 1 day
+  signaldStartupTime: 3000 * 60, // 3 min
+}
+
+const testInterval = 50
+
+const development = {
+  ...defaults,
+  healthcheckInterval: 1000 * 60, // 60 sec
+  recycleInterval: 1000 * 5, // 5 secs
+  recycleGracePeriod: 1000 * 30, // 30 sec
 }
 
 const test = {
   ...defaults,
-  inviteDeletionInterval: 100, // 100 millis
+  testInterval,
+  healthcheckInterval: testInterval, // millis
+  inviteDeletionInterval: testInterval,
+  recycleInterval: testInterval,
+  signaldStartupTime: 1, //  millis
   inviteExpiryInMillis: 200, // 200 millis
 }
 
 module.exports = {
-  development: defaults,
+  development,
   test,
   production: defaults,
 }

app/config/signal.js

@@ -4,7 +4,6 @@ const defaults = {
   broadcastSpacing: 100, // 100 millis
   defaultMessageExpiryTime: 60 * 60 * 24 * 7, // 1 week
   expiryUpdateDelay: 200, // 200 millis
-  healtcheckInterval: 1000 * 60 * 15, // 15 min
   healthcheckTimeout: 1000 * 60 * 15, // 15 min
   healtcheckSpacing: 100, // 100 millis
   intervalBetweenRegistrationBatches: 120000, // 2 minutes
@@ -18,7 +17,6 @@ const defaults = {
   signaldRequestTimeout: 1000 * 10, // 10 sec
   signaldVerifyTimeout: 1000 * 30, // 30 sec
   signaldSendTimeout: 1000 * 60 * 60, // 60 min
-  signaldStartupTime: 3000 * 60, // 3 min
   supportPhoneNumber: (process.env.SUPPORT_CHANNEL_NUMBER || '').replace(`"`, ''),
   diagnosticsPhoneNumber: (process.env.DIAGNOSTICS_CHANNEL_NUMBER || '').replace(`"`, ''),
   welcomeDelay: 3000, // 3 sec
@@ -29,7 +27,6 @@ const test = {
   broadcastBatchInterval: 10, // 10 millis
   broadcastBatchSize: 1,
   expiryUpdateDelay: 1, // millis
-  healthcheckInterval: 30, // millis
   healthcheckTimeout: 30, // millis
   intervalBetweenRegistrationBatches: 30, // millis
   intervalBetweenRegistrations: 5, // millis,
@@ -40,7 +37,6 @@ const test = {
   signaldSendTimeout: 40, // millis
   signaldRequestTimeout: 10, // millis
   signaldVerifyTimeout: 20, // millis
-  signaldStartupTime: 1, //  millis
   supportPhoneNumber: '+15555555555',
   welcomeDelay: 0.0001, // millis
   diagnosticsPhoneNumber: '+15554443333',
@@ -48,7 +44,6 @@ const test = {
 
 const development = {
   ...defaults,
-  healtcheckInterval: 1000 * 60, // 60 sec
   healthcheckTimeout: 1000 * 60, // 60 sec
 }
 

app/db/index.js

@@ -10,6 +10,8 @@ const { membershipOf } = require('./models/membership')
 const { messageCountOf } = require('./models/messageCount')
 const { phoneNumberOf } = require('./models/phoneNumber')
 const { smsSenderOf } = require('./models/smsSender')
+const { recycleRequestOf } = require('./models/recycleRequest')
+
 const { wait } = require('../util')
 const { maxConnectionAttempts, connectionInterval } = config
 
@@ -28,6 +30,7 @@ const run = async () => {
     membership: membershipOf(sequelize, Sequelize),
     messageCount: messageCountOf(sequelize, Sequelize),
     phoneNumber: phoneNumberOf(sequelize, Sequelize),
+    recycleRequest: recycleRequestOf(sequelize, Sequelize),
     smsSender: smsSenderOf(sequelize, Sequelize),
   }
 

app/db/migrations/20200623002750-create-recycleablePhoneNumbers-table.js

+'use strict';
+
+module.exports = {
+  up: (queryInterface, Sequelize) => {
+    return queryInterface.createTable('recycleablePhoneNumbers', {
+      channelPhoneNumber: {
+        type: Sequelize.STRING,
+        primaryKey: true,
+        allowNull: false,
+        unique: true,
+      },
+      whenEnqueued: {
+        type: Sequelize.DATE,
+        allowNull: false,
+      },
+      createdAt: {
+        type: Sequelize.DATE,
+        allowNull: false,
+        defaultValue: Sequelize.NOW,
+      },
+      updatedAt: {
+        type: Sequelize.DATE,
+        allowNull: false,
+        defaultValue: Sequelize.NOW,
+      },
+    });
+  },
+  down: (queryInterface, Sequelize) => {
+    return queryInterface.dropTable('recycleablePhoneNumbers');
+  }
+};

app/db/migrations/20200907153345-rename-recyclable-phone-numbers-to-recycle-requests.js

+'use strict';
+
+module.exports = {
+  up: async (queryInterface, Sequelize) => {
+    
+    await queryInterface.createTable('recycleRequests', {
+      phoneNumber: {
+        type: Sequelize.STRING,
+        primaryKey: true,
+        allowNull: false,
+        unique: true,
+      },
+      createdAt: {
+        type: Sequelize.DATE,
+        allowNull: false,
+        defaultValue: Sequelize.NOW,
+      },
+      updatedAt: {
+        type: Sequelize.DATE,
+        allowNull: false,
+        defaultValue: Sequelize.NOW,
+      },
+    })
+
+    await queryInterface.addIndex('recycleRequests', {
+      fields: ['createdAt']
+    })
+
+    return queryInterface.dropTable('recycleablePhoneNumbers')
+  },
+
+  down: async (queryInterface, Sequelize) => {
+    
+    await queryInterface.dropTable('recycleRequests')
+    
+    return queryInterface.createTable('recycleablePhoneNumbers', {
+      channelPhoneNumber: {
+        type: Sequelize.STRING,
+        primaryKey: true,
+        allowNull: false,
+        unique: true,
+      },
+      whenEnqueued: {
+        type: Sequelize.DATE,
+        allowNull: false,
+      },
+      createdAt: {
+        type: Sequelize.DATE,
+        allowNull: false,
+        defaultValue: Sequelize.NOW,
+      },
+      updatedAt: {
+        type: Sequelize.DATE,
+        allowNull: false,
+        defaultValue: Sequelize.NOW,
+      },
+    });
+  }
+};

app/db/models/recycleRequest.js

+const { isPhoneNumber } = require('../validations')
+
+const recycleRequestOf = (sequelize, Sequelize) =>
+  sequelize.define('recycleRequest', {
+    phoneNumber: {
+      type: Sequelize.STRING,
+      primaryKey: true,
+      allowNull: false,
+      unique: true,
+      validate: isPhoneNumber,
+    },
+    createdAt: {
+      type: Sequelize.DATE,
+      allowNull: false,
+      defaultValue: Sequelize.NOW,
+    },
+    updatedAt: {
+      type: Sequelize.DATE,
+      allowNull: false,
+      defaultValue: Sequelize.NOW,
+    },
+  })
+
+module.exports = { recycleRequestOf }

app/db/repositories/channel.js

 const app = require('../../../app')
+const { Op } = require('sequelize')
 const { loggerOf } = require('../../util')
 const { memberTypes } = require('./membership')
+const { map } = require('lodash')
 const {
   signal: { supportPhoneNumber },
 } = require('../../config')
@@ -30,6 +32,14 @@ const update = (phoneNumber, attrs) =>
     .update({ ...attrs }, { where: { phoneNumber }, returning: true })
     .then(([, [pNumInstance]]) => pNumInstance)
 
+// (string, Transaction | null) => Promise<boolean>
+const destroy = async (phoneNumber, transaction) => {
+  const channel = await findByPhoneNumber(phoneNumber)
+  return channel
+    ? channel.destroy({ ...(transaction ? { transaction } : {}) }).then(() => true)
+    : false
+}
+
 const findAll = () => app.db.channel.findAll()
 
 const findAllDeep = () =>
@@ -42,6 +52,17 @@ const findAllDeep = () =>
     ],
   })
 
+const findManyDeep = phoneNumbers =>
+  app.db.channel.findAll({
+    where: { phoneNumber: { [Op.in]: phoneNumbers } },
+    include: [
+      { model: app.db.deauthorization },
+      { model: app.db.invite },
+      { model: app.db.membership },
+      { model: app.db.messageCount },
+    ],
+  })
+
 const findByPhoneNumber = phoneNumber => app.db.channel.findOne({ where: { phoneNumber } })
 
 const findDeep = phoneNumber =>
@@ -72,6 +93,10 @@ const isSysadmin = async phoneNumber => {
 
 // all selectors assume you are operating on an already deeply-fetched channel (with all nested attrs avail)
 const getMemberPhoneNumbers = channel => (channel.memberships || []).map(m => m.memberPhoneNumber)
+const getMembersExcept = (channel, members) => {
+  const phoneNumbersToExclude = new Set(map(members, 'memberPhoneNumber'))
+  return channel.memberships.filter(m => !phoneNumbersToExclude.has(m.memberPhoneNumber))
+}
 const getMemberPhoneNumbersExcept = (channel, phoneNumbers) =>
   getMemberPhoneNumbers(channel).filter(pn => !phoneNumbers.includes(pn))
 
@@ -89,14 +114,17 @@ const getSubscriberPhoneNumbers = channel =>
 
 module.exports = {
   create,
+  destroy,
   findAll,
   findAllDeep,
   findByPhoneNumber,
   findDeep,
+  findManyDeep,
   getAllAdminsExcept,
   getAdminMemberships,
   getAdminPhoneNumbers,
   getMemberPhoneNumbers,
+  getMembersExcept,
   getMemberPhoneNumbersExcept,
   getSubscriberMemberships,
   getSubscriberPhoneNumbers,

app/db/repositories/invite.js

@@ -2,14 +2,12 @@ const app = require('../../../app')
 const moment = require('moment')
 const { Op } = require('sequelize')
 const membershipRepository = require('./membership')
-const { repeatEvery, loggerOf } = require('../../util')
-const logger = loggerOf('db|inviteRepository')
 const {
   defaultLanguage,
-  job: { inviteExpiryInMillis, inviteDeletionInterval },
+  job: { inviteExpiryInMillis },
 } = require('../../config')
 
-// (Database, string, string, string) -> Promise<boolean>
+// (string, string, string) -> Promise<boolean>
 const issue = async (channelPhoneNumber, inviterPhoneNumber, inviteePhoneNumber) => {
   // issues invite IFF invitee is not already invited
   const [, wasCreated] = await app.db.invite.findOrCreate({
@@ -18,26 +16,22 @@ const issue = async (channelPhoneNumber, inviterPhoneNumber, inviteePhoneNumber)
   return wasCreated
 }
 
-// (Database, string, string) -> Promise<number>
+// (string, string) -> Promise<number>
 const count = (channelPhoneNumber, inviteePhoneNumber) =>
   app.db.invite.count({ where: { channelPhoneNumber, inviteePhoneNumber } })
 
-// (Database, string, string, string) -> Promise<Array<Membership,number>>
+// (string, string, string) -> Promise<Array<Membership,number>>
 const accept = (channelPhoneNumber, inviteePhoneNumber, language = defaultLanguage) =>
   Promise.all([
     membershipRepository.addSubscriber(channelPhoneNumber, inviteePhoneNumber, language),
     app.db.invite.destroy({ where: { channelPhoneNumber, inviteePhoneNumber } }),
   ])
 
-// (Database, string, string) -> Promise<number>
+// (string, string) -> Promise<number>
 const decline = async (channelPhoneNumber, inviteePhoneNumber) =>
   app.db.invite.destroy({ where: { channelPhoneNumber, inviteePhoneNumber } })
 
-// (Database, number) -> Promise<void>
-const launchInviteDeletionJob = () =>
-  repeatEvery(() => deleteExpired().catch(logger.error), inviteDeletionInterval)
-
-// Database -> Promise<number>
+// () -> Promise<number>
 const deleteExpired = async () =>
   app.db.invite.destroy({
     where: {
@@ -47,4 +41,4 @@ const deleteExpired = async () =>
     },
   })
 
-module.exports = { issue, count, accept, decline, deleteExpired, launchInviteDeletionJob }
+module.exports = { issue, count, accept, decline, deleteExpired }

app/db/repositories/phoneNumber.js

@@ -10,6 +10,14 @@ const filters = {
 const create = ({ phoneNumber, twilioSid, status }) =>
   app.db.phoneNumber.create({ phoneNumber, twilioSid, status })
 
+// (string, Transaction | null) => Promise<boolean>
+const destroy = async (phoneNumber, transaction) => {
+  const phoneNumberRecord = await find(phoneNumber)
+  return phoneNumberRecord
+    ? phoneNumber.destroy({ ...(transaction ? { transaction } : {}) }).then(() => true)
+    : false
+}
+
 const find = phoneNumber => app.db.phoneNumber.findOne({ where: { phoneNumber } })
 
 const findAll = () => app.db.phoneNumber.findAll()
@@ -35,4 +43,4 @@ const update = (phoneNumber, attrs) =>
     .update({ ...attrs }, { where: { phoneNumber }, returning: true })
     .then(([, [pNumInstance]]) => pNumInstance)
 
-module.exports = { filters, create, find, findAll, findAllPurchased, list, update }
+module.exports = { filters, create, destroy, find, findAll, findAllPurchased, list, update }

app/db/repositories/recycleRequest.js

+const { Op } = require('sequelize')
+const app = require('../../../app')
+const util = require('../../util')
+const { map, partition } = require('lodash')
+const {
+  job: { recycleGracePeriod },
+} = require('../../config')
+
+// (string) -> Promise<{ recycleRequest: RecycleRequest, wasCreated: boolean }>
+const requestToRecycle = phoneNumber =>
+  app.db.recycleRequest
+    .findOrCreate({ where: { phoneNumber } })
+    .then(([recycleRequest, wasCreated]) => ({
+      recycleRequest,
+      wasCreated,
+    }))
+
+// (Array<string>) -> Promise<void>
+const destroyMany = phoneNumbers =>
+  app.db.recycleRequest.destroy({
+    where: { phoneNumber: { [Op.in]: phoneNumbers } },
+  })
+
+const evaluateRecycleRequests = async () => {
+  // channel admins have a 1 day grace period to redeem a channel slated for recycling
+  // by using it. calculate when that grace period started...
+  const gracePeriodStart = util.now().subtract(parseInt(recycleGracePeriod), 'ms')
+
+  // find all the requests issued before the start of the grace period, indicating
+  // channels which should be considered for recycling (b/c their grace period has passed)
+  const matureRequests = await app.db.recycleRequest.findAll({
+    where: { createdAt: { [Op.lte]: gracePeriodStart } },
+  })
+
+  // make lists of redeemed and unredeemed channel phone numbers, where "redeemed" channels
+  // have been used since the start of the grace period, and thus should not be recycled
+  const [redeemed, toRecycle] = partition(
+    await app.db.messageCount.findAll({
+      where: { channelPhoneNumber: { [Op.in]: map(matureRequests, 'phoneNumber') } },
+    }),
+    messageCount => messageCount.updatedAt > gracePeriodStart,
+  )
+
+  // pluck the channel phone numbers and return them for processing!
+  return {
+    redeemed: map(redeemed, 'channelPhoneNumber'),
+    toRecycle: map(toRecycle, 'channelPhoneNumber'),
+  }
+}
+
+module.exports = { requestToRecycle, evaluateRecycleRequests, destroyMany }

app/diagnostics.js

@@ -6,7 +6,7 @@ const metrics = require('./metrics')
 const { zip } = require('lodash')
 const { sdMessageOf } = require('./signal/constants')
 const {
-  signal: { diagnosticsPhoneNumber, healtcheckInterval, healthcheckSpacing, signaldStartupTime },
+  signal: { diagnosticsPhoneNumber, healthcheckSpacing },
 } = require('./config')
 
 const logger = util.loggerOf('diagnostics')
@@ -51,14 +51,7 @@ const respondToHealthcheck = (channelPhoneNumber, healthcheckId) =>
     ),
   )
 
-// () => Promise<void>
-const launchHealthcheckJob = async () => {
-  await util.wait(signaldStartupTime)
-  return diagnosticsPhoneNumber && util.repeatEvery(sendHealthchecks, healtcheckInterval)
-}
-
 module.exports = {
   respondToHealthcheck,
   sendHealthchecks,
-  launchHealthcheckJob,
 }

app/dispatcher/strings/messages/DE.js

@@ -410,9 +410,15 @@ const notifications = {
   channelDestructionFailed: phoneNumber =>
     `Der Kanal mit der Signal-Nummer: ${phoneNumber} konnte nicht zerstört werden`,
 
+  channelEnqueuedForRecycling:
+    'Hallo! Dieser Kanal wird wegen mangelnder Nutzung deaktiviert. Um zu verhindern, dass es deaktiviert wird, senden Sie innerhalb der nächsten 24 Stunden "INFO". Weitere Informationen finden Sie unter signalboost.info/how-to.',
+
   channelRecycled:
     'Der Kanal wurde wegen Inaktivität deaktiviert. Gehe auf https://signalboost.info um einen neuen Kanal zu erstellen.',
 
+  channelRedeemed:
+    'Dieser Kanal sollte wegen mangelnder Nutzung deaktiviert werden. Da Sie den Kanal kürzlich verwendet haben, wird er jedoch nicht mehr deaktiviert. Yay!',
+
   channelRenamed: (oldName, newName) => `Kanal umbenannt von "${oldName}" zu "${newName}."`,
 
   deauthorization: adminPhoneNumber => `

app/dispatcher/strings/messages/EN.js

@@ -401,9 +401,15 @@ const notifications = {
   channelDestructionFailed: phoneNumber =>
     `Failed to destroy channel for phone number: ${phoneNumber}`,
 
+  channelEnqueuedForRecycling:
+    'Hello! This channel is about to be deactivated due to lack of use. To prevent it from being deactivated, send "INFO" within the next 24 hours. For more info, visit signalboost.info/how-to.',
+
   channelRecycled:
     'Channel deactivated due to lack of use. To create a new channel, visit https://signalboost.info',
 
+  channelRedeemed:
+    'This channel was scheduled to be deactivated due to lack of use. However, since you used the channel recently, it will no longer be deactivated. Yay!',
+
   channelRenamed: (oldName, newName) => `Channel renamed from "${oldName}" to "${newName}."`,
 
   deauthorization: adminPhoneNumber => `

app/dispatcher/strings/messages/ES.js

@@ -410,12 +410,18 @@ const notifications = {
 
   channelDestroyed: 'El canal ha sido destruido permanentemente por sus admins.',
 
+  channelEnqueuedForRecycling:
+    '¡Hola! Este canal está a punto de desactivarse por falta de uso. Para evitar que se desactive, envíe "INFO" en las próximas 24 horas. Para obtener más información, visite signalboost.info/how-to. ',
+
   channelDestructionFailed: phoneNumber =>
     `Error al destruir el canal para el número de teléfono:  ${phoneNumber}`,
 
   channelRecycled:
     'Canal desactivado por falta de uso. Para crear un nuevo canal, visite https://signalboost.info',
 
+  channelRedeemed:
+    'Este canal estaba programado para desactivarse por falta de uso. Sin embargo, dado que usó el canal recientemente, ya no estará desactivado. ¡Hurra!',
+
   channelRenamed: (oldName, newName) => `Canal renombrado de "${oldName}" a "${newName}."`,
 
   deauthorization: adminPhoneNumber => `

app/dispatcher/strings/messages/FR.js

@@ -413,13 +413,19 @@ const notifications = {
   adminLeft: 'Un-e admin vient de quitter le canal',
 
   channelDestroyed:
-    'La chaîne et tous les enregistrements associés ont été définitivement détruits.',
+    'La canal et tous les enregistrements associés ont été définitivement détruits.',
+
+  channelEnqueuedForRecycling:
+    "Bonjour! Cette canal est sur le point d'être désactivée faute d'utilisation. Pour éviter qu'il ne soit désactivé, envoyez 'INFO' dans les prochaines 24 heures.Pour plus d'informations, visitez signalboost.info/how-to. ",
 
   channelDestructionFailed: phoneNumber =>
-    `Impossible de détruire la chaîne pour le numéro de téléphone: ${phoneNumber}`,
+    `Impossible de détruire la canal pour le numéro de téléphone: ${phoneNumber}`,
 
   channelRecycled:
-    "Chaîne désactivée par manque d'utilisation. Pour créer une nouvelle chaîne, visitez https://signalboost.info",
+    "Canal désactivée par manque d'utilisation. Pour créer une nouvelle chaîne, visitez https://signalboost.info",
+
+  channelRedeemed:
+    "Cette canal devait être désactivée en raison d'un manque d'utilisation. Cependant, puisque vous avez utilisé la chaîne récemment, elle ne sera plus désactivée. Yay!",
 
   channelRenamed: (oldName, newName) => `Le canal a été renommé de "${oldName}" à "${newName}."`,
 

app/index.js

@@ -7,6 +7,7 @@ const app = {
   socketPool: null,
   api: null,
   metrics: null,
+  jobs: null,
 }
 
 app.run = async ({ db, socketPool, api, metrics, jobs, signal }) => {
@@ -40,7 +41,7 @@ app.run = async ({ db, socketPool, api, metrics, jobs, signal }) => {
   logger.log(`...created metrics registry!`)
 
   logger.log('Running startup jobs...')
-  await jobsService.run().catch(logger.fatalError)
+  app.jobs = jobsService.run().catch(logger.fatalError)
   logger.log('...ran startup jobs!')
 
   logger.log('Starting signal service...')
@@ -54,7 +55,12 @@ app.run = async ({ db, socketPool, api, metrics, jobs, signal }) => {
 app.stop = async () => {
   const { logger } = require('./util')
   logger.log('Shutting down signalboost...')
-  await Promise.all([app.socketPool.stop(), app.db.stop(), app.api.stop()])
+  await Promise.all([
+    () => app.socketPool.stop(),
+    () => app.db.stop(),
+    () => app.api.stop(),
+    () => app.jobs.stop(),
+  ])
   logger.log('...Signalboost shut down!')
 }
 

app/jobs.js

@@ -4,10 +4,26 @@ const inviteRepository = require('./db/repositories/invite')
 const smsSenderRepository = require('./db/repositories/smsSender')
 const hotlineMessageRepository = require('./db/repositories/hotlineMessage')
 const diagnostics = require('./diagnostics')
+const util = require('./util')
+const { values } = require('lodash')
+const {
+  job: { healthcheckInterval, inviteDeletionInterval, recycleInterval, signaldStartupTime },
+  signal: { diagnosticsPhoneNumber },
+} = require('./config')
+
+const cancelations = {
+  deleteInvitesJob: null,
+  recycleJob: null,
+  healtcheckJob: null,
+}
 
 const run = async () => {
   logger.log('--- Running startup jobs...')
 
+  /******************
+   * ONE-OFF JOBS
+   *****************/
+
   if (process.env.REREGISTER_ON_STARTUP === '1') {
     logger.log('----- Registering phone numbers...')
     const regs = await phoneNumberRegistrar.registerAllUnregistered().catch(logger.error)
@@ -15,24 +31,50 @@ const run = async () => {
   }
 
   logger.log('----- Deleting expired sms sender records...')
-  // here we rely on fact of nightly backups to ensure this task runs once every 24 hr.
+  // rely on fact of nightly backups to ensure this task runs at least every 24 hr.
   const sendersDeleted = await smsSenderRepository.deleteExpired()
   logger.log(`----- Deleted ${sendersDeleted} expired sms sender records.`)
 
   logger.log('----- Deleting expired hotline message records...')
-  // here we rely on fact of nightly backups to ensure this task runs once every 24 hr.
+  // rely on fact of nightly backups to ensure this task runs at least every 24 hr.
   const messageIdsDeleted