refactor cron to avoid double cronning - work in progress

website/server/controllers/api-v3/groups.js

@@ -119,7 +119,7 @@ api.getGroup = {
   url: '/groups/:groupId',
   // Disable cron when getting groups to avoid race conditions when the site is loaded
   // and requests for party and user data are concurrent
-  runCron: false,
+  runCron: true,
   middlewares: [authWithHeaders()],
   async handler (req, res) {
     let user = res.locals.user;

website/server/middlewares/api-v3/cron.js

@@ -10,14 +10,16 @@ import { v4 as uuid } from 'uuid';
 
 const daysSince = common.daysSince;
 
-module.exports = function cronMiddleware (req, res, next) {
+module.exports = async function cronMiddleware (req, res, next) {
   let user = res.locals.user;
-
   if (!user) return next(); // User might not be available when authentication is not mandatory
 
   let analytics = res.analytics;
-
   let now = new Date();
+  let _cronSignature = uuid();
+
+  try {
+    console.log('CHECKING RUN CRON', req.originalUrl, req.method, (new Date()).toISOString());
 
     // If the user's timezone has changed (due to travel or daylight savings),
     // cron can be triggered twice in one day, so we check for that and use
@@ -98,44 +100,37 @@ module.exports = function cronMiddleware (req, res, next) {
     }
 
     if (daysMissed <= 0) return next();
+    console.log('RUNNING CRON FOR REAL', req.originalUrl, req.method, (new Date()).toISOString());
 
-  let quest;
-  let progress;
-  let tasks;
-
-  // To avoid double cron we set _cronSignature on the user to a random string
-  // and check that it has remained the same before saving
-  user._cronSignature = uuid();
-
-  User.update({
+    // To avoid double cron we first set _cronSignature to now and then check that it's not changed while processing
+    let userUpdateResult = await User.update({
       _id: user._id,
-    _cronSignature: 'not-running',
+      _cronSignature: 'not-running', // Check that in the meantime another cron has not started
     }, {
       $set: {
-      _cronSignature: user._cronSignature,
+        _cronSignature,
       },
-  }).exec()
-  .then((updateResult) => { // Fetch active tasks (no completed todos)
+    }).exec();
+    console.log('FIRST USER UPDATE?', userUpdateResult, req.originalUrl, req.method, (new Date()).toISOString());
+
     // if the cron signature is set, throw an error and recover later
-    if (updateResult.nMatched === 0 || updateResult.nUpdated === 0) {
+    if (userUpdateResult.nMatched === 0 || userUpdateResult.nModified === 0) {
       throw new Error('cron-already-running');
     }
 
-    return Tasks.Task.find({
+    let tasks = await Tasks.Task.find({
       userId: user._id,
       $or: [ // Exclude completed todos
         {type: 'todo', completed: false},
         {type: {$in: ['habit', 'daily', 'reward']}},
       ],
     }).exec();
-  })
-  .then(tasksFetched => {
-    tasks = tasksFetched;
+
     let tasksByType = {habits: [], dailys: [], todos: [], rewards: []};
     tasks.forEach(task => tasksByType[`${task.type}s`].push(task));
 
     // Run cron
-    progress = cron({user, tasksByType, now, daysMissed, analytics, timezoneOffsetFromUserPrefs});
+    let progress = cron({user, tasksByType, now, daysMissed, analytics, timezoneOffsetFromUserPrefs});
 
     // Clear old completed todos - 30 days for free users, 90 for subscribers
     // Do not delete challenges completed todos TODO unless the task is broken?
@@ -149,74 +144,65 @@ module.exports = function cronMiddleware (req, res, next) {
       'challenge.id': {$exists: false},
     }).exec();
 
-    let ranCron = user.isModified();
-    quest = common.content.quests[user.party.quest.key];
+    let quest = common.content.quests[user.party.quest.key];
 
-    if (ranCron) res.locals.wasModified = true; // TODO remove after v2 is retired
-    if (!ranCron) return next();
+    res.locals.wasModified = true; // TODO remove after v2 is retired
 
     // Group.tavernBoss(user, progress);
+    let reallyModifiedPaths = {}; // Mongoose stores both path and path.nested in user.modifiedPaths()
 
-    // Save user and tasks
-    // Uses mongoose's internals to get update command
-    let mongooseDelta = user.$__delta();
-    if (mongooseDelta instanceof Error) {
-      throw mongooseDelta;
+    user.modifiedPaths().forEach(path => {
+      let rootPath = path.split('.')[0];
+      if (Object.keys(reallyModifiedPaths).indexOf(rootPath) === -1) {
+        let dataForPath = user[rootPath].toObject ? user[rootPath].toObject() : user[rootPath];
+        reallyModifiedPaths[rootPath] = dataForPath;
       }
+    });
+    reallyModifiedPaths._cronSignature = 'not-running'; // Finish running cron
 
-    let mongooseWhere = user.$__where(mongooseDelta[0]);
-    if (mongooseWhere instanceof Error) {
-      throw mongooseWhere;
-    }
-    mongooseWhere._cronSignature = user._cronSignature; // Only update the user if cron signature matches
+    // Save user (only if another cron has done it already!)
+    let secondUserUpdateResult = await User.update({
+      _id: user._id,
+      _cronSignature,
+    }, {
+      $set: reallyModifiedPaths,
+    }).exec();
+    console.log('SECOND USER UPDATE?', secondUserUpdateResult, req.originalUrl, req.method, (new Date()).toISOString());
 
-    return User.update(mongooseWhere, mongooseDelta[1]);
-  })
-  .then(updateResult => {
-    // if the cron signature is set, throw an error and recover later
-    if (updateResult.nMatched === 0 || updateResult.nUpdated === 0) {
+    // if cron already run, throw and recover later
+    if (secondUserUpdateResult.nMatched === 0 || secondUserUpdateResult.nModified === 0) {
       throw new Error('cron-already-running');
     }
 
-    let toSave = [];
+    let tasksToSave = [];
     tasks.forEach(task => {
-      if (task.isModified()) toSave.push(task.save());
+      if (task.isModified()) tasksToSave.push(task.save());
     });
+    await Bluebird.all(tasksToSave);
 
-    return Bluebird.all(toSave);
-  })
-  .then(() => {
     if (!quest) return;
+
     // If user is on a quest, roll for boss & player, or handle collections
     let questType = quest.boss ? 'boss' : 'collect';
     // TODO this saves user, runs db updates, loads user. Is there a better way to handle this?
-    return Group[`${questType}Quest`](user, progress);
-  })
-  .then(() => {
-    User.findByIdAndUpdate(user._id, {
-      $set: {_cronSignature: 'not-running'},
-    }, {
-      new: true, // return the updated document
-    }).exec();
-  }) // fetch the updated user...
-  .then(updatedUser => {
-    user = res.locals.user = updatedUser;
+    await Group[`${questType}Quest`](user, progress);
+
+    res.locals.user = await User.findById(user._id).exec();
 
-    return null;
-  })
-  .then(() => next())
-  .catch((err) => {
-    if (err.message === 'cron-already-running') {
-      // recovering after abort, wait 200ms and reload user
-      setTimeout(() => {
-        User.findById(user._id, (reloadErr, reloadedUser) => {
-          if (reloadErr) return next(reloadErr);
-          user = res.locals.user = reloadedUser;
     return next();
-        });
-      }, 200);
+  } catch (err) {
+    if (err.message === 'cron-already-running') {
+      console.log('RECOVERING FROM CRON', req.originalUrl, req.method, (new Date()).toISOString());
+      // recovering after abort, wait 200ms and reload user
+      Bluebird.delay(200).then(() => {
+        return User.findById(user._id).exec();
+      }).then((reloadedUser) => {
+        res.locals.user = reloadedUser;
+        console.log('RECOVERED FROM CRON', req.originalUrl, req.method, (new Date()).toISOString());
+        return next();
+      }).catch(secondError => next(secondError));
     } else {
       return next(err);
     }
-  });
+  }
 };

website/server/models/group.js

@@ -25,6 +25,9 @@ const Schema = mongoose.Schema;
 export const INVITES_LIMIT = 100;
 export const TAVERN_ID = shared.TAVERN_ID;
 
+const CRON_SAFE_MODE = nconf.get('CRON_SAFE_MODE') === 'true';
+const CRON_SEMI_SAFE_MODE = nconf.get('CRON_SEMI_SAFE_MODE') === 'true';
+
 // NOTE once Firebase is enabled any change to groups' members in MongoDB will have to be run through the API
 // changes made directly to the db will cause Firebase to get out of sync
 export let schema = new Schema({
@@ -516,7 +519,7 @@ schema.statics.bossQuest = async function bossQuest (user, progress) {
   group.quest.progress.hp -= progress.up;
   // TODO Create a party preferred language option so emits like this can be localized. Suggestion: Always display the English version too. Or, if English is not displayed to the players, at least include it in a new field in the chat object that's visible in the database - essential for admins when troubleshooting quests!
   let playerAttack = `${user.profile.name} attacks ${quest.boss.name('en')} for ${progress.up.toFixed(1)} damage.`;
-  let bossAttack = nconf.get('CRON_SAFE_MODE') === 'true' || nconf.get('CRON_SEMI_SAFE_MODE') === 'true' ? `${quest.boss.name('en')} does not attack, because it respects the fact that there are some bugs\` \`post-maintenance and it doesn't want to hurt anyone unfairly. It will continue its rampage soon!` : `${quest.boss.name('en')} attacks party for ${Math.abs(down).toFixed(1)} damage.`;
+  let bossAttack = CRON_SAFE_MODE || CRON_SEMI_SAFE_MODE ? `${quest.boss.name('en')} does not attack, because it respects the fact that there are some bugs\` \`post-maintenance and it doesn't want to hurt anyone unfairly. It will continue its rampage soon!` : `${quest.boss.name('en')} attacks party for ${Math.abs(down).toFixed(1)} damage.`;
   // TODO Consider putting the safe mode boss attack message in an ENV var
   group.sendChat(`\`${playerAttack}\` \`${bossAttack}\``);