From 79fd2d13649180c7c67a0bf37b90518f9fa5a5a3 Mon Sep 17 00:00:00 2001
From: Wu Cheng-Han <jacky_cute0808@hotmail.com>
Date: Sun, 18 Sep 2016 16:50:20 +0800
Subject: [PATCH] Update to add revision saving policy

---
 app.js                 |  2 +-
 lib/models/revision.js | 26 +++++++++++++++++++++++---
 lib/realtime.js        |  4 ++--
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/app.js b/app.js
index 1d3c7a9..339ff6c 100644
--- a/app.js
+++ b/app.js
@@ -526,7 +526,7 @@ models.sequelize.sync().then(function () {
     if (realtime.isReady()) {
         models.Revision.checkAllNotesRevision(function (err, notes) {
             if (err) return new Error(err);
-            if (notes.length <= 0) return startListen();
+            if (!notes || notes.length <= 0) return startListen();
         });
     }
 });
diff --git a/lib/models/revision.js b/lib/models/revision.js
index 5d66f9f..b497f0e 100644
--- a/lib/models/revision.js
+++ b/lib/models/revision.js
@@ -167,7 +167,7 @@ module.exports = function (sequelize, DataTypes) {
             checkAllNotesRevision: function (callback) {
                 Revision.saveAllNotesRevision(function (err, notes) {
                     if (err) return callback(err, null);
-                    if (notes.length <= 0) {
+                    if (!notes || notes.length <= 0) {
                         return callback(null, notes);
                     } else {
                         Revision.checkAllNotesRevision(callback);
@@ -176,6 +176,7 @@ module.exports = function (sequelize, DataTypes) {
             },
             saveAllNotesRevision: function (callback) {
                 sequelize.models.Note.findAll({
+                    // query all notes that need to save for revision
                     where: {
                         $and: [
                             {
@@ -201,11 +202,30 @@ module.exports = function (sequelize, DataTypes) {
                     }
                 }).then(function (notes) {
                     if (notes.length <= 0) return callback(null, notes);
+                    var savedNotes = [];
                     async.each(notes, function (note, _callback) {
-                        Revision.saveNoteRevision(note, _callback);
+                        // revision saving policy: note not been modified for 5 mins or not save for 10 mins
+                        if (note.lastchangeAt && note.savedAt) {
+                            var lastchangeAt = moment(note.lastchangeAt);
+                            var savedAt = moment(note.savedAt);
+                            if (moment().isAfter(lastchangeAt.add(1, 'minutes'))) {
+                                savedNotes.push(note);
+                                Revision.saveNoteRevision(note, _callback);
+                            } else if (lastchangeAt.isAfter(savedAt.add(2, 'minutes'))) {
+                                savedNotes.push(note);
+                                Revision.saveNoteRevision(note, _callback);
+                            } else {
+                                return _callback(null, null);
+                            }
+                        } else {
+                            savedNotes.push(note);
+                            Revision.saveNoteRevision(note, _callback);
+                        }
                     }, function (err) {
                         if (err) return callback(err, null);
-                        return callback(null, notes);
+                        // return null when no notes need saving at this moment but have delayed tasks to be done 
+                        var result = ((savedNotes.length == 0) && (notes.length > savedNotes.length)) ? null : savedNotes;
+                        return callback(null, result);
                     });
                 }).catch(function (err) {
                     return callback(err, null);
diff --git a/lib/realtime.js b/lib/realtime.js
index 2f5bbe3..0c68a25 100644
--- a/lib/realtime.js
+++ b/lib/realtime.js
@@ -187,13 +187,13 @@ var cleaner = setInterval(function () {
         if (err) return logger.error('cleaner error', err);
     });
 }, 60000);
-var saverSleep = true;
+var saverSleep = false;
 // save note revision in interval
 var saver = setInterval(function () {
     if (saverSleep) return;
     models.Revision.saveAllNotesRevision(function (err, notes) {
         if (err) return logger.error('revision saver failed: ' + err);
-        if (notes.length <= 0) {
+        if (notes && notes.length <= 0) {
             saverSleep = true;
             return;
         }