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make scoring client-side too for latency compensation

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This commit is contained in:
Sacha Greif 2013-10-29 13:30:35 +09:00
parent 2fbb506096
commit 9b441c1048
4 changed files with 47 additions and 51 deletions
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2
client/views/posts/post_item.html
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@ -4,10 +4,8 @@
<ul class="post-actions">
<li class="post-share desktop"><a href="#" class="share-link"><i class="icon-share"></i><span class="action">Share</span></a>
<div class="share-options hidden">
{{#constant}}
<div data-url="{{#if url}}{{url}}{{else}}{{current_domain}}/posts/{{_id}}{{/if}}" data-text="{{headline}}" class="share-replace">
</div>
{{/constant}}
</div>
</li>
<li class="post-discuss">

45
lib/scoring.js Normal file
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@ -0,0 +1,45 @@
updateScore = function (collection, id, forceUpdate) {
var forceUpdate = typeof forceUpdate !== 'undefined' ? forceUpdate : false;
// For performance reasons, the database is only updated if the difference between the old score and the new score
// is meaningful enough. To find out, we calculate the "power" of a single vote after n days.
// We assume that after n days, a single vote will not be powerful enough to affect posts' ranking order.
// Note: sites whose posts regularly get a lot of votes can afford to use a lower n.
// n = number of days after which a single vote will not have a big enough effect to trigger a score update
// and posts can become inactive
var n = 30;
// x = score increase amount of a single vote after n days (for n=100, x=0.000040295)
var x = 1/Math.pow(n*24+2,1.3);
// time decay factor
var f = 1.3;
var object = collection.findOne(id);
// use submitted timestamp if available, else (for pending posts) calculate score using createdAt
var age = object.submitted || object.createdAt;
// use baseScore if defined, if not just use the number of votes
// note: for transition period, also use votes if there are more votes than baseScore
// var baseScore = Math.max(object.votes || 0, object.baseScore || 0);
var baseScore = object.baseScore;
// now multiply by 'age' exponentiated
// FIXME: timezones <-- set by server or is getTime() ok?
var ageInHours = (new Date().getTime() - age) / (60 * 60 * 1000);
// HN algorithm
var newScore = baseScore / Math.pow(ageInHours + 2, f);
// Note: before the first time updateScore runs on a new item, its score will be at 0
var scoreDiff = Math.abs(object.score - newScore);
// only update database if difference is larger than x to avoid unnecessary updates
if (forceUpdate || scoreDiff > x){
collection.update(id, {$set: {score: newScore, inactive: false}});
return 1;
}else if(ageInHours > n*24){
// only set a post as inactive if it's older than n days
collection.update(id, {$set: {inactive: true}});
}
return 0;
};

4
lib/vote.js
View file

@ -42,8 +42,8 @@
$inc: {votes: vote, baseScore: votePower},
$set: {inactive: false}
});
if(!this.isSimulation)
updateScore(collection, id, true);
updateScore(collection, id, true);
// Karma
// user's posts and comments do not impact his own karma:

47
server/scoring.js
View file

@ -1,50 +1,3 @@
// "secret" server code to recalculate scores
updateScore = function (collection, id, forceUpdate) {
var forceUpdate = typeof forceUpdate !== 'undefined' ? forceUpdate : false;
// For performance reasons, the database is only updated if the difference between the old score and the new score
// is meaningful enough. To find out, we calculate the "power" of a single vote after n days.
// We assume that after n days, a single vote will not be powerful enough to affect posts' ranking order.
// Note: sites whose posts regularly get a lot of votes can afford to use a lower n.
// n = number of days after which a single vote will not have a big enough effect to trigger a score update
// and posts can become inactive
var n = 30;
// x = score increase amount of a single vote after n days (for n=100, x=0.000040295)
var x = 1/Math.pow(n*24+2,1.3);
// time decay factor
var f = 1.3;
var object = collection.findOne(id);
// use submitted timestamp if available, else (for pending posts) calculate score using createdAt
var age = object.submitted || object.createdAt;
// use baseScore if defined, if not just use the number of votes
// note: for transition period, also use votes if there are more votes than baseScore
// var baseScore = Math.max(object.votes || 0, object.baseScore || 0);
var baseScore = object.baseScore;
// now multiply by 'age' exponentiated
// FIXME: timezones <-- set by server or is getTime() ok?
var ageInHours = (new Date().getTime() - age) / (60 * 60 * 1000);
// HN algorithm
var newScore = baseScore / Math.pow(ageInHours + 2, f);
// Note: before the first time updateScore runs on a new item, its score will be at 0
var scoreDiff = Math.abs(object.score - newScore);
// only update database if difference is larger than x to avoid unnecessary updates
if (forceUpdate || scoreDiff > x){
collection.update(id, {$set: {score: newScore, inactive: false}});
return 1;
}else if(ageInHours > n*24){
// only set a post as inactive if it's older than n days
collection.update(id, {$set: {inactive: true}});
}
return 0;
};
Meteor.startup(function () {
var scoreInterval = getSetting("scoreUpdateInterval") || 30;