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https://github.com/agoragames/leaderboard

Leaderboards backed by Redis in Ruby
https://github.com/agoragames/leaderboard

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Leaderboards backed by Redis in Ruby

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# leaderboard



Leaderboards backed by [Redis](http://redis.io) in Ruby.



Builds off ideas proposed in http://www.agoragames.com/blog/2011/01/01/creating-high-score-tables-leaderboards-using-redis/.



[![Build Status](https://secure.travis-ci.org/agoragames/leaderboard.png)](http://travis-ci.org/agoragames/leaderboard)



## Installation



`gem install leaderboard`



or in your `Gemfile`



```ruby

gem 'leaderboard'

```



Make sure your redis server is running! Redis configuration is outside the scope of this README, but

check out the [Redis documentation](http://redis.io/documentation).



## Compatibility



The gem has been built and tested under 2.2.1.



NOTE: The gem should work fine in earlier versions of Ruby such as 1.8.7 or 1.9.3. There are no specific aspects of Ruby 2.x that we utilize at this time.



## Usage



### Creating a leaderboard



Be sure to require the leaderboard library:



```ruby

require 'leaderboard'

```



Create a new leaderboard or attach to an existing leaderboard named 'highscores':



```ruby

  highscore_lb = Leaderboard.new('highscores')

   => #>

```



### Defining leaderboard options



The `Leaderboard::DEFAULT_OPTIONS` are as follows:



```ruby

DEFAULT_OPTIONS = {

  :page_size => DEFAULT_PAGE_SIZE,

  :reverse => false,

  :member_key => :member,

  :rank_key => :rank,

  :score_key => :score,

  :member_data_key => :member_data,

  :member_data_namespace => 'member_data',

  :global_member_data => false

}

```



The `DEFAULT_PAGE_SIZE` is 25.



You would use the option, `:reverse => true`, if you wanted a leaderboard sorted from lowest-to-highest score. You may also set the `reverse` option on a leaderboard after you have created a new instance of a leaderboard. The various `..._key` options above control what data is returned in the hash of leaderboard data from calls such as `leaders` or `around_me`. Finally, the `global_member_data` option allows you to control whether optional member data is per-leaderboard (`false`) or global (`true`).



If you need to pass in options for Redis, you can do this in the initializer:



```ruby

  redis_options = {:host => 'localhost', :port => 6379, :db => 1}

   => {:host=>"localhost", :port=>6379, :db=>1}

  highscore_lb = Leaderboard.new('highscores', Leaderboard::DEFAULT_OPTIONS, redis_options)

   => #>

```



You can pass in an existing connection to Redis using `:redis_connection` in the `redis_options` hash:



```ruby

  redis = Redis.new

   => #

  redis_options = {:redis_connection => redis}

   => {:redis_connection=>#}

  highscore_lb = Leaderboard.new('highscores', Leaderboard::DEFAULT_OPTIONS, redis_options)

   => #>

```



To use the same connection for multiple leaderboards, reset the options hash before instantiating more leaderboards:



```ruby

redis = Redis.new

 => #

redis_options = {:redis_connection => redis}

 => {:redis_connection=>#}

highscore_lb = Leaderboard.new('highscores', Leaderboard::DEFAULT_OPTIONS, redis_options)

redis_options = {:redis_connection => redis}

other_highscore_lb = Leaderboard.new('other_highscores', Leaderboard::DEFAULT_OPTIONS, redis_options)

```



You can set the page size to something other than the default page size (25):



```ruby

  highscore_lb.page_size = 5

   => 5

  highscore_lb

   => #>

```



### Ranking members in the leaderboard



Add members to your leaderboard using `rank_member`:



```ruby

  1.upto(10) do |index|

    highscore_lb.rank_member("member_#{index}", index)

  end

   => 1

```



You can call `rank_member` with the same member and the leaderboard will be updated automatically.



Get some information about your leaderboard:



```ruby

  highscore_lb.total_members

   => 10

  highscore_lb.total_pages

   => 1

```



The `rank_member` call will also accept an optional parameter, `member_data` that could

be used to store other information about a given member in the leaderboard. This

may be useful in situations where you are storing member IDs in the leaderboard and

you want to be able to store a member name for display. You could use JSON to

encode a Hash of member data. Example:



```ruby

require 'json'

highscore_lb.rank_member('84849292', 1, {'username' => 'member_name'}.to_json)

```



You can retrieve, update and remove the optional member data using the

`member_data_for`, `update_member_data` and `remove_member_data` calls. Example:



```ruby

JSON.parse(highscore_lb.member_data_for('84849292'))

 => {"username"=>"member_name"}



highscore_lb.update_member_data('84849292', {'last_updated' => Time.now, 'username' => 'updated_member_name'}.to_json)

 => "OK"

JSON.parse(highscore_lb.member_data_for('84849292'))

 => {"username"=>"updated_member_name", "last_updated"=>"2012-06-09 09:11:06 -0400"}



highscore_lb.remove_member_data('84849292')

```



If you delete the leaderboard, ALL of the member data is deleted as well.



#### Optional member data notes



If you use optional member data, the use of the `remove_members_in_score_range` or `remove_members_outside_rank` methods

will leave data around in the member data hash. This is because the internal Redis method, `zremrangebyscore`,

only returns the number of items removed. It does not return the members that it removed.



Get some information about a specific member(s) in the leaderboard:



```ruby

  highscore_lb.score_for('member_4')

   => 4.0

  highscore_lb.rank_for('member_4')

   => 7

  highscore_lb.rank_for('member_10')

   => 1

```



### Retrieving members from the leaderboard



Get page 1 in the leaderboard:



```ruby

  highscore_lb.leaders(1)

   => [{:member=>"member_10", :rank=>1, :score=>10.0}, {:member=>"member_9", :rank=>2, :score=>9.0}, {:member=>"member_8", :rank=>3, :score=>8.0}, {:member=>"member_7", :rank=>4, :score=>7.0}, {:member=>"member_6", :rank=>5, :score=>6.0}, {:member=>"member_5", :rank=>6, :score=>5.0}, {:member=>"member_4", :rank=>7, :score=>4.0}, {:member=>"member_3", :rank=>8, :score=>3.0}, {:member=>"member_2", :rank=>9, :score=>2.0}, {:member=>"member_1", :rank=>10, :score=>1.0}]

```



You can pass various options to the calls `leaders`, `all_leaders`, `around_me`, `members_from_score_range`, `members_from_rank_range` and `ranked_in_list`. Valid options are:



* `:with_member_data` - `true` or `false` (default) to return the optional member data.

* `:page_size` - An integer value to change the page size for that call.

* `:members_only` - `true` or `false` (default) to return only the members without their score and rank.

* `:sort_by` - Valid values for `:sort_by` are `:none` (default), `:score` and `:rank`.

* `:include_missing` - `true` (default) or `false` to return members that are not ranked.



You can also use the `members` and `members_in` methods as aliases for the `leaders` and `leaders_in` methods.



There are also a few convenience methods to be able to retrieve all leaders from a given leaderboard. They are `all_leaders` and `all_leaders_from`. You may also use the aliases `all_members` or `all_members_from`. Use any of these methods sparingly as all the information in the leaderboard will be returned.



Add more members to your leaderboard:



```ruby

  50.upto(95) do |index|

    highscore_lb.rank_member("member_#{index}", index)

  end

   => 50

  highscore_lb.total_pages

   => 3

```



Get an "Around Me" leaderboard page for a given member, which pulls members above and below the given member:



```ruby

  highscore_lb.around_me('member_53')

   => [{:member=>"member_65", :rank=>31, :score=>65.0}, {:member=>"member_64", :rank=>32, :score=>64.0}, {:member=>"member_63", :rank=>33, :score=>63.0}, {:member=>"member_62", :rank=>34, :score=>62.0}, {:member=>"member_61", :rank=>35, :score=>61.0}, {:member=>"member_60", :rank=>36, :score=>60.0}, {:member=>"member_59", :rank=>37, :score=>59.0}, {:member=>"member_58", :rank=>38, :score=>58.0}, {:member=>"member_57", :rank=>39, :score=>57.0}, {:member=>"member_56", :rank=>40, :score=>56.0}, {:member=>"member_55", :rank=>41, :score=>55.0}, {:member=>"member_54", :rank=>42, :score=>54.0}, {:member=>"member_53", :rank=>43, :score=>53.0}, {:member=>"member_52", :rank=>44, :score=>52.0}, {:member=>"member_51", :rank=>45, :score=>51.0}, {:member=>"member_50", :rank=>46, :score=>50.0}, {:member=>"member_10", :rank=>47, :score=>10.0}, {:member=>"member_9", :rank=>48, :score=>9.0}, {:member=>"member_8", :rank=>49, :score=>8.0}, {:member=>"member_7", :rank=>50, :score=>7.0}, {:member=>"member_6", :rank=>51, :score=>6.0}, {:member=>"member_5", :rank=>52, :score=>5.0}, {:member=>"member_4", :rank=>53, :score=>4.0}, {:member=>"member_3", :rank=>54, :score=>3.0}, {:member=>"member_2", :rank=>55, :score=>2.0}]

```



Get rank and score for an arbitrary list of members (e.g. friends) from the leaderboard:



```ruby

  highscore_lb.ranked_in_list(['member_1', 'member_62', 'member_67'])

   => [{:member=>"member_1", :rank=>56, :score=>1.0}, {:member=>"member_62", :rank=>34, :score=>62.0}, {:member=>"member_67", :rank=>29, :score=>67.0}]

```



Retrieve members from the leaderboard in a given score range:



```ruby

members = highscore_lb.members_from_score_range(4, 19)

 => [{:member=>"member_10", :rank=>47, :score=>10.0}, {:member=>"member_9", :rank=>48, :score=>9.0}, {:member=>"member_8", :rank=>49, :score=>8.0}, {:member=>"member_7", :rank=>50, :score=>7.0}, {:member=>"member_6", :rank=>51, :score=>6.0}, {:member=>"member_5", :rank=>52, :score=>5.0}, {:member=>"member_4", :rank=>53, :score=>4.0}]

```



Retrieve a single member from the leaderboard at a given position:



```ruby

members = highscore_lb.member_at(4)

 => {:member=>"member_92", :rank=>4, :score=>92.0}

```



Retrieve a range of members from the leaderboard within a given rank range:



```ruby

members = highscore_lb.members_from_rank_range(1, 5)

 => [{:member=>"member_95", :rank=>1, :score=>95.0}, {:member=>"member_94", :rank=>2, :score=>94.0}, {:member=>"member_93", :rank=>3, :score=>93.0}, {:member=>"member_92", :rank=>4, :score=>92.0}, {:member=>"member_91", :rank=>5, :score=>91.0}]

```



The option `:sort_by` is useful for retrieving an arbitrary list of

members from a given leaderboard where you would like the data sorted

when returned. The follow examples demonstrate its use:



```ruby

friends = highscore_lb.ranked_in_list(['member_6', 'member_1', 'member_10'], :sort_by => :rank)

 => [{:member=>"member_10", :rank=>47, :score=>10.0}, {:member=>"member_6", :rank=>51, :score=>6.0}, {:member=>"member_1", :rank=>56, :score=>1.0}]

```



```ruby

friends = highscore_lb.ranked_in_list(['member_6', 'member_1', 'member_10'], :sort_by => :score)

 => [{:member=>"member_1", :rank=>56, :score=>1.0}, {:member=>"member_6", :rank=>51, :score=>6.0}, {:member=>"member_10", :rank=>47, :score=>10.0}]

```



### Conditionally rank a member in the leaderboard



You can pass a lambda to the `rank_member_if` method to conditionally rank a member in the leaderboard. The lambda is passed the following 5 parameters:



* `member`: Member name.

* `current_score`: Current score for the member in the leaderboard. May be `nil` if the member is not currently ranked in the leaderboard.

* `score`: Member score.

* `member_data`: Optional member data.

* `leaderboard_options`: Leaderboard options, e.g. :reverse => Value of reverse option



```ruby

highscore_check = lambda do |member, current_score, score, member_data, leaderboard_options|

  return true if current_score.nil?

  return true if score > current_score

  false

end



highscore_lb.rank_member_if(highscore_check, 'david', 1337)

highscore_lb.score_for('david')

 => 1337.0

highscore_lb.rank_member_if(highscore_check, 'david', 1336)

highscore_lb.score_for('david')

 => 1337.0

highscore_lb.rank_member_if(highscore_check, 'david', 1338)

highscore_lb.score_for('david')

 => 1338.0

```



NOTE: Use a lambda and not a proc, otherwise you will get a `LocalJumpError` as a return statement in the proc will return from the method enclosing the proc.



### Ranking multiple members in a leaderboard at once



Insert multiple data items for members and their associated scores:



As a splat:



```ruby

highscore_lb.rank_members('member_1', 1, 'member_5', 5, 'member_10', 10)

```



Or as an array:



```ruby

highscore_lb.rank_members(['member_1', 1, 'member_5', 5, 'member_10', 10])

```



Use this method to do bulk insert of data, but be mindful of the amount of data you are inserting since a single transaction can get quite large.



### Ranking a member across multiple leaderboards



```ruby

highscore_lb.rank_member_across(['highscores', 'more_highscores'], 'david', 50000, { :member_name => "david" })

```



### Alternate leaderboard types



The leaderboard library offers 3 styles of ranking. This is only an issue for members with the same score in a leaderboard.



Default: The `Leaderboard` class uses the default Redis sorted set ordering, whereby different members having the same score are ordered lexicographically. As per the Redis documentation on Redis sorted sets, "The lexicographic ordering used is binary, it compares strings as array of bytes."



Tie ranking: The `TieRankingLeaderboard` subclass of `Leaderboard` allows you to define a leaderboard where members with the same score are given the same rank. For example, members in a leaderboard with the associated scores would have the ranks of:



```

| member     | score | rank |

-----------------------------

| member_1   | 50    | 1    |

| member_2   | 50    | 1    |

| member_3   | 30    | 2    |

| member_4   | 30    | 2    |

| member_5   | 10    | 3    |

```



The `TieRankingLeaderboard` accepts one additional option, `:ties_namespace` (default: ties), when initializing a new instance of this class. Please note that in its current implementation, the `TieRankingLeaderboard` class uses an additional sorted set to rank the scores, so please keep this in mind when you are doing any capacity planning for Redis with respect to memory usage.



Competition ranking: The `CompetitionRankingLeaderboard` subclass of `Leaderboard` allows you to define a leaderboard where members with the same score will have the same rank, and then a gap is left in the ranking numbers. For example, members in a leaderboard with the associated scores would have the ranks of:



```

| member     | score | rank |

-----------------------------

| member_1   | 50    | 1    |

| member_2   | 50    | 1    |

| member_3   | 30    | 3    |

| member_4   | 30    | 3    |

| member_5   | 10    | 5    |

```



### Other useful methods



```

  delete_leaderboard: Delete the current leaderboard

  member_data_for(member): Retrieve the optional member data for a given member in the leaderboard

  members_data_for(members): Retrieve the optional member data for a given list of members in the leaderboard

  update_member_data(member, member_data): Update the optional member data for a given member in the leaderboard

  remove_member_data(member): Remove the optional member data for a given member in the leaderboard

  remove_member(member): Remove a member from the leaderboard

  total_members: Total # of members in the leaderboard

  total_pages: Total # of pages in the leaderboard given the leaderboard's page_size

  total_members_in_score_range(min_score, max_score): Count the number of members within a score range in the leaderboard

  total_scores: Sum of scores for all members in leaderboard

  change_score_for(member, delta): Change the score for a member by some amount delta (delta could be positive or negative)

  rank_for(member): Retrieve the rank for a given member in the leaderboard

  score_for(member): Retrieve the score for a given member in the leaderboard

  check_member?(member): Check to see whether member is in the leaderboard

  score_and_rank_for(member): Retrieve the score and rank for a member in a single call

  remove_members_in_score_range(min_score, max_score): Remove members from the leaderboard within a score range

  remove_members_outside_rank(rank): Remove members from the leaderboard outside a given rank

  percentile_for(member): Calculate the percentile for a given member

  score_for_percentile(percentile): Calculate the score for a given percentile value in the leaderboard

  page_for(member, page_size): Determine the page where a member falls in the leaderboard

  expire_leaderboard(seconds): Expire the leaderboard in a set number of seconds.

  expire_leaderboard_at(timestamp): Expire the leaderboard at a specific UNIX timestamp.

  rank_members(members_and_scores): Rank an array of members in the leaderboard where you can call via (member_name, score) or pass in an array of [member_name, score]

  merge_leaderboards(destination, keys, options = {:aggregate => :min}): Merge leaderboards given by keys with this leaderboard into destination

  intersect_leaderboards(destination, keys, options = {:aggregate => :min}): Intersect leaderboards given by keys with this leaderboard into destination

  top(number, options): Retrieve members from the leaderboard within a range from 1 to the number given.

```



Check the [online documentation](http://rubydoc.info/gems/leaderboard/frames) for more detail on each method.



## Performance Metrics



10 million sequential scores insert:



```ruby

  highscore_lb = Leaderboard.new('highscores')

   => #>



  insert_time = Benchmark.measure do

    1.upto(10000000) do |index|

      highscore_lb.rank_member("member_#{index}", index)

    end

  end

   => 323.070000 148.560000 471.630000 (942.068307)

```



Average time to request an arbitrary page from the leaderboard:



```ruby

  requests_to_make = 50000

   => 50000

  lb_request_time = 0

   => 0

  1.upto(requests_to_make) do

    lb_request_time += Benchmark.measure do

      highscore_lb.leaders(rand(highscore_lb.total_pages))

    end.total

  end

   => 1

  p lb_request_time / requests_to_make

  0.001513999999999998

   => 0.001513999999999998

```



10 million random scores insert:



```ruby

  insert_time = Benchmark.measure do

    1.upto(10000000) do |index|

      highscore_lb.rank_member("member_#{index}", rand(50000000))

    end

  end

   => 338.480000 155.200000 493.680000 (2188.702475)

```



Average time to request an arbitrary page from the leaderboard:



```ruby

  1.upto(requests_to_make) do

    lb_request_time += Benchmark.measure do

      highscore_lb.leaders(rand(highscore_lb.total_pages))

    end.total

  end

   => 1

  p lb_request_time / requests_to_make

  0.0014615999999999531

   => 0.0014615999999999531

```



### Bulk insert performance



Ranking individual members:



```ruby

insert_time = Benchmark.measure do

  1.upto(1000000) do |index|

    highscore_lb.rank_member("member_#{index}", index)

  end

end

 =>  29.340000  15.050000  44.390000 ( 81.673507)

```



Ranking multiple members at once:



```ruby

member_data = []

 => []

1.upto(1000000) do |index|

  member_data << "member_#{index}"

  member_data << index

end

 => 1

insert_time = Benchmark.measure do

  highscore_lb.rank_members(member_data)

end

 =>  22.390000   6.380000  28.770000 ( 31.144027)

```



## Ports



The following ports have been made of the [leaderboard gem](https://github.com/agoragames/leaderboard).



Officially supported:



* CoffeeScript: https://github.com/agoragames/leaderboard-coffeescript

* Python: https://github.com/agoragames/leaderboard-python

* Ruby: https://github.com/agoragames/leaderboard



Unofficially supported (they need some feature parity love):



* Java: https://github.com/agoragames/java-leaderboard

* PHP: https://github.com/agoragames/php-leaderboard

* Scala: https://github.com/agoragames/scala-leaderboard



## Contributing to leaderboard



* Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet

* Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it

* Fork the project

* Start a feature/bugfix branch

* Commit and push until you are happy with your contribution

* Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.

* Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.



## Copyright



Copyright (c) 2011-2017 David Czarnecki. See LICENSE.txt for further details.