leaderboard

Leaderboards backed by Redis in Ruby.

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

Installation

gem install leaderboard

or in your Gemfile

gem 'leaderboard'

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

require 'leaderboard'

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

  highscore_lb = Leaderboard.new('highscores')
   => #<Leaderboard:0x0000010307b530 @leaderboard_name="highscores", @page_size=25, @redis_connection=#<Redis client v2.2.2 connected to redis://localhost:6379/0 (Redis v2.2.5)>>

Defining leaderboard options

The Leaderboard::DEFAULT_OPTIONS are as follows:

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:

  redis_options = {:host => 'localhost', :port => 6379, :db => 1}
   => {:host=>"localhost", :port=>6379, :db=>1}
  highscore_lb = Leaderboard.new('highscores', Leaderboard::DEFAULT_OPTIONS, redis_options)
   => #<Leaderboard:0x00000103095200 @leaderboard_name="highscores", @page_size=25, @redis_connection=#<Redis client v2.2.2 connected to redis://localhost:6379/1 (Redis v2.2.5)>>

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

  redis = Redis.new
   => #<Redis client v2.2.2 connected to redis://127.0.0.1:6379/0 (Redis v2.2.5)>
  redis_options = {:redis_connection => redis}
   => {:redis_connection=>#<Redis client v2.2.2 connected to redis://127.0.0.1:6379/0 (Redis v2.2.5)>}
  highscore_lb = Leaderboard.new('highscores', Leaderboard::DEFAULT_OPTIONS, redis_options)
   => #<Leaderboard:0x000001028791e8 @leaderboard_name="highscores", @page_size=25, @redis_connection=#<Redis client v2.2.2 connected to redis://127.0.0.1:6379/0 (Redis v2.2.5)>>

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

redis = Redis.new
 => #<Redis client v2.2.2 connected to redis://127.0.0.1:6379/0 (Redis v2.2.5)>
redis_options = {:redis_connection => redis}
 => {:redis_connection=>#<Redis client v2.2.2 connected to redis://127.0.0.1:6379/0 (Redis v2.2.5)>}
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):

  highscore_lb.page_size = 5
   => 5
  highscore_lb
   => #<Leaderboard:0x000001028791e8 @leaderboard_name="highscores", @page_size=5, @redis_connection=#<Redis client v2.2.2 connected to redis://127.0.0.1:6379/0 (Redis v2.2.5)>>

Ranking members in the leaderboard

Add members to your leaderboard using rank_member:

  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:

  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:

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:

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:

  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:

  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:

  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:

  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:

  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:

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:

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:

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:

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}]

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

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:

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

Or as an array:

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

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 for more detail on each method.

Performance Metrics

10 million sequential scores insert:

  highscore_lb = Leaderboard.new('highscores')
   => #<Leaderboard:0x0000010205fc50 @leaderboard_name="highscores", @page_size=25, @redis_connection=#<Redis client v2.2.2 connected to redis://localhost:6379/0 (Redis v2.2.5)>>

  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:

  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:

  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:

  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:

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:

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.

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):

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.

agoragames/leaderboard

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