Class: RedisRing::Master

Inherits:
Object
  • Object
show all
Defined in:
lib/redis_ring/master.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(zookeeper_connection, ring_size, node_provider) ⇒ Master

Returns a new instance of Master.



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# File 'lib/redis_ring/master.rb', line 7

def initialize(zookeeper_connection, ring_size, node_provider)
  @zookeeper_connection = zookeeper_connection
  @ring_size = ring_size
  @node_provider = node_provider
  @node_ids = []
  @is_master = false
end

Instance Attribute Details

#node_provider ⇒ Object (readonly)

Returns the value of attribute node_provider.



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# File 'lib/redis_ring/master.rb', line 5

def node_provider
  @node_provider
end

#ring_size ⇒ Object (readonly)

Returns the value of attribute ring_size.



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# File 'lib/redis_ring/master.rb', line 5

def ring_size
  @ring_size
end

#zookeeper_connection ⇒ Object (readonly)

Returns the value of attribute zookeeper_connection.



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# File 'lib/redis_ring/master.rb', line 5

def zookeeper_connection
  @zookeeper_connection
end

Instance Method Details

#became_master ⇒ Object 



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# File 'lib/redis_ring/master.rb', line 15

def became_master
  return if is_master?

  puts "BECAME MASTER"

  @is_master = true
end

#is_master? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/redis_ring/master.rb', line 59

def is_master?
  return @is_master
end

#no_longer_is_master ⇒ Object 



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# File 'lib/redis_ring/master.rb', line 23

def no_longer_is_master
  return unless is_master?

  puts "LOST MASTER STATUS"

  @is_master = false
end

#node_joined(node_id) ⇒ Object 



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# File 'lib/redis_ring/master.rb', line 46

def node_joined(node_id)
  puts "NODE JOINED #{node_id}"

  reassign_shards
end

#node_leaving(node_id) ⇒ Object 



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# File 'lib/redis_ring/master.rb', line 52

def node_leaving(node_id)
  puts "NODE LEAVING #{node_id}"

  node_ids.delete(node_id)
  reassign_shards
end

#nodes_changed(changed_node_ids) ⇒ Object 



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# File 'lib/redis_ring/master.rb', line 31

def nodes_changed(changed_node_ids)
  return unless is_master?

  new_nodes = changed_node_ids - node_ids
  removed_nodes = node_ids - changed_node_ids

  puts "NODES CHANGED"
  puts "NEW: #{new_nodes.join(", ")}" if new_nodes.any?
  puts "REMOVED: #{removed_nodes.join(', ')}" if removed_nodes.any?

  @node_ids = changed_node_ids

  reassign_shards
end

#reassign_shards ⇒ Object 



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# File 'lib/redis_ring/master.rb', line 63

def reassign_shards
  update_node_statuses

  running_shards = {}
  best_candidates = {}
  best_candidates_timestamps = Hash.new(0)

  nodes.each do |node_id, node|
    node.running_shards.dup.each do |shard_no|
      if running_shards.key?(shard_no)
        node.stop_shard(shard_no)
      else
        running_shards[shard_no] = node_id
      end
    end

    node.available_shards.each do |shard_no, timestamp|
      if timestamp > best_candidates_timestamps[shard_no]
        best_candidates[shard_no] = node_id
        best_candidates_timestamps[shard_no] = timestamp
      end
    end
  end

  offline_shards = (0...ring_size).to_a - running_shards.keys
  shards_per_node = (1.0 * ring_size / nodes.size).floor
  rest = ring_size - shards_per_node * nodes.size

  nodes.each do |node_id, node|
    next unless node.joined?
    break if offline_shards.empty?
    count_to_assign = shards_per_node - node.running_shards.size
    count_to_assign += 1 if node_ids.index(node_id) < rest
    count_to_assign.times do
      shard_no = offline_shards.shift
      break unless shard_no
      node.start_shard(shard_no)
    end
  end

  zookeeper_connection.update_status(status)
end

#status ⇒ Object 



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# File 'lib/redis_ring/master.rb', line 106

def status
  {
    :ring_size => ring_size,
    :shards => shards
  }
end