Class: Herdis::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/herdis/client.rb

Defined Under Namespace

Classes: DeadClusterException, ReDistributed

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Client

Returns a new instance of Client.



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# File 'lib/herdis/client.rb', line 46

def initialize(*args)
  @options = args.last.is_a?(Hash) ? args.pop : {}
  @shepherds = {}
  args.each_with_index do |url, index|
    @shepherds["initial#{index}"] = {"url" => url}
  end
  begin
    refresh_cluster
  rescue DeadClusterException => e
    raise "No such cluster: #{url}"
  end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(meth, *args, &block) ⇒ Object 



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# File 'lib/herdis/client.rb', line 118

def method_missing(meth, *args, &block)
  if @dredis
    begin
      @dredis.send(meth, *args, &block)
    rescue DeadClusterException => e
      refresh_cluster
      retry
    rescue Errno::ECONNREFUSED => e
      refresh_cluster
      retry
    rescue RuntimeError => e
      if e.message == "ERR operation not permitted"
        refresh_cluster
        retry
      else
        raise e
      end
    end
  else
    super.send(meth, *args, &block)
  end
end

Instance Attribute Details

#dredis ⇒ Object (readonly)

Returns the value of attribute dredis.



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# File 'lib/herdis/client.rb', line 44

def dredis
  @dredis
end

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/herdis/client.rb', line 44

def options
  @options
end

#shepherds ⇒ Object (readonly)

Returns the value of attribute shepherds.



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# File 'lib/herdis/client.rb', line 44

def shepherds
  @shepherds
end

Instance Method Details

#create_urls(cluster) ⇒ Object 



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# File 'lib/herdis/client.rb', line 59

def create_urls(cluster)
  hash = {}
  cluster.each do |shepherd_id, shepherd_status|
    shepherd_url = URI.parse(shepherd_status["url"])
    (shepherd_status["masters"] || []).each do |shard_id|
      hash[shard_id.to_i] = "redis://#{shepherd_url.host}:#{shepherd_status["first_port"].to_i + shard_id.to_i}/"
    end
  end
  urls = hash.keys.sort.collect do |key|
    hash[key]
  end
end

#refresh_cluster ⇒ Object 



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# File 'lib/herdis/client.rb', line 87

def refresh_cluster
  cluster = nil
  while cluster.nil?
    raise DeadClusterException.new if @shepherds.empty?
    random_shepherd_id = @shepherds.keys[rand(@shepherds.size)]
    cluster_request = 
      EM::HttpRequest.new(@shepherds[random_shepherd_id]["url"]).get(:path => "/cluster",
                                                                     :head => {"Accept" => "application/json"})
    if cluster_request.response_header.status == 0
      @shepherds.delete(random_shepherd_id)
    else
      cluster = Yajl::Parser.parse(cluster_request.response)
      begin
        urls = create_urls(cluster)
        validate(urls)
      rescue Errno::ECONNREFUSED => e
        cluster = nil
      rescue RuntimeError => e
        if e.message == "ERR operation not permitted"
          cluster = nil
        else
          raise e
        end
      end
    end
  end
  @shepherds = cluster
  @dredis = ReDistributed.new(urls,
                              @options)
end

#validate(urls) ⇒ Object 



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# File 'lib/herdis/client.rb', line 72

def validate(urls)
  unless urls.size == Herdis::Common::SHARDS
    raise "Broken cluster, there should be #{Herdis::Common::SHARDS} shards, but are #{urls.size}"
  end
  creators = Set.new
  urls.each_with_index do |url, index|
    parsed = URI.parse(url)
    r = Redis.new(:host => parsed.host, :port => parsed.port)
    claimed_shard = r.get("Herdis::Shepherd::Shard.id").to_i
    creators << r.get("Herdis::Shepherd::Shard.created_by")
    raise "Broken cluster, shard #{index} claims to be shard #{claimed_shard}" unless claimed_shard == index
    raise "Broken cluster, multiple creators: #{creators.inspect}" if creators.size > 1
  end
end