Class: Remix::Stash::Cluster

Inherits:
Object
  • Object
show all
Includes:
Socket::Constants
Defined in:
lib/remix/stash/cluster.rb

Constant Summary collapse

@@connections = 
{}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(hosts) ⇒ Cluster

Returns a new instance of Cluster.



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# File 'lib/remix/stash/cluster.rb', line 11

def initialize(hosts)
  @hosts = hosts.map {|x|
    host, port = x.split(':')
    [x, host, (port || 11211).to_i]
  }.sort_by {|(_,h,p)| [h,p]}
end

Instance Attribute Details

#hosts ⇒ Object (readonly)

Returns the value of attribute hosts.



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# File 'lib/remix/stash/cluster.rb', line 9

def hosts
  @hosts
end

Instance Method Details

#each ⇒ Object 



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# File 'lib/remix/stash/cluster.rb', line 18

def each
  @hosts.each do |h|
    begin
      io = host_to_io(*h)
      break yield(io)
    rescue Errno::EPIPE, Errno::ECONNRESET, Remix::Stash::ProtocolError
      io.close
      retry
    rescue Errno::EAGAIN, Errno::ECONNREFUSED
      next
    end
  end
end

#select(key) ⇒ Object

Note: Later, I’d like to support richer cluster definitions. This should do the trick for now… and it’s fast.

Raises:



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# File 'lib/remix/stash/cluster.rb', line 34

def select(key)
  count = @hosts.size
  hash = nil
  if count > 1
    digest = Digest::MD5.digest(key)
    hash = digest.unpack("L")[0]
  else
    hash = 0
  end
  count.times do |try|
    begin
      io = host_to_io(*@hosts[(hash + try) % count])
      return yield(io)
    rescue Errno::EPIPE, Errno::ECONNRESET, Remix::Stash::ProtocolError
      io.close
      retry
    rescue Errno::EAGAIN, Errno::ECONNREFUSED
      next
    end
  end
  raise Remix::Stash::ClusterError,
    "Unable to find suitable host to communicate with for #{key.inspect} (MD5-32=#{hash})"
end