Class: RubySkynet::Zookeeper::ServiceRegistry

Inherits:
Object
  • Object
show all
Includes:
SemanticLogger::Loggable
Defined in:
lib/ruby_skynet/zookeeper/service_registry.rb

Defined Under Namespace

Classes: ServerInfo

Instance Method Summary collapse

Constructor Details

#initialize(params = {}) ⇒ ServiceRegistry

Create a service registry See: RubyDoozer::Registry for the parameters



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# File 'lib/ruby_skynet/zookeeper/service_registry.rb', line 19

def initialize(params = {})
  # Registry has the following format
  #  Key: [String] 'name/version/region'
  #  Value: [Array<String>] 'host:port', 'host:port'
  @cache = ThreadSafe::Hash.new
  @notifications_cache = ThreadSafe::Hash.new

  # Keep a list of registered services so that they can be re-registered
  # if the connection is lost
  @services = ThreadSafe::Hash.new

  # Supply block to load the current keys from the Registry
  params[:root] = '/instances'
  params[:ephemeral] = true
  params[:on_connect] = Proc.new do |registry|
    # Re-Register services every time the connection to ZooKeeper is lost
    @services.values.each {|v| register_service(*v)}
  end
  @registry = Zookeeper::Registry.new(params) do |key, value|
    service_info_created(key, value)
  end
  # Register Callbacks
  @registry.on_create {|path, value| service_info_created(path, value) }
  @registry.on_update {|path, value| service_info_updated(path, value) }
  @registry.on_delete {|path|        service_info_deleted(path) }
end

Instance Method Details

#deregister_service(name, version, region, hostname, port) ⇒ Object

Deregister the supplied service from the Registry



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# File 'lib/ruby_skynet/zookeeper/service_registry.rb', line 66

def deregister_service(name, version, region, hostname, port)
  uuid = "#{hostname}:#{port}-#{$$}-#{name}-#{version}"
  @registry.delete(File.join(uuid,'addr'), false)
  @registry.delete(File.join(uuid,'name'), false)
  @registry.delete(File.join(uuid,'version'), false)
  @registry.delete(File.join(uuid,'region'), false)
  @registry.delete(File.join(uuid,'registered'), false)
  @registry.delete(uuid, false)
  # Remove from local services list
  @services.delete(uuid)
 uuid
end

#on_server_removed(server, &block) ⇒ Object

Invokes registered callbacks when a specific server is shutdown or terminates Not when a server de-registers itself The callback will only be called once and will need to be re-registered after being called if future callbacks are required for that server



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# File 'lib/ruby_skynet/zookeeper/service_registry.rb', line 112

def on_server_removed(server, &block)
  ((@on_server_removed_callbacks ||= ThreadSafe::Hash.new)[server] ||= ThreadSafe::Array.new) << block
end

#register_service(name, version, region, hostname, port) ⇒ Object

Register the supplied service at this Skynet Server host and Port Returns the UUID for the service that was created



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# File 'lib/ruby_skynet/zookeeper/service_registry.rb', line 53

def register_service(name, version, region, hostname, port)
  uuid = "#{hostname}:#{port}-#{$$}-#{name}-#{version}"
  @registry[File.join(uuid,'addr')]       = "#{hostname}:#{port}"
  @registry[File.join(uuid,'name')]       = name
  @registry[File.join(uuid,'version')]    = version
  @registry[File.join(uuid,'region')]     = region
  @registry[File.join(uuid,'registered')] = true
  # Add to local services list
  @services[uuid] = [name, version, region, hostname, port]
  uuid
end

#server_for(name, version = '*', region = RubySkynet.region) ⇒ Object

Return a server that implements the specified service



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# File 'lib/ruby_skynet/zookeeper/service_registry.rb', line 80

def server_for(name, version='*', region=RubySkynet.region)
  if servers = servers_for(name, version, region)
    # Randomly select one of the servers offering the service
    servers[rand(servers.size)]
  else
    msg = "No servers available for service: #{name} with version: #{version} in region: #{region}"
    logger.warn msg
    raise ServiceUnavailable.new(msg)
  end
end

#servers_for(name, version = '*', region = RubySkynet.region) ⇒ Object

Returns [Array<String>] a list of servers implementing the requested service



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# File 'lib/ruby_skynet/zookeeper/service_registry.rb', line 92

def servers_for(name, version='*', region=RubySkynet.region)
  if version == '*'
    # Find the highest version for the named service in this region
    version = -1
    @cache.keys.each do |key|
      if match = key.match(/#{name}\/(\d+)\/#{region}/)
        ver = match[1].to_i
        version = ver if ver > version
      end
    end
  end
  if server_infos = @cache["#{name}/#{version}/#{region}"]
    server_infos.first.servers
  end
end

#to_h ⇒ Object

Returns the Service Registry as a Hash



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# File 'lib/ruby_skynet/zookeeper/service_registry.rb', line 47

def to_h
  @cache.dup
end