Class: Isono::NodeModules::RpcChannel

Inherits:
Base
  • Object
show all
Includes:
Logger
Defined in:
lib/isono/node_modules/rpc_channel.rb

Defined Under Namespace

Classes: DuplicateEndpointError, OneshotResponseContext, RequestContext, ResponseContext, RpcError, UnknownEndpointError

Instance Attribute Summary collapse

Attributes inherited from Base

#node

Instance Method Summary collapse

Methods included from Logger

included, initialize

Methods inherited from Base

#config_section, #initialize, #manifest, #value_object

Constructor Details

This class inherits a constructor from Isono::NodeModules::Base

Instance Attribute Details

#amq ⇒ Object (readonly)

Returns the value of attribute amq.



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# File 'lib/isono/node_modules/rpc_channel.rb', line 71

def amq
  @amq
end

Instance Method Details

#register_endpoint(endpoint, app, opts = {}) ⇒ Object

Register a new RPC endpoint.

This method works in sync mode if called at non-EM reactor thread.

Parameters:

  • endpoint (String)
  • app (has call() method)
  • opts (Hash) (defaults to: {}) —

    :exclusive :prefetch

Raises:

  • (TypeError) 


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# File 'lib/isono/node_modules/rpc_channel.rb', line 131

def register_endpoint(endpoint, app, opts={})
  raise TypeError unless app.respond_to?(:call)
  opts = {:exclusive=>true, :prefetch=>0}.merge(opts)
  
  # create receive queue for new RPC endpoint.
  endpoint_proc = proc { |header, data|

    data = Serializer.instance.unmarshal(data)

    resctx = if data[:oneshot]
               OneshotResponseContext.new(@endpoints[endpoint][:ch].response_exchange, header)
             else
               ResponseContext.new(@endpoints[endpoint][:ch].response_exchange, header)
             end
    begin
      req = Rack::Request.new({:sender=>header.reply_to['command-recv.'.size..-1],
                                :message_id=>header.message_id
                              }.merge(data))
      res = Rack::Response.new(resctx)
      ret = app.call(req, res)
    rescue ::Exception => e
      logger.error(e)
      resctx.response(e) unless resctx.responded?
    end
  }

  
  EventMachine.schedule {
    ch = if opts[:prefetch].to_i > 0
           # create per endpoint channel
           node.create_channel
         else
           # use default channel
           @amq
         end
    ch.instance_eval %Q{
      def endpoint_queue
        self.queue("isono.rpc.endpoint.#{endpoint}", {:exclusive=>false, :auto_delete=>true})
      end

      def response_exchange
        self.direct('')
      end
    }
    ch.prefetch(opts[:prefetch].to_i) if opts[:prefetch].to_i > 0
    # stores hash here that is for thread safety.
    @endpoints[endpoint]={:app=>app, :opts=>opts, :ch=>ch}

    ch.endpoint_queue.subscribe(:ack=>true, &endpoint_proc)
    event.publish('rpc/register', :args=>[endpoint])
  }
end

#request(endpoint, command, *args, &blk) ⇒ RequestContext, any

Make a RPC request to an endpoint.

Examples:

create a sync RPC request.

rpc.request('endpoint1', 'func1', xxxx)

call RPC in async mode.

rpc.request('endpoint1', 'func1', xxxx) { |req|
  req.on_success { |r|
    puts r
  }
  req.on_error { |r|
    puts r
  }
}

setup request context and do wait().

Note that callbacks are 
rpc.request('endpoint1', 'func1', xxxx) { |req|
  # send new attribute
  req.request[:xxxx] = "sdfsdf"
  # returns synchronized RequestContext to block caller.
  req.synchronize
}.wait # request() get back the altered RequestCotenxt that has wait().

Create async oneshot call. (do not expect response)

rpc.request('endpoint1', 'func1') { |req|
  req.oneshot = true
}

Parameters:

  • endpoint (String)
  • command (String)
  • args (Array)
  • &blk (Proc) —

    Block to setup the request context.

Returns:



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# File 'lib/isono/node_modules/rpc_channel.rb', line 106

def request(endpoint, command, *args, &blk)
  req = RequestContext.new(endpoint, command, args)
  # the block is to setup the request context prior to sending.
  if blk
    # async 
    r = blk.call(req)
    req = r if r.is_a?(RequestContext)
    send_request(req)
    req
  else
    # sync
    req = req.synchronize
    send_request(req)
    req.wait
  end
end

#unregister_endpoint(endpoint) ⇒ Object

Unregister endpoint.

Parameters:

  • endpoint (String) —

    endpoint name to be removed



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# File 'lib/isono/node_modules/rpc_channel.rb', line 187

def unregister_endpoint(endpoint)
  if @endpoints.has_key?(endpoint)
    EventMachine.schedule {
      data = @endpoints.delete(endpoint)
      # endpoint_queue is :auto_delete=>true so that it will be deleted
      # in case of zero consumers.
      data[:ch].endpoint_queue.unsubscribe
      event.publish('rpc/unregister', :args=>[endpoint])
    }
  end
end