Feature: support static config for Semian::NetHTTP and Semian::GRPC

[jychen7]

Background

MySQL and Redis supports static config, while NetHTTP and GRPC currently only Proc. e.g.

semian/lib/semian/mysql2.rb

Lines 137 to 140 in 1d4b53b

	def raw_semian_options
	return query_options[:semian] if query_options.key?(:semian)
	return query_options["semian"] if query_options.key?("semian")
	end

semian/lib/semian/net_http.rb

Lines 67 to 69 in 1d4b53b

	def retrieve_semian_configuration(host, port)
	@semian_configuration.call(host, port) if @semian_configuration.respond_to?(:call)
	end

semian/lib/semian/grpc.rb

Lines 48 to 50 in 1d4b53b

	def retrieve_semian_configuration(host)
	@semian_configuration.call(host) if @semian_configuration.respond_to?(:call)
	end

Problem

If pass a static config to NetHTTP and GRPC, semian is disabled because retrieve_semian_configuration returns nil.

Proposal

allow static config if it is not callable

def retrieve_semian_configuration(host, port)
  return @semian_configuration unless @semian_configuration.respond_to?(:call) 

 @semian_configuration.call(host, port)
 end 

Alternative

Add validation to semian_configuration setter, assert whether static config or Proc is expected

semian/lib/semian/net_http.rb

Lines 61 to 64 in 1d4b53b

	def semian_configuration=(configuration)
	raise Semian::NetHTTP::SemianConfigurationChangedError unless @semian_configuration.nil?
	@semian_configuration = configuration