Add call factory with deadline handling

fixtures/protocol/grpc/test_middleware.rb

@@ -9,7 +9,6 @@
 require "protocol/grpc/body/readable"
 require "protocol/grpc/body/writable"
 require "protocol/grpc/header"
-require "async/deadline"
 
 # Test implementation of Middleware with service routing
 class TestMiddleware < Protocol::GRPC::Middleware
@@ -51,11 +50,7 @@ def dispatch(request)
 			response_headers["grpc-encoding"] = encoding
 		end
 
-		if timeout = request.headers["grpc-timeout"]&.to_seconds
-			deadline = Async::Deadline.start(timeout)
-		end
-
-		call = Protocol::GRPC::Call.new(request, deadline: deadline)
+		call = Protocol::GRPC::Call.for(request)
 
 		# Delegate to service handler wrapper
 		result = wrapper.call(input, output, call)
@@ -126,4 +121,3 @@ def call(input, output, call)
 		end
 	end
 end
-

lib/protocol/grpc/call.rb

@@ -10,6 +10,19 @@ module Protocol
 	module GRPC
 		# Represents context for a single RPC call.
 		class Call
+			# Create a new RPC call context for the given request and response.
+			# Automatically computes a deadline from the `grpc-timeout` request header, if present.
+			# @parameter request [Protocol::HTTP::Request] The HTTP request
+			# @parameter response [Protocol::HTTP::Response | Nil] The HTTP response
+			# @returns [Call] The new call context.
+			def self.for(request, response = nil)
+				if timeout = request.headers["grpc-timeout"]
+					deadline = Async::Deadline.start(timeout.to_seconds)
+				end
+
+				return new(request, response, deadline: deadline)
+			end
+
 			# Initialize a new RPC call context.
 			# @parameter request [Protocol::HTTP::Request] The HTTP request
 			# @parameter response [Protocol::HTTP::Response | Nil] The HTTP response (for setting metadata and trailers)

lib/protocol/grpc/interface.rb

@@ -25,6 +25,12 @@ def initialize(message_class)
 		class Interface
 			# RPC method definition
 			RPC = Struct.new(:name, :request_class, :response_class, :streaming, :method, keyword_init: true) do
+				# Initialize a new RPC method definition.
+				# @parameter name [Symbol] The RPC method name.
+				# @parameter request_class [Class | Streaming | Nil] The request message class.
+				# @parameter response_class [Class | Streaming | Nil] The response message class.
+				# @parameter streaming [Symbol] The streaming mode.
+				# @parameter method [Symbol | Nil] The Ruby method name.
 				def initialize(name:, request_class:, response_class:, streaming: :unary, method: nil)
 					super
 				end

test/protocol/grpc/call.rb

@@ -10,6 +10,31 @@
 describe Protocol::GRPC::Call do
 	let(:headers) {Protocol::HTTP::Headers.new([["authorization", "Bearer token123"]])}
 	let(:request) {Protocol::HTTP::Request.new("https", "localhost", "POST", "/service/method", nil, headers, nil)}
+	let(:response) {Protocol::HTTP::Response[200, {}, []]}
+
+	with ".for" do
+		it "creates a call with request and response" do
+			call = subject.for(request, response)
+
+			expect(call.request).to be == request
+			expect(call.response).to be == response
+		end
+
+		it "computes deadline from grpc-timeout" do
+			headers = Protocol::GRPC::Methods.build_headers(timeout: 0.3)
+			request = Protocol::HTTP::Request.new("https", "localhost", "POST", "/service/method", nil, headers, nil)
+			call = subject.for(request, response)
+
+			expect(call.deadline).to be_a(Async::Deadline)
+			expect(call.time_remaining).to be <= 0.3
+		end
+
+		it "does not set a deadline without grpc-timeout" do
+			call = subject.for(request, response)
+
+			expect(call.deadline).to be_nil
+		end
+	end
 
 	it "has request" do
 		call = subject.new(request)