Initial implementation (not working).

gems.rb

@@ -7,6 +7,8 @@
 
 gemspec
 
+gem "faraday", git: "https://github.com/lostisland/faraday.git", branch: "mg/parallel-manager-execute"
+
 group :maintenance, optional: true do
 	gem "bake-modernize"
 	gem "bake-gem"

lib/async/http/faraday/adapter.rb

@@ -12,6 +12,8 @@
 
 require 'faraday'
 require 'faraday/adapter'
+
+require 'async/barrier'
 require 'kernel/sync'
 
 require 'async/http/client'
@@ -48,8 +50,41 @@ def read
 				end
 			end
 
+			class ParallelManager
+				def initialize(options = {})
+					@options = options
+					@barrier = nil
+				end
+
+				def run
+					raise NotImplementedError, "Please update your Faraday version!"
+				end
+
+				def async(&block)
+					@barrier.async(&block)
+				end
+
+				def execute(&block)
+					Sync do
+						@barrier = Async::Barrier.new
+
+						yield
+
+						@barrier.wait
+					ensure
+						@barrier&.stop
+					end
+				end
+			end
+
 			# An adapter that allows Faraday to use Async::HTTP as the underlying HTTP client.
 			class Adapter < ::Faraday::Adapter
+				self.supports_parallel = true
+
+				def self.setup_parallel_manager(**options)
+					ParallelManager.new(options)
+				end
+
 				# The exceptions that are considered connection errors and result in a `Faraday::ConnectionFailed` exception.
 				CONNECTION_EXCEPTIONS = [
 					Errno::EADDRNOTAVAIL,
@@ -98,6 +133,23 @@ def call(env)
 					# For compatibility with the default adapter:
 					env.url.path = '/' if env.url.path.empty?
 
+					if parallel_manager = env.parallel_manager
+						parallel_manager.async do
+							perform_request(env)
+
+							# Do I need this line?
+							env.response.finish(env)
+						end
+					else
+						perform_request(env)
+					end
+
+					return env.response
+				end
+
+				private
+
+				def perform_request(env)
 					with_client(env) do |endpoint, client|
 						if body = env.body
 							# We need to ensure the body is wrapped in a Readable object so that it can be read in chunks:
@@ -149,8 +201,6 @@ def call(env)
 					raise ::Faraday::ConnectionFailed, e
 				end
 
-				private
-
 				def with_client(env)
 					Sync do
 						endpoint = Endpoint.new(env.url)

test/async/http/faraday/adapter/parallel.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2024, by Samuel Williams.
+
+require 'async/http/faraday'
+
+require 'sus/fixtures/async/reactor_context'
+require 'sus/fixtures/async/http/server_context'
+
+describe Async::HTTP::Faraday::Adapter do
+	with "a local http server" do
+		include Sus::Fixtures::Async::ReactorContext
+		include Sus::Fixtures::Async::HTTP::ServerContext
+
+
+		let(:app) do
+			Protocol::HTTP::Middleware.for do |request|
+				Protocol::HTTP::Response[200, {}, ['Hello World']]
+			end
+		end
+
+		it "client can get resource" do
+			adapter = Faraday.new(bound_url) do |builder|
+				builder.adapter :async_http
+			end
+
+			response1 = response2 = response3 = nil
+
+			adapter.in_parallel do
+				response1 = adapter.get("/index")
+				response2 = adapter.get("/index")
+				resposne3 = adapter.get("/index")
+			end
+
+			expect(response1.body).to be == 'Hello World'
+			expect(response2.body).to be == 'Hello World'
+			expect(response3.body).to be == 'Hello World'
+		ensure
+			adapter&.close
+		end
+	end
+end