Add support for IO::Event::WorkerPool. (#393)

Author: samuel-williams-shopify

async.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |spec|
 
 	spec.add_dependency "console", "~> 1.29"
 	spec.add_dependency "fiber-annotation"
-	spec.add_dependency "io-event", "~> 1.9"
+	spec.add_dependency "io-event", "~> 1.11"
 	spec.add_dependency "traces", "~> 0.15"
 	spec.add_dependency "metrics", "~> 0.12"
 end

lib/async/scheduler.rb

@@ -8,7 +8,6 @@
 require_relative "clock"
 require_relative "task"
 require_relative "timeout"
-require_relative "worker_pool"
 
 require "io/event"
 
@@ -45,7 +44,29 @@ def initialize(message = "Scheduler is closed!")
 		def self.supported?
 			true
 		end
+
+		# Used to augment the scheduler to add support for blocking operations.
+		module BlockingOperationWait
+			# Wait for the given work to be executed.
+			#
+			# @public Since *Async v2.21* and *Ruby v3.4*.
+			# @asynchronous May be non-blocking.
+			#
+			# @parameter work [Proc] The work to execute on a background thread.
+			# @returns [Object] The result of the work.
+			def blocking_operation_wait(work)
+				@worker_pool.call(work)
+			end
+		end
+
+		private_constant :BlockingOperationWait
 
+		if ::IO::Event.const_defined?(:WorkerPool)
+			WorkerPool = ::IO::Event::WorkerPool
+		else
+			WorkerPool = nil
+		end
+
 		# Create a new scheduler.
 		#
 		# @public Since *Async v1*.
@@ -65,14 +86,15 @@ def initialize(parent = nil, selector: nil, profiler: Profiler&.default, worker_
 			@idle_time = 0.0
 
 			@timers = ::IO::Event::Timers.new
+			
 			if worker_pool == true
-				@worker_pool = WorkerPool.new
+				@worker_pool = WorkerPool&.new
 			else
 				@worker_pool = worker_pool
 			end
-			
+
 			if @worker_pool
-				self.singleton_class.prepend(WorkerPool::BlockingOperationWait)
+				self.singleton_class.prepend(BlockingOperationWait)
 			end
 		end
 

lib/async/worker_pool.rb

@@ -1,5 +1,13 @@
 # Releases
 
+## Unreleased
+
+### Use `IO::Event::WorkerPool` for Blocking Operations
+
+The `Async::WorkerPool` implementation has been removed in favor of using `IO::Event::WorkerPool` directly. This change simplifies the codebase by delegating worker pool functionality to the `io-event` gem, which provides a more efficient and well-tested implementation.
+
+To enable the worker pool, you can set the `ASYNC_SCHEDULER_WORKER_POOL` environment variable to `true`. This will allow the scheduler to use a worker pool for blocking operations, which can help improve performance in applications that perform a lot of CPU-bound operations (e.g. `rb_nogvl`).
+
 ## v2.24.0
 
   - Ruby v3.1 support is dropped.