Barrier waits return nil or number of tasks waited on.

Author: ioquatix

lib/async/barrier.rb

@@ -81,12 +81,17 @@ def empty?
 		# Wait for all tasks to complete by invoking {Task#wait} on each waiting task, which may raise an error. As long as the task has completed, it will be removed from the barrier.
 		#
 		# @yields {|task| ...} If a block is given, the unwaited task is yielded. You must invoke {Task#wait} yourself. In addition, you may `break` if you have captured enough results.
+		# @returns [Integer | Nil] The number of tasks which were waited for, or `nil` if there were no tasks to wait for.
 		#
 		# @asynchronous Will wait for tasks to finish executing.
 		def wait
-			while !@tasks.empty?
+			return nil if @tasks.empty?
+			count = 0
+			
+			while true
 				# Wait for a task to finish (we get the task node):
-				return unless waiting = @finished.wait
+				break unless waiting = @finished.wait
+				count += 1
 
 				# Remove the task as it is now finishing:
 				@tasks.remove?(waiting)
@@ -101,7 +106,11 @@ def wait
 					# Wait for it to either complete or raise an error:
 					task.wait
 				end
+				
+				break if @tasks.empty?
 			end
+			
+			return count
 		end
 
 		# Cancel all tasks held by the barrier.

releases.md

@@ -1,5 +1,9 @@
 # Releases
 
+## Unreleased
+
+  - `Async::Barrier#wait` now returns the number of tasks that were waited for, or `nil` if there were no tasks to wait for. This provides better feedback about the operation, and allows you to know how many tasks were involved in the wait.
+
 ## v2.38.1
 
   - Fix `Barrier#async` when `parent.async` yields before the child block executes. Previously, `Barrier#wait` could return early and miss tracking the task entirely, because the task had not yet appended itself to the barrier's task list.

test/async/barrier.rb

@@ -135,6 +135,18 @@
 			end
 		end
 
+		it "returns nil when there are no tasks" do
+			expect(barrier.wait).to be_nil
+		end
+		
+		it "returns the number of tasks waited for" do
+			3.times do
+				barrier.async{}
+			end
+			
+			expect(barrier.wait).to be == 3
+		end
+		
 		it "waits even if the child task yields immediately" do
 			class Yielder
 				def async(*arguments, **options, &block)