AppPool middleware now compatible with Fibers

This enables the safe use of Rainbows::AppPool with all
concurrency models, not just threaded ones.  AppPool is now
effective with *all* Fiber-based concurrency models including
Revactor (and of course the new Fiber{Pool,Spawn} ones).

1 files changed, 33 insertions, 0 deletions

diff --git a/lib/rainbows/fiber/queue.rb b/lib/rainbows/fiber/queue.rb
new file mode 100644
index 0000000..4c14f19
--- /dev/null
+++ b/lib/rainbows/fiber/queue.rb
@@ -0,0 +1,33 @@
+module Rainbows
+  module Fiber
+
+    # a self-sufficient Queue implmentation for Fiber-based concurrency
+    # models
+    class Queue < Struct.new(:queue, :waiters)
+
+      def initialize(queue = [], waiters = [])
+        # move elements of the Queue into an Array
+        if queue.class.name == "Queue"
+          queue = queue.length.times.map { queue.pop }
+        end
+        super queue, waiters
+      end
+
+      def shift
+        # ah the joys of not having to deal with race conditions
+        if queue.empty?
+          waiters << ::Fiber.current
+          ::Fiber.yield
+        end
+        queue.shift
+      end
+
+      def <<(obj)
+        queue << obj
+        blocked = waiters.shift and blocked.resume
+        queue # not quite 100% compatible but no-one's looking :>
+      end
+
+    end
+  end
+end