CHEF-4423: extract cookbook upload threaded queue into utility class

1 files changed, 61 insertions, 0 deletions

diff --git a/lib/chef/util/threaded_job_queue.rb b/lib/chef/util/threaded_job_queue.rb
new file mode 100644
index 0000000000..824cd0a3c4
--- /dev/null
+++ b/lib/chef/util/threaded_job_queue.rb
@@ -0,0 +1,61 @@
+# Copyright:: Copyright (c) 2014 Opscode, Inc.
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+require 'thread'
+
+class Chef
+  class Util
+    # A simple threaded job queue
+    #
+    # Create a queue:
+    #
+    #     queue = ThreadedJobQueue.new
+    #
+    # Add jobs:
+    #
+    #     queue << lambda { |lock| foo.the_bar }
+    #
+    # A job is a callable that optionally takes a Mutex instance as its only
+    # parameter.
+    #
+    # Then start processing jobs with +n+ threads:
+    #
+    #     queue.process(n)
+    #
+    class ThreadedJobQueue
+      def initialize
+        @queue = Queue.new
+        @lock = Mutex.new
+      end
+
+      def <<(job)
+        @queue << job
+      end
+
+      def process(concurrency = 10)
+        workers = (1..concurrency).map do
+          Thread.new do
+            loop do
+              fn = @queue.pop
+              fn.arity == 1 ? fn.call(@lock) : fn.call
+            end
+          end
+        end
+        workers.each { |worker| self << Thread.method(:exit) }
+        workers.each { |worker| worker.join }
+      end
+    end
+  end
+end