Initial commit

lib/tasks/thread_pool.rb

@@ -0,0 +1,56 @@
+require 'monitor'
+
+# Basic thread pool with (unlimited) queue
+# Based on http://burgestrand.se/code/ruby-thread-pool/
+class ThreadPool
+
+  def initialize(size, sleep_time=0.1)
+    @size = size
+    @sleep_time = sleep_time
+    @workers_queue = []
+    @workers_queue.extend(MonitorMixin)
+    @mutex = @workers_queue.new_cond
+
+    @pool = Array.new(@size) do |i|
+      Thread.new do
+        Thread.current[:id] = i
+        catch(:exit) do
+          loop do
+            unless @workers_queue.empty?
+              @workers_queue.synchronize do
+                @mutex.wait_while { @workers_queue.empty? }
+              end
+              job, args = @workers_queue.pop
+              job.call(*args)
+              job = nil
+              args = nil
+            end
+          end
+        end
+      end
+    end
+  end
+
+  def schedule(*args, &block)
+    enqueued = false
+    begin
+      if @workers_queue.length < @size
+        @workers_queue.synchronize do
+          @workers_queue << [block, args]
+          enqueued = true
+          @mutex.broadcast
+        end
+      else
+        sleep(@sleep_time)
+      end
+    end while (!enqueued)
+  end
+
+  def shutdown
+    @size.times do
+      schedule { throw :exit }
+    end
+    @pool.map(&:join)
+  end
+
+end