Merge pull request #166 from obrok/indirect-immediate-executor

Create an IndirectImmediateExecutor

Author: jdantonio

lib/concurrent/executor/indirect_immediate_executor.rb

@@ -0,0 +1,46 @@
+require 'concurrent/executor/executor'
+
+module Concurrent
+  # An executor service which runs all operations on a new thread, blocking
+  # until it completes. Operations are performed in the order they are received
+  # and no two operations can be performed simultaneously.
+  #
+  # This executor service exists mainly for testing an debugging. When used it
+  # immediately runs every `#post` operation on a new thread, blocking the
+  # current thread until the operation is complete. This is similar to how the
+  # ImmediateExecutor works, but the operation has the full stack of the new
+  # thread at its disposal. This can be helpful when the operations will spawn
+  # more operations on the same executor and so on - such a situation might
+  # overflow the single stack in case of an ImmediateExecutor, which is
+  # inconsistent with how it would behave for a threaded executor.
+  #
+  # @note Intended for use primarily in testing and debugging.
+  class IndirectImmediateExecutor < ImmediateExecutor
+    # Creates a new executor
+    def initialize
+      super
+      @internal_executor = PerThreadExecutor.new
+    end
+
+    # @!macro executor_method_post
+    def post(*args, &task)
+      raise ArgumentError.new("no block given") unless block_given?
+      return false unless running?
+
+      event = Concurrent::Event.new
+      internal_executor.post do
+        begin
+          task.call(*args)
+        ensure
+          event.set
+        end
+      end
+      event.wait
+
+      true
+    end
+
+    private
+    attr_reader :internal_executor
+  end
+end

lib/concurrent/executors.rb

@@ -1,6 +1,7 @@
 require 'concurrent/executor/cached_thread_pool'
 require 'concurrent/executor/fixed_thread_pool'
 require 'concurrent/executor/immediate_executor'
+require 'concurrent/executor/indirect_immediate_executor'
 require 'concurrent/executor/per_thread_executor'
 require 'concurrent/executor/safe_task_executor'
 require 'concurrent/executor/single_thread_executor'

spec/concurrent/executor/indirect_immediate_executor_spec.rb

@@ -0,0 +1,26 @@
+require 'spec_helper'
+require_relative 'executor_service_shared'
+
+module Concurrent
+
+  describe IndirectImmediateExecutor do
+
+    subject { IndirectImmediateExecutor.new }
+
+    it_should_behave_like :executor_service
+
+    it "runs its tasks synchronously" do
+      start = Time.now
+      subject.post { sleep 0.1 }
+
+      expect(Time.now - start).to be >= 0.1
+    end
+
+    it "runs the task on a separate thread" do
+      used_thread = nil
+      subject.post { used_thread = Thread.current }
+
+      expect(used_thread).not_to be(Thread.current)
+    end
+  end
+end