Add bin and edit workflow

bin/gems/eventmachine-1.2.7/lib/em/threaded_resource.rb

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+module EventMachine
+  # = EventMachine::ThreadedResource
+  #
+  # A threaded resource is a "quick and dirty" wrapper around the concept of
+  # wiring up synchronous code into a standard EM::Pool. This is useful to keep
+  # interfaces coherent and provide a simple approach at "making an interface
+  # async-ish".
+  #
+  # General usage is to wrap libraries that do not support EventMachine, or to
+  # have a specific number of dedicated high-cpu worker resources.
+  #
+  # == Basic Usage example
+  #
+  # This example requires the cassandra gem. The cassandra gem contains an
+  # EventMachine interface, but it's sadly Fiber based and thus only works on
+  # 1.9. It also requires (potentially) complex stack switching logic to reach
+  # completion of nested operations. By contrast this approach provides a block
+  # in which normal synchronous code can occur, but makes no attempt to wire the
+  # IO into EventMachines C++ IO implementations, instead relying on the reactor
+  # pattern in rb_thread_select.
+  #
+  #    cassandra_dispatcher = ThreadedResource.new do
+  #      Cassandra.new('allthethings', '127.0.0.1:9160')
+  #    end
+  #
+  #    pool = EM::Pool.new
+  #
+  #    pool.add cassandra_dispatcher
+  #
+  #    # If we don't care about the result:
+  #    pool.perform do |dispatcher|
+  #      # The following block executes inside a dedicated thread, and should not
+  #      # access EventMachine things:
+  #      dispatcher.dispatch do |cassandra|
+  #        cassandra.insert(:Things, '10', 'stuff' => 'things')
+  #      end
+  #    end
+  #
+  #    # Example where we care about the result:
+  #    pool.perform do |dispatcher|
+  #      # The dispatch block is executed in the resources thread.
+  #      completion = dispatcher.dispatch do |cassandra|
+  #        cassandra.get(:Things, '10', 'stuff')
+  #      end
+  #
+  #      # This block will be yielded on the EM thread:
+  #      completion.callback do |result|
+  #        EM.do_something_with(result)
+  #      end
+  #
+  #      completion
+  #    end
+  class ThreadedResource
+
+    # The block should return the resource that will be yielded in a dispatch.
+    def initialize
+      @resource = yield
+
+      @running = true
+      @queue   = ::Queue.new
+      @thread  = Thread.new do
+        @queue.pop.call while @running
+      end
+    end
+
+    # Called on the EM thread, generally in a perform block to return a
+    # completion for the work.
+    def dispatch
+      completion = EM::Completion.new
+      @queue << lambda do
+        begin
+          result = yield @resource
+          completion.succeed result
+        rescue => e
+          completion.fail e
+        end
+      end
+      completion
+    end
+
+    # Kill the internal thread. should only be used to cleanup - generally
+    # only required for tests.
+    def shutdown
+      @running = false
+      @queue << lambda {}
+      @thread.join
+    end
+
+  end
+end