#2798

Committed 24 Nov 2014 04:45PM UTC coverage: 91.282% (-0.4%) from 91.64%

Build # #2798

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Commit Message

Merge pull request #191 from jrochkind/thread_pool_overview_doc

expanded and updated thread pool overview doc

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94.34

/lib/concurrent/executor/serialized_execution.rb

require 'delegate'
require 'concurrent/executor/executor'
require 'concurrent/logging'
require 'concurrent/atomic/synchronization'

module Concurrent

  # Ensures passed jobs in a serialized order never running at the same time.
  class SerializedExecution
    include Logging
    include Synchronization

    Job = Struct.new(:executor, :args, :block) do
      def call
        block.call *args
      end
    end

    def initialize
      synchronize do
        @being_executed = false
        @stash          = []
      end
    end

    # Submit a task to the executor for asynchronous processing.
    #
    # @param [Executor] executor to be used for this job
    #
    # @param [Array] args zero or more arguments to be passed to the task
    #
    # @yield the asynchronous task to perform
    #
    # @return [Boolean] `true` if the task is queued, `false` if the executor
    #   is not running
    #
    # @raise [ArgumentError] if no task is given
    def post(executor, *args, &task)
      posts [[executor, args, task]]
      true
    end

    # As {#post} but allows to submit multiple tasks at once, it's guaranteed that they will not
    # be interleaved by other tasks.
    #
    # @param [Array<Array(Executor, Array<Object>, Proc)>] posts array of triplets where
    #   first is a {Executor}, second is array of args for task, third is a task (Proc)
    def posts(posts)
      # if can_overflow?
      #   raise ArgumentError, 'SerializedExecution does not support thread-pools which can overflow'
      # end

      return nil if posts.empty?

      jobs = posts.map { |executor, args, task| Job.new executor, args, task }

      job_to_post = synchronize do
        if @being_executed
          @stash.push(*jobs)
          nil
        else
          @being_executed = true
          @stash.push(*jobs[1..-1])
          jobs.first
        end
      end

      call_job job_to_post if job_to_post
      true
    end

    private

    def call_job(job)
      did_it_run = begin
        job.executor.post { work(job) }
        true
      rescue RejectedExecutionError => ex
        false
      end

      # TODO not the best idea to run it myself
      unless did_it_run
        begin
          work job
        rescue => ex
          # let it fail
          log DEBUG, ex
        end
      end
    end

    # ensures next job is executed if any is stashed
    def work(job)
      job.call
    ensure
      synchronize do
        job = @stash.shift || (@being_executed = false)
      end

      call_job job if job
    end
  end

  # A wrapper/delegator for any `Executor` or `ExecutorService` that
  # guarantees serialized execution of tasks.
  #
  # @see [SimpleDelegator](http://www.ruby-doc.org/stdlib-2.1.2/libdoc/delegate/rdoc/SimpleDelegator.html)
  # @see Concurrent::SerializedExecution
  class SerializedExecutionDelegator < SimpleDelegator
    include SerialExecutor

    def initialize(executor)
      @executor   = executor
      @serializer = SerializedExecution.new
      super(executor)
    end

    # @!macro executor_method_post
    def post(*args, &task)
      raise ArgumentError.new('no block given') unless block_given?
      return false unless running?
      @serializer.post(@executor, *args, &task)
    end
  end
end

1	require 'delegate'	1✔
2	require 'concurrent/executor/executor'	1✔
3	require 'concurrent/logging'	1✔
4	require 'concurrent/atomic/synchronization'	1✔
5
6	module Concurrent	1✔
7
8	# Ensures passed jobs in a serialized order never running at the same time.
9	class SerializedExecution	1✔
10	include Logging	1✔
11	include Synchronization	1✔
12
13	Job = Struct.new(:executor, :args, :block) do	1✔
14	def call	1✔
15	block.call *args	2,593✔
16	end
17	end
18
19	def initialize	1✔
20	synchronize do	399✔
21	@being_executed = false	399✔
22	@stash = []	399✔
23	end
24	end
25
26	# Submit a task to the executor for asynchronous processing.
27	#
28	# @param [Executor] executor to be used for this job
29	#
30	# @param [Array] args zero or more arguments to be passed to the task
31	#
32	# @yield the asynchronous task to perform
33	#
34	# @return [Boolean] `true` if the task is queued, `false` if the executor
35	# is not running
36	#
37	# @raise [ArgumentError] if no task is given
38	def post(executor, *args, &task)	1✔
39	posts [[executor, args, task]]	2,604✔
40	true	2,604✔
41	end
42
43	# As {#post} but allows to submit multiple tasks at once, it's guaranteed that they will not
44	# be interleaved by other tasks.
45	#
46	# @param [Array<Array(Executor, Array<Object>, Proc)>] posts array of triplets where
47	# first is a {Executor}, second is array of args for task, third is a task (Proc)
48	def posts(posts)	1✔
49	# if can_overflow?
50	# raise ArgumentError, 'SerializedExecution does not support thread-pools which can overflow'
51	# end
52
53	return nil if posts.empty?	2,604✔
54
55	jobs = posts.map { \|executor, args, task\| Job.new executor, args, task }	5,208✔
56
57	job_to_post = synchronize do	2,604✔
58	if @being_executed	2,604✔
59	@stash.push(*jobs)	1,081✔
60	nil	1,081✔
61	else
62	@being_executed = true	1,523✔
63	@stash.push(*jobs[1..-1])	1,523✔
64	jobs.first	1,523✔
65	end
66	end
67
68	call_job job_to_post if job_to_post	2,604✔
69	true	2,604✔
70	end
71
72	private	1✔
73
74	def call_job(job)	1✔
75	did_it_run = begin
76	job.executor.post { work(job) }	5,195✔
77	true	2,602✔
78	rescue RejectedExecutionError => ex
79	false	×
80	end
81
82	# TODO not the best idea to run it myself
83	unless did_it_run	2,602✔
84	begin
85	work job	×
86	rescue => ex
87	# let it fail
88	log DEBUG, ex	×
89	end
90	end
91	end
92
93	# ensures next job is executed if any is stashed
94	def work(job)	1✔
95	job.call	2,593✔
96	ensure
97	synchronize do	2,593✔
98	job = @stash.shift \|\| (@being_executed = false)	2,593✔
99	end
100
101	call_job job if job	2,593✔
102	end
103	end
104
105	# A wrapper/delegator for any `Executor` or `ExecutorService` that
106	# guarantees serialized execution of tasks.
107	#
108	# @see [SimpleDelegator](http://www.ruby-doc.org/stdlib-2.1.2/libdoc/delegate/rdoc/SimpleDelegator.html)
109	# @see Concurrent::SerializedExecution
110	class SerializedExecutionDelegator < SimpleDelegator	1✔
111	include SerialExecutor	1✔
112
113	def initialize(executor)	1✔
114	@executor = executor	25✔
115	@serializer = SerializedExecution.new	25✔
116	super(executor)	25✔
117	end
118
119	# @!macro executor_method_post
120	def post(*args, &task)	1✔
121	raise ArgumentError.new('no block given') unless block_given?	32✔
122	return false unless running?	31✔
123	@serializer.post(@executor, *args, &task)	22✔
124	end
125	end
126	end

ruby-concurrency / concurrent-ruby / #2798

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