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require 'concurrent/utility/engine'
require 'concurrent/executor/ruby_single_thread_executor'
module Concurrent
if Concurrent.on_jruby?
require 'concurrent/executor/java_single_thread_executor'
end
SingleThreadExecutorImplementation = case
when Concurrent.on_jruby?
JavaSingleThreadExecutor
else
RubySingleThreadExecutor
end
private_constant :SingleThreadExecutorImplementation
# @!macro single_thread_executor
#
# A thread pool with a single thread an unlimited queue. Should the thread
# die for any reason it will be removed and replaced, thus ensuring that
# the executor will always remain viable and available to process jobs.
#
# A common pattern for background processing is to create a single thread
# on which an infinite loop is run. The thread's loop blocks on an input
# source (perhaps blocking I/O or a queue) and processes each input as it
# is received. This pattern has several issues. The thread itself is highly
# susceptible to errors during processing. Also, the thread itself must be
# constantly monitored and restarted should it die. `SingleThreadExecutor`
# encapsulates all these bahaviors. The task processor is highly resilient
# to errors from within tasks. Also, should the thread die it will
# automatically be restarted.
#
# The API and behavior of this class are based on Java's `SingleThreadExecutor`.
#
# @!macro abstract_executor_service_public_api
class SingleThreadExecutor < SingleThreadExecutorImplementation
# @!macro single_thread_executor_method_initialize
#
# Create a new thread pool.
#
# @option opts [Symbol] :fallback_policy (:discard) the policy for handling new
# tasks that are received when the queue size has reached
# `max_queue` or the executor has shut down
#
# @raise [ArgumentError] if `:fallback_policy` is not one of the values specified
# in `FALLBACK_POLICIES`
#
# @see http://docs.oracle.com/javase/tutorial/essential/concurrency/pools.html
# @see http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/Executors.html
# @see http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html
# @!method initialize(opts = {})
# @!macro single_thread_executor_method_initialize
end
end
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