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# frozen_string_literal: true
# Released under the MIT License.
# Copyright, 2024, by Samuel Williams.
module Async
# A load balancing mechanism that can be used process work when the system is idle.
class Idler
# Create a new idler.
# @public Since `stable-v2`.
#
# @parameter maximum_load [Numeric] The maximum load before we start shedding work.
# @parameter backoff [Numeric] The initial backoff time, used for delaying work.
# @parameter parent [Interface(:async) | Nil] The parent task to use for async operations.
def initialize(maximum_load = 0.8, backoff: 0.01, parent: nil)
@maximum_load = maximum_load
@backoff = backoff
@parent = parent
end
# Wait until the system is idle, then execute the given block in a new task.
#
# @asynchronous Executes the given block concurrently.
#
# @parameter arguments [Array] The arguments to pass to the block.
# @parameter parent [Interface(:async) | Nil] The parent task to use for async operations.
# @parameter options [Hash] The options to pass to the task.
# @yields {|task| ...} When the system is idle, the block will be executed in a new task.
def async(*arguments, parent: (@parent or Task.current), **options, &block)
wait
# It is crucial that we optimistically execute the child task, so that we prevent a tight loop invoking this method from consuming all available resources.
parent.async(*arguments, **options, &block)
end
# Wait until the system is idle, according to the maximum load specified.
#
# If the scheduler is overloaded, this method will sleep for an exponentially increasing amount of time.
def wait
scheduler = Fiber.scheduler
backoff = nil
while true
load = scheduler.load
break if load < @maximum_load
if backoff
sleep(backoff)
backoff *= 2.0
else
scheduler.yield
backoff = @backoff
end
end
end
end
end
Version data entries
9 entries across 9 versions & 1 rubygems