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Contents
# frozen_string_literal: true
export_default :ResourcePool
# Implements a limited resource pool
class ResourcePool
attr_reader :limit, :size
# Initializes a new resource pool
# @param opts [Hash] options
# @param &block [Proc] allocator block
def initialize(opts, &block)
@allocator = block
@stock = []
@queue = []
@limit = opts[:limit] || 4
@size = 0
end
def available
@stock.size
end
def acquire
Gyro.ref
resource = wait_for_resource
return unless resource
yield resource
ensure
Gyro.unref
release(resource) if resource
end
def wait_for_resource
fiber = Fiber.current
@queue << fiber
ready_resource = from_stock
return ready_resource if ready_resource
suspend
ensure
@queue.delete(fiber)
end
def release(resource)
if resource.__discarded__
@size -= 1
elsif resource
return_to_stock(resource)
dequeue
end
end
def dequeue
return if @queue.empty? || @stock.empty?
@queue.shift.schedule(@stock.shift)
end
def return_to_stock(resource)
@stock << resource
end
def from_stock
@stock.shift || (@size < @limit && allocate)
end
def method_missing(sym, *args, &block)
acquire { |r| r.send(sym, *args, &block) }
end
def respond_to_missing?(*_args)
true
end
# Extension to allow discarding of resources
module ResourceExtensions
def __discarded__
@__discarded__
end
def __discard__
@__discarded__ = true
end
end
# Allocates a resource
# @return [any] allocated resource
def allocate
@size += 1
@allocator.().tap { |r| r.extend ResourceExtensions }
end
def <<(resource)
@size += 1
resource.extend ResourceExtensions
@stock << resource
dequeue
end
def preheat!
(@limit - @size).times { @stock << allocate }
end
end
Version data entries
13 entries across 13 versions & 1 rubygems