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https://github.com/aasm/aasm
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a8a8f10d16
Ever since AASM supported multiple named state machines in a single class, it has accessed and stored its state machines in class variables. However accesses to the state machines are not thread-safe causing exceptions when multiple threads attempt to access the same state machine at the same time during lazy initialization. Using a Concurrent Map makes calls to state machines, and lazy initialization thread safe.
76 lines
2.1 KiB
Ruby
76 lines
2.1 KiB
Ruby
require 'concurrent'
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module AASM
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class StateMachineStore
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@stores = Concurrent::Map.new
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class << self
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def stores
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@stores
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end
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# do not overwrite existing state machines, which could have been created by
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# inheritance, see AASM::ClassMethods method inherited
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def register(klass, overwrite = false, state_machine = nil)
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raise "Cannot register #{klass}" unless klass.is_a?(Class)
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case name = template = overwrite
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when FalseClass then stores[klass.to_s] ||= new
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when TrueClass then stores[klass.to_s] = new
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when Class then stores[klass.to_s] = stores[template.to_s].clone
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when Symbol then stores[klass.to_s].register(name, state_machine)
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when String then stores[klass.to_s].register(name, state_machine)
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else raise "Don't know what to do with #{overwrite}"
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end
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end
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alias_method :[]=, :register
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def fetch(klass, fallback = nil)
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stores[klass.to_s] || fallback && begin
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match = klass.ancestors.find do |ancestor|
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ancestor.include? AASM and stores[ancestor.to_s]
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end
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stores[match.to_s]
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end
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end
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alias_method :[], :fetch
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def unregister(klass)
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stores.delete(klass.to_s)
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end
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end
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def initialize
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@machines = Concurrent::Map.new
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end
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def clone
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StateMachineStore.new.tap do |store|
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@machines.each_pair do |name, machine|
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store.register(name, machine.clone)
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end
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end
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end
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def machine(name)
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@machines[name.to_s]
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end
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alias_method :[], :machine
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def machine_names
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@machines.keys
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end
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alias_method :keys, :machine_names
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def register(name, machine, force = false)
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raise "Cannot use #{name.inspect} for machine name" unless name.is_a?(Symbol) or name.is_a?(String)
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raise "Cannot use #{machine.inspect} as a machine" unless machine.is_a?(AASM::StateMachine)
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if force
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@machines[name.to_s] = machine
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else
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@machines[name.to_s] ||= machine
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end
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end
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end
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end
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