diff options
Diffstat (limited to 'activesupport/lib/active_support/execution_wrapper.rb')
-rw-r--r-- | activesupport/lib/active_support/execution_wrapper.rb | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/execution_wrapper.rb b/activesupport/lib/active_support/execution_wrapper.rb new file mode 100644 index 0000000000..3384d12d5b --- /dev/null +++ b/activesupport/lib/active_support/execution_wrapper.rb @@ -0,0 +1,126 @@ +require "active_support/callbacks" + +module ActiveSupport + class ExecutionWrapper + include ActiveSupport::Callbacks + + Null = Object.new # :nodoc: + def Null.complete! # :nodoc: + end + + define_callbacks :run + define_callbacks :complete + + def self.to_run(*args, &block) + set_callback(:run, *args, &block) + end + + def self.to_complete(*args, &block) + set_callback(:complete, *args, &block) + end + + class RunHook < Struct.new(:hook) # :nodoc: + def before(target) + hook_state = target.send(:hook_state) + hook_state[hook] = hook.run + end + end + + class CompleteHook < Struct.new(:hook) # :nodoc: + def before(target) + hook_state = target.send(:hook_state) + if hook_state.key?(hook) + hook.complete hook_state[hook] + end + end + alias after before + end + + # Register an object to be invoked during both the +run+ and + # +complete+ steps. + # + # +hook.complete+ will be passed the value returned from +hook.run+, + # and will only be invoked if +run+ has previously been called. + # (Mostly, this means it won't be invoked if an exception occurs in + # a preceding +to_run+ block; all ordinary +to_complete+ blocks are + # invoked in that situation.) + def self.register_hook(hook, outer: false) + if outer + to_run RunHook.new(hook), prepend: true + to_complete :after, CompleteHook.new(hook) + else + to_run RunHook.new(hook) + to_complete CompleteHook.new(hook) + end + end + + # Run this execution. + # + # Returns an instance, whose +complete!+ method *must* be invoked + # after the work has been performed. + # + # Where possible, prefer +wrap+. + def self.run! + if active? + Null + else + new.tap do |instance| + success = nil + begin + instance.run! + success = true + ensure + instance.complete! unless success + end + end + end + end + + # Perform the work in the supplied block as an execution. + def self.wrap + return yield if active? + + instance = run! + begin + yield + ensure + instance.complete! + end + end + + class << self # :nodoc: + attr_accessor :active + end + + def self.inherited(other) # :nodoc: + super + other.active = Concurrent::Hash.new + end + + self.active = Concurrent::Hash.new + + def self.active? # :nodoc: + @active[Thread.current] + end + + def run! # :nodoc: + self.class.active[Thread.current] = true + run_callbacks(:run) + end + + # Complete this in-flight execution. This method *must* be called + # exactly once on the result of any call to +run!+. + # + # Where possible, prefer +wrap+. + def complete! + run_callbacks(:complete) + ensure + self.class.active.delete Thread.current + end + + private + def hook_state + @_hook_state ||= {} + end + end +end |