93 lines
3.2 KiB
Ruby
93 lines
3.2 KiB
Ruby
require "log4r"
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module Vagrant
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module Action
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# The action warden is a middleware which injects itself between
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# every other middleware, watching for exceptions which are raised
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# and performing proper cleanup on every action by calling the `recover`
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# method. The warden therefore allows middlewares to not worry about
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# exceptional events, and by providing a simple callback, can clean up
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# in any erroneous case.
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#
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# Warden will "just work" behind the scenes, and is not of particular
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# interest except to those who are curious about the internal workings
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# of Vagrant.
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class Warden
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attr_accessor :actions, :stack
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def initialize(actions, env)
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@stack = []
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@actions = actions.map { |m| finalize_action(m, env) }
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@logger = Log4r::Logger.new("vagrant::action::warden")
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end
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def call(env)
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return if @actions.empty?
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begin
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# Call the next middleware in the sequence, appending to the stack
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# of "recoverable" middlewares in case something goes wrong!
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raise Errors::VagrantInterrupt if env[:interrupted]
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action = @actions.shift
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@logger.info("Calling action: #{action}")
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@stack.unshift(action).first.call(env)
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raise Errors::VagrantInterrupt if env[:interrupted]
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rescue SystemExit
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# This means that an "exit" or "abort" was called. In these cases,
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# we just exit immediately.
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raise
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rescue Exception => e
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@logger.error("Error occurred: #{e}")
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env["vagrant.error"] = e
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# Something went horribly wrong. Start the rescue chain then
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# reraise the exception to properly kick us out of limbo here.
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begin_rescue(env)
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raise
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end
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end
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# Begins the recovery sequence for all middlewares which have run.
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# It does this by calling `recover` (if it exists) on each middleware
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# which has already run, in reverse order.
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def begin_rescue(env)
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@stack.each do |act|
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if act.respond_to?(:recover)
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@logger.info("Calling recover: #{act}")
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act.recover(env)
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end
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end
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# Clear stack so that warden down the middleware chain doesn't
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# rescue again.
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@stack.clear
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end
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# A somewhat confusing function which simply initializes each
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# middleware properly to call the next middleware in the sequence.
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def finalize_action(action, env)
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klass, args, block = action
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# Default the arguments to an empty array. Otherwise in Ruby 1.8
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# a `nil` args will actually pass `nil` into the class.
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args ||= []
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if klass.is_a?(Class)
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# A action klass which is to be instantiated with the
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# app, env, and any arguments given
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klass.new(self, env, *args, &block)
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elsif klass.respond_to?(:call)
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# Make it a lambda which calls the item then forwards
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# up the chain
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lambda do |e|
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klass.call(e)
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self.call(e)
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end
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else
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raise "Invalid action: #{action.inspect}"
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end
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end
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end
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end
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end
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