Class: Automate::Chain

Inherits:
Object
  • Object
show all
Includes:
Messenger
Defined in:
lib/automate/chain.rb

Overview

Captures the entire command chain to be executed. Thus, the main objective of this class is to capture and execute the ‘ChainLinks`. All the capturing happens in the `go` method, and the executing in the `run` method.

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Messenger

#fail, #format, #msg, #notice, #success

Class Method Details

.which(task, &block) ⇒ Object

Factory method that creates a new command chain.



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# File 'lib/automate/chain.rb', line 12

def self.which(task, &block)
  c = new(task)
  c.instance_exec(&block)
  c
end

Instance Method Details

#go(desc, &block) ⇒ Object

Add a new link to the command chain



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# File 'lib/automate/chain.rb', line 19

def go(desc, &block)
  add_command(desc, block)
end

#run(args = {}) ⇒ Object

Run all the command chain links. Will abort the command chain if any chain link should fail.



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# File 'lib/automate/chain.rb', line 26

def run(args = {})
  notice "About to run command chain which '#{@task}'"

  success = true
  begin
    args = run_command_list(@cmd_list, args)
  rescue ChainFailedError => e
    fail("Chain link ##{e.chain} (#{e.description}) failed.")
    success = false
  end

  notice "Running deferred commands"

  # Note that deferred commands are executed in reverse order, so that
  # the cleanup actions for the last command is executed first.
  # E.g. if the definition order is as follows:
  #
  #   C1, C1_defer, C2, C3, C4, C4_defer
  #
  # The execution order will be
  #
  #   C1, C2, C3, C4, C4_defer, C1_defer
  #
  args = run_command_list(@defer_list.reverse, args)
  if !success
    false
  else
    args
  end

rescue ChainFailedError => e
  fail("Defer command ##{e.chain} (#{e.description}) failed.")
  false
end

#run_command_list(list, args) ⇒ Object 



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# File 'lib/automate/chain.rb', line 62

def run_command_list(list, args)
  list.each_with_index do |cmd, index|
    desc, proc = cmd
    success "#{timestamp} // Running link ##{index+1} - #{desc}"

    error = false
    begin
      ret, out, chain_link_defer = ChainLink.invoke(proc, args)
      @defer_list += chain_link_defer
    rescue ChainLinkFailedError => e
      # TODO: Storing the defer_list in the ChainLinkFailedError is awful,
      # and shall be fixed when there's time to remove this entire exception-based
      # "communication" between chain and chain link.
      @defer_list += e.defer_list
      error = true
    end
    raise ChainFailedError.new(index + 1, desc) if ret == false || error == true

    # Pass the arguments from the last iteration, overwriting everything that
    # was passed from the current one.
    args.merge! out

    # Make it possible to run commands step by step
    if !ENV["AUTOMATE_STEP"].nil?
      puts "Press a key to continue..."
      $stdin.gets
      puts "\n"
    end
  end

  args
end