Class: StateMate::StateSet

Inherits:
Object
  • Object
show all
Defined in:
lib/state_mate.rb

Overview

Error

Defined Under Namespace

Classes: State

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ StateSet

from_spec



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# File 'lib/state_mate.rb', line 152

def initialize
  @spec = nil
  @states = []
  @read_values = {}
  @states_to_change = []
  @new_values = []
  @written_states = []
  @write_error = nil
  # map of states to errors raised when trying to rollback
  @rollback_errors = {}
  # report of changes made
  @changes = {}
end

Instance Attribute Details

#changes ⇒ Object (readonly)

Returns the value of attribute changes.



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# File 'lib/state_mate.rb', line 37

def changes
  @changes
end

#new_values ⇒ Object (readonly)

Returns the value of attribute new_values.



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# File 'lib/state_mate.rb', line 37

def new_values
  @new_values
end

#read_values ⇒ Object (readonly)

Returns the value of attribute read_values.



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# File 'lib/state_mate.rb', line 37

def read_values
  @read_values
end

#rollback_errors ⇒ Object (readonly)

Returns the value of attribute rollback_errors.



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# File 'lib/state_mate.rb', line 37

def rollback_errors
  @rollback_errors
end

#spec ⇒ Object

Returns the value of attribute spec.



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# File 'lib/state_mate.rb', line 36

def spec
  @spec
end

#states ⇒ Object (readonly)

Returns the value of attribute states.



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# File 'lib/state_mate.rb', line 37

def states
  @states
end

#states_to_change ⇒ Object (readonly)

Returns the value of attribute states_to_change.



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# File 'lib/state_mate.rb', line 37

def states_to_change
  @states_to_change
end

#write_error ⇒ Object (readonly)

Returns the value of attribute write_error.



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# File 'lib/state_mate.rb', line 37

def write_error
  @write_error
end

#written_states ⇒ Object (readonly)

Returns the value of attribute written_states.



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# File 'lib/state_mate.rb', line 37

def written_states
  @written_states
end

Class Method Details

.from_spec(spec) ⇒ Object 



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# File 'lib/state_mate.rb', line 53

def self.from_spec spec
  state_set = self.new
  state_set.spec = spec

  unless spec.is_a? Hash
    raise Error::TypeError.new spec, 
      "spec must be a Hash of adapter names to states"
  end

  spec.each do |adapter_name, states|
    adapter = StateMate.get_adapter adapter_name

    states = case states
    when Hash
      [states]
    when Array
      states
    else
      raise Error::TypeError.new states, "        each value of the spec needs to be a single state hash or an\n        array or state\n      BLOCK\n    end\n\n    states.each do |state|\n      unless spec.is_a? Hash\n        raise Error::TypeError.new state, \"each state needs to be a Hash\"\n      end\n\n      key = nil\n      directives = []\n      type_name = nil\n      options = state['options'] || {}\n      \n      unless options.is_a? Hash\n        raise TypeError.new binding.erb <<-END\n          options must be a hash, found <%= options.class %>:\n          \n          <%= options.inspect %>\n          \n          state:\n          \n          <%= state.inspect %>\n          \n        END\n      end\n      \n      state.each do |k, v|\n        if k == 'key'\n          key = v\n        elsif k == 'options'\n          # pass, dealt with above\n        elsif DIRECTIVES.include? k\n          directives << [k, v]\n        elsif k == 'type'\n          type_name = v\n        else\n          # any other keys are set as options\n          # this is a little convience feature that avoids having to\n          # nest inside an `options` key unless your option conflicts\n          # with 'key' or a directive.\n          #\n          # check for conflicts\n          if options.key? k\n            raise ArgumentError.new binding.erb <<-END\n              top-level state key \#{ k.inspect } was also provided in the\n              options.\n              \n              state:\n              \n              <%= state.inspect %>\n              \n            END\n          end\n          \n          options[k] = v\n        end\n      end\n\n      directive, value = case directives.length\n      when 0\n        raise \"no directive found in \#{ state.inspect }\"\n      when 1\n        directives.first\n      else\n        raise \"multiple directives found in \#{ state.inspect }\"\n      end\n      \n      unless type_name.nil?\n        value = StateMate.cast type_name, value\n      end\n\n      state_set.add adapter, key, directive, value, options\n    end # state.each\n  end # states.each\n\n  state_set\nend\n".unblock

Instance Method Details

#add(adapter, key, directive, value, options = {}) ⇒ Object 



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# File 'lib/state_mate.rb', line 166

def add adapter, key, directive, value, options = {}
  @states << State.new(adapter, key, directive, value, options)
end

#execute ⇒ Object 



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# File 'lib/state_mate.rb', line 170

def execute
  # find out what needs to be changed
  @states.each do |state|
    # read the current value
    read_value = state.adapter.read state.key, state.options

    # store it for use in the actual change
    @read_values[state] = read_value

    # the test method is the directive with a '?' appended,
    # like `set?` or `array_contains?`
    test_method = StateMate.method "#{ state.directive }?"

    # find out if the state is in sync
    in_sync = test_method.call state.key, read_value, state.value, state.adapter

    # add to the list of changes to be made for states that are
    # out of sync
    @states_to_change << state unless in_sync
  end

  # if everything is in sync, no changes need to be attempted
  # reutrn the empty hash of changes
  return @changes if @states_to_change.empty?

  # do the change to each in-memory value
  # this will raise an excption if the operation can't be done for
  # some reason
  states_to_change.each do |state|
    sync_method = StateMate.method state.directive
    # we want to catch any error and report it
    begin
      new_value = sync_method.call  state.key,
                                    @read_values[state],
                                    state.value,
                                    state.options
    rescue Exception => e
      @new_value_error = e
      raise Error::ValueChangeError.new binding.erb "        an error occured when changing a values:\n\n        <%= @new_value_error.format %>\n\n        no changes were attempted to the system, so there is no rollback\n        neessicary.\n      BLOCK\n    end\n    # change successful, store the new value along-side the state\n    # for use in the next block\n    @new_values << [state, new_value]\n  end\n\n  new_values.each do |state, new_value|\n    begin\n      state.adapter.write state.key, new_value, state.options\n    rescue Exception => e\n      @write_error = e\n      rollback\n      raise Error::WriteError.new binding.erb <<-BLOCK\n        an error occured when writing new state values:\n\n        <%= @write_error.format %>\n\n        <% if @written_states.empty? %>\n          the error occured on the first write, so no values were rolled\n          back.\n\n        <% else %>\n          <% if @rollback_errors.empty? %>\n            all values were sucessfully rolled back:\n\n          <% else %>\n            some values failed to rollback:\n\n          <% end %>\n\n          <% @written_states.each do |state| %>\n            <% if @rollback_errors[state] %>\n              <% state.key %>: <% @rollback_errors[state].format.indent(8) %>\n            <% else %> \n              <%= state.key %>: rolled back.\n            <% end %>\n          <% end %>\n        <% end %>\n        BLOCK\n    else\n      @written_states << state\n    end # begin / rescue / else\n  end # new_values.each\n\n  # ok, we made it. report the changes\n  new_values_hash = Hash[@new_values]\n  @written_states.each do |state|\n    @changes[[state.adapter.name, state.key]] = [@read_values[state], new_values_hash[state]]\n  end\n  \n  @changes\nend\n"