Module: CouchRest::Model::Rotation::ClassMethods

Defined in:
lib/couchrest/model/rotation.rb

Instance Method Summary collapse

Instance Method Details

#create_database!(name = nil) ⇒ Object

create a new empty database.



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# File 'lib/couchrest/model/rotation.rb', line 134

def create_database!(name=nil)
  db = if name
    self.server.database!(db_name_with_prefix(name))
  else
    self.database!
  end
  create_rotation_filter(db)
  if self.respond_to?(:design_doc, true)
    design_doc.sync!(db)
    # or maybe this?:
    #self.design_docs.each do |design|
    #  design.migrate(to_db)
    #end
  end
  return db
end

#rotate_database(base_name, options = {}) ⇒ Object

Set up database rotation.

base_name – the name of the db before the rotation number is appended.

options – one of:

  • :every – frequency of rotation

  • :expiration_field - what field to use to determine if a

    document is expired.

  • :timestamp_field - alternately, what field to use for the

    document timestamp.

  • :timeout – used to expire documents with only a timestamp

    field (in minutes)



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# File 'lib/couchrest/model/rotation.rb', line 61

def rotate_database(base_name, options={})
  @rotation_base_name = base_name
  @rotation_every = (options.delete(:every) || 30.days).to_i
  @expiration_field = options.delete(:expiration_field)
  @timestamp_field = options.delete(:timestamp_field)
  @timeout = options.delete(:timeout)
  if options.any?
    raise ArgumentError.new('Could not understand options %s' % options.keys)
  end
end

#rotate_database_now(options = {}) ⇒ Object

Check to see if dbs should be rotated. The :window argument specifies how far in advance we should create the new database (default 1.day).

This method relies on the assumption that it is called at least once within each @rotation_every period.



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# File 'lib/couchrest/model/rotation.rb', line 80

def rotate_database_now(options={})
  window = options[:window] || 1.day

  now = Time.now.utc
  current_name = rotated_database_name(now)
  current_count = now.to_i/@rotation_every

  next_time = window.from_now.utc
  next_name = rotated_database_name(next_time)
  next_count = current_count+1

  prev_name = current_name.sub(/(\d+)$/) {|i| i.to_i-1}
  replication_started = false
  old_name = prev_name.sub(/(\d+)$/) {|i| i.to_i-1} # even older than prev_name
  trailing_edge_time = window.ago.utc

  if !database_exists?(current_name)
    # we should have created the current db earlier, but if somehow
    # it is missing we must make sure it exists.
    create_new_rotated_database(:from => prev_name, :to => current_name)
    replication_started = true
  end

  if next_time.to_i/@rotation_every >= next_count && !database_exists?(next_name)
    # time to create the next db in advance of actually needing it.
    create_new_rotated_database(:from => current_name, :to => next_name)
  end

  if trailing_edge_time.to_i/@rotation_every == current_count
    # delete old dbs, but only after window time has past since the last rotation
    if !replication_started && database_exists?(prev_name)
      # delete previous, but only if we didn't just start replicating from it
      self.server.database(db_name_with_prefix(prev_name)).delete!
    end
    if database_exists?(old_name)
      # there are some edge cases, when rotate_database_now is run
      # infrequently, that an older db might be left around.
      self.server.database(db_name_with_prefix(old_name)).delete!
    end
  end
end

#rotated_database_name(time = nil) ⇒ Object 



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# File 'lib/couchrest/model/rotation.rb', line 122

def rotated_database_name(time=nil)
  unless @rotation_base_name && @rotation_every
    raise ArgumentError.new('missing @rotation_base_name or @rotation_every')
  end
  time ||= Time.now.utc
  units = time.to_i / @rotation_every.to_i
  "#{@rotation_base_name}_#{units}"
end