Class: NoSE::Backend::FileBackend

Inherits:
Backend show all
Includes:
Subtype
Defined in:
lib/nose/backend/file.rb

Overview

Simple backend which persists data to a file

Defined Under Namespace

Modules: RowMatcher Classes: DeleteStatementStep, IndexLookupStatementStep, InsertStatementStep

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Subtype

included

Methods inherited from Backend

#by_id_graph, #drop_index, #indexes_sample, #prepare, #prepare_query, #prepare_update, #query, #update

Methods included from Supertype

included

Methods included from Listing

included

Constructor Details

#initialize(model, indexes, plans, update_plans, config) ⇒ FileBackend

Returns a new instance of FileBackend.



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# File 'lib/nose/backend/file.rb', line 9

def initialize(model, indexes, plans, update_plans, config)
  super

  # Try to load data from file or start fresh
  @index_data = if !config[:file].nil? && File.file?(config[:file])
                  Marshal.load File.open(config[:file])
                else
                  {}
                end

  # Ensure the data is saved when we exit
  ObjectSpace.define_finalizer self, self.class.finalize(@index_data,
                                                         config[:file])
end

Class Method Details

.finalize(index_data, file) ⇒ Object

Save data when the object is destroyed



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# File 'lib/nose/backend/file.rb', line 25

def self.finalize(index_data, file)
  proc do
    Marshal.dump(index_data, File.open(file, 'w'))
  end
end

Instance Method Details

#client ⇒ Hash

We just produce the data here which can be manipulated as needed

Returns:

  • (Hash) 


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# File 'lib/nose/backend/file.rb', line 76

def client
  @index_data
end

#generate_id ⇒ Object

Generate a simple UUID



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# File 'lib/nose/backend/file.rb', line 47

def generate_id
  SecureRandom.uuid
end

#index_empty?(index) ⇒ Boolean

Check for an empty array for the data

Returns:

  • (Boolean) 


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# File 'lib/nose/backend/file.rb', line 32

def index_empty?(index)
  !index_exists?(index) || @index_data[index.key].empty?
end

#index_exists?(index) ⇒ Boolean

Check if we have prepared space for this index

Returns:

  • (Boolean) 


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# File 'lib/nose/backend/file.rb', line 37

def index_exists?(index)
  @index_data.key? index.key
end

#index_insert_chunk(index, chunk) ⇒ Object

This method is abstract.

Subclasses implement to allow inserting



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# File 'lib/nose/backend/file.rb', line 42

def index_insert_chunk(index, chunk)
  @index_data[index.key].concat chunk
end

#index_sample(index, count) ⇒ Object

Sample a number of values from the given index



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# File 'lib/nose/backend/file.rb', line 69

def index_sample(index, count)
  data = @index_data[index.key]
  data.nil? ? [] : data.sample(count)
end

#indexes_ddl(execute = false, skip_existing = false, drop_existing = false) ⇒ Object

Allocate space for data on the new indexes



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# File 'lib/nose/backend/file.rb', line 52

def indexes_ddl(execute = false, skip_existing = false,
                drop_existing = false)
  @indexes.each do |index|
    # Do the appropriate behaviour based on the flags passed in
    if index_exists?(index)
      next if skip_existing
      fail unless drop_existing
    end

    @index_data[index.key] = []
  end if execute

  # We just use the original index definition as DDL
  @indexes.map(&:inspect)
end