Class: FakeDynamo::Storage

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Storage

Returns a new instance of Storage.



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# File 'lib/fake_dynamo/storage.rb', line 15

def initialize
  init_db
end

Instance Attribute Details

#compacted ⇒ Object

Returns the value of attribute compacted.



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# File 'lib/fake_dynamo/storage.rb', line 7

def compacted
  @compacted
end

#loaded ⇒ Object

Returns the value of attribute loaded.



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# File 'lib/fake_dynamo/storage.rb', line 7

def loaded
  @loaded
end

Class Method Details

.instance ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 10

def instance
  @storage ||= Storage.new
end

Instance Method Details

#compact! ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 91

def compact!
  return if @compacted
  @aof = Tempfile.new('compact')
  puts "Compacting db ..."
  db.tables.each do |_, table|
    persist('CreateTable', table.create_table_data)
    table.items.each do |_, item|
      persist('PutItem', table.put_item_data(item))
    end
  end
  @aof.close
  FileUtils.mv(@aof.path, db_path)
  @aof = nil
  @compacted = true
end

#compact_if_necessary ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 84

def compact_if_necessary
  return unless File.exists? db_path
  if File.stat(db_path).size > compact_threshold
    compact!
  end
end

#compact_threshold ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 80

def compact_threshold
  100 * 1024 * 1024 # 100mb
end

#db ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 42

def db
  DB.instance
end

#db_aof ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 46

def db_aof
  @aof ||= File.new(db_path, 'a')
end

#db_path ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 27

def db_path
  '/usr/local/var/fake_dynamo/db.fdb'
end

#delete_db ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 37

def delete_db
  return unless File.exists? db_path
  FileUtils.rm(db_path)
end

#init_db ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 31

def init_db
  return if File.exists? db_path
  FileUtils.mkdir_p(File.dirname(db_path))
  FileUtils.touch(db_path)
end

#load_aof ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 64

def load_aof
  return if @loaded
  file = File.new(db_path, 'r')
  puts "Loading fake_dynamo data ..."
  loop do
    operation = file.readline.chomp
    size = Integer(file.readline.chomp)
    data = file.read(size)
    db.process(operation, JSON.parse(data))
  end
rescue EOFError
  file.close
  compact_if_necessary
  @loaded = true
end

#persist(operation, data) ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 55

def persist(operation, data)
  return unless write_command?(operation)
  db_aof.puts(operation)
  data = data.to_json
  db_aof.puts(data.bytesize + "\n".bytesize)
  db_aof.puts(data)
  db_aof.flush
end

#shutdown ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 50

def shutdown
  puts "shutting down fake_dynamo ..."
  @aof.close if @aof
end

#write_command?(command) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fake_dynamo/storage.rb', line 23

def write_command?(command)
  write_commands.include?(command)
end

#write_commands ⇒ Object 



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# File 'lib/fake_dynamo/storage.rb', line 19

def write_commands
  %w[CreateTable DeleteItem DeleteTable PutItem UpdateItem UpdateTable]
end