Class: FileStore::MemoryMetaManager

Inherits:
MetaManager show all
Includes:
Logger, OberservedSubject
Defined in:
lib/filestore/memory_meta.rb

Overview

Class implementing a memory based MetaManager

Constant Summary collapse

FILE =

Constant defining the default file path

'meta.yaml'

Instance Attribute Summary collapse

Attributes included from OberservedSubject

#observers

Attributes included from Logger

#logger

Instance Method Summary collapse

Methods included from OberservedSubject

included, #inform, #initialize_obs, #register, #unregister

Constructor Details

#initialize(persistentFile = '', logger) ⇒ MemoryMetaManager

Creates a new instance of MemoryMetaManager

Arguments: persistentFile: The file where the manager class is persisted to



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# File 'lib/filestore/memory_meta.rb', line 25

def initialize(persistentFile = '', logger)
  @logger = logger
  @data = Hash.new
  @removed = Hash.new
  @file = (persistentFile.nil? or persistentFile == '')? MemoryMetaManager::FILE : persistentFile
  
  self.initialize_obs
  
  begin
    if File.exists?(@file)
      @logger.info "loading meta yaml from #{@file}"
      @mm = YAML.load_file(@file) if File.exists?(@file)
      @logger.info "Loaded meta yaml: #{@mm}"
      @data = @mm[:current]
      @removed = @mm[:removed]
    else
      @logger.info "Creating new meta store in #{@file}"
    end
  rescue Exception => e
    raise FileStoreException, "Couldn't load meta data from file #{@file}.\nCause: #{e}"        
  end
    
end

Instance Attribute Details

#file ⇒ Object (readonly)

Accessor for the file to store data to



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# File 'lib/filestore/memory_meta.rb', line 18

def file
  @file
end

Instance Method Details

#add_or_update(id, metaData) ⇒ Object

see: MetaManager::add_or_update

Raises:



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# File 'lib/filestore/memory_meta.rb', line 59

def add_or_update(id, metaData)
  raise FileStoreException, "Only hashsets can be added" if not metaData.is_a?(Hash)
  raise FileStoreException, "Only Strings can be used as keys" if not id.is_a?(String)
  
  @data[id] = (@data.key?(id) ? @data[id].merge!(metaData) : @data[id] = metaData)
  
  self.inform ObserverAction.new(:type => ObserverAction::TYPE_META_ADD, 
     :objects => [id, metaData], :msg => "Added/Updated file to meta store")
end

#get_data(id) ⇒ Object

see: MetaManager::get_data

Raises:



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# File 'lib/filestore/memory_meta.rb', line 51

def get_data(id)
  raise FileStoreException, "No meta data available for ID #{id}" if not @data.key?(id)
  
  return @data[id]
end

#has_id?(id) ⇒ Boolean

see: MetaManager::has_id?

Returns:

  • (Boolean) 


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# File 'lib/filestore/memory_meta.rb', line 114

def has_id?(id)
  @data.key?(id)
end

#remove(id) ⇒ Object

see: MetaManager::remove

Raises:



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# File 'lib/filestore/memory_meta.rb', line 71

def remove(id)
  raise FileStoreException, "Only Strings can be used as keys" if not id.is_a?(String)
  raise FileStoreException, "ID #{id} not found in meta store" if not @data.key?(id)
  
  @removed[id] = @data[id]
  @data.delete(id)
  
  self.inform ObserverAction.new(:type => ObserverAction::TYPE_META_REMOVE, 
     :objects => [id], :msg => "Removed file to meta store")
end

#restore(id) ⇒ Object

see: MetaManager::restore

Raises:



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# File 'lib/filestore/memory_meta.rb', line 84

def restore(id)
  raise FileStoreException, "Only Strings can be used as keys" if not id.is_a?(String)
  raise FileStoreException, "ID #{id} not found in deleted meta store" if not @removed.key?(id)
  
  @data[id] = @removed[id]
  @removed.delete(id)
  
  self.inform ObserverAction.new(:type => ObserverAction::TYPE_META_RESTORE, 
     :objects => [id], :msg => "Restored file in meta store")
end

#shutdown ⇒ Object

see: MetaManager::shutdown



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# File 'lib/filestore/memory_meta.rb', line 97

def shutdown
  begin
    File.open(@file, "wb+") do |fh|
      YAML.dump({:current => @data, :removed => @removed}, fh)
    end
    
    @data = nil
    
    self.inform ObserverAction.new(:type => ObserverAction::TYPE_META_SHUTDOWN, 
        :msg => "Restored file in meta store")
  rescue Exception => e
    raise FileStoreException, "Couldn't serialize meta manager to file #{@file}.\n#{e.message}"
  end
end