Module: Persistence::Cursor::CursorInterface

Includes:
Enumerable
Included in:
Persistence::Cursor
Defined in:
lib/persistence/cursor/cursor_interface.rb

Overview

Interface implementation for Cursor class instances.

Instance Method Summary collapse

Instance Method Details

#any(any_count = 1) ⇒ Object+

Persist any object in cursor context.

Parameters:

  • any_count (Integer) (defaults to: 1) —

    How many objects to persist from cursor context.

Returns:



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# File 'lib/persistence/cursor/cursor_interface.rb', line 247

def any( any_count = 1 )
  
  object = nil
  
  if total_count = count
    begin
      @adapter_cursor.first
      objects = [ ]
      any_count.times do
        skip_records = rand( total_count - ( any_count + 1 ) )
        skip_records.times do
          @adapter_cursor.next
        end
        objects.push( self.next )
      end
      objects = objects[ 0 ] if objects.count <= 1
      # reset to first
      @adapter_cursor.first
    rescue StopIteration
    end      
  end
  
  return objects
  
end

#atomize ⇒ Object

Enable cursor as atomic cursor, causing objects to be loaded with atomic properties,

regardless how they are configured.

Returns:

  • self



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# File 'lib/persistence/cursor/cursor_interface.rb', line 59

def atomize
  
  extend( ::Persistence::Cursor::Atomic )
  
  return self
  
end

#close ⇒ Object

Declare cursor use complete.

Returns:

  • self



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# File 'lib/persistence/cursor/cursor_interface.rb', line 41

def close
  
  @adapter_cursor.close
  
  return self
  
end

#current ⇒ Object+

Persist current object in cursor context.

Returns:



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# File 'lib/persistence/cursor/cursor_interface.rb', line 282

def current

  first unless @has_position

  return get_object( @adapter_cursor.current )

end

#each {|object| ... } ⇒ Object

Iterate objects in current cursor context.

Yields:

  • (object) —

    Current object for cursor context.

Yield Parameters:

  • object —

    Object stored in cursor context.



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# File 'lib/persistence/cursor/cursor_interface.rb', line 140

def each

  # we have to set position if it's not already set before we can iterate
  first unless @has_position

  return to_enum unless block_given?

  # support for Enumerator#feed - permit a return value
  feed_value = nil

  begin
    while yield_object = self.next
      feed_value = yield( yield_object )
    end
  rescue StopIteration
  end

  return feed_value
  
end

#first(first_count = 1) ⇒ Object+

Persist first object in cursor context.

Parameters:

  • first_count (Integer) (defaults to: 1) —

    How many objects to persist from start of cursor context.

Returns:



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# File 'lib/persistence/cursor/cursor_interface.rb', line 172

def first( first_count = 1 )

  objects = nil

  if @has_position = persisted?
    begin
      if first_count == 1
        objects = current
      else
        objects = [ ]
        first_count.times do
          objects.push( self.next )
        end
      end
      # reset to first
      @adapter_cursor.first
    rescue StopIteration
    end
  end

  return objects

end

#get_object(global_id) ⇒ Hash{String,Symbol=>Object}

Get persistence hash for object with specified persistence ID.

Parameters:

  • global_id —

    Object persistence ID for retrieval.

Returns:

  • (Hash{String,Symbol=>Object}) —

    Persistence hash of object properties for persistence ID.



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# File 'lib/persistence/cursor/cursor_interface.rb', line 331

def get_object( global_id )

  return @persistence_bucket.get_object( global_id )

end

#initialize(bucket_instance, index_instance = nil) ⇒ Object

Parameters:

  • bucket_instance —

    Bucket to use for cursor context.

  • index_instance (defaults to: nil) —

    Index to use for cursor context.



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# File 'lib/persistence/cursor/cursor_interface.rb', line 18

def initialize( bucket_instance, index_instance = nil )

  @persistence_bucket = bucket_instance
  @parent_index = index_instance
  
  # use persistence port, bucket, index, value to instantiate adapter cursor
  if index_instance
    @adapter_cursor = index_instance.adapter_index.cursor
  else
    @adapter_cursor = bucket_instance.adapter_bucket.cursor
  end
  
end

#last(last_count = 1) ⇒ Object+

Persist last object in cursor context.

Parameters:

  • last_count (Integer) (defaults to: 1) —

    How many objects to persist from end of cursor context.

Returns:



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# File 'lib/persistence/cursor/cursor_interface.rb', line 207

def last( last_count = 1 )
  
  objects = nil
  
  if total_count = count
    begin
      first
      skip_records = total_count - last_count
      skip_records.times do
        @adapter_cursor.next
      end
      if last_count == 1
        objects = self.next
      else
        objects = [ ]
        last_count.times do
          objects.push( self.next )
        end
      end
      # reset to first
      @adapter_cursor.first
    rescue StopIteration
    end
  end
  
  return objects
  
end

#next(count = 1) ⇒ Object

Return the next object in cursor’s current context.

Returns:

  • (Object) —

    Next object in cursor’s current context.



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# File 'lib/persistence/cursor/cursor_interface.rb', line 299

def next( count = 1 )

  objects = nil

  if count > 1

    objects = [ ]
    count.times do
      objects.push( get_object( @adapter_cursor.next ) )
    end

  else

    objects = get_object( @adapter_cursor.next )

  end

  return objects

end

#persist(global_id) ⇒ Object

Load object with specified persistence ID.

Parameters:

  • global_id —

    Object persistence ID for retrieval.

Returns:

  • (Object) —

    Object for persistence ID.



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# File 'lib/persistence/cursor/cursor_interface.rb', line 117

def persist( global_id )

  object = nil

  if @has_position = @adapter_cursor.persisted?( global_id )
    object = get_object( @adapter_cursor.current )
  end

  return object

end

#persisted?(key, ...) ⇒ true, false

Query whether keys are persisted in cursor’s current context.

Parameters:

  • Key (Object) —

    to look up.

Returns:

  • (true, false) —

    Whether key(s) exist in cursor’s current context.



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# File 'lib/persistence/cursor/cursor_interface.rb', line 80

def persisted?( *args )

  # [ global_id, ... ]

  persisted = false

  # args => global_id, ...
  # positions on last id or false if one of ids is not persisted
  if args.count > 0

    args.each do |this_global_id|
      break unless persisted = @adapter_cursor.persisted?( this_global_id )
    end

  # no args
  # positions on first if keys or false if no keys
  else

    persisted = @adapter_cursor.persisted?

  end

  return @has_position = persisted

end