siena::FIB Class Reference

Basic services of a forwarding table. More...

#include <forwarding.h>

Inheritance diagram for siena::FIB:

Public Member Functions
virtual	~FIB ()
	Destroys the forwarding including all its internal data structures.
virtual void	consolidate ()
	Prepares the forwarding table for matching. More...
virtual void	clear ()=0
	Clears the forwarding table. More...
virtual void	clear_recycle ()=0
	Clears the forwarding table. More...
virtual size_t	allocated_bytesize () const =0
	Memory allocated by the forwarding table. More...
virtual size_t	bytesize () const =0
	Memory used by the forwarding table. More...

Detailed Description

Basic services of a forwarding table.

A forwarding table implements the forwarding function of a specific routing scheme. This class abstracts the essential services of a forwarding table that do not depend on the routing scheme. These amount to little more than memory management.

Depending on the implementation, a forwarding table is typically a dictionary data structure, meaning that it is compiled once and then used for matching repeatedly. The table can be compiled by adding associations between predicates and interfaces (or whatever is specific of the addressing and routing scheme) but can not be modified by removing or modifying individual associations. In order to modify individual associations, the forwarding table must be completely cleared, using the clear or clear_recycle methods, and built over again.

More specifically, the forwarding table operates in two modes. Initially the forwarding table is in configuration mode. While in configuration mode, the forwarding table can be configured by associating predicates to interfaces (e.g., using the ifconfig method). Once all the interfaces have been associated with their predicate, the forwarding table must be prepared for matching by calling the consolidate method. The consolidate method switches the forwarding table to matching mode, which means that the forwarding table can be used to match messages. The forwarding table, can then be cleared and restored to configuration mode with the clear or clear_recycle methods.

Once in matching mode, the forwarding table can match incoming messages with the match method. The forwarding table delegates the processing of matched notifications to a given handler. The MatchHandler class defines the interface of a handler.

The forwarding table manages its memory allocation through a dedicated block-allocator. When cleared with clear(), the forwarding table releases all the previously allocated memory. clear_recycle() can be used to clear the forwarding table and recycle previously allocated memory. In this latter case, previously allocated memory is saved for future use.

Member Function Documentation

virtual size_t siena::FIB::allocated_bytesize ( ) const

pure virtual

Memory allocated by the forwarding table.

returns the number of bytes of memory allocated by the forwarding table. This value is always greater than or equal to the value returned by bytesize().

virtual size_t siena::FIB::bytesize ( ) const

pure virtual

Memory used by the forwarding table.

returns the number of bytes of memory used by the forwarding table. This value is always less than or equal to the value returned by allocated_bytesize().

virtual void siena::FIB::clear ( )

pure virtual

Clears the forwarding table.

This method removes all the associations from the forwarding table and releases allocated memory. After a call to this method, the forwarding table is ready to be configured with siena::AttributesFIB::ifconfig().

See Also

siena::AttributesFIB::ifconfig()

consolidate()

virtual void siena::FIB::clear_recycle ( )

pure virtual

Clears the forwarding table.

This method removes all the associations from the forwarding table recycling the allocated memory. After a call to this method, the forwarding table is ready to be configured with siena::AttributesFIB::ifconfig().

See Also

siena::AttributesFIB::ifconfig()

consolidate()

virtual void siena::FIB::consolidate ( )

inlinevirtual

Prepares the forwarding table for matching.

This function processes the forwarding table, packing some of its internal data structures and preparing them to be used to match events. This function must therefore be called after all the necessary calls to ifconfig and before matching messages with match().

The forwarding table can be reset by calling clear or clear_recycle.

See Also

clear()

recycle_clear()