le::ghs Namespace Reference

Classes
struct	Edge
	A struct to hold all the communication edge information. More...
class	GhsState
	The main state machine for the GHS algorithm More...
class	Msg
	An aggregate type containing all the data to exchange with to/from information. More...

Typedefs
typedef int	agent_t
	problems for GhsState More...
typedef unsigned long	metric_t
typedef int	level_t
	A "level" which is an internal item for GhsState to track how many times the MST has merged with another.

Enumerations
enum	status_t { UNKNOWN = 0, MST = 1, MST_PARENT =2, DELETED =-1 }
	A status enumeration, for the ghs edges. More...

Functions
bool	is_valid (const agent_t a)
Edge	worst_edge ()
bool	is_valid (const Edge e)
bool	is_valid (const metric_t m)

Variables
const agent_t	NO_AGENT =-1
const metric_t	WORST_METRIC =std::numeric_limits<metric_t>::max()
const metric_t	METRIC_NOT_SET =0
const level_t	LEVEL_START =0
	All levels start at 0.
const unsigned int	MAX_MSG_SZ = sizeof(Msg)

Detailed Description

GHS

The GHS namespace

Typedef Documentation

agent_t

le::ghs::agent_t

problems for GhsState

The ghs implementation supports arbitrary integers, as long as they are greater than or equal to zero. Use is_valid() to ensure an agent_t will

metric_t

typedef unsigned long le::ghs::metric_t

A typedef to hold the metrics. There's some work to do to make sure the metrics are:

• Symmetric (both peer and root agree on the value)
• unique (no two agents have the same metric)

However, that is not captured here, and is handled at a "higher level". See unique_link_metric_to()

See also

DemoComms::unique_link_metric_to()

Enumeration Type Documentation

status_t

enum le::ghs::status_t

A status enumeration, for the ghs edges.

Enumerator
UNKNOWN	We have not probed this edge for information yet, or have not recieved a reponse.
MST	We have added this edge as an MST link.
MST_PARENT	We have added this edge as parent MST link.
DELETED	We have decided not to further consider this edge, either it was "bad", or it is already part of our partition.

Function Documentation

is_valid() [1/3]

bool le::ghs::is_valid

(

const agent_t

a

)

Just in case you want an official alias for a>=0.

Returns

true if a>=0

false if a==NO_AGENT or is otherwise <0

is_valid() [2/3]

bool le::ghs::is_valid

(

const Edge

e

)

Parameters

e

an Edge

Returns

true if edge is not worst_edge() and does not have any uninitialized components.

is_valid() [3/3]

bool le::ghs::is_valid

(

const metric_t

m

)

Parameters

m	a metric_t

Returns

true if the metric_t is not NOT_SET or WORST_METRIC

worst_edge()

Edge le::ghs::worst_edge

(

)

Returns the worst possible edge, useful for comparisons in the search for the minimum weight outgoing edge.

Variable Documentation

MAX_MSG_SZ

const unsigned int le::ghs::MAX_MSG_SZ = sizeof(Msg)

For an external class that is interested in allocating static storage to queue a set of Msg s, this is the maximum size of the Msg class.

METRIC_NOT_SET

const metric_t le::ghs::METRIC_NOT_SET =0

This is set to zero because metrics are usually zero initialized by default, and we do not want to have a bunch of zeros floating around in our search

NO_AGENT

const agent_t le::ghs::NO_AGENT =-1

This means not set

WORST_METRIC

const metric_t le::ghs::WORST_METRIC =std::numeric_limits<metric_t>::max()

This is the "worst" metric possible, defined simply as the maximum value reachable.

We all need to agree on the worst metric, since we're all comparing against this to determine if we found a minimum weight outgoing edge. See mwoe()

See also

GhsState::mwoe() for how it is used

DemoComms::unique_link_metric_to() for why it is a size_t

DemoComms::little_iperf()