freenet.node.probe

Class Probe

java.lang.Object

freenet.node.probe.Probe

All Implemented Interfaces:

ByteCounter

public class Probe
extends java.lang.Object
implements ByteCounter

Handles starting, routing, and responding to Metropolis-Hastings corrected probes. Possible future additions to these probes' results include:

• Starting a regular request for a key.
• Success rates for remote requests by HTL; perhaps over some larger amount of time than the past hour.

See Also:

Explanation of Metropolis-Hastings correction

Field Summary

Fields

Modifier and Type	Field and Description
int	COUNTER_MAX_LOCAL Maximum number of probes started locally in the past minute.
int	COUNTER_MAX_PEER Maximum number of probes accepted from a single peer in the past minute.
static float	DECREMENT_PROBABILITY Probability of HTL decrement at HTL = 1.
static byte	MAX_HTL Maximum hopsToLive value to clamp requests to.
static int	MAX_SEND_ATTEMPTS Maximum number of forwarding attempts to make before failing with DISCONNECTED.
static long	TIMEOUT_HTL1 In ms, to account for probabilistic decrement at HTL = 1.
static long	TIMEOUT_PER_HTL In ms, per HTL above HTL = 1.
static long	WAIT_BASE To make the timing less obvious when a node responds with a local result instead of forwarding at HTL = 1, delay for a number of milliseconds, specifically an exponential distribution with this constant as its mean.
static long	WAIT_MAX Maximum number of milliseconds to wait before sending a response.

Constructor Summary

Constructors

Constructor and Description
Probe(Node node)

Method Summary

Modifier and Type	Method and Description
void	receivedBytes(int bytes) Counts as probe request transfer.
void	request(Message message, PeerNode source) Processes an incoming probe request; relays results back to source.
void	sentBytes(int bytes) Counts as probe request transfer.
void	sentPayload(int bytes) No payload in probes.
void	start(byte htl, long uid, Type type, Listener listener) Sends an outgoing probe request.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MAX_HTL

public static final byte MAX_HTL

Maximum hopsToLive value to clamp requests to.

See Also:

Constant Field Values

MAX_SEND_ATTEMPTS

public static final int MAX_SEND_ATTEMPTS

Maximum number of forwarding attempts to make before failing with DISCONNECTED.

See Also:

Constant Field Values

DECREMENT_PROBABILITY

public static final float DECREMENT_PROBABILITY

Probability of HTL decrement at HTL = 1.

See Also:

Constant Field Values

TIMEOUT_PER_HTL

public static final long TIMEOUT_PER_HTL

In ms, per HTL above HTL = 1.

TIMEOUT_HTL1

public static final long TIMEOUT_HTL1

In ms, to account for probabilistic decrement at HTL = 1.

WAIT_BASE

public static final long WAIT_BASE

To make the timing less obvious when a node responds with a local result instead of forwarding at HTL = 1, delay for a number of milliseconds, specifically an exponential distribution with this constant as its mean.

WAIT_MAX

public static final long WAIT_MAX

Maximum number of milliseconds to wait before sending a response.

COUNTER_MAX_PEER

public final int COUNTER_MAX_PEER

Maximum number of probes accepted from a single peer in the past minute.

See Also:

Constant Field Values

COUNTER_MAX_LOCAL

public final int COUNTER_MAX_LOCAL

Maximum number of probes started locally in the past minute. This is the maximum conceivable value; the probes should be used with a number of requests per minute closer to the per-peer limit times the minimum expected number of peers. Around this value, and certainly above it, remote OVERLOADs may start coming in, which are not useful. The Metropolis-Hastings correction makes behavior potentially inconsistent, so keeping an eye on remote OVERLOADs is wise.

See Also:

Constant Field Values

Constructor Detail

Probe

public Probe(Node node)

Method Detail

sentBytes

public void sentBytes(int bytes)

Counts as probe request transfer.

Specified by:

sentBytes in interface ByteCounter

Parameters:

bytes - Bytes received.

receivedBytes

public void receivedBytes(int bytes)

Counts as probe request transfer.

Specified by:

receivedBytes in interface ByteCounter

Parameters:

bytes - Bytes received.

sentPayload

public void sentPayload(int bytes)

No payload in probes.

Specified by:

sentPayload in interface ByteCounter

Parameters:

bytes - Ignored.

start

public void start(byte htl,
                  long uid,
                  Type type,
                  Listener listener)

Sends an outgoing probe request.

Parameters:

htl - htl for this outgoing probe: should be [1, MAX_HTL]

listener - will be called with results.

See Also:

Listener

request

public void request(Message message,
                    PeerNode source)

Processes an incoming probe request; relays results back to source. If the probe has a positive HTL, routes with MH correction and probabilistically decrements HTL. If the probe comes to have an HTL of zero: (an incoming HTL of less than one is discarded.) Returns (as node settings allow) exactly one of:

• unique identifier and integer 7-day uptime percentage
• uptime: 48-hour percentage or 7-day percentage
• output bandwidth
• store size
• link lengths
• location
• build number

Parameters:

message - probe request, containing HTL