ai.eloquent.raft

Class LocalTransport

java.lang.Object

ai.eloquent.raft.LocalTransport

All Implemented Interfaces:

RaftTransport

public class LocalTransport
extends java.lang.Object
implements RaftTransport

A mocked transport, that delivers messages to others listening on the same transport instance.

Nested Class Summary

Nested classes/interfaces inherited from interface ai.eloquent.raft.RaftTransport

RaftTransport.Type

Field Summary

Fields

Modifier and Type	Field and Description
long	delayMax The maximum amount of network delay.
long	delayMin The minimum amount of network delay.
double	dropProb The probability of dropping a packet on the "network."
java.util.List<java.lang.Throwable>	exceptions The list of exceptions encountered by the transport.
double	ioExceptionProb The probability of getting an IO exception when calling a transport function.
long	numRPCsSent The number of RPC messages this transport has sent.
boolean	trueTime If true, run in real-time (or close to).

Constructor Summary

Constructors

Constructor and Description
LocalTransport() Creates a stable transport.
LocalTransport(boolean stable) A constructor that has presets for whether the transport is stable (i.e., lossless, etc.) or not
LocalTransport(boolean stable, boolean trueTime) A constructor that has presets for whether the transport is stable (i.e., lossless, etc.) or not, and whether we should run in true time
LocalTransport(long delayMin, long delayMax, double dropProb, double ioExceptionProb, boolean trueTime, long randomSeed) Create a mock transport.

Method Summary

Modifier and Type	Method and Description
void	assertInvariantsHold() This checks several invariants across all the Raft nodes attached to the LocalTransport.
LocalTransport	assertNoErrors() Checks that there are no errors on this transport in the course of operation.
void	bind(RaftAlgorithm listener) Register a listener for RPCs.
java.util.Collection<RaftAlgorithm>	boundAlgorithms() Get the collection of algorithms that have been bound to this transport.
void	broadcastTransport(java.lang.String sender, EloquentRaftProto.RaftMessage message) Broadcast an RPC request over the transport to all members of the cluster.
Span	expectedNetworkDelay() The expected delay, in milliseconds, for a round-trip on this transport.
protected void	finalize()
<E> E	getFuture(java.util.concurrent.CompletableFuture<E> future, java.time.Duration timeout) Get a future.
void	liftPartitions() Lift all of our network partitions.
long	now() The current (local) time on the transport.
void	partitionOff(long fromMillis, long toMillis, java.lang.String... nodeNames) Create a nework partition of the given nodes, separating them from the rest of the cluster (but allowing them to talk to each other just fine).
void	rpcTransport(java.lang.String sender, java.lang.String destination, EloquentRaftProto.RaftMessage message, java.util.function.Consumer<EloquentRaftProto.RaftMessage> onResponseReceived, java.lang.Runnable onTimeout, long timeout) Send an RPC request over the transport, expecting a reply.
void	schedule(long interval, int count, java.util.function.Consumer<java.lang.Long> task) The current time on the transport.
void	schedule(SafeTimerTask task, long delay) Schedule an event on the transport's time.
void	scheduleAtFixedRate(SafeTimerTask task, long period) Schedule an event on the transport's time.
void	sendTransport(java.lang.String sender, java.lang.String destination, EloquentRaftProto.RaftMessage message) Send an RPC request over the transport, not necessarily expecting a reply.
void	sleep(long millis) Sleep for the given number of milliseconds.
void	start() Start the transport, if it hasn't already started
void	stop() Stop this transport.
void	synchronizedRun(java.lang.Runnable r) Run a block of code while synrhronizing on the current timestep.
boolean	threadsCanBlock() If true, we are allowed to block while running on this transport.
void	waitForSilence() Wait for the transport to fall silent.

Methods inherited from class java.lang.Object

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

Methods inherited from interface ai.eloquent.raft.RaftTransport

broadcastTransport, create, messageType, mkRaftMessage, mkRaftMessage, mkRaftRPC, rpcTransport, rpcTransportAsFuture, rpcTransportAsFuture, sendTransport

Field Detail

delayMin

public final long delayMin

The minimum amount of network delay.

delayMax

public final long delayMax

The maximum amount of network delay.

dropProb

public final double dropProb

The probability of dropping a packet on the "network."

ioExceptionProb

public final double ioExceptionProb

The probability of getting an IO exception when calling a transport function.

trueTime

public final boolean trueTime

If true, run in real-time (or close to). Otherwise, mock the transport time.

numRPCsSent

public long numRPCsSent

The number of RPC messages this transport has sent.

exceptions

public final java.util.List<java.lang.Throwable> exceptions

The list of exceptions encountered by the transport. This should usually be empty at the end of a test. You can verify this with assertNoErrors().

Constructor Detail

LocalTransport

public LocalTransport(long delayMin,
                      long delayMax,
                      double dropProb,
                      double ioExceptionProb,
                      boolean trueTime,
                      long randomSeed)

Create a mock transport.

LocalTransport

public LocalTransport(boolean stable)

A constructor that has presets for whether the transport is stable (i.e., lossless, etc.) or not

LocalTransport

public LocalTransport(boolean stable,
                      boolean trueTime)

A constructor that has presets for whether the transport is stable (i.e., lossless, etc.) or not, and whether we should run in true time

LocalTransport

public LocalTransport()

Creates a stable transport.

Method Detail

synchronizedRun

public void synchronizedRun(java.lang.Runnable r)

Run a block of code while synrhronizing on the current timestep. This prevents the clock from slipping between lines of code

Parameters:

r - The runnable to run.

waitForSilence

public void waitForSilence()

Wait for the transport to fall silent.

start

public void start()

Start the transport, if it hasn't already started

Specified by:

start in interface RaftTransport

stop

public void stop()

Stop this transport.

Specified by:

stop in interface RaftTransport

threadsCanBlock

public boolean threadsCanBlock()

If true, we are allowed to block while running on this transport. This is useful for, e.g., unit tests. But, in general, we should try to not block as much as posisble. Defaults to false.

Specified by:

threadsCanBlock in interface RaftTransport

finalize

protected void finalize()
                 throws java.lang.Throwable

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable

bind

public void bind(RaftAlgorithm listener)

Register a listener for RPCs. This must be idempotent!

Specified by:

bind in interface RaftTransport

Parameters:

listener - The listener that should be called on all received RPC requests.

boundAlgorithms

public java.util.Collection<RaftAlgorithm> boundAlgorithms()

Get the collection of algorithms that have been bound to this transport. This is primarily useful for unit testing.

Specified by:

boundAlgorithms in interface RaftTransport

expectedNetworkDelay

public Span expectedNetworkDelay()

The expected delay, in milliseconds, for a round-trip on this transport. This is used to calibrate the Raft algorithm, and to test the unit tests.

Specified by:

expectedNetworkDelay in interface RaftTransport

rpcTransport

public void rpcTransport(java.lang.String sender,
                         java.lang.String destination,
                         EloquentRaftProto.RaftMessage message,
                         java.util.function.Consumer<EloquentRaftProto.RaftMessage> onResponseReceived,
                         java.lang.Runnable onTimeout,
                         long timeout)

Send an RPC request over the transport, expecting a reply.

Specified by:

rpcTransport in interface RaftTransport

Parameters:

sender - The name of the node sending the message. In many implementations, this is redundant.

destination - The destination we are sending the message to. This is a server name on the same cluster as the node this transport is bound to.

message - The message to send, as a EloquentRaftProto.RaftMessage.

onResponseReceived - The callback to run when a response is received from the server for the RPC. Either this or onTimeout is always called.

onTimeout - Called when no response is received in the given timeout threshold.

timeout - The number of milliseconds to wait before considering an RPC timed out.

sendTransport

public void sendTransport(java.lang.String sender,
                          java.lang.String destination,
                          EloquentRaftProto.RaftMessage message)

Send an RPC request over the transport, not necessarily expecting a reply.

Specified by:

sendTransport in interface RaftTransport

Parameters:

sender - The name of the node sending the message. In many implementations, this is redundant.

destination - The destination we are sending the message to. This is a server name on the same cluster as the node this transport is bound to.

message - The message to send, as a EloquentRaftProto.RaftMessage.

broadcastTransport

public void broadcastTransport(java.lang.String sender,
                               EloquentRaftProto.RaftMessage message)

Broadcast an RPC request over the transport to all members of the cluster.

Specified by:

broadcastTransport in interface RaftTransport

Parameters:

sender - The name of the node sending the message. In many implementations, this is redundant.

message - The message to send, as a EloquentRaftProto.RaftMessage.

assertNoErrors

public LocalTransport assertNoErrors()

Checks that there are no errors on this transport in the course of operation.

Returns:

this object, to allow for chaining methods.

assertInvariantsHold

public void assertInvariantsHold()

This checks several invariants across all the Raft nodes attached to the LocalTransport. If any invariant fails, this will throw an assert and fail. These invariants are from page 14 of Diego's thesis.

schedule

public void schedule(long interval,
                     int count,
                     java.util.function.Consumer<java.lang.Long> task)

The current time on the transport.

partitionOff

public void partitionOff(long fromMillis,
                         long toMillis,
                         java.lang.String... nodeNames)

Create a nework partition of the given nodes, separating them from the rest of the cluster (but allowing them to talk to each other just fine).

Parameters:

fromMillis - The time at which to install the network partition.

toMillis - The time at which to lift the network partition.

nodeNames - The names of the nodes forming the new partition. These can talk to each other, but cannot talk to anyone else in the cluster (or visa versa).

liftPartitions

public void liftPartitions()

Lift all of our network partitions.

now

public long now()

The current (local) time on the transport. This is usually System.currentTimeMillis() if this isn't a mock.

Specified by:

now in interface RaftTransport

sleep

public void sleep(long millis)

Sleep for the given number of milliseconds. This is purely for mocking for tests.

Specified by:

sleep in interface RaftTransport

scheduleAtFixedRate

public void scheduleAtFixedRate(SafeTimerTask task,
                                long period)

Schedule an event on the transport's time.

Specified by:

scheduleAtFixedRate in interface RaftTransport

schedule

public void schedule(SafeTimerTask task,
                     long delay)

Schedule an event on the transport's time.

Specified by:

schedule in interface RaftTransport

getFuture

public <E> E getFuture(java.util.concurrent.CompletableFuture<E> future,
                       java.time.Duration timeout)
                throws java.lang.InterruptedException,
                       java.util.concurrent.ExecutionException,
                       java.util.concurrent.TimeoutException

Get a future. This is just a mockable alias for CompletableFuture.get(long, TimeUnit).

Specified by:

getFuture in interface RaftTransport

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

java.util.concurrent.TimeoutException