org.apache.cassandra.net

Class Message<T>

java.lang.Object

org.apache.cassandra.net.Message<T>

Type Parameters:

T - The type of the message payload.

public class Message<T>
extends java.lang.Object

Immutable main unit of internode communication - what used to be MessageIn and MessageOut fused in one class.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Message.Builder<T>
static class	Message.Header Split into a separate object to allow partial message deserialization without wasting work and allocation afterwards, if the entire message is necessary and available.
static class	Message.InvalidLegacyProtocolMagic
static class	Message.Serializer Each message contains a header with several fixed fields, an optional key-value params section, and then the message payload itself.

Field Summary

Fields

Modifier and Type	Field and Description
Message.Header	header
T	payload
static Message.Serializer	serializer

Method Summary

Modifier and Type	Method and Description
static <T> Message.Builder<T>	builder(Message<T> message)
static <T> Message.Builder<T>	builder(Verb verb, T payload)
long	createdAtNanos() Creation time of the message.
long	creationTimeMillis()
long	elapsedSinceCreated(java.util.concurrent.TimeUnit units) For how long the message has lived.
Message<NoPayload>	emptyResponse() Builds a response Message with no payload, and all the right fields inferred from request Message
long	expiresAtNanos()
Message<RequestFailureReason>	failureResponse(RequestFailureReason reason) Builds a failure response Message with an explicit reason, and fields inferred from request Message
ForwardingInfo	forwardTo() Used for cross-DC write optimisation - pick one node in the DC and have it relay the write to its local peers
InetAddressAndPort	from() Sender of the message.
long	id() id of the request/message.
static <T> Message<T>	internalResponse(Verb verb, T payload)
boolean	isCrossNode() Whether the message has crossed the node boundary, that is whether it originated from another node.
static <T> Message<T>	out(Verb verb, T payload) Make a request Message with supplied verb and payload.
static <T> Message<T>	out(Verb verb, T payload, long expiresAtNanos)
static <T> Message<T>	outWithFlag(Verb verb, T payload, MessageFlag flag)
static <T> Message<T>	outWithFlags(Verb verb, T payload, MessageFlag flag1, MessageFlag flag2)
InetAddressAndPort	respondTo() The originator of the request - used when forwarding and will differ from from()
<T> Message<T>	responseWith(T payload) Builds a response Message with provided payload, and all the right fields inferred from request Message
int	serializedSize(int version) Serialized size of the entire message, for the provided messaging version.
java.lang.String	toString()
java.util.UUID	traceSession()
Tracing.TraceType	traceType()
boolean	trackRepairedData() See CASSANDRA-14145
Verb	verb()
Message<T>	withForwardTo(ForwardingInfo peers)

Methods inherited from class java.lang.Object

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

Field Detail

header

public final Message.Header header

payload

public final T payload

serializer

public static final Message.Serializer serializer

Method Detail

from

public InetAddressAndPort from()

Sender of the message.

isCrossNode

public boolean isCrossNode()

Whether the message has crossed the node boundary, that is whether it originated from another node.

id

public long id()

id of the request/message. In 4.0+ can be shared between multiple messages of the same logical request, whilst in versions above a new id would be allocated for each message sent.

verb

public Verb verb()

createdAtNanos

public long createdAtNanos()

Creation time of the message. If cross-node timeouts are enabled (DatabaseDescriptor.hasCrossNodeTimeout(), deserialize() will use the marshalled value, otherwise will use current time on the deserializing machine.

expiresAtNanos

public long expiresAtNanos()

elapsedSinceCreated

public long elapsedSinceCreated(java.util.concurrent.TimeUnit units)

For how long the message has lived.

creationTimeMillis

public long creationTimeMillis()

trackRepairedData

public boolean trackRepairedData()

See CASSANDRA-14145

forwardTo

@Nullable
public ForwardingInfo forwardTo()

Used for cross-DC write optimisation - pick one node in the DC and have it relay the write to its local peers

respondTo

@Nullable
public InetAddressAndPort respondTo()

The originator of the request - used when forwarding and will differ from from()

traceSession

@Nullable
public java.util.UUID traceSession()

traceType

@Nullable
public Tracing.TraceType traceType()

out

public static <T> Message<T> out(Verb verb,
                                 T payload)

Make a request Message with supplied verb and payload. Will fill in remaining fields automatically. If you know that you will need to set some params or flags - prefer using variants of out() that allow providing them at point of message constructions, rather than allocating new messages with those added flags and params. See outWithFlag(), outWithFlags(), and outWithParam() family.

out

public static <T> Message<T> out(Verb verb,
                                 T payload,
                                 long expiresAtNanos)

outWithFlag

public static <T> Message<T> outWithFlag(Verb verb,
                                         T payload,
                                         MessageFlag flag)

outWithFlags

public static <T> Message<T> outWithFlags(Verb verb,
                                          T payload,
                                          MessageFlag flag1,
                                          MessageFlag flag2)

internalResponse

public static <T> Message<T> internalResponse(Verb verb,
                                              T payload)

responseWith

public <T> Message<T> responseWith(T payload)

Builds a response Message with provided payload, and all the right fields inferred from request Message

emptyResponse

public Message<NoPayload> emptyResponse()

Builds a response Message with no payload, and all the right fields inferred from request Message

failureResponse

public Message<RequestFailureReason> failureResponse(RequestFailureReason reason)

Builds a failure response Message with an explicit reason, and fields inferred from request Message

withForwardTo

public Message<T> withForwardTo(ForwardingInfo peers)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

builder

public static <T> Message.Builder<T> builder(Message<T> message)

builder

public static <T> Message.Builder<T> builder(Verb verb,
                                             T payload)

serializedSize

public int serializedSize(int version)

Serialized size of the entire message, for the provided messaging version. Caches the calculated value.