zipkin.reporter

Interface Sender

All Superinterfaces:

AutoCloseable, Closeable, zipkin.Component

public interface Sender
extends zipkin.Component

Sends a list of encoded spans to a transport such as http or Kafka. Usually, this involves encoding them into a message and enqueueing them for transport over http or Kafka. The typical end recipient is a zipkin Collector.

Unless mentioned otherwise, senders are not thread-safe. They were designed to be used by AsyncReporter, which has a single reporting thread.

Those looking to initialize eagerly should call Component.check(). This can be used to reduce latency on the first send operation, or to fail fast.

Implementation notes

The parameter is a list of encoded spans as opposed to an encoded message. This allows implementations flexibility on how to encode spans into a message. For example, a large span might need to be sent as a separate message to avoid kafka limits. Also, logging transports like scribe will likely write each span as a separate log line.

This accepts a list of encoded spans, as opposed a list of spans like Span. This allows senders to be re-usable as model shapes change. This also allows them to use their most natural message type. For example, kafka would more naturally send messages as byte arrays.

If performance is critical, thrift encoding is most efficient, sometimes 3x faster than json.

Nested Class Summary

Nested classes/interfaces inherited from interface zipkin.Component

zipkin.Component.CheckResult

Method Summary

Modifier and Type	Method and Description
Encoding	encoding() Returns the encoding this sender requires spans to have.
int	messageMaxBytes() Maximum bytes sendable per message including overhead.
int	messageSizeInBytes(List<byte[]> encodedSpans) Before invoking sendSpans(List, Callback), callers must consider message overhead, which might be more than encoding overhead.
void	sendSpans(List<byte[]> encodedSpans, Callback callback) Sends a list of encoded spans to a transport such as http or Kafka.

Methods inherited from interface zipkin.Component

check, close

Method Detail

encoding

Encoding encoding()

Returns the encoding this sender requires spans to have.

messageMaxBytes

int messageMaxBytes()

Maximum bytes sendable per message including overhead. This can be calculated using messageSizeInBytes(List)

messageSizeInBytes

int messageSizeInBytes(List<byte[]> encodedSpans)

Before invoking sendSpans(List, Callback), callers must consider message overhead, which might be more than encoding overhead. This is used to not exceed messageMaxBytes().

Note this is not always Encoding.listSizeInBytes(List), as some senders have inefficient list encoding. For example, Scribe base64's then tags each span with a category.

sendSpans

void sendSpans(List<byte[]> encodedSpans,
               Callback callback)

Sends a list of encoded spans to a transport such as http or Kafka.

Note: Eventhough there's a callback, there's no guarantee implementations won't block. Accordingly, this method should not be called on the operation being measured's thread.

Parameters:

encodedSpans - list of encoded spans.

callback - signals either completion or failure

Throws:

IllegalStateException - if close was called.