Package io.servicetalk.client.api

Interface RequestTracker

public interface RequestTracker

A tracker of latency of an action over time.

The usage of the RequestTracker is intended to follow the simple workflow:

• At initiation of an action that will be tracked the caller must call beforeRequestStart() and save the timestamp much like would be done when using a stamped lock.
• Once the request event is complete only one of the onRequestSuccess(long) or onRequestError(long, ErrorClass) methods must be called and called exactly once

In other words, every call to beforeRequestStart() must be followed by exactly one call to either of the completion methods onRequestSuccess(long) or onRequestError(long, ErrorClass). Failure to do so can cause state corruption in the RequestTracker implementations which may track not just latency but also the outstanding requests.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static enum	RequestTracker.ErrorClass	Enumeration of the main failure classes.

Field Summary

Fields

Modifier and Type	Field	Description
static final ContextMap.Key<RequestTracker>	REQUEST_TRACKER_KEY

Method Summary

Modifier and Type	Method	Description
long	beforeRequestStart()	Invoked before each start of the action for which latency is to be tracked.
void	onRequestError(long beforeStartTimeNs, RequestTracker.ErrorClass errorClass)	Records a failed completion of the action for which latency is to be tracked.
void	onRequestSuccess(long beforeStartTimeNs)	Records a successful completion of the action for which latency is to be tracked.

Field Details

REQUEST_TRACKER_KEY

static final ContextMap.Key<RequestTracker> REQUEST_TRACKER_KEY

Method Details

beforeRequestStart

long beforeRequestStart()

Invoked before each start of the action for which latency is to be tracked.

Returns:

Current time in nanoseconds.

onRequestSuccess

void onRequestSuccess(long beforeStartTimeNs)

Records a successful completion of the action for which latency is to be tracked.

Parameters:

beforeStartTimeNs - return value from beforeRequestStart().

onRequestError

void onRequestError(long beforeStartTimeNs,
 RequestTracker.ErrorClass errorClass)

Records a failed completion of the action for which latency is to be tracked.

Parameters:

beforeStartTimeNs - return value from beforeRequestStart().

errorClass - the class of error that triggered this method.