class DefaultMetrics

A default implementation of ClientMetrics that exposes the driver events as Node.js events.

An instance of DefaultMetrics is configured by default in the client, you can access this instance using Client#metrics property.

Members

EventEmitter

errors

Emits all the error events.

Use each of the properties to measure events of specific errors.

Properties:
Name Type Description
authentication EventEmitter

Emits the authentication timeout error events.
clientTimeout EventEmitter

Emits the client timeout error events.
connection EventEmitter

Emits the connection error events.
readTimeout EventEmitter

Emits the read timeout error events obtained from the server.
other EventEmitter

Emits the error events, that are not part of the other categories.
unavailable EventEmitter

Emits the unavailable error events obtained from the server.
writeTimeout EventEmitter

Emits the write timeout error events obtained from the server
EventEmitter

ignoredErrors

Emits events when an error is ignored by the retry policy.

EventEmitter

responses

Emits events when a response message is obtained.

Properties:
Name Type Description
success EventEmitter

Emits when a response was obtained as the result of a successful execution.
EventEmitter

retries

Emits all the retry events.

Use each of the properties to measure events of specific retries.

Properties:
Name Type Description
clientTimeout EventEmitter

Emits when an execution is retried as a result of an client timeout.
other EventEmitter

Emits the error events, that are not part of the other categories.
readTimeout EventEmitter

Emits an execution is retried as a result of an read timeout error from the server (coordinator to replica).
unavailable EventEmitter

Emits an execution is retried as a result of an unavailable error from the server.
writeTimeout EventEmitter

Emits an execution is retried as a result of a write timeout error from the server (coordinator to replica).
EventEmitter

speculativeExecutions

Emits events when a speculative execution is started.

Constructor

new

DefaultMetrics

()

Creates a new instance of DefaultMetrics.

Examples:
Listening to events emitted
defaultMetrics.errors.on('increment', err => totalErrors++);
defaultMetrics.errors.clientTimeout.on('increment', () => clientTimeoutErrors++);
defaultMetrics.speculativeRetries.on('increment', () => specExecsCount++);
defaultMetrics.responses.on('increment', latency => myHistogram.record(latency));

Methods

onAuthenticationError

(AuthenticationError or Error e)

Method invoked when an authentication error is obtained from the server.

Parameters:
Name Type Description
e AuthenticationError or Error

The error encountered.

onClientTimeoutError

(OperationTimedOutError e)

Method invoked when an error (different than a server or client timeout, authentication or connection error) is encountered when executing a request.

Parameters:
Name Type Description
e OperationTimedOutError

The timeout error.

onClientTimeoutRetry

(Error e)

Method invoked when an execution is retried as a result of a client-level timeout.

Parameters:
Name Type Description
e Error

The error that caused the retry.

onConnectionError

(Error e)

Method invoked when there is a connection error.

Parameters:
Name Type Description
e Error

The error encountered.

onIgnoreError

(Error e)

Method invoked when an error is marked as ignored by the retry policy.

Parameters:
Name Type Description
e Error

The error that was ignored by the retry policy.

onOtherError

(Error e)

Method invoked when an error (different than a server or client timeout, authentication or connection error) is encountered when executing a request.

Parameters:
Name Type Description
e Error

The error encountered.

onOtherErrorRetry

(Error e)

Method invoked when an error (other than a server or client timeout) is retried.

Parameters:
Name Type Description
e Error

The error that caused the retry.

onReadTimeoutError

(ResponseError e)

Method invoked when a read timeout error is obtained from the server.

Parameters:
Name Type Description
e ResponseError

The error encountered.

onReadTimeoutRetry

(Error e)

Method invoked when an execution is retried as a result of a read timeout from the server (coordinator to replica).

Parameters:
Name Type Description
e Error

The error that caused the retry.

onResponse

(Array<Number> latency)

Method invoked when any response is obtained, the response can be the result of a successful execution or a server-side error.

Parameters:
Name Type Description
latency Array<Number>

The latency represented in a [seconds, nanoseconds] tuple Array, where nanoseconds is the remaining part of the real time that can’t be represented in second precision.

onSpeculativeExecution

()

Method invoked when a speculative execution is started.

onSuccessfulResponse

(Array<Number> latency)

Method invoked when a response is obtained successfully.

Parameters:
Name Type Description
latency Array<Number>

The latency represented in a [seconds, nanoseconds] tuple Array, where nanoseconds is the remaining part of the real time that can’t be represented in second precision.

onUnavailableError

(ResponseError e)

Method invoked when an unavailable error is obtained from the server.

Parameters:
Name Type Description
e ResponseError

The error encountered.

onUnavailableRetry

(Error e)

Method invoked when an execution is retried as a result of an unavailable error from the server.

Parameters:
Name Type Description
e Error

The error that caused the retry.

onWriteTimeoutError

(ResponseError e)

Method invoked when a write timeout error is obtained from the server.

Parameters:
Name Type Description
e ResponseError

The error encountered.

onWriteTimeoutRetry

(Error e)

Method invoked when an execution is retried as a result of a write timeout from the server (coordinator to replica).

Parameters:
Name Type Description
e Error

The error that caused the retry.