log

Log elements flowing through the stream as well as completion and erroring.

Simple operators

Signature

Source.logSource.log Flow.logFlow.log

Description

Log elements flowing through the stream as well as completion and erroring. By default element and completion signals are logged on debug level, and errors are logged on Error level. This can be changed by calling Attributes.logLevels(...) Attributes.createLogLevels(...) on the given Flow.

See also logWithMarker.

Example

Scala
import akka.stream.Attributes

.log(name = "myStream")
.addAttributes(
  Attributes.logLevels(
    onElement = Attributes.LogLevels.Off,
    onFinish = Attributes.LogLevels.Info,
    onFailure = Attributes.LogLevels.Error))
Java
import akka.event.LogMarker;
import akka.stream.Attributes;

.log("myStream")
.addAttributes(
    Attributes.createLogLevels(
        Attributes.logLevelOff(), // onElement
        Attributes.logLevelInfo(), // onFinish
        Attributes.logLevelError())) // onFailure

Reactive Streams semantics

emits when upstream emits

backpressures when downstream backpressures

completes when upstream completes

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