metrics4-scala
API
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metrics4-scala/nl.grons.metrics4.scala

nl.grons.metrics4.scala

package nl.grons.metrics4.scala

Members list

Type members

Classlikes

trait BaseBuilder

Attributes

Supertypes
class Object
trait Matchable
class Any
Known subtypes
final class ByName[+T](expression: => T) extends () => T

Provides a wrapper for by-name expressions with the intent that they can become eligible for implicit conversions and implicit resolution.

Provides a wrapper for by-name expressions with the intent that they can become eligible for implicit conversions and implicit resolution.

Type parameters

T

Result type of the evaluated expression

Value parameters

expression

A by-name parameter that will yield a result of type T when evaluated

Attributes

Companion
object
Supertypes
trait () => T
class Object
trait Matchable
class Any
object ByName

Attributes

Companion
class
Supertypes
class Object
trait Matchable
class Any
Self type
ByName.type
trait CheckedBuilder extends BaseBuilder

The mixin trait for creating a class which creates health checks.

The mixin trait for creating a class which creates health checks.

Attributes

Supertypes
trait BaseBuilder
class Object
trait Matchable
class Any
Known subtypes
class Counter(metric: Counter)

A Scala facade class for DropwizardCounter.

A Scala facade class for DropwizardCounter.

Attributes

Supertypes
class Object
trait Matchable
class Any
trait DefaultInstrumented extends InstrumentedBuilder, CheckedBuilder

A mixin trait for creating a class that publishes metrics and health checks to the "default" registries.

A mixin trait for creating a class that publishes metrics and health checks to the "default" registries.

This follows the Dropwizard 1.0.0+ application convention of storing the metric registry to SharedMetricRegistries under the name "default". This was extended with storing the health check registry to SharedHealthCheckRegistries under the same name.

After mixing in this trait, metrics and health checks can be defined. For example:

class Example(db: Database) extends DefaultInstrumented {
 // Define a health check:
 healthCheck("alive") { workerThreadIsActive() }

 // Define a timer metric:
 private[this] val loading = metrics.timer("loading")

 // Use the timer metric:
 def loadStuff(): Seq[Row] = loading.time {
   db.fetchRows()
 }
}

See InstrumentedBuilder for instruction on overriding the metric base name or using hdrhistograms. See CheckedBuilder for instructions on overriding the timeout for scala.concurrent.Future executions.

Attributes

Supertypes
trait BaseBuilder
class Object
trait Matchable
class Any
Show all
trait DeprecatedMetricBuilder

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Supertypes
class Object
trait Matchable
class Any
Known subtypes
Self type
class DropwizardSettableGaugeWithTimeout[A] extends SettableGauge[A]

Attributes

Supertypes
trait SettableGauge[A]
trait Gauge[A]
trait Metric
class Object
trait Matchable
class Any
Show all
trait FreshHealthCheckRegistry

A mixin trait to get a fresh empty health check registry every time.

A mixin trait to get a fresh empty health check registry every time.

See FreshRegistries for more information.

Attributes

Supertypes
class Object
trait Matchable
class Any
Self type
trait FreshMetricRegistry

A mixin trait to get a fresh empty metric registry every time.

A mixin trait to get a fresh empty metric registry every time.

See FreshRegistries for more information.

Attributes

Supertypes
class Object
trait Matchable
class Any
Self type
trait FreshRegistries

A mixin trait to get a fresh empty metric and health check registry every time.

A mixin trait to get a fresh empty metric and health check registry every time.

Often a singleton service class defines a gauge with a static name. However, during testing multiple instances are needed. Unfortunately the metrics registry doesn't allow registering a gauge under the same name twice. This is not a problem when a new registry is used for each instance.

The same is the case for health checks (since dropwizard-metrics 4.1).

Example

With the following gauge in class Example:

class Example(db: Database) extends nl.grons.metrics4.scala.DefaultInstrumented {
 // Define a gauge with a static name
 metrics.gauge("aGauge") { db.rowCount() }
}

This trait can be mixed in with any instance of Example:

 val example = new Example(db) with FreshRegistries

See also FreshMetricRegistry and FreshHealthCheckRegistry in case your class only extends InstrumentedBuilder or CheckedBuilder respectively.

Attributes

Supertypes
class Object
trait Matchable
class Any
Self type
object Gauge

Attributes

Companion
class
Supertypes
class Object
trait Matchable
class Any
Self type
Gauge.type
class Gauge[T](metric: Gauge[T])

A Scala facade class for DropwizardGauge.

A Scala facade class for DropwizardGauge.

Attributes

Companion
object
Supertypes
class Object
trait Matchable
class Any
sealed trait HealthCheckMagnet

Magnet for the checker. See http://spray.io/blog/2012-12-13-the-magnet-pattern/.

Magnet for the checker. See http://spray.io/blog/2012-12-13-the-magnet-pattern/.

Attributes

Companion
object
Supertypes
class Object
trait Matchable
class Any
object HealthCheckMagnet

Attributes

Companion
trait
Supertypes
class Object
trait Matchable
class Any
Self type
class Histogram(val metric: Histogram)

A Scala facade class for DropwizardHistogram.

A Scala facade class for DropwizardHistogram.

Attributes

Supertypes
class Object
trait Matchable
class Any
object Implicits

Implicit conversions of Scala functions to Metric interfaces.

Implicit conversions of Scala functions to Metric interfaces.

NOTE: no longer needed in Scala 2.12 and later due to due to SAM.

Attributes

Supertypes
class Object
trait Matchable
class Any
Self type
Implicits.type
trait InstrumentedBuilder extends BaseBuilder

The mixin trait for creating a class which is instrumented with metrics.

The mixin trait for creating a class which is instrumented with metrics.

Use it as follows:

object Application {
 // The application wide metrics registry.
 val metricRegistry = new com.codahale.metrics.MetricRegistry()
}
trait Instrumented extends InstrumentedBuilder {
 val metricRegistry = Application.metricRegistry
}

class Example(db: Database) extends Instrumented {
 private[this] val loading = metrics.timer("loading")

 def loadStuff(): Seq[Row] = loading.time {
   db.fetchRows()
 }
}

As an alternative to your own Instrumented as above, it is possible to use DefaultInstrumented instead.

By default metric names are prefixed with the name of the current class. You can override this metric base name. For example:

class Example(db: Database) extends Instrumented {
 override lazy val metricBaseName = MetricName("Overridden.Base.Name")
 private[this] val loading = metrics.timer("loading")

 def loadStuff(): Seq[Row] = loading.time {
   db.fetchRows()
 }
}

If you want to use hdrhistograms, you can override the metric builder as follows:

trait Instrumented extends InstrumentedBuilder {
 override lazy protected val metricBuilder = new HdrMetricBuilder(metricBaseName, metricRegistry, false)
 val metricRegistry = Application.metricRegistry
}

See the the manual for more instructions on using hdrhistogram.

Attributes

Supertypes
trait BaseBuilder
class Object
trait Matchable
class Any
Known subtypes
class Meter(metric: Meter)

A Scala facade class for DropwizardMeter.

A Scala facade class for DropwizardMeter.

Example usage:

 class Example(val db: Db) extends Instrumented {
   private[this] val rowsLoadedMeter = metrics.meter("rowsLoaded")

   def load(id: Long): Seq[Row] = {
     val rows = db.load(id)
     rowsLoaded.mark(rows.size)
     rows
   }
 }

Attributes

Supertypes
class Object
trait Matchable
class Any
class MetricBuilder(val baseName: MetricName, val registry: MetricRegistry) extends DeprecatedMetricBuilder

Builds and registers metrics.

Builds and registers metrics.

Attributes

Supertypes
class Object
trait Matchable
class Any
object MetricName

Attributes

Companion
class
Supertypes
class Object
trait Matchable
class Any
Self type
MetricName.type
class MetricName

The (base)name of a metric.

The (base)name of a metric.

Constructed via the companion object, e.g. MetricName(getClass, "requests").

Attributes

Companion
object
Supertypes
class Object
trait Matchable
class Any
class PushGauge[A]

A gauge to which you can push new values.

A gauge to which you can push new values.

For more information see MetricBuilder.pushGauge.

Attributes

Supertypes
class Object
trait Matchable
class Any
Known subtypes
class PushGaugeWithTimeout[A] extends PushGauge[A]

A gauge to which you can push new values. Values are forgotten after some time.

A gauge to which you can push new values. Values are forgotten after some time.

For more information see MetricBuilder.pushGaugeWithTimeout.

Attributes

Supertypes
class PushGauge[A]
class Object
trait Matchable
class Any
class Timer(val metric: Timer)

A Scala facade class for DropwizardTimer.

A Scala facade class for DropwizardTimer.

Features:

  • measure the execution duration of a block of code with time
  • measure the time until a future is completed with timeFuture
  • add an execution duration measurement as a side effect to a partial function with timePF
  • direct access to the underlying timer with update, timerContext, count, max, etc.

Example usage:

 class Example(val db: Db) extends Instrumented {
   private[this] val loadTimer = metrics.timer("load")

   def load(id: Long) = loadTimer.time {
     db.load(id)
   }
 }

Attributes

Supertypes
class Object
trait Matchable
class Any
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