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/* =========================================================================================
* Copyright © 2013-2014 the kamon project <http://kamon.io/>
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
* =========================================================================================
*/
package kamon
import _root_.akka.actor
import _root_.akka.actor._
import _root_.akka.event.Logging
import com.typesafe.config.{ ConfigFactory, Config }
import kamon.metric._
import kamon.trace.{ TracerModuleImpl, TracerModule }
object Kamon {
trait Extension extends actor.Extension
private case class KamonCoreComponents(metrics: MetricsModule, tracer: TracerModule)
private val shouldAutoStart = isSystemPropertyEnabled("kamon.auto-start")
private val shouldWarnOnDuplicateStart = !isSystemPropertyEnabled("kamon.disable-duplicate-start-warning")
@volatile private var _system: ActorSystem = _
@volatile private var _coreComponents: Option[KamonCoreComponents] = None
def start(config: Config): Unit = synchronized {
def resolveInternalConfig: Config = {
val internalConfig = config.getConfig("kamon.internal-config")
config
.withoutPath("akka")
.withoutPath("spray")
.withFallback(internalConfig)
}
if (_coreComponents.isEmpty) {
val metrics = MetricsModuleImpl(config)
val tracer = TracerModuleImpl(metrics, config)
_coreComponents = Some(KamonCoreComponents(metrics, tracer))
_system = ActorSystem("kamon", resolveInternalConfig)
metrics.start(_system)
tracer.start(_system)
_system.registerExtension(ModuleLoader)
} else if (shouldWarnOnDuplicateStart) {
val logger = Logging(_system, "Kamon")
logger.warning("An attempt to start Kamon has been made, but Kamon has already been started.")
}
}
private def isSystemPropertyEnabled(propertyName: String): Boolean =
sys.props.get(propertyName).map(_.equals("true")).getOrElse(false)
def start(): Unit =
start(ConfigFactory.load)
def shutdown(): Unit = {
_coreComponents = None
_system.shutdown()
_system = null
}
def metrics: MetricsModule =
ifStarted(_.metrics)
def tracer: TracerModule =
ifStarted(_.tracer)
def apply[T <: Kamon.Extension](key: ExtensionId[T]): T =
ifStarted { _ ⇒
if (_system ne null)
key(_system)
else
sys.error("Cannot retrieve extensions while Kamon is being initialized.")
}
def extension[T <: Kamon.Extension](key: ExtensionId[T]): T =
apply(key)
private def ifStarted[T](thunk: KamonCoreComponents ⇒ T): T =
_coreComponents.map(thunk(_)) getOrElse {
if (shouldAutoStart) {
start()
thunk(_coreComponents.get)
} else sys.error("Kamon has not been started yet. You must either explicitlt call Kamon.start(...) or enable " +
"automatic startup by adding -Dkamon.auto-start=true to your JVM options.")
}
}
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