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- Counters -- these are the workhorse of the metrics system. These gather information on how many times some event occurs, or some piece of code is executed during a period of time. These can give you information on where most of the work is happening in the system.
- Range Samplers -- Not currently used in RNode
- Gauges -- Currently used to record numbers of peers (see comm/rp/Connect.scala and comm/discovery/KademliaNodeDiscovery.scala). In addition, a variety of information derived from the JVM is recorded using Gauges. These are collected in node/diagnostics/JvmMetrics.scala and use a wrapper called simply “g”.
- Histograms -- Currently used to record the amount of time to connect to a peer. See comm/rp/Connect.scala.
- Timers – Are not currently exposed in node/diagnostics/package.scala. Timers can record a start and stop time for an individual event.
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