Class CounterResolver

java.lang.Object
org.apache.logging.log4j.layout.template.json.resolver.CounterResolver
All Implemented Interfaces:
EventResolver, TemplateResolver<LogEvent>
public class CounterResolver extends Object implements EventResolver
Resolves a number from an internal counter.

Configuration

config      = [ start ] , [ overflowing ] , [ stringified ]
start       = "start" -> number
overflowing = "overflowing" -> boolean
stringified = "stringified" -> boolean
Unless provided, start and overflowing are respectively set to zero and true by default.

When overflowing is set to true, the internal counter is created using a long, which is subject to overflow while incrementing, though garbage-free. Otherwise, a BigInteger is used, which does not overflow, but incurs allocation costs.

When stringified is enabled, which is set to false by default, the resolved number will be converted to a string.

Examples

Resolves a sequence of numbers starting from 0. Once Long.MAX_VALUE is reached, counter overflows to Long.MIN_VALUE. 
{
  "$resolver": "counter"
}
Resolves a sequence of numbers starting from 1000. Once Long.MAX_VALUE is reached, counter overflows to Long.MIN_VALUE. 
{
  "$resolver": "counter",
  "start": 1000
}
Resolves a sequence of numbers starting from 0 and keeps on doing as long as JVM heap allows. 
{
  "$resolver": "counter",
  "overflowing": false
}