Kitura's detailed logging is applied sparingly at present (we don't do much logging), because there is a small overhead to a log statement. Having many of these on the critical path hurts performance measurably.
Even though log statements wrap the message String in an @autoclosure (#18), the arguments still have to get passed through to a call (that then typically does nothing). This includes default values of #file, #function as well as the creation of the closure itself.
There are a couple of things we could try in this area:
- We could provide alternate versions of 'expensive' log levels (verbose, debug, entry, exit) which can be used to disable those levels at compile time, for example:
#if PRODUCTION
public class func debug(_ msg: @autoclosure () -> String, functionName: String = "",
lineNum: Int = 0, fileName: String = "") {
return
}
#else
(existing implementation)
#endif
- Swift 4.2 introduces an @inlinable attribute which would allow calls to an empty function (like the above) to be completely eliminated.
Kitura's detailed logging is applied sparingly at present (we don't do much logging), because there is a small overhead to a log statement. Having many of these on the critical path hurts performance measurably.
Even though log statements wrap the message String in an
@autoclosure(#18), the arguments still have to get passed through to a call (that then typically does nothing). This includes default values of#file,#functionas well as the creation of the closure itself.There are a couple of things we could try in this area: