com.launchdarkly.logging

Class LogValues

java.lang.Object

com.launchdarkly.logging.LogValues

public abstract class LogValues
extends java.lang.Object

Helper methods for logging special variables.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	LogValues.StringProvider Functional interface for use with defer(com.launchdarkly.logging.LogValues.StringProvider).

Method Summary

Modifier and Type	Method and Description
static java.lang.Object	defer(LogValues.StringProvider stringProvider) Converts any method or lambda returning a string into an object for calling it lazily.
static java.lang.Object	exceptionSummary(java.lang.Throwable e) Returns an object whose toString() method returns only the class name and optional message of the exception.
static java.lang.Object	exceptionTrace(java.lang.Throwable e) Returns an object that lazily constructs an exception stacktrace.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

defer

public static java.lang.Object defer(LogValues.StringProvider stringProvider)

Converts any method or lambda returning a string into an object for calling it lazily.

This returns an object which delegates its toString() implementation to the specified method or lambda.

Sometimes log messages may include a computed value that has enough computational overhead that you would prefer not to compute it unless it really will be logged. The LDLogger methods that take parameters of type Object do not call toString() to convert those parameters to strings immediately; if logging of this message has been disabled, for instance by level filtering, or if all logging is disabled because the destination is Logs.none(), then toString() is not called.

   // Here, computeJsonData is only called if debug-level logging is enabled
   logger.debug("The JSON data is: {}", () -> computeJsonData());
 

Parameters:

stringProvider - a method or lambda that returns a string

Returns:

an object that calls stringProvider if toString is called

exceptionSummary

public static java.lang.Object exceptionSummary(java.lang.Throwable e)

Returns an object whose toString() method returns only the class name and optional message of the exception.

That is already the behavior of Exception.toString(), so this method just returns the exception itself. It is provided here in order to make the intended behavior clearer in logging code (and for consistency with the LogValues.ExceptionSummary method in the .NET equivalent of this package). Also, future versions of this package might define additional behavior, with the constraint that it will never include a stacktrace.

Parameters:

e - an exception

Returns:

the same exception

exceptionTrace

public static java.lang.Object exceptionTrace(java.lang.Throwable e)

Returns an object that lazily constructs an exception stacktrace.

Calling toString() on the object returned by this method returns the exception's stacktrace as a string. This string is not constructed unless toString() is called, so writing exceptions to the log in this way incurs very little overhead if logging is not enabled for the specified log level.

   try { ... }
   catch (Exception e) {
     logger.error("Error: {}", LogValues.exceptionSummary(e));
     logger.debug("{}", LogValues, exceptionTrace(e));
 

Parameters:

e - an exception

Returns:

an object whose toString() method provides a stacktrace