Showing posts from December, 2021

System wide unique nanosecond timestamps

A Unique Identifier can be very useful for tracing. Those ids are even more useful when they contain a high-resolution timestamp.  Not only do they record the time of an event, but if unique can help trace events as they pass through the system. Such unique timestamps however can be expensive depending on how they are implemented.   This post explores a lightweight means of producing a unique, monotonically increasing system-wide nano-second resolution timestamp available in our open-source library. Uses for Unique Identifiers Unique identifiers can be useful to associate with a piece of information so that information can be referred to later unambiguously. This could be an event, a request, an order id, or a customer id. They can naturally be used as a primary key in a database or key/value store to retrieve that information later. One of the challenges of generating these identifiers is avoiding creating duplicates while not having an increasing cost.  You could record every identi

Unusual Java: StackTrace Extends Throwable

There are things you can do in Java you rarely see, generally because there is no use for it. However, there are some unusual things in Java that could be surprisingly useful. Chronicle Software uses a number of different usual patterns in it’s low-level libraries most developers wouldn’t generally come across. One of them is a class that extends Throwable but isn’t an Error or an Exception. StackTrace Extends Throwable package net.openhft.chronicle.core; /** * Throwable created purely for the purposes of reporting a stack trace. * This is not an Error or an Exception and is not expected to be thrown or caught. */ public class StackTrace extends Throwable {     public StackTrace() { this ( "stack trace" ); }     public StackTrace(String message) { this (message, null ); }     public StackTrace(String message, Throwable cause) {         super (message + " on " + Thread. currentThread ().getName(), cause);    }     public static StackTrace forThread(Thread t) {