Suggesting improve initialization performance

[timlueg]

Description

I was happy to see that there are logging libraries in java that don't need multiple 100s of milliseconds just for initialization.

Here I made some suggestions to reduces the tinylogs init performance further by ~10ms

• Replace ClassContextSecurityManager() with StackWalker
• Use direct call instead of reflection in getCurrentProcess (unsure why it uses reflection here)
• Use System.currentTimeMillis() instead of JVM start time. Really unsure if this would be acceptable but this save about 5ms it think.

Agreements

• I agree that my changes will be published under the terms of the Apache License 2.0 (mandatory)
• I agree that my GitHub user name will be published in the release notes (optional)

[codecov]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.31%. Comparing base (7590ad1) to head (292e94c).

Files	Patch %	Lines
...in/java/org/tinylog/runtime/ModernJavaRuntime.java	95.23%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               v2.8     #753      +/-   ##
============================================
+ Coverage     94.25%   94.31%   +0.05%     
+ Complexity     2838     2835       -3     
============================================
  Files           149      149              
  Lines          5502     5505       +3     
  Branches        727      723       -4     
============================================
+ Hits           5186     5192       +6     
+ Misses          176      175       -1     
+ Partials        140      138       -2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[pmwmedia]

Thanks for the draft! I'm curious to observe your changes. Just let me know when you are done, so I can review the changes.

To answer your questions:

Use direct call instead of reflection in getCurrentProcess (unsure why it uses reflection here)

Reflections where used for compatibility with Android as Android doesn't provide the class ProcessHandle, which was a cause for issues. However, I don't think that this workaround is still required.

Use System.currentTimeMillis() instead of JVM start time. Really unsure if this would be acceptable but this save about 5ms it think.

The JVM start time is nice if tinylog will be initialized much later. However, if you can provide a benchmark that shows significant performance improvements, we can change this.

[timlueg]

ManagementFactory.getRuntimeMXBean().getStartTime(); Takes 6-10 ms on my system (with openjdk-22.0.1)
Where as System.currentTimeMillis() takes <0.002 ms.

(It was tricky to get this project build locally (at least in Intellij), I experienced issues with JDK certificates, probably because of the old jdk version requirement. Don't want to spam more commits to get build in ci working)

[pmwmedia]

You can fix the build by applying these changes to ModernJavaRuntime.java:

	@IgnoreJRERequirement
	private static final class ClassNameExtractorByDepth implements Function<Stream<StackFrame>, String> {
		private final int depth;

		private ClassNameExtractorByDepth(final int depth) {
			this.depth = depth;
		}

		@Override
		public String apply(final Stream<StackFrame> frames) {
			return frames.skip(depth)
					.findFirst()
					.map(new ClassNameMapper())
					.orElse(null);
		}
	}

	@IgnoreJRERequirement
	private static final class ClassNameExtractorByLoggerClassName implements Function<Stream<StackFrame>, String> {
		private final String loggerClassName;

		private ClassNameExtractorByLoggerClassName(final String loggerClassName) {
			this.loggerClassName = loggerClassName;
		}

		@Override
		public String apply(final Stream<StackFrame> stream) {
			return stream.map(new ClassNameMapper()).dropWhile(new Predicate<String>() {
				@Override
				public boolean test(final String name) {
					return !name.equals(loggerClassName);
				}
			}).skip(1).findFirst().orElse(null);
		}
	}

	/**
	 * Mapper for getting the class name from a {@link StackFrame}.
	 */
	@IgnoreJRERequirement
	private static final class ClassNameMapper implements Function<StackFrame, String> {

		/** */
		private ClassNameMapper() {
		}

		@Override
		public String apply(final StackFrame stackFrame) {
			return stackFrame.getClassName();
		}

	}