package com.ankurm.vt;

// Explained in docs/01-inheritable-threadlocal.md -- run via scripts/run-all.sh, output captured in docs/output/

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/** Confirms, with no Spring involved, how InheritableThreadLocal behaves for
 *  (a) a fresh platform Thread, (b) a reused thread from a fixed pool, and
 *  (c) a fresh virtual thread. */
public class Demo1PlainThreadLocal {

    static final InheritableThreadLocal<String> CTX = new InheritableThreadLocal<>();

    public static void main(String[] args) throws Exception {
        System.out.println("=== Demo 1: InheritableThreadLocal across thread models ===");

        // (a) fresh platform Thread inherits at construction time
        CTX.set("request-A");
        Thread t = new Thread(() -> System.out.println("fresh platform thread sees: " + CTX.get()));
        t.start();
        t.join();

        // (b) reused thread from a fixed pool: the SECOND task on the same worker
        // still carries whatever was set when the pool thread was originally created
        ExecutorService pool = Executors.newFixedThreadPool(1);
        CTX.set("request-B");
        pool.submit(() -> System.out.println("pool thread, task 1, sees: " + CTX.get())).get();
        CTX.set("request-C"); // caller's context changed
        pool.submit(() -> System.out.println("pool thread, task 2 (reused), sees: " + CTX.get()
                + "  <-- stale, not request-C")).get();
        pool.shutdown();

        // (c) fresh virtual thread, never reused
        CTX.set("request-D");
        Thread vt = Thread.ofVirtual().start(() ->
                System.out.println("fresh virtual thread sees: " + CTX.get()));
        vt.join();

        CTX.remove();
    }
}