feature: Rewrite thread-local storage pattern (#2452)

thread-local-storage/src/main/java/com/iluwatar/AbstractThreadLocalExample.java

@@ -0,0 +1,44 @@
+package com.iluwatar;
+
+import java.security.SecureRandom;
+import java.util.concurrent.locks.LockSupport;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+/**
+ * Class with main logic.
+ */
+public abstract class AbstractThreadLocalExample implements Runnable {
+
+  private static final SecureRandom RND = new SecureRandom();
+
+  private static final Integer RANDOM_THREAD_PARK_START = 1_000_000_000;
+  private static final Integer RANDOM_THREAD_PARK_END = 2_000_000_000;
+
+  @Override
+  public void run() {
+    long nanosToPark = RND.nextInt(RANDOM_THREAD_PARK_START, RANDOM_THREAD_PARK_END);
+    LockSupport.parkNanos(nanosToPark);
+
+    System.out.println(getThreadName() + ", before value changing: " + getter().get());
+    setter().accept(RND.nextInt());
+  }
+
+  /**
+   * Setter for our value.
+   *
+   * @return consumer
+   */
+  protected abstract Consumer<Integer> setter();
+
+  /**
+   * Getter for our value.
+   *
+   * @return supplier
+   */
+  protected abstract Supplier<Integer> getter();
+
+  private String getThreadName() {
+    return Thread.currentThread().getName();
+  }
+}

thread-local-storage/src/main/java/com/iluwatar/WithThreadLocal.java

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+package com.iluwatar;
+
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+import lombok.AllArgsConstructor;
+
+/**
+ * Example of runnable with use of {@link ThreadLocal}.
+ */
+@AllArgsConstructor
+public class WithThreadLocal extends AbstractThreadLocalExample {
+
+  private final ThreadLocal<Integer> value;
+
+  /**
+   * Removes the current thread's value for this thread-local variable.
+   */
+  public void remove() {
+    this.value.remove();
+  }
+
+  @Override
+  protected Consumer<Integer> setter() {
+    return value::set;
+  }
+
+  @Override
+  protected Supplier<Integer> getter() {
+    return value::get;
+  }
+}

thread-local-storage/src/main/java/com/iluwatar/WithoutThreadLocal.java

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+package com.iluwatar;
+
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+import lombok.AllArgsConstructor;
+
+/**
+ * Example of runnable without usage of {@link ThreadLocal}.
+ */
+@AllArgsConstructor
+public class WithoutThreadLocal extends AbstractThreadLocalExample {
+
+  private Integer value;
+
+  @Override
+  protected Consumer<Integer> setter() {
+    return integer -> value = integer;
+  }
+
+  @Override
+  protected Supplier<Integer> getter() {
+    return () -> value;
+  }
+}