Cooldowns: add missing docs, implement min-zero time difference, improve tests

src/main/java/com/cosimo/utilities/timed/Cooldown.java

@@ -4,6 +4,9 @@
 
 import java.util.concurrent.TimeUnit;
 
+/**
+ * Mutable implementation where the cooldown can be extended by a duration.
+ */
 public class Cooldown implements ICooldown {
 
     /**
@@ -17,7 +20,6 @@ public class Cooldown implements ICooldown {
      *
      * @param duration For how long this cooldown will last
      * @param unit     {@link TimeUnit} of the given cooldown duration parameter
-     * @see Cooldown - duration unit conversion to milliseconds
      */
     public Cooldown(long duration, @NonNull TimeUnit unit) {
         this.end = this.getCurrentTime() + this.toThisTime(duration, unit);

src/main/java/com/cosimo/utilities/timed/Cooldowns.java

@@ -6,13 +6,14 @@
 import java.util.Map;
 
 /**
- * A {@link Map} of {@link ICooldown} updated lazily, on access, with the {@link #cleanup()} method for purging expired
- * entries when needed.
+ * A {@link Map} of {@link ICooldown} cleared lazily with the {@link #clearExpired()} method for purging expired entries
+ * when needed.
  *
  * @param <K> Key type of this class's {@link Map}, {@link String} is suggested as it provides many variations for
  *            unique keys
  * @param <V> Expected {@link ICooldown} implementation
  */
+@SuppressWarnings("unused")
 public class Cooldowns<K, V extends ICooldown> extends HashMap<K, V> {
     public Cooldowns(int initialCapacity, float loadFactor) {
         super(initialCapacity, loadFactor);
@@ -26,18 +27,16 @@ public Cooldowns() {
         super();
     }
 
-    public Cooldowns(@NonNull Map<? extends K, ? extends V> map) {
+    public Cooldowns(@NonNull Map<K, ? extends V> map) {
         super(map);
     }
 
     /**
      * Removes all {@link ICooldown} that have expired.
      *
-     * @return This instance, useful for chaining
+     * @return Whether any {@link ICooldown} has expired and was removed
      */
-    @NonNull
-    public Cooldowns<K, V> cleanup() {
-        this.entrySet().removeIf(entry -> entry.getValue().isExpired());
-        return this;
+    public boolean clearExpired() {
+        return this.entrySet().removeIf(entry -> entry.getValue().isExpired());
     }
 }

src/main/java/com/cosimo/utilities/timed/ICooldown.java

@@ -16,21 +16,43 @@ default boolean isExpired() {
     }
 
     /**
-     * Returns how much time is left until the end of this cooldown, expressed in a given {@link TimeUnit}.
+     * Returns how much time is left until the end of this cooldown, expressed in a given {@link TimeUnit}, minimally
+     * zero.
      *
      * @param unit {@link TimeUnit} in which the remaining milliseconds should be converted to
-     * @return The remaining cooldown time, expressed as a double in the given {@link TimeUnit}
+     * @return The remaining cooldown time that can't be negative, expressed as a long in the given {@link TimeUnit}
      */
     default long getRemaining(@NonNull TimeUnit unit) {
-        return this.fromThisTime(this.getRemaining(), unit);
+        return Math.max(0, this.getDifference(unit));
     }
 
     /**
-     * Returns how much time is left until the end of this cooldown, even negative if it has already expired.
+     * Returns the timestamp difference between current one and the end of this cooldown, minimally zero, which would
+     * indicate it has already expired.
      *
-     * @return Remaining time of any sign
+     * @return Remaining time that can't be negative
      */
     default long getRemaining() {
+        return Math.max(0, this.getDifference());
+    }
+
+    /**
+     * Returns the timestamp difference between current one and the end of this cooldown, expressed in a given
+     * {@link TimeUnit}.
+     *
+     * @param unit {@link TimeUnit} in which the remaining milliseconds should be converted to
+     * @return The remaining cooldown time, expressed as a long in the given {@link TimeUnit}
+     */
+    default long getDifference(@NonNull TimeUnit unit) {
+        return this.fromThisTime(this.getDifference(), unit);
+    }
+
+    /**
+     * Returns how much time is left until the end of this cooldown, even negative if it has already expired.
+     *
+     * @return Remaining time of any mathematical sign
+     */
+    default long getDifference() {
         return this.getExpiration() - this.getCurrentTime();
     }
 

src/main/java/com/cosimo/utilities/timed/ImmutableCooldown.java

@@ -4,6 +4,10 @@
 
 import java.util.concurrent.TimeUnit;
 
+/**
+ * Immutable implementation for tracking cooldown expiration only.
+ */
+@SuppressWarnings("unused")
 public class ImmutableCooldown implements ICooldown {
 
     /**

src/test/java/com/cosimo/utilities/timed/CooldownTests.java

@@ -1,18 +1,21 @@
 package com.cosimo.utilities.timed;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.parallel.Execution;
+import org.junit.jupiter.api.parallel.ExecutionMode;
 
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
 import static org.junit.jupiter.api.Assertions.*;
 
+@Execution(ExecutionMode.CONCURRENT)
 public class CooldownTests {
 
     /**
      * Permitted time difference from setting a time value to testing it.
      */
-    public static final int TOLERANCE = 50;
+    public static final int MILLISECOND_TOLERANCE = 50;
 
     @Test
     public void testToThisTime() {
@@ -33,26 +36,43 @@ public void testFromThisTime() {
     @Test
     public void testGetCurrentTime() {
         final TimeStandard timeStandard = new TimeStandard() {
+            @Override
+            public long getCurrentTime() {
+                return System.nanoTime();
+            }
         };
-        final long currentTime = System.currentTimeMillis();
+        final long currentTime = System.nanoTime();
+        final long diffInMs = Math.abs(timeStandard.getCurrentTime() - currentTime) / 1000;
 
-        assertTrue(Math.abs(timeStandard.getCurrentTime() - currentTime) < TOLERANCE);
+        assertTrue(diffInMs < MILLISECOND_TOLERANCE);
     }
 
     @Test
     public void testIsExpired() throws InterruptedException {
         final ICooldown cooldown = new Cooldown(50);
+
         assertFalse(cooldown.isExpired());
+
         Thread.sleep(60);
+
         assertTrue(cooldown.isExpired());
+
+        assertEquals(0, cooldown.getRemaining());
+        assertEquals(0, cooldown.getRemaining(TimeUnit.SECONDS));
+
+        assertTrue(cooldown.getDifference() < 0);
+        assertTrue(cooldown.getDifference(TimeUnit.NANOSECONDS) < 0);
     }
 
     @Test
-    public void testGetRemaining() {
+    public void testGetRemainingAndDifference() {
         final ICooldown cooldown = new Cooldown(5_000);
+        final long difference = cooldown.getDifference();
         final long remaining = cooldown.getRemaining();
 
-        assertTrue(remaining <= 5_000 && remaining > 0);
+        assertTrue(difference <= 5_000 && difference > 0);
+        assertEquals(difference, remaining);
+        assertTrue(cooldown.getDifference(TimeUnit.SECONDS) <= 5);
         assertTrue(cooldown.getRemaining(TimeUnit.SECONDS) <= 5);
     }
 
@@ -93,18 +113,20 @@ public void testCooldownsCleanup() throws InterruptedException {
         cooldowns.put("test1", new Cooldown(50));
         cooldowns.put("test2", new Cooldown(5_000));
 
-        Thread.sleep(50 + TOLERANCE);
+        Thread.sleep(50 + MILLISECOND_TOLERANCE);
 
-        cooldowns.cleanup();
+        assertTrue(cooldowns.clearExpired());
 
         assertFalse(cooldowns.containsKey("test1"));
         assertTrue(cooldowns.containsKey("test2"));
+
+        assertFalse(cooldowns.clearExpired());
     }
 
     @Test
     public void testCooldownsConstructorWithMap() {
         final var initialMap = Map.of("key1", new Cooldown(5000));
-        final Cooldowns<String, ICooldown> cooldowns = new Cooldowns<>(initialMap);
+        final var cooldowns = new Cooldowns<>(initialMap);
 
         assertTrue(cooldowns.containsKey("key1"));
     }