GH-76 Add delay

eternalcode-commons-shared/build.gradle.kts

@@ -5,6 +5,10 @@ plugins {
     `commons-java-unit-test`
 }
 
+dependencies {
+    implementation("com.github.ben-manes.caffeine:caffeine:3.2.3")
+}
+
 tasks.test {
     useJUnitPlatform()
 }

eternalcode-commons-shared/src/main/java/com/eternalcode/commons/delay/Delay.java

@@ -0,0 +1,58 @@
+package com.eternalcode.commons.delay;
+
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.function.Supplier;
+
+public class Delay<T> {
+
+    private final Cache<T, Instant> cache;
+    private final Supplier<Duration> defaultDelay;
+
+    private Delay(Supplier<Duration> defaultDelay) {
+        if (defaultDelay == null) {
+            throw new IllegalArgumentException("defaultDelay cannot be null");
+        }
+
+        this.defaultDelay = defaultDelay;
+        this.cache = Caffeine.newBuilder()
+            .expireAfter(new InstantExpiry<T>())
+            .build();
+    }
+
+    public static <T> Delay<T> withDefault(Supplier<Duration> defaultDelay) {
+        return new Delay<>(defaultDelay);
+    }
+
+    public void markDelay(T key, Duration delay) {
+        if (delay.isZero() || delay.isNegative()) {
+            this.cache.invalidate(key);
+        }
+
+        this.cache.put(key, Instant.now().plus(delay));
+    }
+
+    public void markDelay(T key) {
+        this.markDelay(key, this.defaultDelay.get());
+    }
+
+    public void unmarkDelay(T key) {
+        this.cache.invalidate(key);
+    }
+
+    public boolean hasDelay(T key) {
+        Instant delayExpireMoment = this.getExpireAt(key);
+        return Instant.now().isBefore(delayExpireMoment);
+    }
+
+    public Duration getRemaining(T key) {
+        return Duration.between(Instant.now(), this.getExpireAt(key));
+    }
+
+    private Instant getExpireAt(T key) {
+        return this.cache.asMap().getOrDefault(key, Instant.MIN);
+    }
+}

eternalcode-commons-shared/src/main/java/com/eternalcode/commons/delay/InstantExpiry.java

@@ -0,0 +1,39 @@
+package com.eternalcode.commons.delay;
+
+import com.github.benmanes.caffeine.cache.Expiry;
+
+import java.time.Duration;
+import java.time.Instant;
+
+public class InstantExpiry<T> implements Expiry<T, Instant> {
+
+    private static long timeToExpire(Instant expireTime) {
+        Duration toExpire = Duration.between(Instant.now(), expireTime);
+        if (toExpire.isNegative()) {
+            return 0;
+        }
+
+        long nanos = toExpire.toNanos();
+        if (nanos == 0) {
+            return 1;
+        }
+
+        return nanos;
+    }
+
+    @Override
+    public long expireAfterCreate(T key, Instant expireTime, long currentTime) {
+        return timeToExpire(expireTime);
+    }
+
+    @Override
+    public long expireAfterUpdate(T key, Instant newExpireTime, long currentTime, long currentDuration) {
+        return timeToExpire(newExpireTime);
+    }
+
+    @Override
+    public long expireAfterRead(T key, Instant value, long currentTime, long currentDuration) {
+        return currentDuration;
+    }
+
+}