part2

src/main/java/part2/cache/CachingDataStorageImpl.java

@@ -3,6 +3,7 @@
 import db.DataStorage;
 import db.SlowCompletableFutureDb;
 
+import java.util.Optional;
 import java.util.concurrent.*;
 
 public class CachingDataStorageImpl<T> implements CachingDataStorage<String, T> {
@@ -32,12 +33,29 @@ public CachingDataStorageImpl(DataStorage<String, T> db, int timeout, TimeUnit t
 
     @Override
     public OutdatableResult<T> getOutdatable(String key) {
-        // TODO implement
-        // TODO use ScheduledExecutorService to remove outdated result from cache - see SlowCompletableFutureDb implementation
-        // TODO complete OutdatableResult::outdated after removing outdated result from cache
-        // TODO don't use obtrudeException on result - just don't
-        // TODO use remove(Object key, Object value) to remove target value
-        // TODO Start timeout after receiving result in CompletableFuture, not after receiving CompletableFuture itself
-        throw new UnsupportedOperationException();
+
+        CompletableFuture<T> result = new CompletableFuture<>();
+        CompletableFuture<Void> outdated = new CompletableFuture<>();
+        OutdatableResult<T> outdatableResult = new OutdatableResult<>(result, outdated);
+        OutdatableResult<T> cachedResult = cache.putIfAbsent(key, outdatableResult);
+
+        if (cachedResult != null)
+            return cachedResult;
+        db.get(key).whenComplete((t, thr) -> {
+            if (thr != null) {
+                result.completeExceptionally(thr);
+            } else {
+                result.complete(t);
+            }
+            scheduledExecutorService.schedule(
+                    () -> {
+                        cache.remove(key, outdatableResult);
+                        outdated.complete(null);
+                    },
+                    timeout,
+                    timeoutUnits);
+        });
+
+        return outdatableResult;
     }
 }