Part2 (Olga Li)

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

@@ -38,6 +38,30 @@ public OutdatableResult<T> getOutdatable(String key) {
         // 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 outdated = new CompletableFuture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> newResult = new OutdatableResult<>(result, outdated);
+        OutdatableResult<T> cacheResult = cache.putIfAbsent(key, newResult);
+
+        if (cacheResult != null) {
+            return cacheResult;
+        }
+
+        db.get(key).whenComplete((e, t) -> {
+            if (t != null) {
+                result.completeExceptionally(t);
+            } else {
+                result.complete(e);
+            }
+            scheduledExecutorService.schedule(() -> {
+                        cache.remove(key, newResult);
+                        outdated.complete(null);
+                    },
+                    timeout,
+                    timeoutUnits);
+        });
+        return newResult;
     }
 }