chore: import upstream snapshot with attribution

decoding/GAD/fairseq/data/lru_cache_dataset.py

@@ -0,0 +1,21 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+from functools import lru_cache
+
+from . import BaseWrapperDataset
+
+
+class LRUCacheDataset(BaseWrapperDataset):
+    def __init__(self, dataset, token=None):
+        super().__init__(dataset)
+
+    @lru_cache(maxsize=8)
+    def __getitem__(self, index):
+        return self.dataset[index]
+
+    @lru_cache(maxsize=8)
+    def collater(self, samples):
+        return self.dataset.collater(samples)