[Refactor] Refactor contiguous (#716)

(cherry picked from commit b4c91e8)

tensordict/_lazy.py

@@ -2824,8 +2824,6 @@ def is_contiguous(self) -> bool:
  return all([value.is_contiguous() for _, value in self.items()])
 
  def contiguous(self) -> T:
- if self.is_contiguous():
- return self
  return self._fast_apply(lambda x: x.contiguous())
 
  def rename_key_(

tensordict/_td.py

@@ -2048,9 +2048,17 @@ def _clone(self, recurse: bool = True) -> T:
  return result
 
  def contiguous(self) -> T:
- if not self.is_contiguous():
- return self.clone()
- return self
+ source = {key: value.contiguous() for key, value in self.items()}
+ batch_size = self.batch_size
+ device = self.device
+ out = TensorDict(
+ source=source,
+ batch_size=batch_size,
+ device=device,
+ names=self.names,
+ _run_checks=False,
+ )
+ return out
 
  def empty(self, recurse=False) -> T:
  if not recurse:
@@ -2738,11 +2746,9 @@ def is_contiguous(self) -> bool:
  return all(value.is_contiguous() for value in self.values())
 
  def contiguous(self) -> T:
- if self.is_contiguous():
- return self
  return TensorDict(
  batch_size=self.batch_size,
- source={key: value for key, value in self.items()},
+ source={key: value.contiguous() for key, value in self.items()},
  device=self.device,
  names=self.names,
  _run_checks=False,