resources: Catch ConnectionResourceError in downloading resources

This handles an error we see within GitHub Actions that
occassionally occurs when downloading resources.  We retry in the
same way we do when handling HTTPErrors.

Change-Id: I4dce5d607ccc41ad53b51e39082c486e644d815c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/71858
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>

src/python/gem5/resources/downloader.py

@@ -139,6 +139,22 @@ def _download(url: str, download_to: str, max_attempts: int = 6) -> None:
                 time.sleep((2**attempt) + random.uniform(0, 1))
             else:
                 raise e
+        except ConnectionResetError as e:
+            # This catches the ConnectionResetError we see occassionally see
+            # when accessing resources on GitHub Actions.  It retries using a
+            # Truncated Exponential backoff algorithm, truncating after
+            # "max_attempts". If any other is retrieved we raise the error.
+            if e.errno == 104:
+                attempt += 1
+                if attempt >= max_attempts:
+                    raise Exception(
+                        f"After {attempt} attempts, the resource json could "
+                        "not be retrieved. OS Error Code retrieved: "
+                        f"{e.errno}"
+                    )
+                time.sleep((2**attempt) + random.uniform(0, 1))
+            else:
+                raise e
         except ValueError as e:
             raise Exception(
                 "Environment variable GEM5_USE_PROXY is set to "