cache_implementation: test

metadata_service/adapter/datastore.py

@@ -1,10 +1,13 @@
 import json
+from typing import Tuple
 
 from metadata_service.config import environment
 from metadata_service.domain.version import Version
 from metadata_service.exceptions.exceptions import DataNotFoundException
 
 DATASTORE_ROOT_DIR = environment.get("DATASTORE_ROOT_DIR")
+NEWEST_CACHE: Tuple[str, dict] = ("", {})
+LAST_REQUEST_CACHE: Tuple[str, dict] = ("", {})
 
 
 def get_draft_version() -> dict:
@@ -21,18 +24,44 @@ def get_datastore_versions() -> dict:
         return json.load(f)
 
 
-def get_metadata_all(version: Version) -> str:
+def get_from_cache(file_version: str) -> dict | None:
+    if file_version == NEWEST_CACHE[0]:
+        return NEWEST_CACHE[1]
+    if file_version == LAST_REQUEST_CACHE[0]:
+        return LAST_REQUEST_CACHE[1]
+    return None
+
+
+def update_cache(file_version: str, metadata_all):
+    global NEWEST_CACHE
+    global LAST_REQUEST_CACHE
+    if NEWEST_CACHE[0] == "" or LAST_REQUEST_CACHE[0] == "":
+        NEWEST_CACHE = (file_version, metadata_all)
+        LAST_REQUEST_CACHE = (file_version, metadata_all)
+    elif file_version > NEWEST_CACHE[0]:
+        NEWEST_CACHE = (file_version, metadata_all)
+    else:
+        LAST_REQUEST_CACHE = (file_version, metadata_all)
+
+
+def get_metadata_all(version: Version) -> dict:
     if version.is_draft():
         file_version = "DRAFT"
     else:
         file_version = version.to_3_underscored()
+        metadata_all = get_from_cache(file_version)
+        if metadata_all is not None:
+            return metadata_all
 
     metadata_all_file_path = (
         f"{DATASTORE_ROOT_DIR}/datastore/metadata_all__{file_version}.json"
     )
     try:
         with open(metadata_all_file_path, "r", encoding="utf-8") as f:
-            return json.load(f)
+            metadata_all = json.load(f)
+            if not version.is_draft():
+                update_cache(file_version, metadata_all)
+            return metadata_all
     except FileNotFoundError as e:
         raise DataNotFoundException(
             f"metadata_all for version {version} not found"