From fb2009590a028f3f31deb9f4337b51775fc5b143 Mon Sep 17 00:00:00 2001
From: Matthew Richards <matthew.richards@stfc.ac.uk>
Date: Mon, 15 Mar 2021 12:37:17 +0000
Subject: [PATCH]  #209: Add client cache size as a configurable option

---
 config.json.example                    |  1 +
 datagateway_api/common/config.py       |  6 ++++++
 datagateway_api/common/icat/helpers.py |  2 +-
 test/test_config.py                    | 10 ++++++++++
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/config.json.example b/config.json.example
index d44534ec..deae7156 100644
--- a/config.json.example
+++ b/config.json.example
@@ -1,5 +1,6 @@
 {
   "backend": "db",
+  "client_cache_size": 28,
   "DB_URL": "mysql+pymysql://icatdbuser:icatdbuserpw@localhost:3306/icatdb",
   "ICAT_URL": "https://localhost:8181",
   "icat_check_cert": false,
diff --git a/datagateway_api/common/config.py b/datagateway_api/common/config.py
index 9b5090a4..d45507c7 100644
--- a/datagateway_api/common/config.py
+++ b/datagateway_api/common/config.py
@@ -34,6 +34,12 @@ def set_backend_type(self, backend_type):
         """
         self.config["backend"] = backend_type
 
+    def get_client_cache_size(self):
+        try:
+            return self.config["client_cache_size"]
+        except KeyError:
+            sys.exit("Missing config value, client_cache_size")
+
     def get_db_url(self):
         try:
             return self.config["DB_URL"]
diff --git a/datagateway_api/common/icat/helpers.py b/datagateway_api/common/icat/helpers.py
index 7cc5bb1d..018be84e 100644
--- a/datagateway_api/common/icat/helpers.py
+++ b/datagateway_api/common/icat/helpers.py
@@ -72,7 +72,7 @@ def wrapper_requires_session(*args, **kwargs):
     return wrapper_requires_session
 
 
-@lru_cache(maxsize=28)
+@lru_cache(maxsize=config.get_client_cache_size())
 def get_cached_client(session_id):
     """
     TODO - Add docstring
diff --git a/test/test_config.py b/test/test_config.py
index 4d5da769..a3a4a910 100644
--- a/test/test_config.py
+++ b/test/test_config.py
@@ -30,6 +30,16 @@ def test_invalid_backend_type(self, invalid_config):
             invalid_config.get_backend_type()
 
 
+class TestGetClientCacheSize:
+    def test_valid_client_cache_size(self, valid_config):
+        cache_size = valid_config.get_client_cache_size()
+        assert cache_size == 28
+
+    def test_invalid_client_cache_size(self, invalid_config):
+        with pytest.raises(SystemExit):
+            invalid_config.get_client_cache_size()
+
+
 class TestGetDBURL:
     def test_valid_db_url(self, valid_config):
         db_url = valid_config.get_db_url()