Add option to re-use schema cache between requests (#2979)

* Add option to reuse database controller between requests. Clear schema cache when deleting everything

* Add test

* Rename setting to persistSchemaCache to more accurately reflect effect

* Repurpose option to determine whether to randomize cache prefix. Restore Config.js controller creation. Add tests

* Fix bug with missing parameter passed to to SchemaCache

* Renaming and formatting

* Fix property name typo

* Rename option to avoid double negative and still be falsey by default. Style fix

src/ParseServer.js

@@ -139,6 +139,7 @@ class ParseServer {
     expireInactiveSessions = defaults.expireInactiveSessions,
     revokeSessionOnPasswordReset = defaults.revokeSessionOnPasswordReset,
     schemaCacheTTL = defaults.schemaCacheTTL, // cache for 5s
+    enableSingleSchemaCache = false,
     __indexBuildCompletionCallbackForTests = () => {},
   }) {
     // Initialize the node client SDK automatically
@@ -181,7 +182,7 @@ class ParseServer {
     const analyticsController = new AnalyticsController(analyticsControllerAdapter);
 
     const liveQueryController = new LiveQueryController(liveQuery);
-    const databaseController = new DatabaseController(databaseAdapter, new SchemaCache(cacheController, schemaCacheTTL));
+    const databaseController = new DatabaseController(databaseAdapter, new SchemaCache(cacheController, schemaCacheTTL, enableSingleSchemaCache));
     const hooksController = new HooksController(appId, databaseController, webhookKey);
 
     const dbInitPromise = databaseController.performInitizalization();
@@ -221,7 +222,8 @@ class ParseServer {
       jsonLogs,
       revokeSessionOnPasswordReset,
       databaseController,
-      schemaCacheTTL
+      schemaCacheTTL,
+      enableSingleSchemaCache
     });
 
     // To maintain compatibility. TODO: Remove in some version that breaks backwards compatability