cache.get(): disable again, for now

We need to think about the API carefully.

NEWS

@@ -30,7 +30,7 @@ Improvements
 - bring in performace improvements provided by libknot 2.7
 - old name "Knot DNS Resolver" is replaced by unambiguous "Knot Resolver"
   to prevent confusion with "Knot DNS" authoritative server
-
+- lua: resurrect cache.clear('name')
 
 Knot Resolver 2.4.1 (2018-08-02)
 ================================
@@ -49,9 +49,6 @@ Bugfixes
   This fixes lower hit rate in NSEC3 zones (since 2.4.0).
 - minor TCP and TLS fixes (!623, !624, !626)
 
-Improvements
-------------
-- lua: resurrect cache.get('name') and cache.clear('name'), with caveats
 
 Knot Resolver 2.4.0 (2018-07-03)
 ================================

daemon/README.rst

@@ -827,6 +827,10 @@ daemons or manipulated from other processes, making for example synchronised loa
 
 .. function:: cache.get([domain])
 
+  This function is not implemented at this moment.
+  We plan to re-introduce it soon, probably with a slightly different API.
+
+..
   :return: table of records in cache matching the prefix
 
   .. error:: **Caveats:**

daemon/bindings.c

@@ -1075,6 +1075,7 @@ static int cache_close(lua_State *L)
 	return 1;
 }
 
+#if 0
 /** @internal Prefix walk. */
 static int cache_prefixed(struct kr_cache *cache, const char *prefix, bool exact_name,
 			  knot_db_val_t keyval[][2], int maxcount)
@@ -1087,6 +1088,7 @@ static int cache_prefixed(struct kr_cache *cache, const char *prefix, bool exact
 	/* Start prefix search */
 	return kr_cache_match(cache, buf, exact_name, keyval, maxcount);
 }
+#endif
 
 /** Prune expired/invalid records. */
 static int cache_prune(lua_State *L)
@@ -1134,6 +1136,7 @@ static int cache_clear_everything(lua_State *L)
 	return 1;
 }
 
+#if 0
 /** @internal Dump cache key into table on Lua stack. */
 static void cache_dump(lua_State *L, knot_db_val_t keyval[])
 {
@@ -1192,6 +1195,14 @@ static int cache_get(lua_State *L)
 	}
 	return 1;
 }
+#endif
+static int cache_get(lua_State *L)
+{
+	int ret = kr_error(ENOSYS);
+	format_error(L, kr_strerror(ret));
+	lua_error(L);
+	return ret;
+}
 
 /** Set time interval for cleaning rtt cache.
  * Servers with score >= KR_NS_TIMEOUTED will be cleaned after