Merge branch '580-add-cache-usage-to-cache-stats' into 'master'

cache: add percentage usage to cache stats

Closes #580

See merge request !1025

NEWS

@@ -4,6 +4,7 @@ Knot Resolver 5.2.0 (2020-0m-dd)
 Improvements
 ------------
 - capabilities are no longer constrained when running as root (!1012)
+- cache: add percentage usage to cache.stats() (!1025)
 
 Bugfixes
 --------

daemon/bindings/cache.c

@@ -3,6 +3,7 @@
  */
 
 #include "daemon/bindings/impl.h"
+#include "lib/cache/cdb_lmdb.h"
 
 #include "daemon/worker.h"
 #include "daemon/zimport.h"
@@ -93,6 +94,12 @@ static int cache_stats(lua_State *L)
 	add_stat(match_miss);
 	add_stat(read_leq);
 	add_stat(read_leq_miss);
+	/* usage_percent statistics special case - double */
+	struct libknot_lmdb_env *libknot_db = knot_db_t_kres2libknot(cache->db);
+	cache->stats.usage_percent = cache->api->usage_percent(libknot_db);
+	lua_pushnumber(L, cache->stats.usage_percent);
+	lua_setfield(L, -2, "usage_percent");
+	free(libknot_db);
 #undef add_stat
 
 	return 1;

daemon/cache.test/clear.test.lua

@@ -186,17 +186,29 @@ local function test_complete_flush()
 	is(cache.count(), 0, 'cache is empty after full clear')
 end
 
+local function test_cache_used(lower, upper)
+	return function()
+		local usage = cache.stats().usage_percent
+		ok(usage >= lower and usage <= upper, string.format('cache percentage usage is between <%d, %d>', lower, upper))
+	end
+end
+
 return {
+	test_cache_used(0, 1),
 	import_zone,
+	test_cache_used(11, 12),
 	test_exact_match_qtype,
 	test_exact_match_qname,
 	test_callback,
 	import_zone,
 	test_subtree,
+	test_cache_used(10, 11),
 	test_subtree_limit,
+	test_cache_used(5, 6),
 	test_apex,
 	import_zone,
 	test_root,
 	import_zone,
 	test_complete_flush,
+	test_cache_used(0, 1),
 }

daemon/lua/kres-gen.lua

@@ -210,6 +210,7 @@ struct kr_cdb_stats {
 	uint64_t match_miss;
 	uint64_t read_leq;
 	uint64_t read_leq_miss;
+	double usage_percent;
 };
 struct kr_cache {
 	knot_db_t *db;

lib/cache/cdb_api.h

@@ -29,6 +29,7 @@ struct kr_cdb_stats {
 	uint64_t match_miss;
 	uint64_t read_leq;
 	uint64_t read_leq_miss;
+	double usage_percent;
 };
 
 
@@ -74,4 +75,6 @@ struct kr_cdb_api {
 	 * return: 0 for equality, > 0 for less, < 0 kr_error */
 	int (*read_leq)(knot_db_t *db, struct kr_cdb_stats *stat,
 			knot_db_val_t *key, knot_db_val_t *val);
+
+	double (*usage_percent)(knot_db_t *db);
 };

lib/cache/cdb_lmdb.c

@@ -17,6 +17,7 @@
 #include "lib/cache/cdb_lmdb.h"
 #include "lib/cache/cdb_api.h"
 #include "lib/cache/api.h"
+#include <lib/cache/impl.h>
 #include "lib/utils.h"
 
 
@@ -24,6 +25,8 @@
 #define LMDB_DIR_MODE   0770
 #define LMDB_FILE_MODE  0660
 
+/* TODO: we rely on mirrors of these two structs not changing layout
+ * in libknot and knot resolver! */
 struct lmdb_env
 {
 	size_t mapsize;
@@ -43,6 +46,14 @@ struct lmdb_env
 	} txn;
 };
 
+struct libknot_lmdb_env {
+	bool shared;
+	unsigned dbi;
+	void *env;
+	knot_mm_t *pool;
+};
+
+
 /** @brief Convert LMDB error code. */
 static int lmdb_error(int error)
 {
@@ -77,7 +88,6 @@ static inline MDB_val val_knot2mdb(knot_db_val_t v)
 	return (MDB_val){ .mv_size = v.len, .mv_data = v.data };
 }
 
-
 /*! \brief Set the environment map size.
  * \note This also sets the maximum database size, see \fn mdb_env_set_mapsize
  */
@@ -704,6 +714,30 @@ static int cdb_read_leq(knot_db_t *env, struct kr_cdb_stats *stats,
 	return ret;
 }
 
+static double cdb_usage(knot_db_t *db)
+{
+	const size_t db_size = knot_db_lmdb_get_mapsize(db);
+	const size_t db_usage_abs = knot_db_lmdb_get_usage(db);
+	const double db_usage = (double)db_usage_abs / db_size * 100.0;
+
+	return db_usage;
+}
+
+
+/** Conversion between knot and lmdb structs. */
+knot_db_t *knot_db_t_kres2libknot(const knot_db_t * db)
+{
+	/* this is struct lmdb_env as in resolver/cdb_lmdb.c */
+	const struct lmdb_env *kres_db = db;
+	struct libknot_lmdb_env *libknot_db = malloc(sizeof(*libknot_db));
+	if (libknot_db != NULL) {
+		libknot_db->shared = false;
+		libknot_db->pool = NULL;
+		libknot_db->env = kres_db->env;
+		libknot_db->dbi = kres_db->dbi;
+	}
+	return libknot_db;
+}
 
 const struct kr_cdb_api *kr_cdb_lmdb(void)
 {
@@ -712,7 +746,8 @@ const struct kr_cdb_api *kr_cdb_lmdb(void)
 		cdb_init, cdb_deinit, cdb_count, cdb_clear, cdb_commit,
 		cdb_readv, cdb_writev, cdb_remove,
 		cdb_match,
-		cdb_read_leq
+		cdb_read_leq,
+		cdb_usage,
 	};
 
 	return &api;

lib/cache/cdb_lmdb.h

@@ -9,3 +9,6 @@
 
 KR_EXPORT KR_CONST
 const struct kr_cdb_api *kr_cdb_lmdb(void);
+
+KR_EXPORT
+knot_db_t *knot_db_t_kres2libknot(const knot_db_t * db);

utils/cache_gc/db.c

@@ -3,6 +3,7 @@
 
 #include "db.h"
 
+#include "lib/cache/cdb_lmdb.h"
 #include <lib/cache/impl.h>
 //#include <lib/defines.h>
 
@@ -10,34 +11,6 @@
 #include <time.h>
 #include <sys/stat.h>
 
-//TODO: we rely on mirrors of these two structs not changing layout in knot-dns and knot-resolver!
-struct libknot_lmdb_env {
-	bool shared;
-	unsigned dbi;
-	void *env;
-	knot_mm_t *pool;
-};
-
-struct kres_lmdb_env {
-	size_t mapsize;
-	unsigned dbi;
-	void *env;
-	// sub-struct txn ommited
-};
-
-static knot_db_t *knot_db_t_kres2libknot(const knot_db_t * db)
-{
-	const struct kres_lmdb_env *kres_db = db;	// this is struct lmdb_env as in resolver/cdb_lmdb.c
-	struct libknot_lmdb_env *libknot_db = malloc(sizeof(*libknot_db));
-	if (libknot_db != NULL) {
-		libknot_db->shared = false;
-		libknot_db->pool = NULL;
-		libknot_db->env = kres_db->env;
-		libknot_db->dbi = kres_db->dbi;
-	}
-	return libknot_db;
-}
-
 int kr_gc_cache_open(const char *cache_path, struct kr_cache *kres_db,
 		     knot_db_t ** libknot_db)
 {

utils/cache_gc/kr_cache_gc.c

@@ -13,6 +13,7 @@
 #include <lib/cache/api.h>
 #include <lib/cache/impl.h>
 #include <lib/defines.h>
+#include "lib/cache/cdb_lmdb.h"
 
 #include "kr_cache_gc.h"
 
@@ -176,9 +177,8 @@ int kr_cache_gc(kr_cache_gc_cfg_t *cfg, kr_cache_gc_state_t **state)
 	}
 	knot_db_t *const db = (*state)->db; // frequently used shortcut
 
-	const size_t db_size = knot_db_lmdb_get_mapsize(db);
-	const size_t db_usage_abs = knot_db_lmdb_get_usage(db);
-	const double db_usage = (double)db_usage_abs / db_size * 100.0;
+	const struct kr_cdb_api *cache_api = kr_cdb_lmdb();
+	const double db_usage = cache_api->usage_percent(db);
 #if 0				// Probably not worth it, better reduce the risk by checking more often.
 	if (db_usage > 90.0) {
 		free(*libknot_db);
@@ -190,11 +190,7 @@ int kr_cache_gc(kr_cache_gc_cfg_t *cfg, kr_cache_gc_state_t **state)
 #endif
 	const bool large_usage = db_usage >= cfg->cache_max_usage;
 	if (cfg->dry_run || large_usage) {	// don't print this on every size check
-		const size_t MiB = 1024 * 1024;
-		#define MiB_round(n) (((n) + MiB/2) / MiB)
-		printf("Usage: %.2lf%% (%zu / %zu MiB)\n",
-			db_usage, MiB_round(db_usage_abs), MiB_round(db_size));
-		#undef MiB_round
+		printf("Usage: %.2lf%%\n", db_usage);
 	}
 	if (cfg->dry_run || !large_usage) {
 		return KNOT_EOK;