Add a precise gauge of the number of objects in memory (in fdb tree)

Related to #45

CHANGES.rst

@@ -25,6 +25,8 @@ fellow
 
 * Improved code coverage and added Coverity for additional linting.
 
+* Added g_mem_obj gauge.
+
 * Added an absolute maximum of 31 and dynamic maximum to the readahead
   parameter to avoid single object deliveries holding more than 1/16
   of the available memory cache.

src/VSC_fellow.vsc

@@ -120,6 +120,13 @@
 
 	Note: This number is only approximate
 
+.. varnish_vsc:: g_mem_obj
+	:type:	gauge
+	:level:	info
+	:oneliner:	Objects in memory
+
+	Exact number of objects currently in memory (fco_infdb).
+
 .. varnish_vsc:: g_dsk_bytes
 	:type:	gauge
 	:level:	info

src/fellow_cache.c

@@ -759,6 +759,7 @@ struct fellow_cache {
 
 	pthread_mutex_t			fdb_mtx;
 	struct fellow_cache_fdb_head	fdb_head;
+	uint64_t			*g_mem_obj;	// stats
 
 	struct fellow_cache_lrus	lrus[1];
 
@@ -1600,6 +1601,8 @@ fellow_cache_obj_evict_mutate(const struct fellow_cache_lru *lru,
 	AN(FCO_REFCNT(fco));
 	AZ(pthread_mutex_lock(&fc->fdb_mtx));
 	(void) VRBT_REMOVE(fellow_cache_fdb_head, &fc->fdb_head, fco);
+	AN(*fc->g_mem_obj);
+	(*fc->g_mem_obj)--;
 	AZ(pthread_mutex_unlock(&fc->fdb_mtx));
 
 	// state, oc (relevant for lru)
@@ -2655,6 +2658,7 @@ fellow_cache_obj_unbusy(struct fellow_busy *fbo, enum fcol_state wantlog)
 	AZ(pthread_mutex_lock(&fc->fdb_mtx));
 	ofco = VRBT_INSERT(fellow_cache_fdb_head, &fc->fdb_head, fco);
 	AZ(ofco);
+	(*fc->g_mem_obj)++;
 	AZ(pthread_mutex_unlock(&fc->fdb_mtx));
 
 	if (likely(fco->logstate == FCOL_DUNNO))
@@ -4864,6 +4868,8 @@ fellow_cache_obj_deref_locked(struct fellow_lru_chgbatch *lcb,
 		/* REF_FDB_REMOVE */
 		AZ(pthread_mutex_lock(&fc->fdb_mtx));
 		(void) VRBT_REMOVE(fellow_cache_fdb_head, &fc->fdb_head, fco);
+		AN(*fc->g_mem_obj);
+		(*fc->g_mem_obj)--;
 		AZ(pthread_mutex_unlock(&fc->fdb_mtx));
 	}
 	return (refcnt);
@@ -4947,6 +4953,7 @@ struct objcore **ocp, uintptr_t priv2, unsigned crit)
 	else if (ocp) {
 		AZ(nfco->oc);
 		TAKE_OBJ_NOTNULL(nfco->oc, ocp, OBJCORE_MAGIC);
+		(*fc->g_mem_obj)++;
 	}
 	AZ(pthread_mutex_unlock(&fc->fdb_mtx));
 
@@ -5389,7 +5396,7 @@ fellow_cache_assert_disk_fmt(void)
 
 struct fellow_cache *
 fellow_cache_init(struct fellow_fd *ffd, buddy_t *membuddy,
-    struct stvfe_tune *tune, fellow_task_run_t taskrun)
+    struct stvfe_tune *tune, fellow_task_run_t taskrun, uint64_t *g_mem_obj)
 {
 	struct fellow_cache *fc;
 
@@ -5410,6 +5417,8 @@ fellow_cache_init(struct fellow_fd *ffd, buddy_t *membuddy,
 
 	AZ(pthread_mutex_init(&fc->fdb_mtx, &fc_mtxattr_errorcheck));
 	VRBT_INIT(&fc->fdb_head);
+	fc->g_mem_obj = g_mem_obj;
+	AZ(*g_mem_obj);
 
 	fellow_cache_async_init(fc, taskrun);
 
@@ -5435,6 +5444,7 @@ fellow_cache_fini(struct fellow_cache **fcp)
 	fellow_cache_lrus_fini(fc->lrus);
 
 	assert(VRBT_EMPTY(&fc->fdb_head));
+	AZ(*fc->g_mem_obj);
 
 	fellow_cache_async_fini(fc);
 
@@ -6119,6 +6129,7 @@ t_cache(const char *fn, unsigned chksum)
 	struct fellow_cache_res fcr;
 	int injcount;
 	char *ptr;
+	uint64_t g_mem_obj = 0;
 
 	DBGSZ(fellow_disk_seg);
 	DBGSZ(fellow_disk_seglist);
@@ -6152,7 +6163,8 @@ t_cache(const char *fn, unsigned chksum)
 	XXXAN(ffd);
 	fellow_log_open(ffd, resurrect_discard, &resur_priv);
 
-	fc = fellow_cache_init(ffd, membuddy, tune, fellow_simple_task_run);
+	fc = fellow_cache_init(ffd, membuddy, tune, fellow_simple_task_run,
+	    &g_mem_obj);
 
 	t_lcb(fc);
 
@@ -6439,8 +6451,9 @@ t_cache(const char *fn, unsigned chksum)
 		XXXAN(ffd);
 		fellow_log_open(ffd, resurrect_keep, &resur_priv);
 
+		AZ(g_mem_obj);
 		fc = fellow_cache_init(ffd, membuddy, tune,
-		    fellow_simple_task_run);
+		    fellow_simple_task_run, &g_mem_obj);
 	}
 }
 

src/fellow_cache.h

@@ -49,7 +49,7 @@ struct fellow_cache_res {
 
 struct fellow_cache *
 fellow_cache_init(struct fellow_fd *, buddy_t *, struct stvfe_tune *,
-    fellow_task_run_t);
+    fellow_task_run_t, uint64_t *);
 void fellow_cache_fini(struct fellow_cache **);
 
 void fellow_cache_obj_delete(struct fellow_cache *fc,

src/fellow_storage.c

@@ -2415,7 +2415,7 @@ sfe_open_scope(struct stevedore *stv)
 	}
 
 	fc = fellow_cache_init(ffd, stvfe->membuddy, &stvfe->tune,
-	    sfe_taskrun);
+	    sfe_taskrun, &stvfe->stats->g_mem_obj);
 	if (fc == NULL) {
 		/* should never happen, unless we turn assertions into
 		 * errors */