X-Git-Url: https://git.tokkee.org/?p=sysdb.git;a=blobdiff_plain;f=src%2Fcore%2Fstore.c;h=19faee43994bdde816a6a84f4c09061bfb25bb4f;hp=db57d2e5ba9506bc7adafba2a48a58263a1edca0;hb=742c60b383c9373b2156c3af5ff9e7605c056e60;hpb=ae3324ade282506976a21dbab487e99e41935b88

diff --git a/src/core/store.c b/src/core/store.c
index db57d2e..7671e98 100644
--- a/src/core/store.c
+++ b/src/core/store.c
@@ -1,6 +1,6 @@
 /*
  * SysDB - src/core/store.c
- * Copyright (C) 2012 Sebastian 'tokkee' Harl <sh@tokkee.org>
+ * Copyright (C) 2012-2013 Sebastian 'tokkee' Harl <sh@tokkee.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -25,10 +25,15 @@
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#if HAVE_CONFIG_H
+#	include "config.h"
+#endif /* HAVE_CONFIG_H */
+
 #include "sysdb.h"
-#include "core/store.h"
+#include "core/store-private.h"
+#include "core/plugin.h"
+#include "utils/avltree.h"
 #include "utils/error.h"
-#include "utils/llist.h"
 
 #include <assert.h>
 
@@ -38,623 +43,1105 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <math.h>
 #include <pthread.h>
 
 /*
- * private data types
+ * private variables
  */
 
-/* type used for looking up named objects */
 typedef struct {
-	sdb_object_t parent;
-	const char *obj_name;
-} sdb_store_lookup_obj_t;
-#define SDB_STORE_LOOKUP_OBJ_INIT { SDB_OBJECT_INIT, NULL }
+	sdb_object_t super;
 
-/*
- * private variables
- */
+	/* hosts are the top-level entries and
+	 * reference everything else */
+	sdb_avltree_t *hosts;
+	pthread_rwlock_t host_lock;
+} sdb_store_t;
+#define ST(obj) ((sdb_store_t *)(obj))
 
-static sdb_llist_t *host_list = NULL;
-static pthread_rwlock_t host_lock = PTHREAD_RWLOCK_INITIALIZER;
+sdb_store_t *global_store = NULL;
 
 /*
- * private helper functions
+ * private types
  */
 
+static sdb_type_t host_type;
+static sdb_type_t service_type;
+static sdb_type_t metric_type;
+static sdb_type_t attribute_type;
+
 static int
-sdb_store_obj_cmp_by_name(const sdb_object_t *a, const sdb_object_t *b)
+store_init(sdb_object_t *obj, va_list __attribute__((unused)) ap)
 {
-	const sdb_store_obj_t *h1 = (const sdb_store_obj_t *)a;
-	const sdb_store_obj_t *h2 = (const sdb_store_obj_t *)b;
+	int err;
+	if (! (ST(obj)->hosts = sdb_avltree_create()))
+		return -1;
+	if ((err = pthread_rwlock_init(&ST(obj)->host_lock, /* attr = */ NULL))) {
+		char errbuf[128];
+		sdb_log(SDB_LOG_ERR, "store: Failed to initialize lock: %s",
+				sdb_strerror(err, errbuf, sizeof(errbuf)));
+		return -1;
+	}
+	return 0;
+} /* store_init */
 
-	assert(h1 && h2);
-	return strcasecmp(h1->name, h2->name);
-} /* sdb_store_obj_cmp_by_name */
+static void
+store_destroy(sdb_object_t *obj)
+{
+	int err;
+	if ((err = pthread_rwlock_destroy(&ST(obj)->host_lock))) {
+		char errbuf[128];
+		sdb_log(SDB_LOG_ERR, "store: Failed to destroy lock: %s",
+				sdb_strerror(err, errbuf, sizeof(errbuf)));
+		return;
+	}
+	sdb_avltree_destroy(ST(obj)->hosts);
+	ST(obj)->hosts = NULL;
+} /* store_destroy */
 
 static int
-sdb_cmp_store_obj_with_name(const sdb_object_t *a, const sdb_object_t *b)
+store_obj_init(sdb_object_t *obj, va_list ap)
 {
-	const sdb_store_obj_t *obj = (const sdb_store_obj_t *)a;
-	const sdb_store_lookup_obj_t *lookup = (const sdb_store_lookup_obj_t *)b;
+	sdb_store_obj_t *sobj = STORE_OBJ(obj);
 
-	assert(obj && lookup);
-	return strcasecmp(obj->name, lookup->obj_name);
-} /* sdb_cmp_store_obj_with_name */
+	sobj->type = va_arg(ap, int);
 
-/*
- * private types
- */
+	sobj->last_update = va_arg(ap, sdb_time_t);
+	sobj->interval = 0;
+	sobj->backends = NULL;
+	sobj->backends_num = 0;
+	sobj->parent = NULL;
+	return 0;
+} /* store_obj_init */
 
-static int
-sdb_host_init(sdb_object_t *obj, va_list ap)
+static void
+store_obj_destroy(sdb_object_t *obj)
 {
-	const char *name = va_arg(ap, const char *);
+	sdb_store_obj_t *sobj = STORE_OBJ(obj);
+	size_t i;
 
-	SDB_HOST(obj)->_name = strdup(name);
-	if (! SDB_HOST(obj)->_name)
-		return -1;
+	for (i = 0; i < sobj->backends_num; ++i)
+		free(sobj->backends[i]);
+	free(sobj->backends);
+	sobj->backends = NULL;
+	sobj->backends_num = 0;
+
+	// We don't currently keep an extra reference for parent objects to
+	// avoid circular self-references which are not handled correctly by
+	// the ref-count base management layer.
+	//sdb_object_deref(SDB_OBJ(sobj->parent));
+} /* store_obj_destroy */
+
+static int
+host_init(sdb_object_t *obj, va_list ap)
+{
+	sdb_host_t *sobj = HOST(obj);
+	int ret;
 
-	SDB_HOST(obj)->_last_update = sdb_gettime();
-	/* ignore errors -> last_update will be updated later */
+	/* this will consume the first argument (type) of ap */
+	ret = store_obj_init(obj, ap);
+	if (ret)
+		return ret;
 
-	SDB_HOST(obj)->attributes = sdb_llist_create();
-	if (! SDB_HOST(obj)->attributes)
+	sobj->services = sdb_avltree_create();
+	if (! sobj->services)
+		return -1;
+	sobj->metrics = sdb_avltree_create();
+	if (! sobj->metrics)
 		return -1;
-	SDB_HOST(obj)->services = sdb_llist_create();
-	if (! SDB_HOST(obj)->services)
+	sobj->attributes = sdb_avltree_create();
+	if (! sobj->attributes)
 		return -1;
 	return 0;
-} /* sdb_host_init */
+} /* host_init */
 
 static void
-sdb_host_destroy(sdb_object_t *obj)
+host_destroy(sdb_object_t *obj)
 {
+	sdb_host_t *sobj = HOST(obj);
 	assert(obj);
 
-	if (SDB_HOST(obj)->_name)
-		free(SDB_HOST(obj)->_name);
+	store_obj_destroy(obj);
 
-	if (SDB_HOST(obj)->attributes)
-		sdb_llist_destroy(SDB_HOST(obj)->attributes);
-	if (SDB_HOST(obj)->services)
-		sdb_llist_destroy(SDB_HOST(obj)->services);
-} /* sdb_host_destroy */
+	if (sobj->services)
+		sdb_avltree_destroy(sobj->services);
+	if (sobj->metrics)
+		sdb_avltree_destroy(sobj->metrics);
+	if (sobj->attributes)
+		sdb_avltree_destroy(sobj->attributes);
+} /* host_destroy */
 
 static int
-sdb_attr_init(sdb_object_t *obj, va_list ap)
+service_init(sdb_object_t *obj, va_list ap)
 {
-	const char *hostname = va_arg(ap, const char *);
-	const char *name = va_arg(ap, const char *);
-	const char *value = va_arg(ap, const char *);
+	sdb_service_t *sobj = SVC(obj);
+	int ret;
 
-	SDB_ATTR(obj)->hostname = strdup(hostname);
-	SDB_ATTR(obj)->_name = strdup(name);
-	SDB_ATTR(obj)->attr_value = strdup(value);
-	if ((! SDB_ATTR(obj)->hostname)
-			|| (! SDB_ATTR(obj)->_name) || (! SDB_ATTR(obj)->attr_value))
-		return -1;
+	/* this will consume the first argument (type) of ap */
+	ret = store_obj_init(obj, ap);
+	if (ret)
+		return ret;
 
-	SDB_ATTR(obj)->_last_update = sdb_gettime();
+	sobj->attributes = sdb_avltree_create();
+	if (! sobj->attributes)
+		return -1;
 	return 0;
-} /* sdb_attr_init */
+} /* service_init */
 
 static void
-sdb_attr_destroy(sdb_object_t *obj)
+service_destroy(sdb_object_t *obj)
 {
+	sdb_service_t *sobj = SVC(obj);
 	assert(obj);
 
-	if (SDB_ATTR(obj)->hostname)
-		free(SDB_ATTR(obj)->hostname);
-	if (SDB_ATTR(obj)->_name)
-		free(SDB_ATTR(obj)->_name);
-	if (SDB_ATTR(obj)->attr_value)
-		free(SDB_ATTR(obj)->attr_value);
-} /* sdb_attr_destroy */
+	store_obj_destroy(obj);
+
+	if (sobj->attributes)
+		sdb_avltree_destroy(sobj->attributes);
+} /* service_destroy */
 
 static int
-sdb_svc_init(sdb_object_t *obj, va_list ap)
+metric_init(sdb_object_t *obj, va_list ap)
 {
-	const char *hostname = va_arg(ap, const char *);
-	const char *name = va_arg(ap, const char *);
+	sdb_metric_t *sobj = METRIC(obj);
+	int ret;
 
-	SDB_SVC(obj)->hostname = strdup(hostname);
-	SDB_SVC(obj)->_name = strdup(name);
-	if ((! SDB_SVC(obj)->hostname) || (! SDB_SVC(obj)->_name))
+	/* this will consume the first argument (type) of ap */
+	ret = store_obj_init(obj, ap);
+	if (ret)
+		return ret;
+
+	sobj->attributes = sdb_avltree_create();
+	if (! sobj->attributes)
 		return -1;
 
-	SDB_SVC(obj)->_last_update = sdb_gettime();
-	/* ignore errors -> last_update will be updated later */
+	sobj->store.type = sobj->store.id = NULL;
 	return 0;
-} /* sdb_svc_init */
+} /* metric_init */
 
 static void
-sdb_svc_destroy(sdb_object_t *obj)
+metric_destroy(sdb_object_t *obj)
 {
+	sdb_metric_t *sobj = METRIC(obj);
 	assert(obj);
 
-	if (SDB_SVC(obj)->hostname)
-		free(SDB_SVC(obj)->hostname);
-	if (SDB_SVC(obj)->_name)
-		free(SDB_SVC(obj)->_name);
-} /* sdb_svc_destroy */
+	store_obj_destroy(obj);
+
+	if (sobj->attributes)
+		sdb_avltree_destroy(sobj->attributes);
+
+	if (sobj->store.type)
+		free(sobj->store.type);
+	if (sobj->store.id)
+		free(sobj->store.id);
+} /* metric_destroy */
+
+static int
+attr_init(sdb_object_t *obj, va_list ap)
+{
+	const sdb_data_t *value;
+	int ret;
+
+	/* this will consume the first two arguments
+	 * (type and last_update) of ap */
+	ret = store_obj_init(obj, ap);
+	if (ret)
+		return ret;
+	value = va_arg(ap, const sdb_data_t *);
+
+	if (value)
+		if (sdb_data_copy(&ATTR(obj)->value, value))
+			return -1;
+	return 0;
+} /* attr_init */
+
+static void
+attr_destroy(sdb_object_t *obj)
+{
+	assert(obj);
 
-static sdb_type_t sdb_host_type = {
-	sizeof(sdb_host_t),
+	store_obj_destroy(obj);
+	sdb_data_free_datum(&ATTR(obj)->value);
+} /* attr_destroy */
 
-	sdb_host_init,
-	sdb_host_destroy
+static sdb_type_t store_type = {
+	/* size = */ sizeof(sdb_store_t),
+	/* init = */ store_init,
+	/* destroy = */ store_destroy,
 };
 
-static sdb_type_t sdb_attr_type = {
-	sizeof(sdb_attribute_t),
+static sdb_type_t host_type = {
+	/* size = */ sizeof(sdb_host_t),
+	/* init = */ host_init,
+	/* destroy = */ host_destroy
+};
 
-	sdb_attr_init,
-	sdb_attr_destroy
+static sdb_type_t service_type = {
+	/* size = */ sizeof(sdb_service_t),
+	/* init = */ service_init,
+	/* destroy = */ service_destroy
 };
 
-static sdb_type_t sdb_svc_type = {
-	sizeof(sdb_service_t),
+static sdb_type_t metric_type = {
+	/* size = */ sizeof(sdb_metric_t),
+	/* init = */ metric_init,
+	/* destroy = */ metric_destroy
+};
 
-	sdb_svc_init,
-	sdb_svc_destroy
+static sdb_type_t attribute_type = {
+	/* size = */ sizeof(sdb_attribute_t),
+	/* init = */ attr_init,
+	/* destroy = */ attr_destroy
 };
 
 /*
- * public API
+ * private helper functions
  */
 
-sdb_host_t *
-sdb_host_create(const char *name)
+static sdb_host_t *
+lookup_host(sdb_store_t *st, const char *name, bool canonicalize)
 {
-	sdb_object_t *obj;
+	sdb_host_t *host;
+	char *cname;
 
-	if (! name)
-		return NULL;
+	assert(name);
+	if (! canonicalize)
+		return HOST(sdb_avltree_lookup(st->hosts, name));
 
-	obj = sdb_object_create(sdb_host_type, name);
-	if (! obj)
+	cname = strdup(name);
+	cname = sdb_plugin_cname(cname);
+	if (! cname) {
+		sdb_log(SDB_LOG_ERR, "store: strdup failed");
 		return NULL;
-	return SDB_HOST(obj);
-} /* sdb_host_create */
+	}
+
+	host = HOST(sdb_avltree_lookup(st->hosts, cname));
+	free(cname);
+	return host;
+} /* lookup_host */
 
-sdb_host_t *
-sdb_host_clone(const sdb_host_t *host)
+static int
+record_backend(sdb_store_obj_t *obj)
 {
-	sdb_host_t *new;
+	const sdb_plugin_info_t *info;
+	char **tmp;
+	size_t i;
 
-	new = sdb_host_create(host->_name);
-	if (! new)
-		return NULL;
+	info = sdb_plugin_current();
+	if (! info)
+		return 0;
 
-	/* make sure these are initialized; else sdb_object_deref() might access
-	 * arbitrary memory in case of an error */
-	new->services = new->attributes = NULL;
+	for (i = 0; i < obj->backends_num; ++i)
+		if (!strcasecmp(obj->backends[i], info->plugin_name))
+			return 0;
 
-	if (host->attributes) {
-		new->attributes = sdb_llist_clone(host->attributes);
-		if (! new->attributes) {
-			sdb_object_deref(SDB_OBJ(new));
-			return NULL;
-		}
-	}
+	tmp = realloc(obj->backends,
+			(obj->backends_num + 1) * sizeof(*obj->backends));
+	if (! tmp)
+		return -1;
 
-	new->_last_update = host->_last_update;
-	if (host->services) {
-		new->services = sdb_llist_clone(host->services);
-		if (! new->services) {
-			sdb_object_deref(SDB_OBJ(new));
-			return NULL;
-		}
-	}
-	return new;
-} /* sdb_host_clone */
+	obj->backends = tmp;
+	obj->backends[obj->backends_num] = strdup(info->plugin_name);
+	if (! obj->backends[obj->backends_num])
+		return -1;
 
-int
-sdb_store_host(const sdb_host_t *host)
-{
-	sdb_store_lookup_obj_t lookup = SDB_STORE_LOOKUP_OBJ_INIT;
-	sdb_time_t last_update;
+	++obj->backends_num;
+	return 0;
+} /* record_backend */
 
-	sdb_host_t *old;
+static int
+store_obj(sdb_store_obj_t *parent, sdb_avltree_t *parent_tree,
+		int type, const char *name, sdb_time_t last_update,
+		sdb_store_obj_t **updated_obj)
+{
+	sdb_store_obj_t *old, *new;
 	int status = 0;
 
-	if ((! host) || (! host->_name))
-		return -1;
+	assert(parent_tree);
 
-	last_update = host->_last_update;
 	if (last_update <= 0)
 		last_update = sdb_gettime();
 
-	pthread_rwlock_wrlock(&host_lock);
-
-	if (! host_list) {
-		if (! (host_list = sdb_llist_create())) {
-			pthread_rwlock_unlock(&host_lock);
-			return -1;
-		}
-	}
-
-	lookup.obj_name = host->_name;
-	old = SDB_HOST(sdb_llist_search(host_list, (const sdb_object_t *)&lookup,
-				sdb_cmp_store_obj_with_name));
-
+	old = STORE_OBJ(sdb_avltree_lookup(parent_tree, name));
 	if (old) {
-		if (old->_last_update > last_update) {
-			sdb_log(SDB_LOG_DEBUG, "store: Cannot update host '%s' - "
-					"value too old (%"PRIscTIME" < %"PRIscTIME")",
-					host->_name, last_update, old->_last_update);
-			/* don't report an error; the host may be updated by multiple
+		if (old->last_update > last_update) {
+			sdb_log(SDB_LOG_DEBUG, "store: Cannot update %s '%s' - "
+					"value too old (%"PRIsdbTIME" < %"PRIsdbTIME")",
+					SDB_STORE_TYPE_TO_NAME(type), name,
+					last_update, old->last_update);
+			/* don't report an error; the object may be updated by multiple
 			 * backends */
 			status = 1;
 		}
+		else if (old->last_update == last_update) {
+			/* don't report an error and also don't even log this to avoid
+			 * excessive noise on high sampling frequencies */
+			status = 1;
+		}
 		else {
-			old->_last_update = last_update;
+			sdb_time_t interval = last_update - old->last_update;
+			old->last_update = last_update;
+			if (interval) {
+				if (old->interval)
+					old->interval = (sdb_time_t)((0.9 * (double)old->interval)
+							+ (0.1 * (double)interval));
+				else
+					old->interval = interval;
+			}
 		}
+
+		new = old;
+		sdb_object_deref(SDB_OBJ(old));
 	}
 	else {
-		sdb_host_t *new = sdb_host_clone(host);
-		if (! new) {
-			char errbuf[1024];
-			sdb_log(SDB_LOG_ERR, "store: Failed to clone host object: %s",
-					sdb_strerror(errno, errbuf, sizeof(errbuf)));
-			pthread_rwlock_unlock(&host_lock);
-			return -1;
+		if (type == SDB_ATTRIBUTE) {
+			/* the value will be updated by the caller */
+			new = STORE_OBJ(sdb_object_create(name, attribute_type,
+						type, last_update, NULL));
 		}
-
-		if (! new->attributes) {
-			if (! (new->attributes = sdb_llist_create())) {
-				char errbuf[1024];
-				sdb_log(SDB_LOG_ERR, "store: Failed to initialize "
-						"host object '%s': %s", host->_name,
-						sdb_strerror(errno, errbuf, sizeof(errbuf)));
-				sdb_object_deref(SDB_OBJ(new));
-				pthread_rwlock_unlock(&host_lock);
-				return -1;
-			}
+		else {
+			sdb_type_t t;
+			t = type == SDB_HOST
+				? host_type
+				: type == SDB_SERVICE
+					? service_type
+					: metric_type;
+			new = STORE_OBJ(sdb_object_create(name, t, type, last_update));
 		}
 
-		if (! new->services) {
-			if (! (new->services = sdb_llist_create())) {
-				char errbuf[1024];
-				sdb_log(SDB_LOG_ERR, "store: Failed to initialize "
-						"host object '%s': %s", host->_name,
-						sdb_strerror(errno, errbuf, sizeof(errbuf)));
-				sdb_object_deref(SDB_OBJ(new));
-				pthread_rwlock_unlock(&host_lock);
-				return -1;
-			}
+		if (new) {
+			status = sdb_avltree_insert(parent_tree, SDB_OBJ(new));
+
+			/* pass control to the tree or destroy in case of an error */
+			sdb_object_deref(SDB_OBJ(new));
+		}
+		else {
+			char errbuf[1024];
+			sdb_log(SDB_LOG_ERR, "store: Failed to create %s '%s': %s",
+					SDB_STORE_TYPE_TO_NAME(type), name,
+					sdb_strerror(errno, errbuf, sizeof(errbuf)));
+			status = -1;
 		}
+	}
 
-		status = sdb_llist_insert_sorted(host_list, SDB_OBJ(new),
-				sdb_store_obj_cmp_by_name);
+	if (status < 0)
+		return status;
+	assert(new);
 
-		/* pass control to the list or destroy in case of an error */
-		sdb_object_deref(SDB_OBJ(new));
+	if (new->parent != parent) {
+		// Avoid circular self-references which are not handled
+		// correctly by the ref-count based management layer.
+		//sdb_object_deref(SDB_OBJ(new->parent));
+		//sdb_object_ref(SDB_OBJ(parent));
+		new->parent = parent;
 	}
 
-	pthread_rwlock_unlock(&host_lock);
+	if (updated_obj)
+		*updated_obj = new;
+
+	if (record_backend(new))
+		return -1;
 	return status;
-} /* sdb_store_host */
+} /* store_obj */
 
-const sdb_host_t *
-sdb_store_get_host(const char *name)
+static int
+store_attr(sdb_store_obj_t *parent, sdb_avltree_t *attributes,
+		const char *key, const sdb_data_t *value, sdb_time_t last_update)
 {
-	sdb_store_lookup_obj_t lookup = SDB_STORE_LOOKUP_OBJ_INIT;
-	sdb_host_t *host;
+	sdb_store_obj_t *attr = NULL;
+	int status;
 
-	if (! name)
-		return NULL;
+	status = store_obj(parent, attributes, SDB_ATTRIBUTE,
+			key, last_update, &attr);
+	if (status)
+		return status;
 
-	lookup.obj_name = name;
-	host = SDB_HOST(sdb_llist_search(host_list, (const sdb_object_t *)&lookup,
-				sdb_cmp_store_obj_with_name));
+	/* don't update unchanged values */
+	if (! sdb_data_cmp(&ATTR(attr)->value, value))
+		return status;
 
-	if (! host)
-		return NULL;
-	return host;
-} /* sdb_store_get_host */
+	assert(attr);
+	if (sdb_data_copy(&ATTR(attr)->value, value))
+		return -1;
+	return status;
+} /* store_attr */
 
-sdb_attribute_t *
-sdb_attribute_create(const char *hostname,
-		const char *name, const char *value)
+static int
+store_metric_store(sdb_metric_t *metric, sdb_metric_store_t *store)
 {
-	sdb_object_t *obj;
+	char *type = metric->store.type;
+	char *id = metric->store.id;
+
+	if ((! metric->store.type) || strcasecmp(metric->store.type, store->type)) {
+		if (! (type = strdup(store->type)))
+			return -1;
+	}
+	if ((! metric->store.id) || strcasecmp(metric->store.id, store->id)) {
+		if (! (id = strdup(store->id))) {
+			if (type != metric->store.type)
+				free(type);
+			return -1;
+		}
+	}
+
+	if (type != metric->store.type) {
+		if (metric->store.type)
+			free(metric->store.type);
+		metric->store.type = type;
+	}
+	if (id != metric->store.id) {
+		if (metric->store.id)
+			free(metric->store.id);
+		metric->store.id = id;
+	}
+	return 0;
+} /* store_metric_store */
 
-	if ((! hostname) || (! name) || (! value))
+/* The store's host_lock has to be acquired before calling this function. */
+static sdb_avltree_t *
+get_host_children(sdb_host_t *host, int type)
+{
+	if ((type != SDB_SERVICE) && (type != SDB_METRIC)
+			&& (type != SDB_ATTRIBUTE))
 		return NULL;
 
-	obj = sdb_object_create(sdb_attr_type, hostname, name, value);
-	if (! obj)
+	if (! host)
 		return NULL;
-	return SDB_ATTR(obj);
-} /* sdb_attribute_create */
 
-sdb_attribute_t *
-sdb_attribute_clone(const sdb_attribute_t *attr)
+	if (type == SDB_ATTRIBUTE)
+		return host->attributes;
+	else if (type == SDB_METRIC)
+		return host->metrics;
+	else
+		return host->services;
+} /* get_host_children */
+
+/*
+ * ts_tojson serializes a time-series to JSON.
+ *
+ * The function never returns an error. Rather, an error message will be part
+ * of the serialized data.
+ */
+static void
+ts_tojson(sdb_timeseries_t *ts, sdb_strbuf_t *buf)
 {
-	sdb_attribute_t *new;
+	char start_str[64];
+	char end_str[64];
 
-	new = sdb_attribute_create(attr->hostname,
-			attr->_name, attr->attr_value);
-	if (! new)
-		return NULL;
+	size_t i;
 
-	new->_last_update = attr->_last_update;
-	return new;
-} /* sdb_attribute_clone */
+	/* TODO: make time format configurable */
+	if (! sdb_strftime(start_str, sizeof(start_str), ts->start))
+		snprintf(start_str, sizeof(start_str), "<error>");
+	start_str[sizeof(start_str) - 1] = '\0';
+	if (! sdb_strftime(end_str, sizeof(end_str), ts->end))
+		snprintf(end_str, sizeof(end_str), "<error>");
+	end_str[sizeof(end_str) - 1] = '\0';
 
-int
-sdb_store_attribute(const sdb_attribute_t *attr)
+	sdb_strbuf_append(buf, "{\"start\": \"%s\", \"end\": \"%s\", \"data\": {",
+			start_str, end_str);
+
+	for (i = 0; i < ts->data_names_len; ++i) {
+		size_t j;
+		sdb_strbuf_append(buf, "\"%s\": [", ts->data_names[i]);
+
+		for (j = 0; j < ts->data_len; ++j) {
+			char time_str[64];
+
+			if (! sdb_strftime(time_str, sizeof(time_str), ts->data[i][j].timestamp))
+				snprintf(time_str, sizeof(time_str), "<error>");
+			time_str[sizeof(time_str) - 1] = '\0';
+
+			/* Some GNU libc versions may print '-nan' which we dont' want */
+			if (isnan(ts->data[i][j].value))
+				sdb_strbuf_append(buf, "{\"timestamp\": \"%s\", "
+						"\"value\": \"nan\"}", time_str);
+			else
+				sdb_strbuf_append(buf, "{\"timestamp\": \"%s\", "
+						"\"value\": \"%f\"}", time_str, ts->data[i][j].value);
+
+			if (j < ts->data_len - 1)
+				sdb_strbuf_append(buf, ",");
+		}
+
+		if (i < ts->data_names_len - 1)
+			sdb_strbuf_append(buf, "],");
+		else
+			sdb_strbuf_append(buf, "]");
+	}
+	sdb_strbuf_append(buf, "}}");
+} /* ts_tojson */
+
+/*
+ * store writer API
+ */
+
+static int
+store_attribute(const char *hostname,
+		const char *key, const sdb_data_t *value,
+		sdb_time_t last_update, sdb_object_t *user_data)
 {
-	sdb_store_lookup_obj_t lookup = SDB_STORE_LOOKUP_OBJ_INIT;
+	sdb_store_t *st = ST(user_data);
+
 	sdb_host_t *host;
+	sdb_avltree_t *attrs;
+	int status = 0;
+
+	if ((! hostname) || (! key))
+		return -1;
+
+	pthread_rwlock_wrlock(&st->host_lock);
+	host = lookup_host(st, hostname, /* canonicalize = */ 1);
+	attrs = get_host_children(host, SDB_ATTRIBUTE);
+	if (! attrs) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store attribute '%s' - "
+				"host '%s' not found", key, hostname);
+		status = -1;
+	}
 
-	sdb_attribute_t *old;
+	if (! status)
+		status = store_attr(STORE_OBJ(host), attrs, key, value, last_update);
 
-	sdb_time_t last_update;
+	sdb_object_deref(SDB_OBJ(host));
+	pthread_rwlock_unlock(&st->host_lock);
+
+	return status;
+} /* store_attribute */
+
+static int
+store_host(const char *name, sdb_time_t last_update, sdb_object_t *user_data)
+{
+	sdb_store_t *st = ST(user_data);
 
+	char *cname = NULL;
 	int status = 0;
 
-	if (! attr)
+	if (! name)
 		return -1;
 
-	last_update = attr->_last_update;
-	if (last_update <= 0)
-		last_update = sdb_gettime();
-
-	if (! host_list)
+	cname = sdb_plugin_cname(strdup(name));
+	if (! cname) {
+		sdb_log(SDB_LOG_ERR, "store: strdup failed");
 		return -1;
+	}
+
+	pthread_rwlock_wrlock(&st->host_lock);
+	status = store_obj(NULL, st->hosts,
+			SDB_HOST, cname, last_update, NULL);
+	pthread_rwlock_unlock(&st->host_lock);
+
+	free(cname);
+	return status;
+} /* store_host */
+
+static int
+store_service_attr(const char *hostname, const char *service,
+		const char *key, const sdb_data_t *value, sdb_time_t last_update,
+		sdb_object_t *user_data)
+{
+	sdb_store_t *st = ST(user_data);
 
-	pthread_rwlock_wrlock(&host_lock);
+	sdb_host_t *host;
+	sdb_service_t *svc;
+	sdb_avltree_t *services;
+	int status = 0;
 
-	lookup.obj_name = attr->hostname;
-	host = SDB_HOST(sdb_llist_search(host_list, (const sdb_object_t *)&lookup,
-				sdb_cmp_store_obj_with_name));
+	if ((! hostname) || (! service) || (! key))
+		return -1;
 
-	if (! host) {
-		pthread_rwlock_unlock(&host_lock);
+	pthread_rwlock_wrlock(&st->host_lock);
+	host = lookup_host(st, hostname, /* canonicalize = */ 1);
+	services = get_host_children(host, SDB_SERVICE);
+	sdb_object_deref(SDB_OBJ(host));
+	if (! services) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store attribute '%s' "
+				"for service '%s' - host '%ss' not found",
+				key, service, hostname);
+		pthread_rwlock_unlock(&st->host_lock);
 		return -1;
 	}
 
-	lookup.obj_name = attr->_name;
-	old = SDB_ATTR(sdb_llist_search(host->attributes,
-				(const sdb_object_t *)&lookup,
-				sdb_cmp_store_obj_with_name));
-
-	if (old) {
-		if (old->_last_update > last_update) {
-			sdb_log(SDB_LOG_DEBUG, "store: Cannot update attribute "
-					"'%s/%s' - value too old (%"PRIscTIME" < %"PRIscTIME")",
-					attr->hostname, attr->_name, last_update,
-					old->_last_update);
-			status = 1;
-		}
-		else {
-			old->_last_update = last_update;
-		}
+	svc = SVC(sdb_avltree_lookup(services, service));
+	if (! svc) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store attribute '%s' - "
+				"service '%s/%s' not found", key, hostname, service);
+		status = -1;
 	}
-	else {
-		sdb_attribute_t *new = sdb_attribute_clone(attr);
-		if (! new) {
-			char errbuf[1024];
-			sdb_log(SDB_LOG_ERR, "store: Failed to clone attribute "
-					"object: %s", sdb_strerror(errno, errbuf, sizeof(errbuf)));
-			pthread_rwlock_unlock(&host_lock);
-			return -1;
-		}
 
-		status = sdb_llist_insert_sorted(host->attributes, SDB_OBJ(new),
-				sdb_store_obj_cmp_by_name);
+	if (! status)
+		status = store_attr(STORE_OBJ(svc), svc->attributes,
+				key, value, last_update);
 
-		/* pass control to the list or destroy in case of an error */
-		sdb_object_deref(SDB_OBJ(new));
-	}
+	sdb_object_deref(SDB_OBJ(svc));
+	pthread_rwlock_unlock(&st->host_lock);
 
-	pthread_rwlock_unlock(&host_lock);
 	return status;
-} /* sdb_store_attribute */
+} /* store_service_attr */
 
-sdb_service_t *
-sdb_service_create(const char *hostname, const char *name)
+static int
+store_service(const char *hostname, const char *name,
+		sdb_time_t last_update, sdb_object_t *user_data)
 {
-	sdb_object_t *obj;
+	sdb_store_t *st = ST(user_data);
+
+	sdb_host_t *host;
+	sdb_avltree_t *services;
+	sdb_data_t d;
+
+	int status = 0;
 
 	if ((! hostname) || (! name))
-		return NULL;
+		return -1;
 
-	obj = sdb_object_create(sdb_svc_type, hostname, name);
-	if (! obj)
-		return NULL;
-	return SDB_SVC(obj);
-} /* sdb_service_create */
+	pthread_rwlock_wrlock(&st->host_lock);
+	host = lookup_host(st, hostname, /* canonicalize = */ 1);
+	services = get_host_children(host, SDB_SERVICE);
+	if (! services) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store service '%s' - "
+				"host '%s' not found", name, hostname);
+		status = -1;
+	}
 
-sdb_service_t *
-sdb_service_clone(const sdb_service_t *svc)
-{
-	sdb_service_t *new;
+	if (! status)
+		status = store_obj(STORE_OBJ(host), services, SDB_SERVICE,
+				name, last_update, NULL);
 
-	new = sdb_service_create(svc->hostname, svc->_name);
-	if (! new)
-		return NULL;
+	sdb_object_deref(SDB_OBJ(host));
+	pthread_rwlock_unlock(&st->host_lock);
 
-	new->_last_update = svc->_last_update;
-	return new;
-} /* sdb_service_clone */
+	if (status)
+		return status;
 
-int
-sdb_store_service(const sdb_service_t *svc)
+	/* record the hostname as an attribute */
+	d.type = SDB_TYPE_STRING;
+	d.data.string = SDB_OBJ(host)->name;
+	if (store_service_attr(hostname, name, "hostname", &d, last_update, user_data))
+		status = -1;
+	return status;
+} /* store_service */
+
+static int
+store_metric_attr(const char *hostname, const char *metric,
+		const char *key, const sdb_data_t *value, sdb_time_t last_update,
+		sdb_object_t *user_data)
 {
-	sdb_store_lookup_obj_t lookup = SDB_STORE_LOOKUP_OBJ_INIT;
+	sdb_store_t *st = ST(user_data);
+
+	sdb_avltree_t *metrics;
 	sdb_host_t *host;
+	sdb_metric_t *m;
+	int status = 0;
 
-	sdb_service_t *old;
+	if ((! hostname) || (! metric) || (! key))
+		return -1;
 
-	sdb_time_t last_update;
+	pthread_rwlock_wrlock(&st->host_lock);
+	host = lookup_host(st, hostname, /* canonicalize = */ 1);
+	metrics = get_host_children(host, SDB_METRIC);
+	sdb_object_deref(SDB_OBJ(host));
+	if (! metrics) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store attribute '%s' "
+				"for metric '%s' - host '%s' not found",
+				key, metric, hostname);
+		pthread_rwlock_unlock(&st->host_lock);
+		return -1;
+	}
 
-	int status = 0;
+	m = METRIC(sdb_avltree_lookup(metrics, metric));
+	if (! m) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store attribute '%s' - "
+				"metric '%s/%s' not found", key, hostname, metric);
+		status = -1;
+	}
 
-	if (! svc)
-		return -1;
+	if (! status)
+		status = store_attr(STORE_OBJ(m), m->attributes,
+				key, value, last_update);
 
-	last_update = svc->_last_update;
-	if (last_update <= 0)
-		last_update = sdb_gettime();
+	sdb_object_deref(SDB_OBJ(m));
+	pthread_rwlock_unlock(&st->host_lock);
 
-	if (! host_list)
-		return -1;
+	return status;
+} /* store_metric_attr */
 
-	pthread_rwlock_wrlock(&host_lock);
+static int
+store_metric(const char *hostname, const char *name,
+		sdb_metric_store_t *store, sdb_time_t last_update,
+		sdb_object_t *user_data)
+{
+	sdb_store_t *st = ST(user_data);
 
-	lookup.obj_name = svc->hostname;
-	host = SDB_HOST(sdb_llist_search(host_list, (const sdb_object_t *)&lookup,
-				sdb_cmp_store_obj_with_name));
+	sdb_store_obj_t *obj = NULL;
+	sdb_host_t *host;
+	sdb_metric_t *metric;
+	sdb_data_t d;
 
-	if (! host) {
-		pthread_rwlock_unlock(&host_lock);
+	sdb_avltree_t *metrics;
+
+	int status = 0;
+
+	if ((! hostname) || (! name))
 		return -1;
-	}
 
-	lookup.obj_name = svc->_name;
-	old = SDB_SVC(sdb_llist_search(host->services, (const sdb_object_t *)&lookup,
-				sdb_cmp_store_obj_with_name));
+	if (store) {
+		if ((store->type != NULL) != (store->id != NULL))
+			return -1;
+		else if (! store->type)
+			store = NULL;
+	}
 
-	if (old) {
-		if (old->_last_update > last_update) {
-			sdb_log(SDB_LOG_DEBUG, "store: Cannot update service "
-					"'%s/%s' - value too old (%"PRIscTIME" < %"PRIscTIME")",
-					svc->hostname, svc->_name, last_update,
-					old->_last_update);
-			status = 1;
-		}
-		else {
-			old->_last_update = last_update;
-		}
+	pthread_rwlock_wrlock(&st->host_lock);
+	host = lookup_host(st, hostname, /* canonicalize = */ 1);
+	metrics = get_host_children(host, SDB_METRIC);
+	if (! metrics) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store metric '%s' - "
+				"host '%s' not found", name, hostname);
+		status = -1;
 	}
-	else {
-		sdb_service_t *new = sdb_service_clone(svc);
-		if (! new) {
-			char errbuf[1024];
-			sdb_log(SDB_LOG_ERR, "store: Failed to clone service "
-					"object: %s", sdb_strerror(errno, errbuf, sizeof(errbuf)));
-			pthread_rwlock_unlock(&host_lock);
-			return -1;
-		}
 
-		status = sdb_llist_insert_sorted(host->services, SDB_OBJ(new),
-				sdb_store_obj_cmp_by_name);
+	if (! status)
+		status = store_obj(STORE_OBJ(host), metrics, SDB_METRIC,
+				name, last_update, &obj);
+	sdb_object_deref(SDB_OBJ(host));
 
-		/* pass control to the list or destroy in case of an error */
-		sdb_object_deref(SDB_OBJ(new));
+	if (status) {
+		pthread_rwlock_unlock(&st->host_lock);
+		return status;
 	}
 
-	pthread_rwlock_unlock(&host_lock);
+	assert(obj);
+	metric = METRIC(obj);
+
+	if (store)
+		if (store_metric_store(metric, store))
+			status = -1;
+	pthread_rwlock_unlock(&st->host_lock);
+
+	/* record the hostname as an attribute */
+	d.type = SDB_TYPE_STRING;
+	d.data.string = SDB_OBJ(host)->name;
+	if (store_metric_attr(hostname, name, "hostname", &d, last_update, user_data))
+		status = -1;
 	return status;
-} /* sdb_store_service */
+} /* store_metric */
+
+static sdb_store_writer_t store_writer = {
+	store_host, store_service, store_metric,
+	store_attribute, store_service_attr, store_metric_attr,
+};
+
+/*
+ * TODO: let prepare and execute accept a store object as their user_data
+ * object
+ */
 
-const sdb_service_t *
-sdb_store_get_service(const sdb_host_t *host, const char *name)
+static sdb_object_t *
+prepare_query(sdb_ast_node_t *ast,
+		sdb_strbuf_t __attribute__((unused)) *errbuf,
+		sdb_object_t __attribute__((unused)) *user_data)
 {
-	sdb_store_lookup_obj_t lookup = SDB_STORE_LOOKUP_OBJ_INIT;
-	sdb_service_t *svc;
+	return SDB_OBJ(sdb_store_query_prepare(ast));
+} /* prepare_query */
+
+static int
+execute_query(sdb_object_t *q,
+		sdb_strbuf_t *buf, sdb_strbuf_t *errbuf,
+		sdb_object_t __attribute__((unused)) *user_data)
+{
+	return sdb_store_query_execute(QUERY(q), buf, errbuf);
+} /* execute_query */
+
+static sdb_store_reader_t store_reader = {
+	prepare_query, execute_query,
+};
+
+/*
+ * public API
+ */
+
+int
+sdb_store_init(void)
+{
+	if (global_store)
+		return 0;
 
-	if ((! host) || (! name))
+	global_store = ST(sdb_object_create("store", store_type));
+	if (! global_store) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to allocate store");
+		return -1;
+	}
+	if (sdb_plugin_register_writer("memstore",
+				&store_writer, SDB_OBJ(global_store)))
+		return -1;
+	return sdb_plugin_register_reader("memstore",
+			&store_reader, SDB_OBJ(global_store));
+} /* sdb_store_init */
+
+void
+sdb_store_clear(void)
+{
+	if (! global_store)
+		return;
+	sdb_avltree_clear(global_store->hosts);
+} /* sdb_store_clear */
+
+sdb_store_obj_t *
+sdb_store_get_host(const char *name)
+{
+	sdb_host_t *host;
+
+	if ((! global_store) || (! name))
 		return NULL;
 
-	lookup.obj_name = name;
-	svc = SDB_SVC(sdb_llist_search(host->services,
-				(const sdb_object_t *)&lookup,
-				sdb_cmp_store_obj_with_name));
+	host = lookup_host(global_store, name, /* canonicalize = */ 0);
+	if (! host)
+		return NULL;
+
+	return STORE_OBJ(host);
+} /* sdb_store_get_host */
+
+sdb_store_obj_t *
+sdb_store_get_child(sdb_store_obj_t *host, int type, const char *name)
+{
+	sdb_avltree_t *children;
 
-	if (! svc)
+	if ((! host) || (host->type != SDB_HOST) || (! name))
 		return NULL;
-	return svc;
-} /* sdb_store_get_service */
+
+	children = get_host_children(HOST(host), type);
+	if (! children)
+		return NULL;
+	return STORE_OBJ(sdb_avltree_lookup(children, name));
+} /* sdb_store_get_child */
 
 int
-sdb_store_dump(FILE *fh)
+sdb_store_get_field(sdb_store_obj_t *obj, int field, sdb_data_t *res)
 {
-	sdb_llist_iter_t *host_iter;
+	sdb_data_t tmp;
 
-	if (! fh)
+	if (! obj)
 		return -1;
 
-	pthread_rwlock_rdlock(&host_lock);
+	switch (field) {
+		case SDB_FIELD_NAME:
+			tmp.type = SDB_TYPE_STRING;
+			tmp.data.string = strdup(SDB_OBJ(obj)->name);
+			if (! tmp.data.string)
+				return -1;
+			break;
+		case SDB_FIELD_LAST_UPDATE:
+			tmp.type = SDB_TYPE_DATETIME;
+			tmp.data.datetime = obj->last_update;
+			break;
+		case SDB_FIELD_AGE:
+			tmp.type = SDB_TYPE_DATETIME;
+			tmp.data.datetime = sdb_gettime() - obj->last_update;
+			break;
+		case SDB_FIELD_INTERVAL:
+			tmp.type = SDB_TYPE_DATETIME;
+			tmp.data.datetime = obj->interval;
+			break;
+		case SDB_FIELD_BACKEND:
+			if (! res)
+				return 0;
+			tmp.type = SDB_TYPE_ARRAY | SDB_TYPE_STRING;
+			tmp.data.array.length = obj->backends_num;
+			tmp.data.array.values = obj->backends;
+			return sdb_data_copy(res, &tmp);
+		case SDB_FIELD_VALUE:
+			if (obj->type != SDB_ATTRIBUTE)
+				return -1;
+			if (! res)
+				return 0;
+			return sdb_data_copy(res, &ATTR(obj)->value);
+		case SDB_FIELD_TIMESERIES:
+			if (obj->type != SDB_METRIC)
+				return -1;
+			tmp.type = SDB_TYPE_BOOLEAN;
+			tmp.data.boolean = METRIC(obj)->store.type != NULL;
+		default:
+			return -1;
+	}
+	if (res)
+		*res = tmp;
+	else
+		sdb_data_free_datum(&tmp);
+	return 0;
+} /* sdb_store_get_field */
+
+int
+sdb_store_get_attr(sdb_store_obj_t *obj, const char *name, sdb_data_t *res,
+		sdb_store_matcher_t *filter)
+{
+	sdb_avltree_t *tree = NULL;
+	sdb_store_obj_t *attr;
+
+	if ((! obj) || (! name))
+		return -1;
+
+	if (obj->type == SDB_HOST)
+		tree = HOST(obj)->attributes;
+	else if (obj->type == SDB_SERVICE)
+		tree = SVC(obj)->attributes;
+	else if (obj->type == SDB_METRIC)
+		tree = METRIC(obj)->attributes;
 
-	host_iter = sdb_llist_get_iter(host_list);
-	if (! host_iter) {
-		pthread_rwlock_unlock(&host_lock);
+	if (! tree)
+		return -1;
+
+	attr = STORE_OBJ(sdb_avltree_lookup(tree, name));
+	if (! attr)
+		return -1;
+	if (filter && (! sdb_store_matcher_matches(filter, attr, NULL))) {
+		sdb_object_deref(SDB_OBJ(attr));
 		return -1;
 	}
 
-	while (sdb_llist_iter_has_next(host_iter)) {
-		sdb_host_t *host = SDB_HOST(sdb_llist_iter_get_next(host_iter));
-		sdb_llist_iter_t *svc_iter;
-		sdb_llist_iter_t *attr_iter;
+	assert(STORE_OBJ(attr)->type == SDB_ATTRIBUTE);
+	if (res)
+		sdb_data_copy(res, &ATTR(attr)->value);
+	sdb_object_deref(SDB_OBJ(attr));
+	return 0;
+} /* sdb_store_get_attr */
+
+/* TODO: sdb_store_fetch_timeseries should move into the plugin module */
 
-		char time_str[64];
+int
+sdb_store_fetch_timeseries(const char *hostname, const char *metric,
+		sdb_timeseries_opts_t *opts, sdb_strbuf_t *buf)
+{
+	sdb_avltree_t *metrics;
+	sdb_host_t *host;
+	sdb_metric_t *m;
 
-		assert(host);
+	sdb_timeseries_t *ts;
 
-		if (! sdb_strftime(time_str, sizeof(time_str),
-					"%F %T %z", host->_last_update))
-			snprintf(time_str, sizeof(time_str), "<error>");
-		time_str[sizeof(time_str) - 1] = '\0';
+	int status = 0;
 
-		fprintf(fh, "Host '%s' (last updated: %s):\n",
-				host->_name, time_str);
+	if ((! global_store) || (! hostname) || (! metric) || (! opts) || (! buf))
+		return -1;
 
-		attr_iter = sdb_llist_get_iter(host->attributes);
-		if (! attr_iter) {
-			char errbuf[1024];
-			fprintf(fh, "Failed to retrieve attributes: %s\n",
-					sdb_strerror(errno, errbuf, sizeof(errbuf)));
-			continue;
-		}
+	pthread_rwlock_rdlock(&global_store->host_lock);
+	host = lookup_host(global_store, hostname, /* canonicalize = */ 1);
+	metrics = get_host_children(host, SDB_METRIC);
+	sdb_object_deref(SDB_OBJ(host));
+	if (! metrics) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to fetch time-series '%s/%s' "
+				"- host '%s' not found", hostname, metric, hostname);
+		pthread_rwlock_unlock(&global_store->host_lock);
+		return -1;
+	}
 
-		while (sdb_llist_iter_has_next(attr_iter)) {
-			sdb_attribute_t *attr = SDB_ATTR(sdb_llist_iter_get_next(attr_iter));
-			assert(attr);
+	m = METRIC(sdb_avltree_lookup(metrics, metric));
+	if (! m) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to fetch time-series '%s/%s' "
+				"- metric '%s' not found", hostname, metric, metric);
+		pthread_rwlock_unlock(&global_store->host_lock);
+		return -1;
+	}
 
-			if (! sdb_strftime(time_str, sizeof(time_str),
-						"%F %T %z", attr->_last_update))
-				snprintf(time_str, sizeof(time_str), "<error>");
-			time_str[sizeof(time_str) - 1] = '\0';
+	if ((! m->store.type) || (! m->store.id)) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to fetch time-series '%s/%s' "
+				"- no data-store configured for the stored metric",
+				hostname, metric);
+		sdb_object_deref(SDB_OBJ(m));
+		pthread_rwlock_unlock(&global_store->host_lock);
+		return -1;
+	}
 
-			fprintf(fh, "\tAttribute '%s' -> '%s' (last updated: %s)\n",
-					attr->_name, attr->attr_value, time_str);
-		}
+	{
+		char type[strlen(m->store.type) + 1];
+		char id[strlen(m->store.id) + 1];
 
-		sdb_llist_iter_destroy(attr_iter);
+		strncpy(type, m->store.type, sizeof(type));
+		strncpy(id, m->store.id, sizeof(id));
+		pthread_rwlock_unlock(&global_store->host_lock);
 
-		svc_iter = sdb_llist_get_iter(host->services);
-		if (! svc_iter) {
-			char errbuf[1024];
-			fprintf(fh, "Failed to retrieve services: %s\n",
-					sdb_strerror(errno, errbuf, sizeof(errbuf)));
-			continue;
+		ts = sdb_plugin_fetch_timeseries(type, id, opts);
+		if (! ts) {
+			sdb_log(SDB_LOG_ERR, "store: Failed to fetch time-series '%s/%s' "
+					"- %s fetcher callback returned no data for '%s'",
+					hostname, metric, type, id);
+			status = -1;
 		}
+	}
 
-		while (sdb_llist_iter_has_next(svc_iter)) {
-			sdb_service_t *svc = SDB_SVC(sdb_llist_iter_get_next(svc_iter));
-			assert(svc);
+	ts_tojson(ts, buf);
+	sdb_object_deref(SDB_OBJ(m));
+	sdb_timeseries_destroy(ts);
+	return status;
+} /* sdb_store_fetch_timeseries */
 
-			if (! sdb_strftime(time_str, sizeof(time_str),
-						"%F %T %z", svc->_last_update))
-				snprintf(time_str, sizeof(time_str), "<error>");
-			time_str[sizeof(time_str) - 1] = '\0';
+int
+sdb_store_scan(int type, sdb_store_matcher_t *m, sdb_store_matcher_t *filter,
+		sdb_store_lookup_cb cb, void *user_data)
+{
+	sdb_avltree_iter_t *host_iter = NULL;
+	int status = 0;
+
+	if ((! global_store) || (! cb))
+		return -1;
+
+	if ((type != SDB_HOST) && (type != SDB_SERVICE) && (type != SDB_METRIC)) {
+		sdb_log(SDB_LOG_ERR, "store: Cannot scan objects of type %d", type);
+		return -1;
+	}
+
+	pthread_rwlock_rdlock(&global_store->host_lock);
+	host_iter = sdb_avltree_get_iter(global_store->hosts);
+	if (! host_iter)
+		status = -1;
 
-			fprintf(fh, "\tService '%s' (last updated: %s)\n",
-					svc->_name, time_str);
+	/* has_next returns false if the iterator is NULL */
+	while (sdb_avltree_iter_has_next(host_iter)) {
+		sdb_store_obj_t *host;
+		sdb_avltree_iter_t *iter = NULL;
+
+		host = STORE_OBJ(sdb_avltree_iter_get_next(host_iter));
+		assert(host);
+
+		if (! sdb_store_matcher_matches(filter, host, NULL))
+			continue;
+
+		if (type == SDB_SERVICE)
+			iter = sdb_avltree_get_iter(HOST(host)->services);
+		else if (type == SDB_METRIC)
+			iter = sdb_avltree_get_iter(HOST(host)->metrics);
+
+		if (iter) {
+			while (sdb_avltree_iter_has_next(iter)) {
+				sdb_store_obj_t *obj;
+				obj = STORE_OBJ(sdb_avltree_iter_get_next(iter));
+				assert(obj);
+
+				if (sdb_store_matcher_matches(m, obj, filter)) {
+					if (cb(obj, filter, user_data)) {
+						sdb_log(SDB_LOG_ERR, "store: Callback returned "
+								"an error while scanning");
+						status = -1;
+						break;
+					}
+				}
+			}
+		}
+		else if (sdb_store_matcher_matches(m, host, filter)) {
+			if (cb(host, filter, user_data)) {
+				sdb_log(SDB_LOG_ERR, "store: Callback returned "
+						"an error while scanning");
+				status = -1;
+			}
 		}
 
-		sdb_llist_iter_destroy(svc_iter);
+		sdb_avltree_iter_destroy(iter);
+		if (status)
+			break;
 	}
 
-	sdb_llist_iter_destroy(host_iter);
-	pthread_rwlock_unlock(&host_lock);
-	return 0;
-} /* sdb_store_dump */
+	sdb_avltree_iter_destroy(host_iter);
+	pthread_rwlock_unlock(&global_store->host_lock);
+	return status;
+} /* sdb_store_scan */
 
 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */