X-Git-Url: https://git.tokkee.org/?p=sysdb.git;a=blobdiff_plain;f=src%2Fcore%2Fstore.c;h=2522233112a8d125024d9853710ff90565f768d4;hp=c66b5236a95b82869d19b532237a0ed0e4832aef;hb=9a96acd759c31211aa512e174339a9c178c4eb83;hpb=1fee763a36a0c9af761244bbce8cd6c233ddbe2a

diff --git a/src/core/store.c b/src/core/store.c
index c66b523..fa72955 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/error.h"
-#include "utils/llist.h"
+#include "core/store-private.h"
+#include "core/plugin.h"
+#include "utils/avltree.h"
+#include "utils/error.h"
 
 #include <assert.h>
 
@@ -41,544 +46,933 @@
 #include <pthread.h>
 
 /*
- * private variables
+ * private types
  */
 
-static sdb_llist_t *host_list = NULL;
-static pthread_rwlock_t host_lock = PTHREAD_RWLOCK_INITIALIZER;
+struct sdb_store {
+	sdb_object_t super;
 
-/*
- * public types
- */
+	/* hosts are the top-level entries and
+	 * reference everything else */
+	sdb_avltree_t *hosts;
+	pthread_rwlock_t host_lock;
+};
+
+/* internal representation of a to-be-stored object */
+typedef struct {
+	sdb_store_obj_t *parent;
+	sdb_avltree_t *parent_tree;
+	int type;
+	const char *name;
+	sdb_time_t last_update;
+	const char * const *backends;
+	size_t backends_num;
+} store_obj_t;
+#define STORE_OBJ_INIT { NULL, NULL, 0, NULL, 0, NULL, 0 }
+
+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_host_init(sdb_object_t *obj, va_list __attribute__((unused)) ap)
+store_init(sdb_object_t *obj, va_list __attribute__((unused)) ap)
 {
-	SDB_HOST(obj)->_last_update = sdb_gettime();
-	/* ignore errors -> last_update will be updated later */
-
-	SDB_HOST(obj)->attributes = sdb_llist_create();
-	if (! SDB_HOST(obj)->attributes)
+	int err;
+	if (! (SDB_STORE(obj)->hosts = sdb_avltree_create()))
 		return -1;
-	SDB_HOST(obj)->services = sdb_llist_create();
-	if (! SDB_HOST(obj)->services)
+	if ((err = pthread_rwlock_init(&SDB_STORE(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;
-} /* sdb_host_init */
+} /* store_init */
 
 static void
-sdb_host_destroy(sdb_object_t *obj)
+store_destroy(sdb_object_t *obj)
 {
-	assert(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 */
+	int err;
+	if ((err = pthread_rwlock_destroy(&SDB_STORE(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(SDB_STORE(obj)->hosts);
+	SDB_STORE(obj)->hosts = NULL;
+} /* store_destroy */
 
-static sdb_object_t *
-sdb_host_do_clone(const sdb_object_t *obj)
+static int
+store_obj_init(sdb_object_t *obj, va_list ap)
 {
-	const sdb_host_t *host = (const sdb_host_t *)obj;
-	sdb_host_t *new;
+	sdb_store_obj_t *sobj = STORE_OBJ(obj);
 
-	new = sdb_host_create(obj->name);
-	if (! new)
-		return NULL;
+	sobj->type = va_arg(ap, int);
 
-	/* make sure these are initialized; else sdb_object_deref() might access
-	 * arbitrary memory in case of an error */
-	new->services = new->attributes = NULL;
+	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 */
 
-	if (host->attributes) {
-		new->attributes = sdb_llist_clone(host->attributes);
-		if (! new->attributes) {
-			sdb_object_deref(SDB_OBJ(new));
-			return NULL;
-		}
-	}
+static void
+store_obj_destroy(sdb_object_t *obj)
+{
+	sdb_store_obj_t *sobj = STORE_OBJ(obj);
+	size_t i;
 
-	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 SDB_OBJ(new);
-} /* sdb_host_do_clone */
+	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
-sdb_attr_init(sdb_object_t *obj, va_list ap)
+host_init(sdb_object_t *obj, va_list ap)
 {
-	const char *hostname = va_arg(ap, const char *);
-	const char *value = va_arg(ap, const char *);
+	host_t *sobj = HOST(obj);
+	int ret;
 
-	SDB_ATTR(obj)->hostname = strdup(hostname);
-	SDB_ATTR(obj)->attr_value = strdup(value);
-	if ((! SDB_ATTR(obj)->hostname) || (! 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->services = sdb_avltree_create();
+	if (! sobj->services)
+		return -1;
+	sobj->metrics = sdb_avltree_create();
+	if (! sobj->metrics)
+		return -1;
+	sobj->attributes = sdb_avltree_create();
+	if (! sobj->attributes)
+		return -1;
 	return 0;
-} /* sdb_attr_init */
+} /* host_init */
 
 static void
-sdb_attr_destroy(sdb_object_t *obj)
+host_destroy(sdb_object_t *obj)
 {
+	host_t *sobj = HOST(obj);
 	assert(obj);
 
-	if (SDB_ATTR(obj)->hostname)
-		free(SDB_ATTR(obj)->hostname);
-	if (SDB_ATTR(obj)->attr_value)
-		free(SDB_ATTR(obj)->attr_value);
-} /* sdb_attr_destroy */
+	store_obj_destroy(obj);
 
-static sdb_object_t *
-sdb_attr_clone(const sdb_object_t *obj)
+	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
+service_init(sdb_object_t *obj, va_list ap)
 {
-	const sdb_attribute_t *attr = (const sdb_attribute_t *)obj;
-	sdb_attribute_t *new;
+	service_t *sobj = SVC(obj);
+	int ret;
 
-	new = sdb_attribute_create(attr->hostname,
-			obj->name, attr->attr_value);
-	if (! new)
-		return NULL;
+	/* this will consume the first argument (type) of ap */
+	ret = store_obj_init(obj, ap);
+	if (ret)
+		return ret;
 
-	new->_last_update = attr->_last_update;
-	return SDB_OBJ(new);
-} /* sdb_attr_clone */
+	sobj->attributes = sdb_avltree_create();
+	if (! sobj->attributes)
+		return -1;
+	return 0;
+} /* service_init */
+
+static void
+service_destroy(sdb_object_t *obj)
+{
+	service_t *sobj = SVC(obj);
+	assert(obj);
+
+	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 *);
+	sdb_metric_t *sobj = METRIC(obj);
+	int ret;
+
+	/* this will consume the first argument (type) of ap */
+	ret = store_obj_init(obj, ap);
+	if (ret)
+		return ret;
 
-	SDB_SVC(obj)->hostname = strdup(hostname);
-	if (! SDB_SVC(obj)->hostname)
+	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);
-} /* sdb_svc_destroy */
+	store_obj_destroy(obj);
 
-static sdb_object_t *
-sdb_svc_clone(const sdb_object_t *obj)
-{
-	const sdb_service_t *svc = (const sdb_service_t *)obj;
-	sdb_service_t *new;
+	if (sobj->attributes)
+		sdb_avltree_destroy(sobj->attributes);
 
-	new = sdb_service_create(svc->hostname, obj->name);
-	if (! new)
-		return NULL;
+	if (sobj->store.type)
+		free(sobj->store.type);
+	if (sobj->store.id)
+		free(sobj->store.id);
+} /* metric_destroy */
 
-	new->_last_update = svc->_last_update;
-	return SDB_OBJ(new);
-} /* sdb_svc_clone */
+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 */
 
-const sdb_type_t sdb_host_type = {
-	sizeof(sdb_host_t),
+static void
+attr_destroy(sdb_object_t *obj)
+{
+	assert(obj);
 
-	sdb_host_init,
-	sdb_host_destroy,
-	sdb_host_do_clone
+	store_obj_destroy(obj);
+	sdb_data_free_datum(&ATTR(obj)->value);
+} /* attr_destroy */
+
+static sdb_type_t store_type = {
+	/* size = */ sizeof(sdb_store_t),
+	/* init = */ store_init,
+	/* destroy = */ store_destroy,
 };
 
-const sdb_type_t sdb_attribute_type = {
-	sizeof(sdb_attribute_t),
+static sdb_type_t host_type = {
+	/* size = */ sizeof(host_t),
+	/* init = */ host_init,
+	/* destroy = */ host_destroy
+};
 
-	sdb_attr_init,
-	sdb_attr_destroy,
-	sdb_attr_clone
+static sdb_type_t service_type = {
+	/* size = */ sizeof(service_t),
+	/* init = */ service_init,
+	/* destroy = */ service_destroy
 };
 
-const sdb_type_t sdb_service_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,
-	sdb_svc_clone
+static sdb_type_t attribute_type = {
+	/* size = */ sizeof(attr_t),
+	/* init = */ attr_init,
+	/* destroy = */ attr_destroy
 };
 
 /*
- * public API
+ * private helper functions
  */
 
-sdb_host_t *
-sdb_host_create(const char *name)
+static int
+record_backends(sdb_store_obj_t *obj,
+		const char * const *backends, size_t backends_num)
 {
-	sdb_object_t *obj;
+	char **tmp;
+	size_t i;
 
-	if (! name)
-		return NULL;
+	for (i = 0; i < backends_num; i++) {
+		bool found = 0;
+		size_t j;
 
-	obj = sdb_object_create(name, sdb_host_type);
-	if (! obj)
-		return NULL;
-	return SDB_HOST(obj);
-} /* sdb_host_create */
+		for (j = 0; j < obj->backends_num; ++j) {
+			if (!strcasecmp(obj->backends[j], backends[i])) {
+				found = 1;
+				break;
+			}
+		}
+		if (found)
+			continue;
 
-int
-sdb_store_host(const sdb_host_t *host)
-{
-	sdb_time_t last_update;
-	sdb_host_t *old;
-	int status = 0;
+		tmp = realloc(obj->backends,
+				(obj->backends_num + 1) * sizeof(*obj->backends));
+		if (! tmp)
+			return -1;
 
-	if ((! host) || (! SDB_CONST_OBJ(host)->name))
-		return -1;
+		obj->backends = tmp;
+		obj->backends[obj->backends_num] = strdup(backends[i]);
+		if (! obj->backends[obj->backends_num])
+			return -1;
 
-	last_update = host->_last_update;
-	if (last_update <= 0)
-		last_update = sdb_gettime();
+		++obj->backends_num;
+	}
+	return 0;
+} /* record_backends */
 
-	pthread_rwlock_wrlock(&host_lock);
+static int
+store_obj(store_obj_t *obj, sdb_store_obj_t **updated_obj)
+{
+	sdb_store_obj_t *old, *new;
+	int status = 0;
 
-	if (! host_list) {
-		if (! (host_list = sdb_llist_create())) {
-			pthread_rwlock_unlock(&host_lock);
-			return -1;
-		}
-	}
+	assert(obj->parent_tree);
 
-	old = SDB_HOST(sdb_llist_search_by_name(host_list,
-				SDB_CONST_OBJ(host)->name));
+	if (obj->last_update <= 0)
+		obj->last_update = sdb_gettime();
 
+	old = STORE_OBJ(sdb_avltree_lookup(obj->parent_tree, obj->name));
 	if (old) {
-		if (old->_last_update > last_update) {
-			sdb_log(SDB_LOG_DEBUG, "store: Cannot update host '%s' - "
-					"value too old (%"PRIscTIME" < %"PRIscTIME")",
-					SDB_CONST_OBJ(host)->name, last_update, old->_last_update);
-			/* don't report an error; the host may be updated by multiple
+		if (old->last_update > obj->last_update) {
+			sdb_log(SDB_LOG_DEBUG, "store: Cannot update %s '%s' - "
+					"value too old (%"PRIsdbTIME" < %"PRIsdbTIME")",
+					SDB_STORE_TYPE_TO_NAME(obj->type), obj->name,
+					obj->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 == obj->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 = obj->last_update - old->last_update;
+			old->last_update = obj->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(sdb_object_clone(SDB_CONST_OBJ(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 (obj->type == SDB_ATTRIBUTE) {
+			/* the value will be updated by the caller */
+			new = STORE_OBJ(sdb_object_create(obj->name, attribute_type,
+						obj->type, obj->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", SDB_CONST_OBJ(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 = obj->type == SDB_HOST
+				? host_type
+				: obj->type == SDB_SERVICE
+					? service_type
+					: metric_type;
+			new = STORE_OBJ(sdb_object_create(obj->name, t,
+						obj->type, obj->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", SDB_CONST_OBJ(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(obj->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(obj->type), obj->name,
+					sdb_strerror(errno, errbuf, sizeof(errbuf)));
+			status = -1;
 		}
+	}
 
-		status = sdb_llist_insert_sorted(host_list, SDB_OBJ(new),
-				sdb_object_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 != obj->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(obj->parent));
+		new->parent = obj->parent;
 	}
 
-	pthread_rwlock_unlock(&host_lock);
+	if (updated_obj)
+		*updated_obj = new;
+
+	if (record_backends(new, obj->backends, obj->backends_num))
+		return -1;
 	return status;
-} /* sdb_store_host */
+} /* store_obj */
 
-const sdb_host_t *
-sdb_store_get_host(const char *name)
+static int
+store_metric_store(sdb_metric_t *metric, sdb_store_metric_t *m)
 {
-	sdb_host_t *host;
+	char *type = metric->store.type;
+	char *id = metric->store.id;
 
-	if (! name)
-		return NULL;
+	if ((! metric->store.type) || strcasecmp(metric->store.type, m->store.type)) {
+		if (! (type = strdup(m->store.type)))
+			return -1;
+	}
+	if ((! metric->store.id) || strcasecmp(metric->store.id, m->store.id)) {
+		if (! (id = strdup(m->store.id))) {
+			if (type != metric->store.type)
+				free(type);
+			return -1;
+		}
+	}
 
-	host = SDB_HOST(sdb_llist_search_by_name(host_list, name));
-	if (! host)
-		return NULL;
-	return host;
-} /* sdb_store_get_host */
+	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 */
 
-sdb_attribute_t *
-sdb_attribute_create(const char *hostname,
-		const char *name, const char *value)
+/* The store's host_lock has to be acquired before calling this function. */
+static sdb_avltree_t *
+get_host_children(host_t *host, int type)
 {
-	sdb_object_t *obj;
-
-	if ((! hostname) || (! name) || (! value))
+	if ((type != SDB_SERVICE) && (type != SDB_METRIC)
+			&& (type != SDB_ATTRIBUTE))
 		return NULL;
 
-	obj = sdb_object_create(name, sdb_attribute_type, hostname, value);
-	if (! obj)
+	if (! host)
 		return NULL;
-	return SDB_ATTR(obj);
-} /* sdb_attribute_create */
 
-int
-sdb_store_attribute(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 */
+
+/*
+ * store writer API
+ */
+
+static int
+store_attribute(sdb_store_attribute_t *attr, sdb_object_t *user_data)
 {
-	sdb_host_t *host;
-	sdb_attribute_t *old;
-	sdb_time_t last_update;
+	sdb_store_t *st = SDB_STORE(user_data);
+	store_obj_t obj = STORE_OBJ_INIT;
+	sdb_store_obj_t *new = NULL;
+	const char *hostname;
+	host_t *host;
 
+	sdb_avltree_t *children = NULL;
 	int status = 0;
 
-	if (! attr)
+	if ((! attr) || (! attr->parent) || (! attr->key))
 		return -1;
 
-	last_update = attr->_last_update;
-	if (last_update <= 0)
-		last_update = sdb_gettime();
-
-	if (! host_list)
+	hostname = attr->hostname;
+	if (attr->parent_type == SDB_HOST)
+		hostname = attr->parent;
+	if (! hostname)
 		return -1;
 
-	pthread_rwlock_wrlock(&host_lock);
-
-	host = SDB_HOST(sdb_llist_search_by_name(host_list, attr->hostname));
+	pthread_rwlock_wrlock(&st->host_lock);
+	host = HOST(sdb_avltree_lookup(st->hosts, hostname));
 	if (! host) {
-		pthread_rwlock_unlock(&host_lock);
-		return -1;
+		sdb_log(SDB_LOG_ERR, "store: Failed to store attribute '%s' - "
+				"host '%s' not found", attr->key, hostname);
+		status = -1;
 	}
 
-	old = SDB_ATTR(sdb_llist_search_by_name(host->attributes,
-				SDB_CONST_OBJ(attr)->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, SDB_CONST_OBJ(attr)->name, last_update,
-					old->_last_update);
-			status = 1;
-		}
-		else {
-			old->_last_update = last_update;
-		}
+	switch (attr->parent_type) {
+	case SDB_HOST:
+		obj.parent = STORE_OBJ(host);
+		obj.parent_tree = get_host_children(host, SDB_ATTRIBUTE);
+		break;
+	case SDB_SERVICE:
+		children = get_host_children(host, SDB_SERVICE);
+		break;
+	case SDB_METRIC:
+		children = get_host_children(host, SDB_METRIC);
+		break;
+	default:
+		status = -1;
+		break;
 	}
-	else {
-		sdb_attribute_t *new = SDB_ATTR(sdb_object_clone(SDB_CONST_OBJ(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_object_cmp_by_name);
+	if (children) {
+		obj.parent = STORE_OBJ(sdb_avltree_lookup(children, attr->parent));
+		if (! obj.parent) {
+			sdb_log(SDB_LOG_ERR, "store: Failed to store attribute '%s' - "
+					"%s '%s/%s' not found", attr->key,
+					SDB_STORE_TYPE_TO_NAME(attr->parent_type),
+					attr->hostname, attr->parent);
+			status = -1;
+		}
+		else
+			obj.parent_tree = attr->parent_type == SDB_SERVICE
+				? SVC(obj.parent)->attributes
+				: METRIC(obj.parent)->attributes;
+	}
 
-		/* pass control to the list or destroy in case of an error */
-		sdb_object_deref(SDB_OBJ(new));
+	obj.type = SDB_ATTRIBUTE;
+	obj.name = attr->key;
+	obj.last_update = attr->last_update;
+	obj.backends = attr->backends;
+	obj.backends_num = attr->backends_num;
+	if (! status)
+		status = store_obj(&obj, &new);
+
+	if (! status) {
+		assert(new);
+		/* update the value if it changed */
+		if (sdb_data_cmp(&ATTR(new)->value, &attr->value))
+			if (sdb_data_copy(&ATTR(new)->value, &attr->value))
+				status = -1;
 	}
 
-	pthread_rwlock_unlock(&host_lock);
+	if (obj.parent != STORE_OBJ(host))
+		sdb_object_deref(SDB_OBJ(obj.parent));
+	sdb_object_deref(SDB_OBJ(host));
+	pthread_rwlock_unlock(&st->host_lock);
+
 	return status;
-} /* sdb_store_attribute */
+} /* store_attribute */
 
-sdb_service_t *
-sdb_service_create(const char *hostname, const char *name)
+static int
+store_host(sdb_store_host_t *host, sdb_object_t *user_data)
 {
-	sdb_object_t *obj;
+	sdb_store_t *st = SDB_STORE(user_data);
+	store_obj_t obj = { NULL, st->hosts, SDB_HOST, NULL, 0, NULL, 0 };
+	int status = 0;
 
-	if ((! hostname) || (! name))
-		return NULL;
+	if ((! host) || (! host->name))
+		return -1;
 
-	obj = sdb_object_create(name, sdb_service_type, hostname);
-	if (! obj)
-		return NULL;
-	return SDB_SVC(obj);
-} /* sdb_service_create */
+	obj.name = host->name;
+	obj.last_update = host->last_update;
+	obj.backends = host->backends;
+	obj.backends_num = host->backends_num;
+	pthread_rwlock_wrlock(&st->host_lock);
+	status = store_obj(&obj, NULL);
+	pthread_rwlock_unlock(&st->host_lock);
 
-int
-sdb_store_service(const sdb_service_t *svc)
+	return status;
+} /* store_host */
+
+static int
+store_service(sdb_store_service_t *service, sdb_object_t *user_data)
 {
-	sdb_host_t *host;
-	sdb_service_t *old;
-	sdb_time_t last_update;
+	sdb_store_t *st = SDB_STORE(user_data);
+	store_obj_t obj = STORE_OBJ_INIT;
+	host_t *host;
 
 	int status = 0;
 
-	if (! svc)
+	if ((! service) || (! service->hostname) || (! service->name))
 		return -1;
 
-	last_update = svc->_last_update;
-	if (last_update <= 0)
-		last_update = sdb_gettime();
+	pthread_rwlock_wrlock(&st->host_lock);
+	host = HOST(sdb_avltree_lookup(st->hosts, service->hostname));
+	obj.parent = STORE_OBJ(host);
+	obj.parent_tree = get_host_children(host, SDB_SERVICE);
+	obj.type = SDB_SERVICE;
+	if (! obj.parent_tree) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store service '%s' - "
+				"host '%s' not found", service->name, service->hostname);
+		status = -1;
+	}
 
-	if (! host_list)
-		return -1;
+	obj.name = service->name;
+	obj.last_update = service->last_update;
+	obj.backends = service->backends;
+	obj.backends_num = service->backends_num;
+	if (! status)
+		status = store_obj(&obj, NULL);
 
-	pthread_rwlock_wrlock(&host_lock);
+	sdb_object_deref(SDB_OBJ(host));
+	pthread_rwlock_unlock(&st->host_lock);
+	return status;
+} /* store_service */
 
-	host = SDB_HOST(sdb_llist_search_by_name(host_list, svc->hostname));
-	if (! host) {
-		pthread_rwlock_unlock(&host_lock);
+static int
+store_metric(sdb_store_metric_t *metric, sdb_object_t *user_data)
+{
+	sdb_store_t *st = SDB_STORE(user_data);
+	store_obj_t obj = STORE_OBJ_INIT;
+	sdb_store_obj_t *new = NULL;
+	host_t *host;
+
+	int status = 0;
+
+	if ((! metric) || (! metric->hostname) || (! metric->name))
 		return -1;
-	}
 
-	old = SDB_SVC(sdb_llist_search_by_name(host->services,
-				SDB_CONST_OBJ(svc)->name));
-	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, SDB_CONST_OBJ(svc)->name, last_update,
-					old->_last_update);
-			status = 1;
-		}
-		else {
-			old->_last_update = last_update;
-		}
-	}
-	else {
-		sdb_service_t *new = SDB_SVC(sdb_object_clone(SDB_CONST_OBJ(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;
-		}
+	if ((metric->store.type != NULL) != (metric->store.id != NULL))
+		return -1;
 
-		status = sdb_llist_insert_sorted(host->services, SDB_OBJ(new),
-				sdb_object_cmp_by_name);
+	pthread_rwlock_wrlock(&st->host_lock);
+	host = HOST(sdb_avltree_lookup(st->hosts, metric->hostname));
+	obj.parent = STORE_OBJ(host);
+	obj.parent_tree = get_host_children(host, SDB_METRIC);
+	obj.type = SDB_METRIC;
+	if (! obj.parent_tree) {
+		sdb_log(SDB_LOG_ERR, "store: Failed to store metric '%s' - "
+				"host '%s' not found", metric->name, metric->hostname);
+		status = -1;
+	}
 
-		/* pass control to the list or destroy in case of an error */
-		sdb_object_deref(SDB_OBJ(new));
+	obj.name = metric->name;
+	obj.last_update = metric->last_update;
+	obj.backends = metric->backends;
+	obj.backends_num = metric->backends_num;
+	if (! status)
+		status = store_obj(&obj, &new);
+	sdb_object_deref(SDB_OBJ(host));
+
+	if (status) {
+		pthread_rwlock_unlock(&st->host_lock);
+		return status;
 	}
 
-	pthread_rwlock_unlock(&host_lock);
+	assert(new);
+	if (metric->store.type && metric->store.id)
+		if (store_metric_store(METRIC(new), metric))
+			status = -1;
+	pthread_rwlock_unlock(&st->host_lock);
 	return status;
+} /* store_metric */
+
+sdb_store_writer_t sdb_store_writer = {
+	store_host, store_service, store_metric, store_attribute,
+};
+
+static sdb_object_t *
+prepare_query(sdb_ast_node_t *ast,
+		sdb_strbuf_t __attribute__((unused)) *errbuf,
+		sdb_object_t __attribute__((unused)) *user_data)
+{
+	return SDB_OBJ(sdb_store_query_prepare(ast));
+} /* prepare_query */
+
+static int
+execute_query(sdb_object_t *q,
+		sdb_store_writer_t *w, sdb_object_t *wd, sdb_strbuf_t *errbuf,
+		sdb_object_t *user_data)
+{
+	return sdb_store_query_execute(SDB_STORE(user_data),
+			QUERY(q), w, wd, errbuf);
+} /* execute_query */
+
+sdb_store_reader_t sdb_store_reader = {
+	prepare_query, execute_query,
+};
+
+/*
+ * public API
+ */
+
+sdb_store_t *
+sdb_store_create(void)
+{
+	return SDB_STORE(sdb_object_create("store", store_type));
+} /* sdb_store_create */
+
+int
+sdb_store_host(sdb_store_t *store, const char *name, sdb_time_t last_update)
+{
+	sdb_store_host_t host = {
+		name, last_update, 0, NULL, 0,
+	};
+	return store_host(&host, SDB_OBJ(store));
+} /* sdb_store_host */
+
+int
+sdb_store_service(sdb_store_t *store, const char *hostname, const char *name,
+		sdb_time_t last_update)
+{
+	sdb_store_service_t service = {
+		hostname, name, last_update, 0, NULL, 0,
+	};
+	return store_service(&service, SDB_OBJ(store));
 } /* sdb_store_service */
 
-const sdb_service_t *
-sdb_store_get_service(const sdb_host_t *host, const char *name)
+int
+sdb_store_metric(sdb_store_t *store, const char *hostname, const char *name,
+		sdb_metric_store_t *metric_store, sdb_time_t last_update)
 {
-	sdb_service_t *svc;
+	sdb_store_metric_t metric = {
+		hostname, name, { NULL, NULL }, last_update, 0, NULL, 0,
+	};
+	if (metric_store) {
+		metric.store.type = metric_store->type;
+		metric.store.id = metric_store->id;
+	}
+	return store_metric(&metric, SDB_OBJ(store));
+} /* sdb_store_metric */
 
-	if ((! host) || (! name))
+int
+sdb_store_attribute(sdb_store_t *store, const char *hostname,
+		const char *key, const sdb_data_t *value, sdb_time_t last_update)
+{
+	sdb_store_attribute_t attr = {
+		NULL, SDB_HOST, hostname, key, SDB_DATA_INIT, last_update, 0, NULL, 0,
+	};
+	if (value) {
+		attr.value = *value;
+	}
+	return store_attribute(&attr, SDB_OBJ(store));
+} /* sdb_store_attribute */
+
+int
+sdb_store_service_attr(sdb_store_t *store, const char *hostname,
+		const char *service, const char *key, const sdb_data_t *value,
+		sdb_time_t last_update)
+{
+	sdb_store_attribute_t attr = {
+		hostname, SDB_SERVICE, service, key, SDB_DATA_INIT, last_update, 0, NULL, 0,
+	};
+	if (value) {
+		attr.value = *value;
+	}
+	return store_attribute(&attr, SDB_OBJ(store));
+} /* sdb_store_service_attr */
+
+int
+sdb_store_metric_attr(sdb_store_t *store, const char *hostname,
+		const char *metric, const char *key, const sdb_data_t *value,
+		sdb_time_t last_update)
+{
+	sdb_store_attribute_t attr = {
+		hostname, SDB_METRIC, metric, key, SDB_DATA_INIT, last_update, 0, NULL, 0,
+	};
+	if (value) {
+		attr.value = *value;
+	}
+	return store_attribute(&attr, SDB_OBJ(store));
+} /* sdb_store_metric_attr */
+
+sdb_store_obj_t *
+sdb_store_get_host(sdb_store_t *store, const char *name)
+{
+	host_t *host;
+
+	if ((! store) || (! name))
 		return NULL;
 
-	svc = SDB_SVC(sdb_llist_search_by_name(host->services, name));
-	if (! svc)
+	host = HOST(sdb_avltree_lookup(store->hosts, name));
+	if (! host)
 		return NULL;
-	return svc;
-} /* sdb_store_get_service */
 
-int
-sdb_store_dump(FILE *fh)
+	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_llist_iter_t *host_iter;
+	sdb_avltree_t *children;
 
-	if (! fh)
-		return -1;
+	if ((! host) || (host->type != SDB_HOST) || (! name))
+		return NULL;
+
+	children = get_host_children(HOST(host), type);
+	if (! children)
+		return NULL;
+	return STORE_OBJ(sdb_avltree_lookup(children, name));
+} /* sdb_store_get_child */
 
-	pthread_rwlock_rdlock(&host_lock);
+int
+sdb_store_get_field(sdb_store_obj_t *obj, int field, sdb_data_t *res)
+{
+	sdb_data_t tmp;
 
-	host_iter = sdb_llist_get_iter(host_list);
-	if (! host_iter) {
-		pthread_rwlock_unlock(&host_lock);
+	if (! obj)
 		return -1;
+
+	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 */
 
-	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;
+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;
 
-		char time_str[64];
+	if ((! obj) || (! name))
+		return -1;
 
-		assert(host);
+	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;
 
-		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';
+	if (! tree)
+		return -1;
 
-		fprintf(fh, "Host '%s' (last updated: %s):\n",
-				SDB_OBJ(host)->name, time_str);
+	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;
+	}
 
-		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;
-		}
+	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 */
 
-		while (sdb_llist_iter_has_next(attr_iter)) {
-			sdb_attribute_t *attr = SDB_ATTR(sdb_llist_iter_get_next(attr_iter));
-			assert(attr);
+int
+sdb_store_scan(sdb_store_t *store, 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 (! 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 ((! store) || (! cb))
+		return -1;
 
-			fprintf(fh, "\tAttribute '%s' -> '%s' (last updated: %s)\n",
-					SDB_OBJ(attr)->name, attr->attr_value, time_str);
-		}
+	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;
+	}
 
-		sdb_llist_iter_destroy(attr_iter);
+	pthread_rwlock_rdlock(&store->host_lock);
+	host_iter = sdb_avltree_get_iter(store->hosts);
+	if (! host_iter)
+		status = -1;
 
-		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;
-		}
+	/* 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;
 
-		while (sdb_llist_iter_has_next(svc_iter)) {
-			sdb_service_t *svc = SDB_SVC(sdb_llist_iter_get_next(svc_iter));
-			assert(svc);
+		host = STORE_OBJ(sdb_avltree_iter_get_next(host_iter));
+		assert(host);
 
-			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';
+		if (! sdb_store_matcher_matches(filter, host, NULL))
+			continue;
 
-			fprintf(fh, "\tService '%s' (last updated: %s)\n",
-					SDB_OBJ(svc)->name, time_str);
+		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(&store->host_lock);
+	return status;
+} /* sdb_store_scan */
 
 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */