X-Git-Url: https://git.tokkee.org/?p=sysdb.git;a=blobdiff_plain;f=src%2Fcore%2Fplugin.c;h=ecd84b5f9c5f5f525017872ecdf54fe234a6267f;hp=c8e8e9e0db06a7799275608b4724eb8929d5b89f;hb=55f6919736b7574b8fb905eced926d8c003411c6;hpb=71fee3e1ba309196cfc07c1df29c366385896223

diff --git a/src/core/plugin.c b/src/core/plugin.c
index c8e8e9e..ecd84b5 100644
--- a/src/core/plugin.c
+++ b/src/core/plugin.c
@@ -25,11 +25,16 @@
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#if HAVE_CONFIG_H
+#	include "config.h"
+#endif /* HAVE_CONFIG_H */
+
 #include "sysdb.h"
 #include "core/plugin.h"
+#include "core/time.h"
 #include "utils/error.h"
 #include "utils/llist.h"
-#include "utils/time.h"
+#include "utils/strbuf.h"
 
 #include <assert.h>
 
@@ -45,258 +50,641 @@
 
 #include <pthread.h>
 
+/* helper to access info attributes */
+#define INFO_GET(i, attr) \
+	((i)->attr ? (i)->attr : #attr" not set")
+
 /*
  * private data types
  */
 
-struct sdb_plugin_info {
-	char *name;
+typedef struct {
+	sdb_object_t super;
+	sdb_plugin_ctx_t public;
+
+	sdb_plugin_info_t info;
+	lt_dlhandle handle;
 
-	char *description;
-	char *copyright;
-	char *license;
+	/* The usage count differs from the object's ref count
+	 * in that it provides higher level information about how
+	 * the plugin is in use. */
+	size_t use_cnt;
+} ctx_t;
+#define CTX_INIT { SDB_OBJECT_INIT, \
+	SDB_PLUGIN_CTX_INIT, SDB_PLUGIN_INFO_INIT, NULL, 0 }
 
-	int   version;
-	int   plugin_version;
-};
-#define SDB_PLUGIN_INFO_INIT { "no name set", "no description set", \
-	/* copyright */ "", /* license */ "", \
-	/* version */ -1, /* plugin_version */ -1 }
+#define CTX(obj) ((ctx_t *)(obj))
 
 typedef struct {
 	sdb_object_t super;
-	char cb_name[64];
 	void *cb_callback;
 	sdb_object_t *cb_user_data;
-	sdb_plugin_ctx_t cb_ctx;
-} sdb_plugin_cb_t;
-#define SDB_PLUGIN_CB_INIT { SDB_OBJECT_INIT, /* name = */ "", \
+	ctx_t *cb_ctx;
+} callback_t;
+#define CB_INIT { SDB_OBJECT_INIT, \
 	/* callback = */ NULL, /* user_data = */ NULL, \
 	SDB_PLUGIN_CTX_INIT }
+#define CB(obj) ((callback_t *)(obj))
+#define CONST_CB(obj) ((const callback_t *)(obj))
 
 typedef struct {
-	sdb_plugin_cb_t super;
-#define ccb_name super.cb_name
+	callback_t super;
 #define ccb_callback super.cb_callback
 #define ccb_user_data super.cb_user_data
 #define ccb_ctx super.cb_ctx
 	sdb_time_t ccb_interval;
 	sdb_time_t ccb_next_update;
-} sdb_plugin_collector_cb_t;
+} collector_t;
+#define CCB(obj) ((collector_t *)(obj))
+#define CONST_CCB(obj) ((const collector_t *)(obj))
+
+typedef struct {
+	callback_t super; /* cb_callback will always be NULL */
+#define w_user_data super.cb_user_data
+#define w_ctx super.cb_ctx
+	sdb_store_writer_t impl;
+} writer_t;
+#define WRITER(obj) ((writer_t *)(obj))
 
-#define SDB_PLUGIN_CB(obj) ((sdb_plugin_cb_t *)(obj))
-#define SDB_PLUGIN_CCB(obj) ((sdb_plugin_collector_cb_t *)(obj))
+typedef struct {
+	callback_t super; /* cb_callback will always be NULL */
+#define r_user_data super.cb_user_data
+#define r_ctx super.cb_ctx
+	sdb_store_reader_t impl;
+} reader_t;
+#define READER(obj) ((reader_t *)(obj))
+
+typedef struct {
+	callback_t super; /* cb_callback will always be NULL */
+#define ts_user_data super.cb_user_data
+#define ts_ctx super.cb_ctx
+	sdb_timeseries_fetcher_t impl;
+} ts_fetcher_t;
+#define TS_FETCHER(obj) ((ts_fetcher_t *)(obj))
 
 /*
  * private variables
  */
 
-static sdb_plugin_ctx_t  plugin_default_ctx = SDB_PLUGIN_CTX_INIT;
+static sdb_plugin_ctx_t  plugin_default_ctx  = SDB_PLUGIN_CTX_INIT;
+static sdb_plugin_info_t plugin_default_info = SDB_PLUGIN_INFO_INIT;
+
+static pthread_key_t     plugin_ctx_key;
+static bool              plugin_ctx_key_initialized = 0;
 
-static pthread_key_t    plugin_ctx_key;
-static _Bool            plugin_ctx_key_initialized = 0;
+/* a list of the plugin contexts of all registered plugins */
+static sdb_llist_t      *all_plugins = NULL;
 
 static sdb_llist_t      *config_list = NULL;
 static sdb_llist_t      *init_list = NULL;
 static sdb_llist_t      *collector_list = NULL;
+static sdb_llist_t      *cname_list = NULL;
 static sdb_llist_t      *shutdown_list = NULL;
+static sdb_llist_t      *log_list = NULL;
+static sdb_llist_t      *timeseries_fetcher_list = NULL;
+static sdb_llist_t      *writer_list = NULL;
+static sdb_llist_t      *reader_list = NULL;
+
+static struct {
+	const char   *type;
+	sdb_llist_t **list;
+} all_lists[] = {
+	{ "config",             &config_list },
+	{ "init",               &init_list },
+	{ "collector",          &collector_list },
+	{ "cname",              &cname_list },
+	{ "shutdown",           &shutdown_list },
+	{ "log",                &log_list },
+	{ "timeseries fetcher", &timeseries_fetcher_list },
+	{ "store writer",       &writer_list },
+	{ "store reader",       &reader_list },
+};
 
 /*
  * private helper functions
  */
 
 static void
-sdb_plugin_ctx_destructor(void *ctx)
+plugin_info_clear(sdb_plugin_info_t *info)
 {
-	if (! ctx)
+	sdb_plugin_info_t empty_info = SDB_PLUGIN_INFO_INIT;
+	if (! info)
 		return;
-	free(ctx);
-} /* sdb_plugin_ctx_destructor */
+
+	if (info->plugin_name)
+		free(info->plugin_name);
+	if (info->filename)
+		free(info->filename);
+
+	if (info->description)
+		free(info->description);
+	if (info->copyright)
+		free(info->copyright);
+	if (info->license)
+		free(info->license);
+
+	*info = empty_info;
+} /* plugin_info_clear */
 
 static void
-sdb_plugin_ctx_init(void)
+ctx_key_init(void)
 {
 	if (plugin_ctx_key_initialized)
 		return;
 
-	pthread_key_create(&plugin_ctx_key, sdb_plugin_ctx_destructor);
+	pthread_key_create(&plugin_ctx_key, /* destructor */ NULL);
 	plugin_ctx_key_initialized = 1;
-} /* sdb_plugin_ctx_init */
+} /* ctx_key_init */
 
-static sdb_plugin_ctx_t *
-sdb_plugin_ctx_create(void)
+static int
+plugin_cmp_next_update(const sdb_object_t *a, const sdb_object_t *b)
 {
-	sdb_plugin_ctx_t *ctx;
+	const collector_t *ccb1 = (const collector_t *)a;
+	const collector_t *ccb2 = (const collector_t *)b;
 
-	ctx = malloc(sizeof(*ctx));
-	if (! ctx)
-		return NULL;
+	assert(ccb1 && ccb2);
+
+	return (ccb1->ccb_next_update > ccb2->ccb_next_update)
+		? 1 : (ccb1->ccb_next_update < ccb2->ccb_next_update)
+		? -1 : 0;
+} /* plugin_cmp_next_update */
+
+static int
+plugin_lookup_by_name(const sdb_object_t *obj, const void *id)
+{
+	const callback_t *cb = CONST_CB(obj);
+	const char *name = id;
 
-	*ctx = plugin_default_ctx;
+	assert(cb && id);
 
-	if (! plugin_ctx_key_initialized)
-		sdb_plugin_ctx_init();
-	pthread_setspecific(plugin_ctx_key, ctx);
-	return ctx;
-} /* sdb_plugin_ctx_create */
+	/* when a plugin was registered from outside a plugin (e.g. the core),
+	 * we don't have a plugin context */
+	if (! cb->cb_ctx)
+		return 1;
+
+	if (!strcasecmp(cb->cb_ctx->info.plugin_name, name))
+		return 0;
+	return 1;
+} /* plugin_lookup_by_name */
+
+/* since this function is called from sdb_plugin_reconfigure_finish()
+ * when iterating through all_plugins, we may not do any additional
+ * modifications to all_plugins except for the optional removal */
+static void
+plugin_unregister_by_name(const char *plugin_name)
+{
+	sdb_object_t *obj;
+	size_t i;
+
+	for (i = 0; i < SDB_STATIC_ARRAY_LEN(all_lists); ++i) {
+		const char  *type =  all_lists[i].type;
+		sdb_llist_t *list = *all_lists[i].list;
+
+		while (1) {
+			callback_t *cb;
+
+			cb = CB(sdb_llist_remove(list,
+						plugin_lookup_by_name, plugin_name));
+			if (! cb)
+				break;
+
+			assert(cb->cb_ctx);
+
+			sdb_log(SDB_LOG_INFO, "core: Unregistering "
+					"%s callback '%s' (module %s)", type, cb->super.name,
+					cb->cb_ctx->info.plugin_name);
+			sdb_object_deref(SDB_OBJ(cb));
+		}
+	}
+
+	obj = sdb_llist_search_by_name(all_plugins, plugin_name);
+	/* when called from sdb_plugin_reconfigure_finish, the object has already
+	 * been removed from the list */
+	if (obj && (obj->ref_cnt <= 1)) {
+		sdb_llist_remove_by_name(all_plugins, plugin_name);
+		sdb_object_deref(obj);
+	}
+	/* else: other callbacks still reference it */
+} /* plugin_unregister_by_name */
+
+/*
+ * store writer wrapper for performing database queries:
+ * It wraps another store writer, adding extra logic as needed.
+ */
+
+typedef struct {
+	sdb_object_t super;
+	sdb_store_writer_t *w;
+	sdb_object_t *ud;
+} query_writer_t;
+#define QUERY_WRITER_INIT(w, ud) { SDB_OBJECT_INIT, (w), (ud) }
+#define QUERY_WRITER(obj) ((query_writer_t *)(obj))
 
 static int
-sdb_plugin_cmp_name(const sdb_object_t *a, const sdb_object_t *b)
+query_store_host(sdb_store_host_t *host, sdb_object_t *user_data)
 {
-	const sdb_plugin_cb_t *cb1 = (const sdb_plugin_cb_t *)a;
-	const sdb_plugin_cb_t *cb2 = (const sdb_plugin_cb_t *)b;
+	query_writer_t *qw = QUERY_WRITER(user_data);
+	return qw->w->store_host(host, qw->ud);
+} /* query_store_host */
 
-	assert(cb1 && cb2);
-	return strcasecmp(cb1->cb_name, cb2->cb_name);
-} /* sdb_plugin_cmp_name */
+static int
+query_store_service(sdb_store_service_t *service, sdb_object_t *user_data)
+{
+	query_writer_t *qw = QUERY_WRITER(user_data);
+	return qw->w->store_service(service, qw->ud);
+} /* query_store_service */
 
 static int
-sdb_plugin_cmp_next_update(const sdb_object_t *a, const sdb_object_t *b)
+query_store_metric(sdb_store_metric_t *metric, sdb_object_t *user_data)
 {
-	const sdb_plugin_collector_cb_t *ccb1
-		= (const sdb_plugin_collector_cb_t *)a;
-	const sdb_plugin_collector_cb_t *ccb2
-		= (const sdb_plugin_collector_cb_t *)b;
+	query_writer_t *qw = QUERY_WRITER(user_data);
+	sdb_timeseries_info_t *infos[metric->stores_num];
+	sdb_metric_store_t stores[metric->stores_num];
 
-	assert(ccb1 && ccb2);
+	const sdb_metric_store_t *orig_stores = metric->stores;
+	int status;
+	size_t i;
+
+	for (i = 0; i < metric->stores_num; i++) {
+		/* TODO: Make this optional using query options. */
+		sdb_metric_store_t *s = stores + i;
+		*s = metric->stores[i];
+		infos[i] = sdb_plugin_describe_timeseries(s->type, s->id);
+		s->info = infos[i];
+	}
 
-	return (ccb1->ccb_next_update > ccb2->ccb_next_update)
-		? 1 : (ccb1->ccb_next_update < ccb2->ccb_next_update)
-		? -1 : 0;
-} /* sdb_plugin_cmp_next_update */
+	metric->stores = stores;
+	status = qw->w->store_metric(metric, qw->ud);
+	metric->stores = orig_stores;
 
-static sdb_plugin_cb_t *
-sdb_plugin_find_by_name(sdb_llist_t *list, const char *name)
+	for (i = 0; i < metric->stores_num; i++)
+		sdb_timeseries_info_destroy(infos[i]);
+	return status;
+} /* query_store_metric */
+
+static int
+query_store_attribute(sdb_store_attribute_t *attr, sdb_object_t *user_data)
 {
-	sdb_plugin_cb_t tmp = SDB_PLUGIN_CB_INIT;
+	query_writer_t *qw = QUERY_WRITER(user_data);
+	return qw->w->store_attribute(attr, qw->ud);
+} /* query_store_attribute */
 
-	sdb_object_t *obj;
-	assert(name);
+static sdb_store_writer_t query_writer = {
+	query_store_host, query_store_service,
+	query_store_metric, query_store_attribute,
+};
 
-	if (! list)
-		return NULL;
+/*
+ * private types
+ */
 
-	snprintf(tmp.cb_name, sizeof(tmp.cb_name), "%s", name);
-	tmp.cb_name[sizeof(tmp.cb_name) - 1] = '\0';
-	obj = sdb_llist_search(list, SDB_OBJ(&tmp), sdb_plugin_cmp_name);
-	if (! obj)
+static int
+ctx_init(sdb_object_t *obj, va_list __attribute__((unused)) ap)
+{
+	ctx_t *ctx = CTX(obj);
+
+	assert(ctx);
+
+	ctx->public = plugin_default_ctx;
+	ctx->info = plugin_default_info;
+	ctx->handle = NULL;
+	ctx->use_cnt = 1;
+	return 0;
+} /* ctx_init */
+
+static void
+ctx_destroy(sdb_object_t *obj)
+{
+	ctx_t *ctx = CTX(obj);
+
+	if (ctx->handle) {
+		const char *err;
+
+		sdb_log(SDB_LOG_INFO, "core: Unloading module %s",
+				ctx->info.plugin_name);
+
+		lt_dlerror();
+		lt_dlclose(ctx->handle);
+		if ((err = lt_dlerror()))
+			sdb_log(SDB_LOG_WARNING, "core: Failed to unload module %s: %s",
+					ctx->info.plugin_name, err);
+	}
+
+	plugin_info_clear(&ctx->info);
+} /* ctx_destroy */
+
+static sdb_type_t ctx_type = {
+	sizeof(ctx_t),
+
+	ctx_init,
+	ctx_destroy
+};
+
+static ctx_t *
+ctx_get(void)
+{
+	if (! plugin_ctx_key_initialized)
+		ctx_key_init();
+	return pthread_getspecific(plugin_ctx_key);
+} /* ctx_get */
+
+static ctx_t *
+ctx_set(ctx_t *new)
+{
+	ctx_t *old;
+
+	if (! plugin_ctx_key_initialized)
+		ctx_key_init();
+
+	old = pthread_getspecific(plugin_ctx_key);
+	if (old)
+		sdb_object_deref(SDB_OBJ(old));
+	if (new)
+		sdb_object_ref(SDB_OBJ(new));
+	pthread_setspecific(plugin_ctx_key, new);
+	return old;
+} /* ctx_set */
+
+static ctx_t *
+ctx_create(const char *name)
+{
+	ctx_t *ctx;
+
+	ctx = CTX(sdb_object_create(name, ctx_type));
+	if (! ctx)
 		return NULL;
-	return SDB_PLUGIN_CB(obj);
-} /* sdb_plugin_find_by_name */
 
-static int
-sdb_plugin_cb_init(sdb_object_t *obj, va_list ap)
+	if (! plugin_ctx_key_initialized)
+		ctx_key_init();
+	ctx_set(ctx);
+	return ctx;
+} /* ctx_create */
+
+/*
+ * plugin_init_ok:
+ * Checks whether the registration of a new plugin identified by 'obj' is
+ * okay. It consumes the first two arguments of 'ap'.
+ */
+static bool
+plugin_init_ok(sdb_object_t *obj, va_list ap)
 {
 	sdb_llist_t **list = va_arg(ap, sdb_llist_t **);
-	const char  *type = va_arg(ap, const char *);
-	const char  *name = va_arg(ap, const char *);
-	void    *callback = va_arg(ap, void *);
-	sdb_object_t   *ud = va_arg(ap, sdb_object_t *);
+	const char *type = va_arg(ap, const char *);
 
-	assert(list);
-	assert(type);
-	assert(obj);
+	assert(list); assert(type);
 
-	if (sdb_plugin_find_by_name(*list, name)) {
-		sdb_log(SDB_LOG_WARNING, "plugin: %s callback '%s' "
+	if (sdb_llist_search_by_name(*list, obj->name)) {
+		sdb_log(SDB_LOG_WARNING, "core: %s callback '%s' "
 				"has already been registered. Ignoring newly "
-				"registered version.\n", type, name);
+				"registered version.", type, obj->name);
+		return 0;
+	}
+	return 1;
+} /* plugin_init_ok */
+
+static int
+plugin_cb_init(sdb_object_t *obj, va_list ap)
+{
+	void *callback;
+	sdb_object_t *ud;
+
+	if (! plugin_init_ok(obj, ap))
+		return -1;
+
+	callback = va_arg(ap, void *);
+	ud = va_arg(ap, sdb_object_t *);
+
+	/* cb_ctx may be NULL if the plugin was not registered by a plugin */
+
+	CB(obj)->cb_callback = callback;
+	CB(obj)->cb_ctx      = ctx_get();
+	sdb_object_ref(SDB_OBJ(CB(obj)->cb_ctx));
+
+	sdb_object_ref(ud);
+	CB(obj)->cb_user_data = ud;
+	return 0;
+} /* plugin_cb_init */
+
+static void
+plugin_cb_destroy(sdb_object_t *obj)
+{
+	assert(obj);
+	sdb_object_deref(CB(obj)->cb_user_data);
+	sdb_object_deref(SDB_OBJ(CB(obj)->cb_ctx));
+} /* plugin_cb_destroy */
+
+static sdb_type_t callback_type = {
+	sizeof(callback_t),
+
+	plugin_cb_init,
+	plugin_cb_destroy
+};
+
+static sdb_type_t collector_type = {
+	sizeof(collector_t),
+
+	plugin_cb_init,
+	plugin_cb_destroy
+};
+
+static int
+plugin_writer_init(sdb_object_t *obj, va_list ap)
+{
+	sdb_store_writer_t *impl;
+	sdb_object_t *ud;
+
+	if (! plugin_init_ok(obj, ap))
+		return -1;
+
+	impl = va_arg(ap, sdb_store_writer_t *);
+	ud = va_arg(ap, sdb_object_t *);
+	assert(impl);
+
+	if ((! impl->store_host) || (! impl->store_service)
+			|| (! impl->store_metric) || (! impl->store_attribute)) {
+		sdb_log(SDB_LOG_ERR, "core: store writer callback '%s' "
+				"does not fully implement the writer interface.",
+				obj->name);
 		return -1;
 	}
 
-	snprintf(SDB_PLUGIN_CB(obj)->cb_name,
-			sizeof(SDB_PLUGIN_CB(obj)->cb_name),
-			"%s", name);
-	SDB_PLUGIN_CB(obj)->cb_name[sizeof(SDB_PLUGIN_CB(obj)->cb_name) - 1] = '\0';
-	SDB_PLUGIN_CB(obj)->cb_callback = callback;
-	SDB_PLUGIN_CB(obj)->cb_ctx      = sdb_plugin_get_ctx();
+	/* ctx may be NULL if the callback was not registered by a plugin */
+
+	WRITER(obj)->impl = *impl;
+	WRITER(obj)->w_ctx  = ctx_get();
+	sdb_object_ref(SDB_OBJ(WRITER(obj)->w_ctx));
 
 	sdb_object_ref(ud);
-	SDB_PLUGIN_CB(obj)->cb_user_data = ud;
+	WRITER(obj)->w_user_data = ud;
 	return 0;
-} /* sdb_plugin_cb_init */
+} /* plugin_writer_init */
 
 static void
-sdb_plugin_cb_destroy(sdb_object_t *obj)
+plugin_writer_destroy(sdb_object_t *obj)
 {
 	assert(obj);
-	sdb_object_deref(SDB_PLUGIN_CB(obj)->cb_user_data);
-} /* sdb_plugin_cb_destroy */
+	sdb_object_deref(WRITER(obj)->w_user_data);
+	sdb_object_deref(SDB_OBJ(WRITER(obj)->w_ctx));
+} /* plugin_writer_destroy */
+
+static sdb_type_t writer_type = {
+	sizeof(writer_t),
+
+	plugin_writer_init,
+	plugin_writer_destroy
+};
 
 static int
-sdb_plugin_add_callback(sdb_llist_t **list, const char *type,
-		const char *name, void *callback, sdb_object_t *user_data)
+plugin_reader_init(sdb_object_t *obj, va_list ap)
 {
-	sdb_object_t *obj;
+	sdb_store_reader_t *impl;
+	sdb_object_t *ud;
 
-	if ((! name) || (! callback))
+	if (! plugin_init_ok(obj, ap))
 		return -1;
 
-	assert(list);
+	impl = va_arg(ap, sdb_store_reader_t *);
+	ud = va_arg(ap, sdb_object_t *);
+	assert(impl);
 
-	if (! *list)
-		*list = sdb_llist_create();
-	if (! *list)
+	if ((! impl->prepare_query) || (! impl->execute_query)) {
+		sdb_log(SDB_LOG_ERR, "core: store reader callback '%s' "
+				"does not fully implement the reader interface.",
+				obj->name);
 		return -1;
+	}
 
-	obj = sdb_object_create(sizeof(sdb_plugin_cb_t), sdb_plugin_cb_init,
-			sdb_plugin_cb_destroy, list, type, name, callback, user_data);
-	if (! obj)
+	/* ctx may be NULL if the callback was not registered by a plugin */
+
+	READER(obj)->impl = *impl;
+	READER(obj)->r_ctx  = ctx_get();
+	sdb_object_ref(SDB_OBJ(READER(obj)->r_ctx));
+
+	sdb_object_ref(ud);
+	READER(obj)->r_user_data = ud;
+	return 0;
+} /* plugin_reader_init */
+
+static void
+plugin_reader_destroy(sdb_object_t *obj)
+{
+	assert(obj);
+	sdb_object_deref(READER(obj)->r_user_data);
+	sdb_object_deref(SDB_OBJ(READER(obj)->r_ctx));
+} /* plugin_reader_destroy */
+
+static sdb_type_t reader_type = {
+	sizeof(reader_t),
+
+	plugin_reader_init,
+	plugin_reader_destroy
+};
+
+static int
+plugin_ts_fetcher_init(sdb_object_t *obj, va_list ap)
+{
+	sdb_timeseries_fetcher_t *impl;
+	sdb_object_t *ud;
+
+	if (! plugin_init_ok(obj, ap))
 		return -1;
 
-	if (sdb_llist_append(*list, obj)) {
-		sdb_object_deref(obj);
+	impl = va_arg(ap, sdb_timeseries_fetcher_t *);
+	ud = va_arg(ap, sdb_object_t *);
+	assert(impl);
+
+	if ((! impl->describe) || (! impl->fetch)) {
+		sdb_log(SDB_LOG_ERR, "core: timeseries fetcher callback '%s' "
+				"does not fully implement the interface.",
+				obj->name);
 		return -1;
 	}
 
-	/* pass control to the list */
-	sdb_object_deref(obj);
+	/* ctx may be NULL if the callback was not registered by a plugin */
 
-	sdb_log(SDB_LOG_INFO, "plugin: Registered %s callback '%s'.\n",
-			type, name);
+	TS_FETCHER(obj)->impl = *impl;
+	TS_FETCHER(obj)->ts_ctx  = ctx_get();
+	sdb_object_ref(SDB_OBJ(TS_FETCHER(obj)->ts_ctx));
+
+	sdb_object_ref(ud);
+	TS_FETCHER(obj)->ts_user_data = ud;
 	return 0;
-} /* sdb_plugin_add_callback */
+} /* plugin_ts_fetcher_init */
 
-/*
- * public API
- */
+static void
+plugin_ts_fetcher_destroy(sdb_object_t *obj)
+{
+	assert(obj);
+	sdb_object_deref(TS_FETCHER(obj)->ts_user_data);
+	sdb_object_deref(SDB_OBJ(TS_FETCHER(obj)->ts_ctx));
+} /* plugin_ts_fetcher_destroy */
 
-int
-sdb_plugin_load(const char *name)
+static sdb_type_t ts_fetcher_type = {
+	sizeof(ts_fetcher_t),
+
+	plugin_ts_fetcher_init,
+	plugin_ts_fetcher_destroy
+};
+
+static int
+module_init(const char *name, lt_dlhandle lh, sdb_plugin_info_t *info)
+{
+	int (*mod_init)(sdb_plugin_info_t *);
+	int status;
+
+	mod_init = (int (*)(sdb_plugin_info_t *))lt_dlsym(lh, "sdb_module_init");
+	if (! mod_init) {
+		sdb_log(SDB_LOG_ERR, "core: Failed to load plugin '%s': "
+				"could not find symbol 'sdb_module_init'", name);
+		return -1;
+	}
+
+	status = mod_init(info);
+	if (status) {
+		sdb_log(SDB_LOG_ERR, "core: Failed to initialize "
+				"module '%s'", name);
+		plugin_unregister_by_name(name);
+		return -1;
+	}
+	return 0;
+} /* module_init */
+
+static int
+module_load(const char *basedir, const char *name,
+		const sdb_plugin_ctx_t *plugin_ctx)
 {
-	char  real_name[strlen(name) > 0 ? strlen(name) : 1];
+	char  base_name[name ? strlen(name) + 1 : 1];
 	const char *name_ptr;
 	char *tmp;
 
 	char filename[1024];
-
 	lt_dlhandle lh;
 
-	int (*mod_init)(sdb_plugin_info_t *);
-	sdb_plugin_info_t plugin_info = SDB_PLUGIN_INFO_INIT;
+	ctx_t *ctx;
 
 	int status;
 
-	if ((! name) || (! *name))
-		return -1;
+	assert(name);
 
-	real_name[0] = '\0';
+	base_name[0] = '\0';
 	name_ptr = name;
 
 	while ((tmp = strstr(name_ptr, "::"))) {
-		strncat(real_name, name_ptr, (size_t)(tmp - name_ptr));
-		strcat(real_name, "/");
+		strncat(base_name, name_ptr, (size_t)(tmp - name_ptr));
+		strcat(base_name, "/");
 		name_ptr = tmp + strlen("::");
 	}
-	strcat(real_name, name_ptr);
+	strcat(base_name, name_ptr);
+
+	if (! basedir)
+		basedir = PKGLIBDIR;
 
-	snprintf(filename, sizeof(filename), "%s/%s.so",
-			PKGLIBDIR, real_name);
+	snprintf(filename, sizeof(filename), "%s/%s.so", basedir, base_name);
 	filename[sizeof(filename) - 1] = '\0';
 
 	if (access(filename, R_OK)) {
 		char errbuf[1024];
-		sdb_log(SDB_LOG_ERR, "plugin: Failed to load plugin '%s' (%s): %s\n",
+		sdb_log(SDB_LOG_ERR, "core: Failed to load plugin '%s' (%s): %s",
 				name, filename, sdb_strerror(errno, errbuf, sizeof(errbuf)));
 		return -1;
 	}
@@ -306,90 +694,323 @@ sdb_plugin_load(const char *name)
 
 	lh = lt_dlopen(filename);
 	if (! lh) {
-		sdb_log(SDB_LOG_ERR, "plugin: Failed to load plugin '%s': %s\n"
+		sdb_log(SDB_LOG_ERR, "core: Failed to load plugin '%s': %s"
 				"The most common cause for this problem are missing "
 				"dependencies.\n", name, lt_dlerror());
 		return -1;
 	}
 
-	mod_init = (int (*)(sdb_plugin_info_t *))lt_dlsym(lh, "sdb_module_init");
-	if (! mod_init) {
-		sdb_log(SDB_LOG_ERR, "plugin: Failed to load plugin '%s': "
-				"could not find symbol 'sdb_module_init'\n", name);
+	if (ctx_get())
+		sdb_log(SDB_LOG_WARNING, "core: Discarding old plugin context");
+
+	ctx = ctx_create(name);
+	if (! ctx) {
+		sdb_log(SDB_LOG_ERR, "core: Failed to initialize plugin context");
 		return -1;
 	}
 
-	status = mod_init(&plugin_info);
-	if (status) {
-		sdb_log(SDB_LOG_ERR, "plugin: Failed to initialize "
-				"plugin '%s'\n", name);
-		return -1;
+	ctx->info.plugin_name = strdup(name);
+	ctx->info.filename = strdup(filename);
+	ctx->handle = lh;
+
+	if (plugin_ctx)
+		ctx->public = *plugin_ctx;
+
+	if ((status = module_init(name, lh, &ctx->info))) {
+		sdb_object_deref(SDB_OBJ(ctx));
+		return status;
 	}
 
 	/* compare minor version */
-	if ((plugin_info.version < 0)
-			|| ((int)(plugin_info.version / 100) != (int)(SDB_VERSION / 100)))
-		sdb_log(SDB_LOG_WARNING, "plugin: WARNING: version of "
+	if ((ctx->info.version < 0)
+			|| ((int)(ctx->info.version / 100) != (int)(SDB_VERSION / 100)))
+		sdb_log(SDB_LOG_WARNING, "core: WARNING: version of "
 				"plugin '%s' (%i.%i.%i) does not match our version "
-				"(%i.%i.%i); this might cause problems\n",
-				name, SDB_VERSION_DECODE(plugin_info.version),
+				"(%i.%i.%i); this might cause problems",
+				name, SDB_VERSION_DECODE(ctx->info.version),
 				SDB_VERSION_DECODE(SDB_VERSION));
 
-	sdb_log(SDB_LOG_INFO, "plugin: Successfully loaded "
-			"plugin '%s' v%i (%s)\n\t%s\n",
-			plugin_info.name, plugin_info.plugin_version,
-			plugin_info.description, plugin_info.copyright);
+	sdb_llist_append(all_plugins, SDB_OBJ(ctx));
+
+	sdb_log(SDB_LOG_INFO, "core: Successfully loaded "
+			"plugin %s v%i (%s)", ctx->info.plugin_name,
+			ctx->info.plugin_version,
+			INFO_GET(&ctx->info, description));
+	sdb_log(SDB_LOG_INFO, "core: Plugin %s: %s, License: %s",
+			ctx->info.plugin_name,
+			INFO_GET(&ctx->info, copyright),
+			INFO_GET(&ctx->info, license));
+
+	/* any registered callbacks took ownership of the context */
+	sdb_object_deref(SDB_OBJ(ctx));
+
+	/* reset */
+	ctx_set(NULL);
 	return 0;
-} /* sdb_plugin_load */
+} /* module_load */
 
-int
-sdb_plugin_set_info(sdb_plugin_info_t *info, int type, ...)
+static char *
+plugin_get_name(const char *name, char *buf, size_t bufsize)
 {
-	va_list ap;
+	ctx_t *ctx = ctx_get();
 
-	if (! info)
+	if (ctx)
+		snprintf(buf, bufsize, "%s::%s", ctx->info.plugin_name, name);
+	else
+		snprintf(buf, bufsize, "core::%s", name);
+	return buf;
+} /* plugin_get_name */
+
+static int
+plugin_add_impl(sdb_llist_t **list, sdb_type_t T, const char *type,
+		const char *name, void *impl, sdb_object_t *user_data)
+{
+	sdb_object_t *obj;
+
+	if ((! name) || (! impl))
 		return -1;
 
-	va_start(ap, type);
+	assert(list);
 
-	switch (type) {
-		case SDB_PLUGIN_INFO_NAME:
-			{
-				char *name = va_arg(ap, char *);
-				info->name = name;
-			}
-			break;
-		case SDB_PLUGIN_INFO_DESC:
-			{
-				char *desc = va_arg(ap, char *);
-				info->description = desc;
-			}
-			break;
-		case SDB_PLUGIN_INFO_COPYRIGHT:
-			{
-				char *copyright = va_arg(ap, char *);
-				info->copyright = copyright;
-			}
-			break;
-		case SDB_PLUGIN_INFO_LICENSE:
-			{
-				char *license = va_arg(ap, char *);
-				info->license = license;
-			}
-			break;
-		case SDB_PLUGIN_INFO_VERSION:
-			{
-				int version = va_arg(ap, int);
-				info->version = version;
-			}
-			break;
-		case SDB_PLUGIN_INFO_PLUGIN_VERSION:
-			{
-				int version = va_arg(ap, int);
-				info->plugin_version = version;
-			}
-			break;
-		default:
+	if (! *list)
+		*list = sdb_llist_create();
+	if (! *list)
+		return -1;
+
+	obj = sdb_object_create(name, T, list, type, impl, user_data);
+	if (! obj)
+		return -1;
+
+	if (sdb_llist_append(*list, obj)) {
+		sdb_object_deref(obj);
+		return -1;
+	}
+
+	/* pass control to the list */
+	sdb_object_deref(obj);
+
+	sdb_log(SDB_LOG_INFO, "core: Registered %s callback '%s'.",
+			type, name);
+	return 0;
+} /* plugin_add_impl */
+
+/*
+ * object meta-data
+ */
+
+typedef struct {
+	int obj_type;
+	sdb_time_t last_update;
+	sdb_time_t interval;
+} interval_fetcher_t;
+
+static int
+interval_fetcher_host(sdb_store_host_t *host, sdb_object_t *user_data)
+{
+	interval_fetcher_t *lu = SDB_OBJ_WRAPPER(user_data)->data;
+	lu->obj_type = SDB_HOST;
+	lu->last_update = host->last_update;
+	return 0;
+} /* interval_fetcher_host */
+
+static int
+interval_fetcher_service(sdb_store_service_t *svc, sdb_object_t *user_data)
+{
+	interval_fetcher_t *lu = SDB_OBJ_WRAPPER(user_data)->data;
+	lu->obj_type = SDB_SERVICE;
+	lu->last_update = svc->last_update;
+	return 0;
+} /* interval_fetcher_service */
+
+static int
+interval_fetcher_metric(sdb_store_metric_t *metric, sdb_object_t *user_data)
+{
+	interval_fetcher_t *lu = SDB_OBJ_WRAPPER(user_data)->data;
+	lu->obj_type = SDB_METRIC;
+	lu->last_update = metric->last_update;
+	return 0;
+} /* interval_fetcher_metric */
+
+static int
+interval_fetcher_attr(sdb_store_attribute_t *attr, sdb_object_t *user_data)
+{
+	interval_fetcher_t *lu = SDB_OBJ_WRAPPER(user_data)->data;
+	lu->obj_type = SDB_ATTRIBUTE;
+	lu->last_update = attr->last_update;
+	return 0;
+} /* interval_fetcher_attr */
+
+static sdb_store_writer_t interval_fetcher = {
+	interval_fetcher_host, interval_fetcher_service,
+	interval_fetcher_metric, interval_fetcher_attr,
+};
+
+static int
+get_interval(int obj_type, const char *hostname,
+		int parent_type, const char *parent, const char *name,
+		sdb_time_t last_update, sdb_time_t *interval_out)
+{
+	sdb_ast_fetch_t fetch = SDB_AST_FETCH_INIT;
+	char hn[hostname ? strlen(hostname) + 1 : 1];
+	char pn[parent ? strlen(parent) + 1 : 1];
+	char n[strlen(name) + 1];
+	int status;
+
+	interval_fetcher_t lu = { 0, 0, 0 };
+	sdb_object_wrapper_t obj = SDB_OBJECT_WRAPPER_STATIC(&lu);
+	sdb_time_t interval;
+
+	assert(name);
+
+	if (hostname)
+		strncpy(hn, hostname, sizeof(hn));
+	if (parent)
+		strncpy(pn, parent, sizeof(pn));
+	strncpy(n, name, sizeof(n));
+
+	fetch.obj_type = obj_type;
+	fetch.hostname = hostname ? hn : NULL;
+	fetch.parent_type = parent_type;
+	fetch.parent = parent ? pn : NULL;
+	fetch.name = n;
+
+	status = sdb_plugin_query(SDB_AST_NODE(&fetch),
+			&interval_fetcher, SDB_OBJ(&obj), NULL);
+	if ((status < 0) || (lu.obj_type != obj_type) || (lu.last_update == 0)) {
+		*interval_out = 0;
+		return 0;
+	}
+
+	if (lu.last_update >= last_update) {
+		if (lu.last_update > last_update)
+			sdb_log(SDB_LOG_DEBUG, "memstore: Cannot update %s '%s' - "
+					"value too old (%"PRIsdbTIME" < %"PRIsdbTIME")",
+					SDB_STORE_TYPE_TO_NAME(obj_type), name,
+					lu.last_update, last_update);
+		*interval_out = lu.interval;
+		return 1;
+	}
+
+	interval = last_update - lu.last_update;
+	if (lu.interval && interval)
+		interval = (sdb_time_t)((0.9 * (double)lu.interval)
+				+ (0.1 * (double)interval));
+	*interval_out = interval;
+	return 0;
+} /* get_interval */
+
+static void
+get_backend(char **backends, size_t *backends_num)
+{
+	const sdb_plugin_info_t *info;
+
+	info = sdb_plugin_current();
+	if ((! info) || (! info->plugin_name) || (! *info->plugin_name)) {
+		*backends_num = 0;
+		return;
+	}
+
+	backends[0] = info->plugin_name;
+	*backends_num = 1;
+} /* get_backend */
+
+/*
+ * public API
+ */
+
+int
+sdb_plugin_load(const char *basedir, const char *name,
+		const sdb_plugin_ctx_t *plugin_ctx)
+{
+	ctx_t *ctx;
+
+	int status;
+
+	if ((! name) || (! *name))
+		return -1;
+
+	if (! all_plugins) {
+		if (! (all_plugins = sdb_llist_create())) {
+			sdb_log(SDB_LOG_ERR, "core: Failed to load plugin '%s': "
+					"internal error while creating linked list", name);
+			return -1;
+		}
+	}
+
+	ctx = CTX(sdb_llist_search_by_name(all_plugins, name));
+	if (ctx) {
+		/* plugin already loaded */
+		if (! ctx->use_cnt) {
+			/* reloading plugin */
+			ctx_t *old_ctx = ctx_set(ctx);
+
+			status = module_init(ctx->info.plugin_name, ctx->handle, NULL);
+			if (status)
+				return status;
+
+			sdb_log(SDB_LOG_INFO, "core: Successfully reloaded plugin "
+					"'%s' (%s)", ctx->info.plugin_name,
+					INFO_GET(&ctx->info, description));
+			ctx_set(old_ctx);
+		}
+		++ctx->use_cnt;
+		return 0;
+	}
+
+	return module_load(basedir, name, plugin_ctx);
+} /* sdb_plugin_load */
+
+int
+sdb_plugin_set_info(sdb_plugin_info_t *info, int type, ...)
+{
+	va_list ap;
+
+	if (! info)
+		return -1;
+
+	va_start(ap, type);
+
+	switch (type) {
+		case SDB_PLUGIN_INFO_DESC:
+			{
+				char *desc = va_arg(ap, char *);
+				if (desc) {
+					if (info->description)
+						free(info->description);
+					info->description = strdup(desc);
+				}
+			}
+			break;
+		case SDB_PLUGIN_INFO_COPYRIGHT:
+			{
+				char *copyright = va_arg(ap, char *);
+				if (copyright)
+					info->copyright = strdup(copyright);
+			}
+			break;
+		case SDB_PLUGIN_INFO_LICENSE:
+			{
+				char *license = va_arg(ap, char *);
+				if (license) {
+					if (info->license)
+						free(info->license);
+					info->license = strdup(license);
+				}
+			}
+			break;
+		case SDB_PLUGIN_INFO_VERSION:
+			{
+				int version = va_arg(ap, int);
+				info->version = version;
+			}
+			break;
+		case SDB_PLUGIN_INFO_PLUGIN_VERSION:
+			{
+				int version = va_arg(ap, int);
+				info->plugin_version = version;
+			}
+			break;
+		default:
 			va_end(ap);
 			return -1;
 	}
@@ -399,32 +1020,64 @@ sdb_plugin_set_info(sdb_plugin_info_t *info, int type, ...)
 } /* sdb_plugin_set_info */
 
 int
-sdb_plugin_register_config(const char *name, sdb_plugin_config_cb callback)
+sdb_plugin_register_config(sdb_plugin_config_cb callback)
 {
-	return sdb_plugin_add_callback(&config_list, "init", name,
-			callback, NULL);
+	ctx_t *ctx = ctx_get();
+
+	if (! ctx) {
+		sdb_log(SDB_LOG_ERR, "core: Invalid attempt to register a "
+				"config callback from outside a plugin");
+		return -1;
+	}
+	return plugin_add_impl(&config_list, callback_type, "config",
+			ctx->info.plugin_name, (void *)callback, NULL);
 } /* sdb_plugin_register_config */
 
 int
 sdb_plugin_register_init(const char *name, sdb_plugin_init_cb callback,
 		sdb_object_t *user_data)
 {
-	return sdb_plugin_add_callback(&init_list, "init", name,
-			callback, user_data);
+	char cb_name[1024];
+	return plugin_add_impl(&init_list, callback_type, "init",
+			plugin_get_name(name, cb_name, sizeof(cb_name)),
+			(void *)callback, user_data);
 } /* sdb_plugin_register_init */
 
 int
 sdb_plugin_register_shutdown(const char *name, sdb_plugin_shutdown_cb callback,
 		sdb_object_t *user_data)
 {
-	return sdb_plugin_add_callback(&shutdown_list, "shutdown", name,
-			callback, user_data);
+	char cb_name[1024];
+	return plugin_add_impl(&shutdown_list, callback_type, "shutdown",
+			plugin_get_name(name, cb_name, sizeof(cb_name)),
+			(void *)callback, user_data);
 } /* sdb_plugin_register_shutdown */
 
+int
+sdb_plugin_register_log(const char *name, sdb_plugin_log_cb callback,
+		sdb_object_t *user_data)
+{
+	char cb_name[1024];
+	return plugin_add_impl(&log_list, callback_type, "log",
+			plugin_get_name(name, cb_name, sizeof(cb_name)),
+			callback, user_data);
+} /* sdb_plugin_register_log */
+
+int
+sdb_plugin_register_cname(const char *name, sdb_plugin_cname_cb callback,
+		sdb_object_t *user_data)
+{
+	char cb_name[1024];
+	return plugin_add_impl(&cname_list, callback_type, "cname",
+			plugin_get_name(name, cb_name, sizeof(cb_name)),
+			callback, user_data);
+} /* sdb_plugin_register_cname */
+
 int
 sdb_plugin_register_collector(const char *name, sdb_plugin_collector_cb callback,
 		const sdb_time_t *interval, sdb_object_t *user_data)
 {
+	char cb_name[1024];
 	sdb_object_t *obj;
 
 	if ((! name) || (! callback))
@@ -435,33 +1088,38 @@ sdb_plugin_register_collector(const char *name, sdb_plugin_collector_cb callback
 	if (! collector_list)
 		return -1;
 
-	obj = sdb_object_create(sizeof(sdb_plugin_collector_cb_t),
-			sdb_plugin_cb_init, sdb_plugin_cb_destroy,
-			&collector_list, "collector", name, callback, user_data);
+	plugin_get_name(name, cb_name, sizeof(cb_name));
+
+	obj = sdb_object_create(cb_name, collector_type,
+			&collector_list, "collector", callback, user_data);
 	if (! obj)
 		return -1;
 
 	if (interval)
-		SDB_PLUGIN_CCB(obj)->ccb_interval = *interval;
+		CCB(obj)->ccb_interval = *interval;
 	else {
-		sdb_time_t tmp = sdb_plugin_get_ctx().interval;
+		ctx_t *ctx = ctx_get();
 
-		if (tmp > 0)
-			SDB_PLUGIN_CCB(obj)->ccb_interval = tmp;
-		else
-			SDB_PLUGIN_CCB(obj)->ccb_interval = 0;
+		if (! ctx) {
+			sdb_log(SDB_LOG_ERR, "core: Cannot determine interval "
+					"for collector %s; none specified and no plugin "
+					"context found", cb_name);
+			return -1;
+		}
+
+		CCB(obj)->ccb_interval = ctx->public.interval;
 	}
 
-	if (! (SDB_PLUGIN_CCB(obj)->ccb_next_update = sdb_gettime())) {
+	if (! (CCB(obj)->ccb_next_update = sdb_gettime())) {
 		char errbuf[1024];
-		sdb_log(SDB_LOG_ERR, "plugin: Failed to determine current "
-				"time: %s\n", sdb_strerror(errno, errbuf, sizeof(errbuf)));
+		sdb_log(SDB_LOG_ERR, "core: Failed to determine current "
+				"time: %s", sdb_strerror(errno, errbuf, sizeof(errbuf)));
 		sdb_object_deref(obj);
 		return -1;
 	}
 
 	if (sdb_llist_insert_sorted(collector_list, obj,
-				sdb_plugin_cmp_next_update)) {
+				plugin_cmp_next_update)) {
 		sdb_object_deref(obj);
 		return -1;
 	}
@@ -469,110 +1127,274 @@ sdb_plugin_register_collector(const char *name, sdb_plugin_collector_cb callback
 	/* pass control to the list */
 	sdb_object_deref(obj);
 
-	sdb_log(SDB_LOG_INFO, "plugin: Registered collector callback '%s' "
-			"(interval = %.3fs).\n", name,
-			SDB_TIME_TO_DOUBLE(SDB_PLUGIN_CCB(obj)->ccb_interval));
+	sdb_log(SDB_LOG_INFO, "core: Registered collector callback '%s' "
+			"(interval = %.3fs).", cb_name,
+			SDB_TIME_TO_DOUBLE(CCB(obj)->ccb_interval));
 	return 0;
 } /* sdb_plugin_register_collector */
 
+int
+sdb_plugin_register_timeseries_fetcher(const char *name,
+		sdb_timeseries_fetcher_t *fetcher, sdb_object_t *user_data)
+{
+	return plugin_add_impl(&timeseries_fetcher_list, ts_fetcher_type, "time-series fetcher",
+			name, fetcher, user_data);
+} /* sdb_plugin_register_timeseries_fetcher */
+
+int
+sdb_plugin_register_writer(const char *name,
+		sdb_store_writer_t *writer, sdb_object_t *user_data)
+{
+	char cb_name[1024];
+	return plugin_add_impl(&writer_list, writer_type, "store writer",
+			plugin_get_name(name, cb_name, sizeof(cb_name)),
+			writer, user_data);
+} /* sdb_store_register_writer */
+
+int
+sdb_plugin_register_reader(const char *name,
+		sdb_store_reader_t *reader, sdb_object_t *user_data)
+{
+	char cb_name[1024];
+	return plugin_add_impl(&reader_list, reader_type, "store reader",
+			plugin_get_name(name, cb_name, sizeof(cb_name)),
+			reader, user_data);
+} /* sdb_plugin_register_reader */
+
+void
+sdb_plugin_unregister_all(void)
+{
+	size_t i;
+
+	for (i = 0; i < SDB_STATIC_ARRAY_LEN(all_lists); ++i) {
+		const char  *type =  all_lists[i].type;
+		sdb_llist_t *list = *all_lists[i].list;
+
+		size_t len = sdb_llist_len(list);
+
+		if (! len)
+			continue;
+
+		sdb_llist_clear(list);
+		sdb_log(SDB_LOG_INFO, "core: Unregistered %zu %s callback%s",
+				len, type, len == 1 ? "" : "s");
+	}
+} /* sdb_plugin_unregister_all */
+
 sdb_plugin_ctx_t
 sdb_plugin_get_ctx(void)
 {
-	sdb_plugin_ctx_t *ctx;
+	ctx_t *c;
 
-	if (! plugin_ctx_key_initialized)
-		sdb_plugin_ctx_init();
-	ctx = pthread_getspecific(plugin_ctx_key);
-
-	if (! ctx)
-		ctx = sdb_plugin_ctx_create();
-	if (! ctx)
+	c = ctx_get();
+	if (! c) {
+		sdb_plugin_log(SDB_LOG_ERR, "core: Invalid read access to plugin "
+				"context outside a plugin");
 		return plugin_default_ctx;
-	return *ctx;
+	}
+	return c->public;
 } /* sdb_plugin_get_ctx */
 
-sdb_plugin_ctx_t
-sdb_plugin_set_ctx(sdb_plugin_ctx_t ctx)
+int
+sdb_plugin_set_ctx(sdb_plugin_ctx_t ctx, sdb_plugin_ctx_t *old)
 {
-	sdb_plugin_ctx_t *tmp;
-	sdb_plugin_ctx_t old;
+	ctx_t *c;
 
-	if (! plugin_ctx_key_initialized)
-		sdb_plugin_ctx_init();
-	tmp = pthread_getspecific(plugin_ctx_key);
-
-	if (! tmp)
-		tmp = sdb_plugin_ctx_create();
-	if (! tmp)
-		return plugin_default_ctx;
+	c = ctx_get();
+	if (! c) {
+		sdb_plugin_log(SDB_LOG_ERR, "core: Invalid write access to plugin "
+				"context outside a plugin");
+		return -1;
+	}
 
-	old = *tmp;
-	*tmp = ctx;
-	return old;
+	if (old)
+		*old = c->public;
+	c->public = ctx;
+	return 0;
 } /* sdb_plugin_set_ctx */
 
+const sdb_plugin_info_t *
+sdb_plugin_current(void)
+{
+	ctx_t *ctx = ctx_get();
+
+	if (! ctx)
+		return NULL;
+	return &ctx->info;
+} /* sdb_plugin_current */
+
 int
 sdb_plugin_configure(const char *name, oconfig_item_t *ci)
 {
-	sdb_plugin_cb_t *plugin;
+	callback_t *plugin;
 	sdb_plugin_config_cb callback;
 
-	sdb_plugin_ctx_t old_ctx;
+	ctx_t *old_ctx;
 
 	int status;
 
 	if ((! name) || (! ci))
 		return -1;
 
-	plugin = sdb_plugin_find_by_name(config_list, name);
+	plugin = CB(sdb_llist_search_by_name(config_list, name));
 	if (! plugin) {
-		/* XXX: check if any such plugin has been loaded */
-		sdb_log(SDB_LOG_ERR, "plugin: Plugin '%s' did not register "
-				"a config callback.\n", name);
+		ctx_t *ctx = CTX(sdb_llist_search_by_name(all_plugins, name));
+		if (! ctx)
+			sdb_log(SDB_LOG_ERR, "core: Cannot configure unknown "
+					"plugin '%s'. Missing 'LoadPlugin \"%s\"'?",
+					name, name);
+		else
+			sdb_log(SDB_LOG_ERR, "core: Plugin '%s' did not register "
+					"a config callback.", name);
 		errno = ENOENT;
 		return -1;
 	}
 
-	old_ctx = sdb_plugin_set_ctx(plugin->cb_ctx);
-	callback = plugin->cb_callback;
+	old_ctx = ctx_set(plugin->cb_ctx);
+	callback = (sdb_plugin_config_cb)plugin->cb_callback;
 	status = callback(ci);
-	sdb_plugin_set_ctx(old_ctx);
+	ctx_set(old_ctx);
 	return status;
 } /* sdb_plugin_configure */
 
+int
+sdb_plugin_reconfigure_init(void)
+{
+	sdb_llist_iter_t *iter;
+
+	iter = sdb_llist_get_iter(config_list);
+	if (config_list && (! iter))
+		return -1;
+
+	/* deconfigure all plugins */
+	while (sdb_llist_iter_has_next(iter)) {
+		callback_t *plugin;
+		sdb_plugin_config_cb callback;
+		ctx_t *old_ctx;
+
+		plugin = CB(sdb_llist_iter_get_next(iter));
+		old_ctx = ctx_set(plugin->cb_ctx);
+		callback = (sdb_plugin_config_cb)plugin->cb_callback;
+		callback(NULL);
+		ctx_set(old_ctx);
+	}
+	sdb_llist_iter_destroy(iter);
+
+	iter = sdb_llist_get_iter(all_plugins);
+	if (all_plugins && (! iter))
+		return -1;
+
+	/* record all plugins as being unused */
+	while (sdb_llist_iter_has_next(iter))
+		CTX(sdb_llist_iter_get_next(iter))->use_cnt = 0;
+	sdb_llist_iter_destroy(iter);
+
+	sdb_plugin_unregister_all();
+	return 0;
+} /* sdb_plugin_reconfigure_init */
+
+int
+sdb_plugin_reconfigure_finish(void)
+{
+	sdb_llist_iter_t *iter;
+
+	iter = sdb_llist_get_iter(all_plugins);
+	if (all_plugins && (! iter))
+		return -1;
+
+	while (sdb_llist_iter_has_next(iter)) {
+		ctx_t *ctx = CTX(sdb_llist_iter_get_next(iter));
+		if (ctx->use_cnt)
+			continue;
+
+		sdb_log(SDB_LOG_INFO, "core: Module %s no longer in use",
+				ctx->info.plugin_name);
+		sdb_llist_iter_remove_current(iter);
+		plugin_unregister_by_name(ctx->info.plugin_name);
+		sdb_object_deref(SDB_OBJ(ctx));
+	}
+	sdb_llist_iter_destroy(iter);
+	return 0;
+} /* sdb_plugin_reconfigure_finish */
+
 int
 sdb_plugin_init_all(void)
 {
 	sdb_llist_iter_t *iter;
+	int ret = 0;
 
 	iter = sdb_llist_get_iter(init_list);
 	while (sdb_llist_iter_has_next(iter)) {
+		callback_t *cb;
 		sdb_plugin_init_cb callback;
-		sdb_plugin_ctx_t old_ctx;
+		ctx_t *old_ctx;
 
 		sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 		assert(obj);
+		cb = CB(obj);
 
-		callback = SDB_PLUGIN_CB(obj)->cb_callback;
+		callback = (sdb_plugin_init_cb)cb->cb_callback;
 
-		old_ctx = sdb_plugin_set_ctx(SDB_PLUGIN_CB(obj)->cb_ctx);
-		if (callback(SDB_PLUGIN_CB(obj)->cb_user_data)) {
-			/* XXX: unload plugin */
+		old_ctx = ctx_set(cb->cb_ctx);
+		if (callback(cb->cb_user_data)) {
+			sdb_log(SDB_LOG_ERR, "core: Failed to initialize plugin "
+					"'%s'. Unregistering all callbacks.", obj->name);
+			ctx_set(old_ctx);
+			plugin_unregister_by_name(cb->cb_ctx->info.plugin_name);
+			++ret;
 		}
-		sdb_plugin_set_ctx(old_ctx);
+		else
+			ctx_set(old_ctx);
 	}
-	return 0;
+	sdb_llist_iter_destroy(iter);
+	return ret;
 } /* sdb_plugin_init_all */
 
+int
+sdb_plugin_shutdown_all(void)
+{
+	sdb_llist_iter_t *iter;
+	int ret = 0;
+
+	iter = sdb_llist_get_iter(shutdown_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		callback_t *cb;
+		sdb_plugin_shutdown_cb callback;
+		ctx_t *old_ctx;
+
+		sdb_object_t *obj = sdb_llist_iter_get_next(iter);
+		assert(obj);
+		cb = CB(obj);
+
+		callback = (sdb_plugin_shutdown_cb)cb->cb_callback;
+
+		old_ctx = ctx_set(cb->cb_ctx);
+		if (callback(cb->cb_user_data)) {
+			sdb_log(SDB_LOG_ERR, "core: Failed to shutdown plugin '%s'.",
+					obj->name);
+			++ret;
+		}
+		ctx_set(old_ctx);
+	}
+	sdb_llist_iter_destroy(iter);
+	return ret;
+} /* sdb_plugin_shutdown_all */
+
 int
 sdb_plugin_collector_loop(sdb_plugin_loop_t *loop)
 {
-	if ((! collector_list) || (! loop))
+	if (! collector_list) {
+		sdb_log(SDB_LOG_WARNING, "core: No collectors registered. "
+				"Quiting main loop.");
+		return -1;
+	}
+
+	if (! loop)
 		return -1;
 
 	while (loop->do_loop) {
 		sdb_plugin_collector_cb callback;
-		sdb_plugin_ctx_t old_ctx;
+		ctx_t *old_ctx;
 
 		sdb_time_t interval, now;
 
@@ -580,72 +1402,83 @@ sdb_plugin_collector_loop(sdb_plugin_loop_t *loop)
 		if (! obj)
 			return -1;
 
-		callback = SDB_PLUGIN_CCB(obj)->ccb_callback;
+		callback = (sdb_plugin_collector_cb)CCB(obj)->ccb_callback;
 
 		if (! (now = sdb_gettime())) {
 			char errbuf[1024];
-			sdb_log(SDB_LOG_ERR, "plugin: Failed to determine current "
-					"time: %s\n", sdb_strerror(errno, errbuf, sizeof(errbuf)));
-			now = SDB_PLUGIN_CCB(obj)->ccb_next_update;
+			sdb_log(SDB_LOG_ERR, "core: Failed to determine current "
+					"time in collector main loop: %s",
+					sdb_strerror(errno, errbuf, sizeof(errbuf)));
+			now = CCB(obj)->ccb_next_update;
 		}
 
-		if (now < SDB_PLUGIN_CCB(obj)->ccb_next_update) {
-			interval = SDB_PLUGIN_CCB(obj)->ccb_next_update - now;
+		if (now < CCB(obj)->ccb_next_update) {
+			interval = CCB(obj)->ccb_next_update - now;
 
 			errno = 0;
 			while (loop->do_loop && sdb_sleep(interval, &interval)) {
 				if (errno != EINTR) {
 					char errbuf[1024];
-					sdb_log(SDB_LOG_ERR, "plugin: Failed to sleep: %s\n",
+					sdb_log(SDB_LOG_ERR, "core: Failed to sleep "
+							"in collector main loop: %s",
 							sdb_strerror(errno, errbuf, sizeof(errbuf)));
+					sdb_llist_insert_sorted(collector_list, obj,
+							plugin_cmp_next_update);
+					sdb_object_deref(obj);
 					return -1;
 				}
 				errno = 0;
 			}
 
-			if (! loop->do_loop)
+			if (! loop->do_loop) {
+				/* put back; don't worry about errors */
+				sdb_llist_insert_sorted(collector_list, obj,
+						plugin_cmp_next_update);
+				sdb_object_deref(obj);
 				return 0;
+			}
 		}
 
-		old_ctx = sdb_plugin_set_ctx(SDB_PLUGIN_CCB(obj)->ccb_ctx);
-		if (callback(SDB_PLUGIN_CCB(obj)->ccb_user_data)) {
+		old_ctx = ctx_set(CCB(obj)->ccb_ctx);
+		if (callback(CCB(obj)->ccb_user_data)) {
 			/* XXX */
 		}
-		sdb_plugin_set_ctx(old_ctx);
+		ctx_set(old_ctx);
 
-		interval = SDB_PLUGIN_CCB(obj)->ccb_interval;
+		interval = CCB(obj)->ccb_interval;
 		if (! interval)
 			interval = loop->default_interval;
 		if (! interval) {
-			sdb_log(SDB_LOG_WARNING, "plugin: No interval configured "
+			sdb_log(SDB_LOG_WARNING, "core: No interval configured "
 					"for plugin '%s'; skipping any further "
-					"iterations.\n", SDB_PLUGIN_CCB(obj)->ccb_name);
+					"iterations.", obj->name);
 			sdb_object_deref(obj);
 			continue;
 		}
 
-		SDB_PLUGIN_CCB(obj)->ccb_next_update += interval;
+		CCB(obj)->ccb_next_update += interval;
 
 		if (! (now = sdb_gettime())) {
 			char errbuf[1024];
-			sdb_log(SDB_LOG_ERR, "plugin: Failed to determine current "
-					"time: %s\n", sdb_strerror(errno, errbuf, sizeof(errbuf)));
-			now = SDB_PLUGIN_CCB(obj)->ccb_next_update;
+			sdb_log(SDB_LOG_ERR, "core: Failed to determine current "
+					"time in collector main loop: %s",
+					sdb_strerror(errno, errbuf, sizeof(errbuf)));
+			now = CCB(obj)->ccb_next_update;
 		}
 
-		if (now > SDB_PLUGIN_CCB(obj)->ccb_next_update) {
-			sdb_log(SDB_LOG_WARNING, "plugin: Plugin '%s' took too "
-					"long; skipping iterations to keep up.\n",
-					SDB_PLUGIN_CCB(obj)->ccb_name);
-			SDB_PLUGIN_CCB(obj)->ccb_next_update = now;
+		if (now > CCB(obj)->ccb_next_update) {
+			sdb_log(SDB_LOG_WARNING, "core: Plugin '%s' took too "
+					"long; skipping iterations to keep up.",
+					obj->name);
+			CCB(obj)->ccb_next_update = now;
 		}
 
 		if (sdb_llist_insert_sorted(collector_list, obj,
-					sdb_plugin_cmp_next_update)) {
-			sdb_log(SDB_LOG_ERR, "plugin: Failed to re-insert "
+					plugin_cmp_next_update)) {
+			sdb_log(SDB_LOG_ERR, "core: Failed to re-insert "
 					"plugin '%s' into collector list. Unable to further "
-					"use the plugin.\n",
-					SDB_PLUGIN_CCB(obj)->ccb_name);
+					"use the plugin.",
+					obj->name);
 			sdb_object_deref(obj);
 			return -1;
 		}
@@ -656,5 +1489,556 @@ sdb_plugin_collector_loop(sdb_plugin_loop_t *loop)
 	return 0;
 } /* sdb_plugin_read_loop */
 
+char *
+sdb_plugin_cname(char *hostname)
+{
+	sdb_llist_iter_t *iter;
+
+	if (! hostname)
+		return NULL;
+
+	if (! cname_list)
+		return hostname;
+
+	iter = sdb_llist_get_iter(cname_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		sdb_plugin_cname_cb callback;
+		char *cname;
+
+		sdb_object_t *obj = sdb_llist_iter_get_next(iter);
+		assert(obj);
+
+		callback = (sdb_plugin_cname_cb)CB(obj)->cb_callback;
+		cname = callback(hostname, CB(obj)->cb_user_data);
+		if (cname) {
+			free(hostname);
+			hostname = cname;
+		}
+		/* else: don't change hostname */
+	}
+	sdb_llist_iter_destroy(iter);
+	return hostname;
+} /* sdb_plugin_cname */
+
+int
+sdb_plugin_log(int prio, const char *msg)
+{
+	sdb_llist_iter_t *iter;
+	int ret = -1;
+
+	bool logged = 0;
+
+	if (! msg)
+		return 0;
+
+	iter = sdb_llist_get_iter(log_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		sdb_plugin_log_cb callback;
+		int tmp;
+
+		sdb_object_t *obj = sdb_llist_iter_get_next(iter);
+		assert(obj);
+
+		callback = (sdb_plugin_log_cb)CB(obj)->cb_callback;
+		tmp = callback(prio, msg, CB(obj)->cb_user_data);
+		if (tmp > ret)
+			ret = tmp;
+
+		if (CB(obj)->cb_ctx)
+			logged = 1;
+		/* else: this is an internally registered callback */
+	}
+	sdb_llist_iter_destroy(iter);
+
+	if (! logged)
+		return fprintf(stderr, "[%s] %s\n", SDB_LOG_PRIO_TO_STRING(prio), msg);
+	return ret;
+} /* sdb_plugin_log */
+
+int
+sdb_plugin_vlogf(int prio, const char *fmt, va_list ap)
+{
+	sdb_strbuf_t *buf;
+	int ret;
+
+	if (! fmt)
+		return 0;
+
+	buf = sdb_strbuf_create(64);
+	if (! buf) {
+		ret = fprintf(stderr, "[%s] ", SDB_LOG_PRIO_TO_STRING(prio));
+		ret += vfprintf(stderr, fmt, ap);
+		return ret;
+	}
+
+	if (sdb_strbuf_vsprintf(buf, fmt, ap) < 0) {
+		sdb_strbuf_destroy(buf);
+		return -1;
+	}
+
+	ret = sdb_plugin_log(prio, sdb_strbuf_string(buf));
+	sdb_strbuf_destroy(buf);
+	return ret;
+} /* sdb_plugin_vlogf */
+
+int
+sdb_plugin_logf(int prio, const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	if (! fmt)
+		return 0;
+
+	va_start(ap, fmt);
+	ret = sdb_plugin_vlogf(prio, fmt, ap);
+	va_end(ap);
+	return ret;
+} /* sdb_plugin_logf */
+
+sdb_timeseries_t *
+sdb_plugin_fetch_timeseries(const char *type, const char *id,
+		sdb_timeseries_opts_t *opts)
+{
+	ts_fetcher_t *fetcher;
+	sdb_timeseries_t *ts;
+
+	ctx_t *old_ctx;
+
+	if ((! type) || (! id) || (! opts))
+		return NULL;
+
+	fetcher = TS_FETCHER(sdb_llist_search_by_name(timeseries_fetcher_list, type));
+	if (! fetcher) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot fetch time-series of type %s: "
+				"no such plugin loaded", type);
+		errno = ENOENT;
+		return NULL;
+	}
+
+	old_ctx = ctx_set(fetcher->ts_ctx);
+	ts = fetcher->impl.fetch(id, opts, fetcher->ts_user_data);
+	ctx_set(old_ctx);
+	return ts;
+} /* sdb_plugin_fetch_timeseries */
+
+sdb_timeseries_info_t *
+sdb_plugin_describe_timeseries(const char *type, const char *id)
+{
+	ts_fetcher_t *fetcher;
+	sdb_timeseries_info_t *ts_info;
+
+	ctx_t *old_ctx;
+
+	if ((! type) || (! id))
+		return NULL;
+
+	fetcher = TS_FETCHER(sdb_llist_search_by_name(timeseries_fetcher_list, type));
+	if (! fetcher) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot describe time-series of type %s: "
+				"no such plugin loaded", type);
+		errno = ENOENT;
+		return NULL;
+	}
+
+	old_ctx = ctx_set(fetcher->ts_ctx);
+	ts_info = fetcher->impl.describe(id, fetcher->ts_user_data);
+	ctx_set(old_ctx);
+	return ts_info;
+} /* sdb_plugin_describe_timeseries */
+
+int
+sdb_plugin_query(sdb_ast_node_t *ast,
+		sdb_store_writer_t *w, sdb_object_t *wd, sdb_strbuf_t *errbuf)
+{
+	query_writer_t qw = QUERY_WRITER_INIT(w, wd);
+	reader_t *reader;
+	sdb_object_t *q;
+
+	size_t n = sdb_llist_len(reader_list);
+	int status = 0;
+
+	if (! ast)
+		return 0;
+
+	if ((ast->type != SDB_AST_TYPE_FETCH)
+			&& (ast->type != SDB_AST_TYPE_LIST)
+			&& (ast->type != SDB_AST_TYPE_LOOKUP)) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot execute query of type %s",
+				SDB_AST_TYPE_TO_STRING(ast));
+		sdb_strbuf_sprintf(errbuf, "Cannot execute query of type %s",
+				SDB_AST_TYPE_TO_STRING(ast));
+		return -1;
+	}
+
+	if (n != 1) {
+		char *msg = (n > 0)
+			? "Cannot execute query: multiple readers not supported"
+			: "Cannot execute query: no readers registered";
+		sdb_strbuf_sprintf(errbuf, "%s", msg);
+		sdb_log(SDB_LOG_ERR, "core: %s", msg);
+		return -1;
+	}
+
+	reader = READER(sdb_llist_get(reader_list, 0));
+	assert(reader);
+
+	q = reader->impl.prepare_query(ast, errbuf, reader->r_user_data);
+	if (q)
+		status = reader->impl.execute_query(q, &query_writer, SDB_OBJ(&qw),
+				errbuf, reader->r_user_data);
+	else
+		status = -1;
+
+	sdb_object_deref(SDB_OBJ(q));
+	sdb_object_deref(SDB_OBJ(reader));
+	return status;
+} /* sdb_plugin_query */
+
+int
+sdb_plugin_store_host(const char *name, sdb_time_t last_update)
+{
+	sdb_store_host_t host = SDB_STORE_HOST_INIT;
+	char *backends[1];
+	char *cname;
+
+	sdb_llist_iter_t *iter;
+	int status = 0;
+
+	if (! name)
+		return -1;
+
+	if (! sdb_llist_len(writer_list)) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot store host: "
+				"no writers registered");
+		return -1;
+	}
+
+	cname = sdb_plugin_cname(strdup(name));
+	if (! cname) {
+		sdb_log(SDB_LOG_ERR, "core: strdup failed");
+		return -1;
+	}
+
+	host.name = cname;
+	host.last_update = last_update ? last_update : sdb_gettime();
+	if (get_interval(SDB_HOST, NULL, -1, NULL, cname,
+				host.last_update, &host.interval)) {
+		free(cname);
+		return 1;
+	}
+	host.backends = (const char * const *)backends;
+	get_backend(backends, &host.backends_num);
+
+	iter = sdb_llist_get_iter(writer_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+		int s;
+		assert(writer);
+		s = writer->impl.store_host(&host, writer->w_user_data);
+		if (((s > 0) && (status >= 0)) || (s < 0))
+			status = s;
+	}
+	sdb_llist_iter_destroy(iter);
+	free(cname);
+	return status;
+} /* sdb_plugin_store_host */
+
+int
+sdb_plugin_store_service(const char *hostname, const char *name,
+		sdb_time_t last_update)
+{
+	sdb_store_service_t service = SDB_STORE_SERVICE_INIT;
+	char *backends[1];
+	char *cname;
+
+	sdb_llist_iter_t *iter;
+	sdb_data_t d;
+
+	int status = 0;
+
+	if ((! hostname) || (! name))
+		return -1;
+
+	if (! sdb_llist_len(writer_list)) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot store service: "
+				"no writers registered");
+		return -1;
+	}
+
+	cname = sdb_plugin_cname(strdup(hostname));
+	if (! cname) {
+		sdb_log(SDB_LOG_ERR, "core: strdup failed");
+		return -1;
+	}
+
+	service.hostname = cname;
+	service.name = name;
+	service.last_update = last_update ? last_update : sdb_gettime();
+	if (get_interval(SDB_SERVICE, cname, -1, NULL, name,
+				service.last_update, &service.interval)) {
+		free(cname);
+		return 1;
+	}
+	service.backends = (const char * const *)backends;
+	get_backend(backends, &service.backends_num);
+
+	iter = sdb_llist_get_iter(writer_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+		int s;
+		assert(writer);
+		s = writer->impl.store_service(&service, writer->w_user_data);
+		if (((s > 0) && (status >= 0)) || (s < 0))
+			status = s;
+	}
+	sdb_llist_iter_destroy(iter);
+
+	if (! status) {
+		/* record the hostname as an attribute */
+		d.type = SDB_TYPE_STRING;
+		d.data.string = cname;
+		if (sdb_plugin_store_service_attribute(cname, name,
+					"hostname", &d, service.last_update))
+			status = -1;
+	}
+
+	free(cname);
+	return status;
+} /* sdb_plugin_store_service */
+
+int
+sdb_plugin_store_metric(const char *hostname, const char *name,
+		sdb_metric_store_t *store, sdb_time_t last_update)
+{
+	sdb_store_metric_t metric = SDB_STORE_METRIC_INIT;
+	char *backends[1];
+	char *cname;
+
+	sdb_llist_iter_t *iter;
+	sdb_data_t d;
+
+	int status = 0;
+
+	if ((! hostname) || (! name))
+		return -1;
+
+	if (! sdb_llist_len(writer_list)) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot store metric: "
+				"no writers registered");
+		return -1;
+	}
+
+	cname = sdb_plugin_cname(strdup(hostname));
+	if (! cname) {
+		sdb_log(SDB_LOG_ERR, "core: strdup failed");
+		return -1;
+	}
+
+	if (store && ((! store->type) || (! store->id)))
+		store = NULL;
+
+	metric.hostname = cname;
+	metric.name = name;
+	if (store) {
+		if (store->last_update < last_update)
+			store->last_update = last_update;
+		metric.stores = store;
+		metric.stores_num = 1;
+	}
+	metric.last_update = last_update ? last_update : sdb_gettime();
+	if (get_interval(SDB_METRIC, cname, -1, NULL, name,
+				metric.last_update, &metric.interval)) {
+		free(cname);
+		return 1;
+	}
+	metric.backends = (const char * const *)backends;
+	get_backend(backends, &metric.backends_num);
+
+	iter = sdb_llist_get_iter(writer_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+		int s;
+		assert(writer);
+		s = writer->impl.store_metric(&metric, writer->w_user_data);
+		if (((s > 0) && (status >= 0)) || (s < 0))
+			status = s;
+	}
+	sdb_llist_iter_destroy(iter);
+
+	if (! status) {
+		/* record the hostname as an attribute */
+		d.type = SDB_TYPE_STRING;
+		d.data.string = cname;
+		if (sdb_plugin_store_metric_attribute(cname, name,
+					"hostname", &d, metric.last_update))
+			status = -1;
+	}
+
+	free(cname);
+	return status;
+} /* sdb_plugin_store_metric */
+
+int
+sdb_plugin_store_attribute(const char *hostname, const char *key,
+		const sdb_data_t *value, sdb_time_t last_update)
+{
+	sdb_store_attribute_t attr = SDB_STORE_ATTRIBUTE_INIT;
+	char *backends[1];
+	char *cname;
+
+	sdb_llist_iter_t *iter;
+	int status = 0;
+
+	if ((! hostname) || (! key) || (! value))
+		return -1;
+
+	if (! sdb_llist_len(writer_list)) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot store attribute: "
+				"no writers registered");
+		return -1;
+	}
+
+	cname = sdb_plugin_cname(strdup(hostname));
+	if (! cname) {
+		sdb_log(SDB_LOG_ERR, "core: strdup failed");
+		return -1;
+	}
+
+	attr.parent_type = SDB_HOST;
+	attr.parent = cname;
+	attr.key = key;
+	attr.value = *value;
+	attr.last_update = last_update ? last_update : sdb_gettime();
+	if (get_interval(SDB_ATTRIBUTE, cname, -1, NULL, key,
+				attr.last_update, &attr.interval)) {
+		free(cname);
+		return 1;
+	}
+	attr.backends = (const char * const *)backends;
+	get_backend(backends, &attr.backends_num);
+
+	iter = sdb_llist_get_iter(writer_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+		int s;
+		assert(writer);
+		s = writer->impl.store_attribute(&attr, writer->w_user_data);
+		if (((s > 0) && (status >= 0)) || (s < 0))
+			status = s;
+	}
+	sdb_llist_iter_destroy(iter);
+	free(cname);
+	return status;
+} /* sdb_plugin_store_attribute */
+
+int
+sdb_plugin_store_service_attribute(const char *hostname, const char *service,
+		const char *key, const sdb_data_t *value, sdb_time_t last_update)
+{
+	sdb_store_attribute_t attr = SDB_STORE_ATTRIBUTE_INIT;
+	char *backends[1];
+	char *cname;
+
+	sdb_llist_iter_t *iter;
+	int status = 0;
+
+	if ((! hostname) || (! service) || (! key) || (! value))
+		return -1;
+
+	if (! sdb_llist_len(writer_list)) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot store service attribute: "
+				"no writers registered");
+		return -1;
+	}
+
+	cname = sdb_plugin_cname(strdup(hostname));
+	if (! cname) {
+		sdb_log(SDB_LOG_ERR, "core: strdup failed");
+		return -1;
+	}
+
+	attr.hostname = cname;
+	attr.parent_type = SDB_SERVICE;
+	attr.parent = service;
+	attr.key = key;
+	attr.value = *value;
+	attr.last_update = last_update ? last_update : sdb_gettime();
+	if (get_interval(SDB_ATTRIBUTE, cname, SDB_SERVICE, service, key,
+				attr.last_update, &attr.interval)) {
+		free(cname);
+		return 1;
+	}
+	attr.backends = (const char * const *)backends;
+	get_backend(backends, &attr.backends_num);
+
+	iter = sdb_llist_get_iter(writer_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+		int s;
+		assert(writer);
+		s = writer->impl.store_attribute(&attr, writer->w_user_data);
+		if (((s > 0) && (status >= 0)) || (s < 0))
+			status = s;
+	}
+	sdb_llist_iter_destroy(iter);
+	free(cname);
+	return status;
+} /* sdb_plugin_store_service_attribute */
+
+int
+sdb_plugin_store_metric_attribute(const char *hostname, const char *metric,
+		const char *key, const sdb_data_t *value, sdb_time_t last_update)
+{
+	sdb_store_attribute_t attr = SDB_STORE_ATTRIBUTE_INIT;
+	char *backends[1];
+	char *cname;
+
+	sdb_llist_iter_t *iter;
+	int status = 0;
+
+	if ((! hostname) || (! metric) || (! key) || (! value))
+		return -1;
+
+	if (! sdb_llist_len(writer_list)) {
+		sdb_log(SDB_LOG_ERR, "core: Cannot store metric attribute: "
+				"no writers registered");
+		return -1;
+	}
+
+	cname = sdb_plugin_cname(strdup(hostname));
+	if (! cname) {
+		sdb_log(SDB_LOG_ERR, "core: strdup failed");
+		return -1;
+	}
+
+	attr.hostname = cname;
+	attr.parent_type = SDB_METRIC;
+	attr.parent = metric;
+	attr.key = key;
+	attr.value = *value;
+	attr.last_update = last_update ? last_update : sdb_gettime();
+	if (get_interval(SDB_ATTRIBUTE, cname, SDB_METRIC, metric, key,
+				attr.last_update, &attr.interval)) {
+		free(cname);
+		return 1;
+	}
+	attr.backends = (const char * const *)backends;
+	get_backend(backends, &attr.backends_num);
+
+	iter = sdb_llist_get_iter(writer_list);
+	while (sdb_llist_iter_has_next(iter)) {
+		writer_t *writer = WRITER(sdb_llist_iter_get_next(iter));
+		int s;
+		assert(writer);
+		s = writer->impl.store_attribute(&attr, writer->w_user_data);
+		if (((s > 0) && (status >= 0)) || (s < 0))
+			status = s;
+	}
+	sdb_llist_iter_destroy(iter);
+	free(cname);
+	return status;
+} /* sdb_plugin_store_metric_attribute */
+
 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */