X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=src%2Finclude%2Fcore%2Fstore.h;h=03677e8feb33a2f5796ed39cc1d945db00a81fa3;hb=b54d9fff4bc9e70efe83123403a4c9f935efb74e;hp=c051252f771616ad3df65eba06fbf9fe1bd3f447;hpb=dbba6b8562bd2a13e77c5381b2fc85931dcaab5d;p=sysdb.git

diff --git a/src/include/core/store.h b/src/include/core/store.h
index c051252..03677e8 100644
--- a/src/include/core/store.h
+++ b/src/include/core/store.h
@@ -62,6 +62,7 @@ enum {
 	SDB_FIELD_INTERVAL,      /* type: datetime */
 	SDB_FIELD_BACKEND,       /* type: array of strings */
 	SDB_FIELD_VALUE,         /* attributes only;  type: type of the value */
+	SDB_FIELD_TIMESERIES,    /* metrics only;  type: boolean */
 };
 #define SDB_STORE_TYPE_TO_NAME(t) \
 	(((t) == SDB_HOST) ? "host" \
@@ -80,6 +81,7 @@ enum {
 		: ((f) == SDB_FIELD_INTERVAL) ? "interval" \
 		: ((f) == SDB_FIELD_BACKEND) ? "backend" \
 		: ((f) == SDB_FIELD_VALUE) ? "value" \
+		: ((f) == SDB_FIELD_TIMESERIES) ? "timeseries" \
 		: "unknown")
 
 #define SDB_FIELD_TYPE(f) \
@@ -89,24 +91,95 @@ enum {
 		: ((f) == SDB_FIELD_INTERVAL) ? SDB_TYPE_DATETIME \
 		: ((f) == SDB_FIELD_BACKEND) ? (SDB_TYPE_ARRAY | SDB_TYPE_STRING) \
 		: ((f) == SDB_FIELD_VALUE) ? -1 /* unknown */ \
+		: ((f) == SDB_FIELD_TIMESERIES) ? SDB_TYPE_BOOLEAN \
 		: -1)
 
 /*
- * sdb_store_obj_t represents the super-class of any object stored in the
- * database. It inherits from sdb_object_t and may safely be cast to a generic
- * object to access its name.
+ * sdb_memstore_t represents an in-memory store. It inherits from sdb_object_t
+ * and may safely be case to a generic object.
  */
-struct sdb_store_obj;
-typedef struct sdb_store_obj sdb_store_obj_t;
+struct sdb_memstore;
+typedef struct sdb_memstore sdb_memstore_t;
+#define SDB_MEMSTORE(obj) ((sdb_memstore_t *)(obj))
 
 /*
- * A metric store describes how to access a metric's data.
+ * sdb_memstore_obj_t represents the super-class of any stored object. It
+ * inherits from sdb_object_t and may safely be cast to a generic object to
+ * access its name.
+ */
+struct sdb_memstore_obj;
+typedef struct sdb_memstore_obj sdb_memstore_obj_t;
+
+/*
+ * sdb_store_host_t represents the meta-data of a stored host object.
+ */
+typedef struct {
+	const char *name;
+
+	sdb_time_t last_update;
+	sdb_time_t interval;
+	const char * const *backends;
+	size_t backends_num;
+} sdb_store_host_t;
+#define SDB_STORE_HOST_INIT { NULL, 0, 0, NULL, 0 }
+
+/*
+ * sdb_store_service_t represents the meta-data of a stored service object.
+ */
+typedef struct {
+	const char *hostname;
+	const char *name;
+
+	sdb_time_t last_update;
+	sdb_time_t interval;
+	const char * const *backends;
+	size_t backends_num;
+} sdb_store_service_t;
+#define SDB_STORE_SERVICE_INIT { NULL, NULL, 0, 0, NULL, 0 }
+
+/*
+ * sdb_metric_store_t specifies how to access a metric's data.
  */
 typedef struct {
 	const char *type;
 	const char *id;
 } sdb_metric_store_t;
 
+/*
+ * sdb_store_metric_t represents the meta-data of a stored metric object.
+ */
+typedef struct {
+	const char *hostname;
+	const char *name;
+	struct {
+		const char *type;
+		const char *id;
+	} store;
+
+	sdb_time_t last_update;
+	sdb_time_t interval;
+	const char * const *backends;
+	size_t backends_num;
+} sdb_store_metric_t;
+#define SDB_STORE_METRIC_INIT { NULL, NULL, { NULL, NULL }, 0, 0, NULL, 0 }
+
+/*
+ * sdb_store_attribute_t represents a stored attribute.
+ */
+typedef struct {
+	const char *hostname; /* optional */
+	int parent_type;
+	const char *parent;
+	const char *key;
+	sdb_data_t value;
+
+	sdb_time_t last_update;
+	sdb_time_t interval;
+	const char * const *backends;
+	size_t backends_num;
+} sdb_store_attribute_t;
+#define SDB_STORE_ATTRIBUTE_INIT { NULL, 0, NULL, NULL, SDB_DATA_INIT, 0, 0, NULL, 0 }
+
 /*
  * Expressions represent arithmetic expressions based on stored objects and
  * their various attributes.
@@ -114,16 +187,15 @@ typedef struct {
  * An expression object inherits from sdb_object_t and, thus, may safely be
  * cast to a generic object.
  */
-struct sdb_store_expr;
-typedef struct sdb_store_expr sdb_store_expr_t;
-#define SDB_STORE_EXPR(obj) ((sdb_store_expr_t *)(obj))
+struct sdb_memstore_expr;
+typedef struct sdb_memstore_expr sdb_memstore_expr_t;
+#define SDB_MEMSTORE_EXPR(obj) ((sdb_memstore_expr_t *)(obj))
 
 /*
- * An expression iterator iterates over the values of an iterable expression
- * (see sdb_store_expr_iterable).
+ * An expression iterator iterates over the values of an iterable expression.
  */
-struct sdb_store_expr_iter;
-typedef struct sdb_store_expr_iter sdb_store_expr_iter_t;
+struct sdb_memstore_expr_iter;
+typedef struct sdb_memstore_expr_iter sdb_memstore_expr_iter_t;
 
 /*
  * Store matchers may be used to lookup hosts from the store based on their
@@ -134,188 +206,152 @@ typedef struct sdb_store_expr_iter sdb_store_expr_iter_t;
  * A store matcher object inherits from sdb_object_t and, thus, may safely be
  * cast to a generic object.
  */
-struct sdb_store_matcher;
-typedef struct sdb_store_matcher sdb_store_matcher_t;
-#define SDB_STORE_MATCHER(obj) ((sdb_store_matcher_t *)(obj))
+struct sdb_memstore_matcher;
+typedef struct sdb_memstore_matcher sdb_memstore_matcher_t;
+#define SDB_MEMSTORE_MATCHER(obj) ((sdb_memstore_matcher_t *)(obj))
 
 /*
  * A JSON formatter converts stored objects into the JSON format.
  * See http://www.ietf.org/rfc/rfc4627.txt
+ *
+ * A JSON formatter object inherits from sdb_object_t and, thus, may safely be
+ * cast to a generic object.
  */
 struct sdb_store_json_formatter;
 typedef struct sdb_store_json_formatter sdb_store_json_formatter_t;
 
 /*
  * A store writer describes the interface for plugins implementing a store.
- */
-typedef struct {
-	int (*store_host)(const char *name, sdb_time_t last_update,
-			sdb_object_t *user_data);
-	int (*store_service)(const char *hostname, const char *name,
-			sdb_time_t last_update, sdb_object_t *user_data);
-	int (*store_metric)(const char *hostname, const char *name,
-			sdb_metric_store_t *store, sdb_time_t last_update,
-			sdb_object_t *user_data);
-	int (*store_attribute)(const char *hostname,
-			const char *key, const sdb_data_t *value, sdb_time_t last_update,
-			sdb_object_t *user_data);
-	int (*store_service_attr)(const char *hostname, const char *service,
-			const char *key, const sdb_data_t *value, sdb_time_t last_update,
-			sdb_object_t *user_data);
-	int (*store_metric_attr)(const char *hostname, const char *metric,
-			const char *key, const sdb_data_t *value, sdb_time_t last_update,
-			sdb_object_t *user_data);
-} sdb_store_writer_t;
-
-/*
- * sdb_store_clear:
- * Clear the entire store and remove all stored objects.
- */
-void
-sdb_store_clear(void);
-
-/*
- * sdb_store_host:
- * Add/update a host in the store. If the host, identified by its
- * canonicalized name, already exists, it will be updated according to the
- * specified name and timestamp. Else, a new entry will be created in the
- * store. Any memory required for storing the entry will be allocated an
- * managed by the store itself.
  *
- * Returns:
+ * Any of the call-back functions shall return:
  *  - 0 on success
  *  - a positive value if the new entry is older than the currently stored
  *    entry (in this case, no update will happen)
  *  - a negative value on error
  */
-int
-sdb_store_host(const char *name, sdb_time_t last_update);
+typedef struct {
+	/*
+	 * store_host:
+	 * Add/update a host in the store. If the host, identified by its
+	 * canonicalized name, already exists, it will be updated according to the
+	 * specified name and timestamp. Else, a new entry will be created in the
+	 * store.
+	 */
+	int (*store_host)(sdb_store_host_t *host, sdb_object_t *user_data);
 
-/*
- * sdb_store_has_host:
- * sdb_store_get_host:
- * Query the store for a host by its (canonicalized) name.
- *
- * sdb_store_get_host increments the ref count of the host object. The caller
- * needs to deref it when no longer using it.
- */
-bool
-sdb_store_has_host(const char *name);
+	/*
+	 * store_service:
+	 * Add/update a service in the store. If the service, identified by its
+	 * name, already exists for the specified host, it will be updated
+	 * according to the specified name and timestamp. If the referenced host
+	 * does not exist, an error will be reported. Else, a new entry will be
+	 * created in the store.
+	 */
+	int (*store_service)(sdb_store_service_t *service, sdb_object_t *user_data);
+
+	/*
+	 * store_metric:
+	 * Add/update a metric in the store. If the metric, identified by its
+	 * name, already exists for the specified host, it will be updated
+	 * according to the specified attributes. If the referenced host does not
+	 * exist, an error will be reported. Else, a new entry will be created in
+	 * the store.
+	 */
+	int (*store_metric)(sdb_store_metric_t *metric, sdb_object_t *user_data);
 
-sdb_store_obj_t *
-sdb_store_get_host(const char *name);
+	/*
+	 * store_attribute:
+	 * Add/update a host's attribute in the store. If the attribute,
+	 * identified by its key, already exists for the specified host, it will
+	 * be updated to the specified values. If the referenced host does not
+	 * exist, an error will be reported. Else, a new entry will be created in
+	 * the store.
+	 */
+	int (*store_attribute)(sdb_store_attribute_t *attr, sdb_object_t *user_data);
+} sdb_store_writer_t;
 
 /*
- * sdb_store_attribute:
- * Add/update a host's attribute in the store. If the attribute, identified by
- * its key, already exists for the specified host, it will be updated to the
- * specified values. If the referenced host does not exist, an error will be
- * reported. Else, a new entry will be created in the store. Any memory
- * required for storing the entry will be allocated and managed by the store
- * itself.
- *
- * Returns:
- *  - 0 on success
- *  - a positive value if the new entry is older than the currently stored
- *    entry (in this case, no update will happen)
- *  - a negative value on error
+ * sdb_memstore_writer:
+ * A store writer implementation that provides an in-memory object store. It
+ * expects a store object as its user-data argument.
  */
-int
-sdb_store_attribute(const char *hostname,
-		const char *key, const sdb_data_t *value,
-		sdb_time_t last_update);
+extern sdb_store_writer_t sdb_memstore_writer;
 
 /*
- * sdb_store_service:
- * Add/update a service in the store. If the service, identified by its name,
- * already exists for the specified host, it will be updated according to the
- * specified 'service' object. If the referenced host does not exist, an error
- * will be reported. Else, a new entry will be created in the store. Any
- * memory required for storing the entry will be allocated an managed by the
- * store itself.
- *
- * Returns:
- *  - 0 on success
- *  - a positive value if the new entry is older than the currently stored
- *    entry (in this case, no update will happen)
- *  - a negative value on error
+ * A store reader describes the interface to query a store implementation.
  */
-int
-sdb_store_service(const char *hostname, const char *name,
-		sdb_time_t last_update);
+typedef struct {
+	/*
+	 * prepare_query:
+	 * Prepare the query described by 'ast' for execution.
+	 */
+	sdb_object_t *(*prepare_query)(sdb_ast_node_t *ast,
+			sdb_strbuf_t *errbuf, sdb_object_t *user_data);
+
+	/*
+	 * execute_query:
+	 * Execute a previously prepared query. The callback may expect that only
+	 * queries prepared by its respective prepare callback will be passed to
+	 * this function. The query result will be passed back via the specified
+	 * store writer.
+	 */
+	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);
+} sdb_store_reader_t;
 
 /*
- * sdb_store_service_attr:
- * Add/update a service's attribute in the store. If the attribute, identified
- * by its key, already exists for the specified service, it will be updated to
- * the specified value. If the references service (for the specified host)
- * does not exist, an error will be reported. Any memory required for storing
- * the entry will be allocated and managed by the store itself.
- *
- * Returns:
- *  - 0 on success
- *  - a positive value if the new entry is older than the currently stored
- *    entry (in this case, no update will happen)
- *  - a negative value on error
+ * sdb_memstore_reader:
+ * A store reader implementation that uses an in-memory object store. It
+ * expects a store object as its user-data argument.
  */
-int
-sdb_store_service_attr(const char *hostname, const char *service,
-		const char *key, const sdb_data_t *value, sdb_time_t last_update);
+extern sdb_store_reader_t sdb_memstore_reader;
 
 /*
- * sdb_store_metric:
- * Add/update a metric in the store. If the metric, identified by its name,
- * already exists for the specified host, it will be updated according to the
- * specified 'metric' object. If the referenced host does not exist, an error
- * will be reported. Else, a new entry will be created in the store. Any
- * memory required for storing the entry will be allocated an managed by the
- * store itself.
- *
- * If specified, the metric store describes where to access the metric's data.
- *
- * Returns:
- *  - 0 on success
- *  - a positive value if the new entry is older than the currently stored
- *    entry (in this case, no update will happen)
- *  - a negative value on error
+ * sdb_memstore_create:
+ * Allocate a new in-memory store.
  */
-int
-sdb_store_metric(const char *hostname, const char *name,
-		sdb_metric_store_t *store, sdb_time_t last_update);
+sdb_memstore_t *
+sdb_memstore_create(void);
 
 /*
- * sdb_store_metric_attr:
- * Add/update a metric's attribute in the store. If the attribute, identified
- * by its key, already exists for the specified metric, it will be updated to
- * the specified value. If the references metric (for the specified host)
- * does not exist, an error will be reported. Any memory required for storing
- * the entry will be allocated and managed by the store itself.
- *
- * Returns:
- *  - 0 on success
- *  - a positive value if the new entry is older than the currently stored
- *    entry (in this case, no update will happen)
- *  - a negative value on error
+ * sdb_memstore_host, sdb_memstore_service, sdb_memstore_metric,
+ * sdb_memstore_attribute, sdb_memstore_metric_attr:
+ * Store an object in the specified store. The hostname is expected to be
+ * canonical.
  */
 int
-sdb_store_metric_attr(const char *hostname, const char *metric,
+sdb_memstore_host(sdb_memstore_t *store, const char *name, sdb_time_t last_update);
+int
+sdb_memstore_service(sdb_memstore_t *store, const char *hostname, const char *name,
+		sdb_time_t last_update);
+int
+sdb_memstore_metric(sdb_memstore_t *store, const char *hostname, const char *name,
+		sdb_metric_store_t *metric_store, sdb_time_t last_update);
+int
+sdb_memstore_attribute(sdb_memstore_t *store, const char *hostname,
 		const char *key, const sdb_data_t *value, sdb_time_t last_update);
+int
+sdb_memstore_service_attr(sdb_memstore_t *store, const char *hostname,
+		const char *service, const char *key, const sdb_data_t *value,
+		sdb_time_t last_update);
+int
+sdb_memstore_metric_attr(sdb_memstore_t *store, const char *hostname,
+		const char *metric, const char *key, const sdb_data_t *value,
+		sdb_time_t last_update);
 
 /*
- * sdb_store_fetch_timeseries:
- * Fetch the time-series described by the specified host's metric and
- * serialize it as JSON into the provided string buffer.
+ * sdb_memstore_get_host:
+ * Query the specified store for a host by its (canonicalized) name.
  *
- * Returns:
- *  - 0 on success
- *  - a negative value else
+ * The function increments the ref count of the host object. The caller needs
+ * to deref it when no longer using it.
  */
-int
-sdb_store_fetch_timeseries(const char *hostname, const char *metric,
-		sdb_timeseries_opts_t *opts, sdb_strbuf_t *buf);
+sdb_memstore_obj_t *
+sdb_memstore_get_host(sdb_memstore_t *store, const char *name);
 
 /*
- * sdb_store_get_child:
+ * sdb_memstore_get_child:
  * Retrieve a host's child object of the specified type and name. The
  * reference count of the child object will be incremented before returning
  * it. The caller is responsible for releasing the object once it's no longer
@@ -325,27 +361,25 @@ sdb_store_fetch_timeseries(const char *hostname, const char *metric,
  *  - the child object on success
  *  - NULL else
  */
-sdb_store_obj_t *
-sdb_store_get_child(sdb_store_obj_t *host, int type, const char *name);
+sdb_memstore_obj_t *
+sdb_memstore_get_child(sdb_memstore_obj_t *host, int type, const char *name);
 
 /*
- * sdb_store_get_field:
+ * sdb_memstore_get_field:
  * Get the value of a stored object's queryable field. The caller is
  * responsible for freeing any dynamically allocated memory possibly stored in
  * the returned value. If 'res' is NULL, the function will return whether the
  * field exists.
  *
- * Note: Retrieving the backend this way is not currently supported.
- *
  * Returns:
  *  - 0 on success
  *  - a negative value else
  */
 int
-sdb_store_get_field(sdb_store_obj_t *obj, int field, sdb_data_t *res);
+sdb_memstore_get_field(sdb_memstore_obj_t *obj, int field, sdb_data_t *res);
 
 /*
- * sdb_store_get_attr:
+ * sdb_memstore_get_attr:
  * Get the value of a stored object's attribute. The caller is responsible for
  * freeing any dynamically allocated memory possibly stored in the returned
  * value. If 'res' is NULL, the function will return whether the attribute
@@ -357,8 +391,8 @@ sdb_store_get_field(sdb_store_obj_t *obj, int field, sdb_data_t *res);
  *  - a negative value else
  */
 int
-sdb_store_get_attr(sdb_store_obj_t *obj, const char *name, sdb_data_t *res,
-		sdb_store_matcher_t *filter);
+sdb_memstore_get_attr(sdb_memstore_obj_t *obj, const char *name, sdb_data_t *res,
+		sdb_memstore_matcher_t *filter);
 
 /*
  * Querying a store:
@@ -374,25 +408,25 @@ sdb_store_get_attr(sdb_store_obj_t *obj, const char *name, sdb_data_t *res,
  */
 
 /*
- * sdb_store_query_t:
+ * sdb_memstore_query_t:
  * A parsed query readily prepared for execution.
  */
-struct sdb_store_query;
-typedef struct sdb_store_query sdb_store_query_t;
+struct sdb_memstore_query;
+typedef struct sdb_memstore_query sdb_memstore_query_t;
 
 /*
- * sdb_store_query_prepare:
+ * sdb_memstore_query_prepare:
  * Prepare the query described by 'ast' for execution in a store.
  *
  * Returns:
  *  - a store query on success
  *  - NULL else
  */
-sdb_store_query_t *
-sdb_store_query_prepare(sdb_ast_node_t *ast);
+sdb_memstore_query_t *
+sdb_memstore_query_prepare(sdb_ast_node_t *ast);
 
 /*
- * sdb_store_query_prepare_matcher:
+ * sdb_memstore_query_prepare_matcher:
  * Prepare the logical expression described by 'ast' for execution as a store
  * matcher.
  *
@@ -400,24 +434,24 @@ sdb_store_query_prepare(sdb_ast_node_t *ast);
  *  - a matcher on success
  *  - NULL else
  */
-sdb_store_matcher_t *
-sdb_store_query_prepare_matcher(sdb_ast_node_t *ast);
+sdb_memstore_matcher_t *
+sdb_memstore_query_prepare_matcher(sdb_ast_node_t *ast);
 
 /*
- * sdb_store_query_execute:
- * Execute a previously prepared query. The query result will be written to
- * 'buf' and any errors to 'errbuf'.
+ * sdb_memstore_query_execute:
+ * Execute a previously prepared query in the specified store. The query
+ * result will be written to 'buf' and any errors to 'errbuf'.
  *
  * Returns:
  *  - the result type (to be used by the server reply)
  *  - a negative value on error
  */
 int
-sdb_store_query_execute(sdb_store_query_t *m,
-		sdb_strbuf_t *buf, sdb_strbuf_t *errbuf);
+sdb_memstore_query_execute(sdb_memstore_t *store, sdb_memstore_query_t *m,
+		sdb_store_writer_t *w, sdb_object_t *wd, sdb_strbuf_t *errbuf);
 
 /*
- * sdb_store_expr_create:
+ * sdb_memstore_expr_create:
  * Creates an arithmetic expression implementing the specified operator on the
  * specified left and right operand.
  *
@@ -425,11 +459,12 @@ sdb_store_query_execute(sdb_store_query_t *m,
  *  - an expression object on success
  *  - NULL else
  */
-sdb_store_expr_t *
-sdb_store_expr_create(int op, sdb_store_expr_t *left, sdb_store_expr_t *right);
+sdb_memstore_expr_t *
+sdb_memstore_expr_create(int op,
+		sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
 
 /*
- * sdb_store_expr_typed:
+ * sdb_memstore_expr_typed:
  * Creates an expression which evaluates in the context of an object's sibling
  * as specified by the given type.
  *
@@ -437,11 +472,11 @@ sdb_store_expr_create(int op, sdb_store_expr_t *left, sdb_store_expr_t *right);
  *  - an expression object on success
  *  - NULL else
  */
-sdb_store_expr_t *
-sdb_store_expr_typed(int typ, sdb_store_expr_t *expr);
+sdb_memstore_expr_t *
+sdb_memstore_expr_typed(int typ, sdb_memstore_expr_t *expr);
 
 /*
- * sdb_store_expr_fieldvalue:
+ * sdb_memstore_expr_fieldvalue:
  * Creates an expression which evaluates to the value of the specified
  * queryable field of a stored object.
  *
@@ -449,11 +484,11 @@ sdb_store_expr_typed(int typ, sdb_store_expr_t *expr);
  *  - an expression object on success
  *  - NULL else
  */
-sdb_store_expr_t *
-sdb_store_expr_fieldvalue(int field);
+sdb_memstore_expr_t *
+sdb_memstore_expr_fieldvalue(int field);
 
 /*
- * sdb_store_expr_attrvalue:
+ * sdb_memstore_expr_attrvalue:
  * Creates an expression which evaluates to the value of the specified
  * attribute of a stored object. Evaluates to a NULL value if the attribute
  * does not exist.
@@ -462,22 +497,22 @@ sdb_store_expr_fieldvalue(int field);
  *  - an expression object on success
  *  - NULL else
  */
-sdb_store_expr_t *
-sdb_store_expr_attrvalue(const char *name);
+sdb_memstore_expr_t *
+sdb_memstore_expr_attrvalue(const char *name);
 
 /*
- * sdb_store_expr_constvalue:
+ * sdb_memstore_expr_constvalue:
  * Creates an expression which evaluates to the specified constant value.
  *
  * Returns:
  *  - an expression object on success
  *  - NULL else
  */
-sdb_store_expr_t *
-sdb_store_expr_constvalue(const sdb_data_t *value);
+sdb_memstore_expr_t *
+sdb_memstore_expr_constvalue(const sdb_data_t *value);
 
 /*
- * sdb_store_expr_eval:
+ * sdb_memstore_expr_eval:
  * Evaluate an expression for the specified stored object and stores the
  * result in 'res'. The result's value will be allocated dynamically if
  * necessary and, thus, should be free'd by the caller (e.g. using
@@ -490,143 +525,133 @@ sdb_store_expr_constvalue(const sdb_data_t *value);
  *  - a negative value else
  */
 int
-sdb_store_expr_eval(sdb_store_expr_t *expr, sdb_store_obj_t *obj,
-		sdb_data_t *res, sdb_store_matcher_t *filter);
+sdb_memstore_expr_eval(sdb_memstore_expr_t *expr, sdb_memstore_obj_t *obj,
+		sdb_data_t *res, sdb_memstore_matcher_t *filter);
 
 /*
- * sdb_store_expr_iterable:
- * Check whether an expression, evaluated in the specified context (HOST,
- * SERVICE, METRIC) is iterable, that is, if it may evaluate to multiple
- * values.
- */
-bool
-sdb_store_expr_iterable(sdb_store_expr_t *expr, int context);
-
-/*
- * sdb_store_expr_iter:
- * Iterate over the elements of an iterable expression. sdb_store_expr_iter
+ * sdb_memstore_expr_iter:
+ * Iterate over the elements of an iterable expression. sdb_memstore_expr_iter
  * returns NULL if the expression is not iterable (for the specified object).
- * See also sdb_store_expr_iterable.
  *
- * sdb_store_expr_iter_get_next returns NULL if there is no next element.
+ * sdb_memstore_expr_iter_get_next returns NULL if there is no next element.
  */
-sdb_store_expr_iter_t *
-sdb_store_expr_iter(sdb_store_expr_t *expr, sdb_store_obj_t *obj,
-		sdb_store_matcher_t *filter);
+sdb_memstore_expr_iter_t *
+sdb_memstore_expr_iter(sdb_memstore_expr_t *expr, sdb_memstore_obj_t *obj,
+		sdb_memstore_matcher_t *filter);
 void
-sdb_store_expr_iter_destroy(sdb_store_expr_iter_t *iter);
+sdb_memstore_expr_iter_destroy(sdb_memstore_expr_iter_t *iter);
 
 bool
-sdb_store_expr_iter_has_next(sdb_store_expr_iter_t *iter);
+sdb_memstore_expr_iter_has_next(sdb_memstore_expr_iter_t *iter);
 sdb_data_t
-sdb_store_expr_iter_get_next(sdb_store_expr_iter_t *iter);
+sdb_memstore_expr_iter_get_next(sdb_memstore_expr_iter_t *iter);
 
 /*
- * sdb_store_dis_matcher:
+ * sdb_memstore_dis_matcher:
  * Creates a matcher matching the disjunction (logical OR) of two matchers.
  */
-sdb_store_matcher_t *
-sdb_store_dis_matcher(sdb_store_matcher_t *left, sdb_store_matcher_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_dis_matcher(sdb_memstore_matcher_t *left, sdb_memstore_matcher_t *right);
 
 /*
- * sdb_store_con_matcher:
+ * sdb_memstore_con_matcher:
  * Creates a matcher matching the conjunction (logical AND) of two matchers.
  */
-sdb_store_matcher_t *
-sdb_store_con_matcher(sdb_store_matcher_t *left, sdb_store_matcher_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_con_matcher(sdb_memstore_matcher_t *left, sdb_memstore_matcher_t *right);
 
 /*
- * sdb_store_inv_matcher::
+ * sdb_memstore_inv_matcher:
  * Creates a matcher matching the inverse (logical NOT) of a matcher.
  */
-sdb_store_matcher_t *
-sdb_store_inv_matcher(sdb_store_matcher_t *m);
+sdb_memstore_matcher_t *
+sdb_memstore_inv_matcher(sdb_memstore_matcher_t *m);
 
 /*
- * sdb_store_any_matcher:
+ * sdb_memstore_any_matcher:
  * Creates a matcher iterating over values of the first expression (which has
  * to be iterable). It matches if *any* of those elements match 'm'. 'm' has
  * to be an ary operation with the left operand unset.
  */
-sdb_store_matcher_t *
-sdb_store_any_matcher(sdb_store_expr_t *iter, sdb_store_matcher_t *m);
+sdb_memstore_matcher_t *
+sdb_memstore_any_matcher(sdb_memstore_expr_t *iter, sdb_memstore_matcher_t *m);
 
 /*
- * sdb_store_all_matcher:
+ * sdb_memstore_all_matcher:
  * Creates a matcher iterating over values of the first expression (which has
  * to be iterable). It matches if *all* of those elements match 'm'. 'm' has
  * to be an ary operation with the left operand unset.
  */
-sdb_store_matcher_t *
-sdb_store_all_matcher(sdb_store_expr_t *iter, sdb_store_matcher_t *m);
+sdb_memstore_matcher_t *
+sdb_memstore_all_matcher(sdb_memstore_expr_t *iter, sdb_memstore_matcher_t *m);
 
 /*
- * sdb_store_in_matcher:
+ * sdb_memstore_in_matcher:
  * Creates a matcher which matches if the right value evaluates to an array
  * value and the left value is included in that array. See sdb_data_inarray
  * for more details.
  */
-sdb_store_matcher_t *
-sdb_store_in_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_in_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
 
 /*
- * sdb_store_lt_matcher, sdb_store_le_matcher, sdb_store_eq_matcher,
- * sdb_store_ge_matcher, sdb_store_gt_matcher:
+ * sdb_memstore_lt_matcher, sdb_memstore_le_matcher, sdb_memstore_eq_matcher,
+ * sdb_memstore_ge_matcher, sdb_memstore_gt_matcher:
  * Create conditional matchers comparing the values of two expressions. The
  * matcher matches if the left expression compres less than, less or equal
  * than, equal to, not equal to, greater or equal than, or greater than the
  * right expression.
  */
-sdb_store_matcher_t *
-sdb_store_lt_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
-sdb_store_matcher_t *
-sdb_store_le_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
-sdb_store_matcher_t *
-sdb_store_eq_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
-sdb_store_matcher_t *
-sdb_store_ne_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
-sdb_store_matcher_t *
-sdb_store_ge_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
-sdb_store_matcher_t *
-sdb_store_gt_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
-
-/*
- * sdb_store_regex_matcher:
+sdb_memstore_matcher_t *
+sdb_memstore_lt_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_le_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_eq_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_ne_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_ge_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_gt_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
+
+/*
+ * sdb_memstore_regex_matcher:
  * Creates a matcher which matches the string value the left expression
  * evaluates to against the regular expression the right expression evaluates
  * to. The right expression may either be a constant value regular expression
  * or string or a dynamic value evaluating to a string. In the latter case,
  * the string is compiled to a regex every time the matcher is executed.
  */
-sdb_store_matcher_t *
-sdb_store_regex_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_regex_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
 
 /*
- * sdb_store_nregex_matcher:
- * Creates a regex matcher just like sdb_store_regex_matcher except that it
+ * sdb_memstore_nregex_matcher:
+ * Creates a regex matcher just like sdb_memstore_regex_matcher except that it
  * matches in case the regular expression does not match.
  */
-sdb_store_matcher_t *
-sdb_store_nregex_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
+sdb_memstore_matcher_t *
+sdb_memstore_nregex_matcher(sdb_memstore_expr_t *left, sdb_memstore_expr_t *right);
 
 /*
- * sdb_store_isnull_matcher:
+ * sdb_memstore_isnull_matcher:
  * Creates a matcher matching NULL values.
  */
-sdb_store_matcher_t *
-sdb_store_isnull_matcher(sdb_store_expr_t *expr);
+sdb_memstore_matcher_t *
+sdb_memstore_isnull_matcher(sdb_memstore_expr_t *expr);
 
 /*
- * sdb_store_istrue_matcher, sdb_store_isfalse_matcher:
+ * sdb_memstore_istrue_matcher, sdb_memstore_isfalse_matcher:
  * Creates a matcher matching boolean values.
  */
-sdb_store_matcher_t *
-sdb_store_istrue_matcher(sdb_store_expr_t *expr);
-sdb_store_matcher_t *
-sdb_store_isfalse_matcher(sdb_store_expr_t *expr);
+sdb_memstore_matcher_t *
+sdb_memstore_istrue_matcher(sdb_memstore_expr_t *expr);
+sdb_memstore_matcher_t *
+sdb_memstore_isfalse_matcher(sdb_memstore_expr_t *expr);
 
 /*
- * sdb_store_matcher_matches:
+ * sdb_memstore_matcher_matches:
  * Check whether the specified matcher matches the specified store object. If
  * specified, the filter will be used to preselect objects for further
  * evaluation. It is applied to any object that's used during the evaluation
@@ -641,40 +666,41 @@ sdb_store_isfalse_matcher(sdb_store_expr_t *expr);
  *  - 0 else
  */
 int
-sdb_store_matcher_matches(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
-		sdb_store_matcher_t *filter);
+sdb_memstore_matcher_matches(sdb_memstore_matcher_t *m, sdb_memstore_obj_t *obj,
+		sdb_memstore_matcher_t *filter);
 
 /*
- * sdb_store_matcher_op_cb:
+ * sdb_memstore_matcher_op_cb:
  * Callback constructing a matcher operator.
  */
-typedef sdb_store_matcher_t *(*sdb_store_matcher_op_cb)
-	(sdb_store_expr_t *, sdb_store_expr_t *);
+typedef sdb_memstore_matcher_t *(*sdb_memstore_matcher_op_cb)
+	(sdb_memstore_expr_t *, sdb_memstore_expr_t *);
 
 /*
- * sdb_store_lookup_cb:
+ * sdb_memstore_lookup_cb:
  * Lookup callback. It is called for each matching object when looking up data
  * in the store passing on the lookup filter and the specified user-data. The
  * lookup aborts early if the callback returns non-zero.
  */
-typedef int (*sdb_store_lookup_cb)(sdb_store_obj_t *obj,
-		sdb_store_matcher_t *filter, void *user_data);
+typedef int (*sdb_memstore_lookup_cb)(sdb_memstore_obj_t *obj,
+		sdb_memstore_matcher_t *filter, void *user_data);
 
 /*
- * sdb_store_scan:
- * Look up objects of the specified type in the store. The specified callback
- * function is called for each object in the store matching 'm'. The function
- * performs a full scan of all objects stored in the database. If specified,
- * the filter will be used to preselect objects for further evaluation. See
- * the description of 'sdb_store_matcher_matches' for details.
+ * sdb_memstore_scan:
+ * Look up objects of the specified type in the specified store. The specified
+ * callback function is called for each object in the store matching 'm'. The
+ * function performs a full scan of all stored objects. If specified, the
+ * filter will be used to preselect objects for further evaluation. See the
+ * description of 'sdb_memstore_matcher_matches' for details.
  *
  * Returns:
  *  - 0 on success
  *  - a negative value else
  */
 int
-sdb_store_scan(int type, sdb_store_matcher_t *m, sdb_store_matcher_t *filter,
-		sdb_store_lookup_cb cb, void *user_data);
+sdb_memstore_scan(sdb_memstore_t *store, int type,
+		sdb_memstore_matcher_t *m, sdb_memstore_matcher_t *filter,
+		sdb_memstore_lookup_cb cb, void *user_data);
 
 /*
  * Flags for JSON formatting.
@@ -692,13 +718,12 @@ sdb_store_json_formatter_t *
 sdb_store_json_formatter(sdb_strbuf_t *buf, int type, int flags);
 
 /*
- * sdb_store_json_emit:
+ * sdb_memstore_emit:
  * Serialize a single object to JSON adding it to the string buffer associated
  * with the formatter object. The serialized object will not include
  * attributes or any child objects. Instead, call the function again for each
  * of those objects. All attributes have to be emitted before any other
- * children types. Use sdb_store_json_emit_full() to emit a full (filtered)
- * object.
+ * children types. Use sdb_memstore_emit_full() to emit a full (filtered) object.
  *
  * Note that the output might not be valid JSON before calling
  * sdb_store_json_finish().
@@ -708,10 +733,10 @@ sdb_store_json_formatter(sdb_strbuf_t *buf, int type, int flags);
  *  - a negative value else
  */
 int
-sdb_store_json_emit(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj);
+sdb_memstore_emit(sdb_memstore_obj_t *obj, sdb_store_writer_t *w, sdb_object_t *wd);
 
 /*
- * sdb_store_json_emit_full:
+ * sdb_memstore_emit_full:
  * Serialize a single object including it's attributes and all children to
  * JSON, adding it to the string buffer associated with the formatter object.
  * The filter, if specified, is applied to each attribute and child object.
@@ -725,8 +750,8 @@ sdb_store_json_emit(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj);
  *  - a negative value else
  */
 int
-sdb_store_json_emit_full(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj,
-		sdb_store_matcher_t *filter);
+sdb_memstore_emit_full(sdb_memstore_obj_t *obj, sdb_memstore_matcher_t *filter,
+		sdb_store_writer_t *w, sdb_object_t *wd);
 
 /*
  * sdb_store_json_finish:
@@ -736,6 +761,13 @@ sdb_store_json_emit_full(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj,
 int
 sdb_store_json_finish(sdb_store_json_formatter_t *f);
 
+/*
+ * sdb_store_json_writer:
+ * A store writer implementation that generates JSON output. It expects a
+ * store JSON formatter as its user-data argument.
+ */
+extern sdb_store_writer_t sdb_store_json_writer;
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif