core: Add the store writer plugin type.

A plugin may now provide an implementation of a store by providing a set of
callbacks. For now, this is only about writing to a store. Queries are not
supported through this interface.

diff --git a/src/core/plugin.c b/src/core/plugin.c
index 7bf3de36d740fb5ec7ebbf93724491ac9f18b6da..4de1c3a4d93f3a8f502844bc67d4fe5801889b6b 100644 (file)
--- a/src/core/plugin.c
+++ b/src/core/plugin.c
@@ -84,6 +84,8 @@ typedef struct {
 #define SDB_PLUGIN_CB_INIT { SDB_OBJECT_INIT, \
        /* callback = */ NULL, /* user_data = */ NULL, \
        SDB_PLUGIN_CTX_INIT }
+#define SDB_PLUGIN_CB(obj) ((sdb_plugin_cb_t *)(obj))
+#define SDB_CONST_PLUGIN_CB(obj) ((const sdb_plugin_cb_t *)(obj))
 
 typedef struct {
        sdb_plugin_cb_t super;
@@ -93,12 +95,17 @@ typedef struct {
        sdb_time_t ccb_interval;
        sdb_time_t ccb_next_update;
 } sdb_plugin_collector_cb_t;
-
-#define SDB_PLUGIN_CB(obj) ((sdb_plugin_cb_t *)(obj))
-#define SDB_CONST_PLUGIN_CB(obj) ((const sdb_plugin_cb_t *)(obj))
 #define SDB_PLUGIN_CCB(obj) ((sdb_plugin_collector_cb_t *)(obj))
 #define SDB_CONST_PLUGIN_CCB(obj) ((const sdb_plugin_collector_cb_t *)(obj))
 
+typedef struct {
+       sdb_object_t super;
+       sdb_store_writer_t impl;
+       sdb_object_t *user_data;
+       ctx_t *ctx;
+} sdb_plugin_writer_t;
+#define SDB_PLUGIN_WRITER(obj) ((sdb_plugin_writer_t *)(obj))
+
 /*
  * private variables
  */
@@ -119,6 +126,7 @@ 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      *ts_fetcher_list = NULL;
+static sdb_llist_t      *writer_list = NULL;
 
 static struct {
        const char   *type;
@@ -131,6 +139,7 @@ static struct {
        { "shutdown",           &shutdown_list },
        { "log",                &log_list },
        { "timeseries fetcher", &ts_fetcher_list },
+       { "store writer",       &writer_list },
 };
 
 /*
@@ -400,6 +409,55 @@ static sdb_type_t sdb_plugin_collector_cb_type = {
        plugin_cb_destroy
 };
 
+static int
+plugin_writer_init(sdb_object_t *obj, va_list ap)
+{
+       sdb_store_writer_t *impl = va_arg(ap, sdb_store_writer_t *);
+       sdb_object_t       *ud   = va_arg(ap, sdb_object_t *);
+
+       assert(impl);
+
+       if ((! impl->store_host) || (! impl->store_service)
+                       || (! impl->store_metric) || (! impl->store_attribute)
+                       || (! impl->store_service_attr) || (! impl->store_metric_attr)) {
+               sdb_log(SDB_LOG_ERR, "core: store writer callback '%s' "
+                               "does not fully implement the writer interface.",
+                               obj->name);
+               return -1;
+       }
+       if (sdb_llist_search_by_name(writer_list, obj->name)) {
+               sdb_log(SDB_LOG_WARNING, "core: store writer callback '%s' "
+                               "has already been registered. Ignoring newly "
+                               "registered version.", obj->name);
+               return -1;
+       }
+
+       /* ctx may be NULL if the plugin was not registered by a plugin */
+
+       SDB_PLUGIN_WRITER(obj)->impl = *impl;
+       SDB_PLUGIN_WRITER(obj)->ctx  = ctx_get();
+       sdb_object_ref(SDB_OBJ(SDB_PLUGIN_WRITER(obj)->ctx));
+
+       sdb_object_ref(ud);
+       SDB_PLUGIN_WRITER(obj)->user_data = ud;
+       return 0;
+} /* plugin_writer_init */
+
+static void
+plugin_writer_destroy(sdb_object_t *obj)
+{
+       assert(obj);
+       sdb_object_deref(SDB_PLUGIN_WRITER(obj)->user_data);
+       sdb_object_deref(SDB_OBJ(SDB_PLUGIN_WRITER(obj)->ctx));
+} /* plugin_writer_destroy */
+
+static sdb_type_t sdb_plugin_writer_type = {
+       sizeof(sdb_plugin_writer_t),
+
+       plugin_writer_init,
+       plugin_writer_destroy
+};
+
 static int
 module_init(const char *name, lt_dlhandle lh, sdb_plugin_info_t *info)
 {
@@ -796,6 +854,41 @@ sdb_plugin_register_ts_fetcher(const char *name,
                        name, callback, user_data);
 } /* sdb_plugin_register_ts_fetcher */
 
+int
+sdb_plugin_register_writer(const char *name,
+               sdb_store_writer_t *writer, sdb_object_t *user_data)
+{
+       char cb_name[1024];
+       sdb_object_t *obj;
+
+       if ((! name) || (! writer))
+               return -1;
+
+       if (! writer_list)
+               writer_list = sdb_llist_create();
+       if (! writer_list)
+               return -1;
+
+       plugin_get_name(name, cb_name, sizeof(cb_name));
+
+       obj = sdb_object_create(cb_name, sdb_plugin_writer_type,
+                       writer, user_data);
+       if (! obj)
+               return -1;
+
+       if (sdb_llist_append(writer_list, obj)) {
+               sdb_object_deref(obj);
+               return -1;
+       }
+
+       /* pass control to the list */
+       sdb_object_deref(obj);
+
+       sdb_log(SDB_LOG_INFO, "core: Registered store writer callback '%s'.",
+                       cb_name);
+       return 0;
+} /* sdb_store_register_writer */
+
 sdb_plugin_ctx_t
 sdb_plugin_get_ctx(void)
 {

diff --git a/src/include/core/plugin.h b/src/include/core/plugin.h
index 6580e90dfcd55a8df4ea52e0ae4ee4ff3ef7d57e..e09bf0f346c42143948843e4e0ef84326f4ee870 100644 (file)
--- a/src/include/core/plugin.h
+++ b/src/include/core/plugin.h
@@ -30,6 +30,7 @@
 
 #include "sysdb.h"
 #include "core/object.h"
+#include "core/store.h"
 #include "core/time.h"
 #include "core/timeseries.h"
 
@@ -258,6 +259,22 @@ int
 sdb_plugin_register_ts_fetcher(const char *name,
                sdb_plugin_fetch_ts_cb callback, sdb_object_t *user_data);
 
+/*
+ * sdb_plugin_register_writer:
+ * Register a "writer" implementation to be used when adding an object to the
+ * store. It is invalid to register an incomplete writer which does not
+ * implement all of the writer interface.
+ *
+ * Arguments:
+ *  - user_data: If specified, this will be passed on to each call of the
+ *    callback. The function will take ownership of the object, that is,
+ *    increment the reference count by one. In case the caller does not longer
+ *    use the object for other purposes, it should thus deref it.
+ */
+int
+sdb_plugin_register_writer(const char *name,
+               sdb_store_writer_t *writer, sdb_object_t *user_data);
+
 /*
  * sdb_plugin_get_ctx, sdb_plugin_set_ctx:
  * The plugin context defines a set of settings that are available whenever a

diff --git a/src/include/core/store.h b/src/include/core/store.h
index a8208bf7d9a0a849e16c6316616af092e4b1e9b5..30ad0ab386b81517128c47fbe0995d8dcf030c86 100644 (file)
--- a/src/include/core/store.h
+++ b/src/include/core/store.h
@@ -94,6 +94,14 @@ enum {
 struct sdb_store_obj;
 typedef struct sdb_store_obj sdb_store_obj_t;
 
+/*
+ * A metric store describes how to access a metric's data.
+ */
+typedef struct {
+       const char *type;
+       const char *id;
+} sdb_metric_store_t;
+
 /*
  * Expressions represent arithmetic expressions based on stored objects and
  * their various attributes.
@@ -125,6 +133,28 @@ typedef struct sdb_store_matcher sdb_store_matcher_t;
 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.
@@ -220,14 +250,6 @@ int
 sdb_store_service_attr(const char *hostname, const char *service,
                const char *key, const sdb_data_t *value, sdb_time_t last_update);
 
-/*
- * A metric store describes how to access a metric's data.
- */
-typedef struct {
-       const char *type;
-       const char *id;
-} sdb_metric_store_t;
-
 /*
  * sdb_store_metric:
  * Add/update a metric in the store. If the metric, identified by its name,