Document plug-in interface

[babeltrace.git] / include / babeltrace / plugin / plugin.h

diff --git a/include/babeltrace/plugin/plugin.h b/include/babeltrace/plugin/plugin.h
index a8aada4eb3eadf8884437154bd0ee116e192db7c..1080e2bb2f2b1e93ac2bce1877f348897dc1bf7d 100644 (file)
--- a/include/babeltrace/plugin/plugin.h
+++ b/include/babeltrace/plugin/plugin.h
@@ -2,7 +2,7 @@
 #define BABELTRACE_PLUGIN_H
 
 /*
- * BabelTrace - Plug-in
+ * BabelTrace - Babeltrace Plug-in Interface
  *
  * Copyright 2015 Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
@@ -27,49 +27,99 @@
  * SOFTWARE.
  */
 
-#include <stdint.h>
+#include <errno.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-struct bt_plugin;
-struct bt_notification;
-
+/**
+ * Plug-in type.
+ */
 enum bt_plugin_type {
-       BT_PLUGIN_TYPE_UNKNOWN = -1,
+       BT_PLUGIN_TYPE_UNKNOWN =        -1,
+
        /* A source plug-in is a notification generator. */
-       BT_PLUGIN_TYPE_SOURCE = 0,
+       BT_PLUGIN_TYPE_SOURCE =         0,
+
        /* A sink plug-in handles incoming notifications. */
-       BT_PLUGIN_TYPE_SINK = 1,
-       /* A filter plug-in implements both SOURCE and SINK interfaces. */
-       BT_PLUGIN_TYPE_FILTER = 2,
+       BT_PLUGIN_TYPE_SINK =           1,
+
+       /* A filter plug-in implements both Source and Sink interfaces. */
+       BT_PLUGIN_TYPE_FILTER =         2,
 };
 
-typedef void (*bt_plugin_destroy_func)(struct bt_plugin *);
+/**
+ * Status code. Errors are always negative.
+ */
+enum bt_plugin_status {
+       /* -12 for compatibility with -ENOMEM */
+       BT_PLUGIN_STATUS_NOMEM =        -12,
+
+       /* -22 for compatibility with -EINVAL */
+       BT_PLUGIN_STATUS_INVAL =        -22,
+
+       BT_PLUGIN_STATUS_UNSUPPORTED =  -2,
+
+       BT_PLUGIN_STATUS_ERROR =        -1,
+
+       BT_PLUGIN_STATUS_OK =           0,
+}
+
+/**
+ * Get plug-in instance name
+ *
+ * @param plugin       Plug-in instance of which to get the name
+ * @returns            Returns a pointer to the plug-in's name
+ */
+extern const char *bt_plugin_get_name(struct bt_plugin *plugin);
+
+/**
+ * Set plug-in instance name
+ *
+ * @param plugin       Plug-in instance of which to set the name
+ * @param name         New plug-in name (will be copied)
+ * @returns            One of #bt_plugin_status values
+ */
+extern enum bt_plugin_status bt_plugin_set_name(
+               struct bt_plugin *plugin, const char *name);
+
+/**
+ * Get plug-in instance type
+ *
+ * @param plugin       Plug-in instance of which to get the type
+ * @returns            One of #bt_plugin_type values
+ */
+extern enum bt_plugin_type bt_plugin_get_type(struct bt_plugin *plugin);
+
+/**
+ * Set a plug-in instance's error stream
+ *
+ * @param plugin       Plug-in instance
+ * @param error_stream Error stream
+ * @returns            One of #bt_plugin_status values
+ */
+extern enum bt_plugin_status bt_plugin_set_error_stream(
+               struct bt_plugin *plugin, FILE *error_stream);
+
+/**
+ * Increments the reference count of \p plugin.
+ *
+ * @param plugin       Plug-in of which to increment the reference count
+ *
+ * @see bt_plugin_put()
+ */
+extern void bt_plugin_get(struct bt_plugin *plugin);
 
 /**
- * Plug-in discovery functions.
+ * Decrements the reference count of \p plugin, destroying it when this
+ * count reaches 0.
  *
- * The Babeltrace plug-in architecture mandates that a given plug-in shared
- * object only define one plug-in. These functions are used to query a about
- * shared object about its attributes.
+ * @param plugin       Plug-in of which to decrement the reference count
  *
- * The functions marked as mandatory MUST be exported by the shared object
- * to be considered a valid plug-in.
+ * @see bt_plugin_get()
  */
-/* Plug-in discovery functions... find a better name */
-enum bt_plugin_type bt_plugin_lib_get_type(void);
-const char *bt_plugin_lib_get_format_name(void);
-
-/* TODO: document mandatory fields and their expected types */
-struct bt_plugin *bt_plugin_create(struct bt_ctf_field *params);
-void *bt_plugin_get_user_data(struct bt_plugin *plugin);
-int bt_plugin_set_error_stream(struct bt_plugin *plugin, FILE *error_stream);
-
-/* Refcounting */
-void bt_plugin_get(struct bt_plugin *plugin);
-void bt_plugin_put(struct bt_plugin *plugin);
+extern void bt_plugin_put(struct bt_plugin *plugin);
 
 #ifdef __cplusplus
 }