plugin: Keep a usage counter for each plugin.

Also, let plugin_load return early if the plugin is already loaded.
This is mostly in preparation for future improvements around plugin handling.

diff --git a/src/core/plugin.c b/src/core/plugin.c
index 6af090bfac233eec2e51a91221e4a762ee3f02f7..a521b89d1f00778233e7465cb3eb25e7692cd74c 100644 (file)
--- a/src/core/plugin.c
+++ b/src/core/plugin.c
@@ -81,9 +81,14 @@ typedef struct {
        sdb_plugin_ctx_t public;
 
        sdb_plugin_info_t info;
+
+       /* 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 }
+       SDB_PLUGIN_CTX_INIT, SDB_PLUGIN_INFO_INIT, 0 }
 
 #define CTX(obj) ((ctx_t *)(obj))
 
@@ -246,6 +251,7 @@ ctx_init(sdb_object_t *obj, va_list __attribute__((unused)) ap)
 
        ctx->public = plugin_default_ctx;
        ctx->info = plugin_default_info;
+       ctx->use_cnt = 1;
        return 0;
 } /* ctx_init */
 
@@ -415,6 +421,13 @@ sdb_plugin_load(const char *name, const sdb_plugin_ctx_t *plugin_ctx)
        }
        strcat(real_name, name_ptr);
 
+       ctx = CTX(sdb_llist_search_by_name(all_plugins, real_name));
+       if (ctx) {
+               /* plugin already loaded */
+               ++ctx->use_cnt;
+               return 0;
+       }
+
        snprintf(filename, sizeof(filename), "%s/%s.so",
                        PKGLIBDIR, real_name);
        filename[sizeof(filename) - 1] = '\0';