src/plugin.c: Document the use of "register_complex_read".

[collectd.git] / src / plugin.c

diff --git a/src/plugin.c b/src/plugin.c
index 7d66bd8..175a89a 100644 (file)
--- a/src/plugin.c
+++ b/src/plugin.c
@@ -96,6 +96,7 @@ static pthread_t      *read_threads = NULL;
 static int             read_threads_num = 0;
 
 static pthread_key_t   plugin_ctx_key;
+static _Bool           plugin_ctx_key_initialized = 0;
 
 /*
  * Static functions
@@ -297,7 +298,7 @@ static int plugin_load_file (char *file, uint32_t flags)
                dlh = lt_dlopenadvise(file, advise);
                lt_dladvise_destroy(&advise);
        } else {
-               dlh = lt_dlopen (file);
+               dlh = lt_dlopen (file);
        }
 #else /* if LIBTOOL_VERSION == 1 */
        if (flags & PLUGIN_FLAGS_GLOBAL)
@@ -803,6 +804,10 @@ int plugin_register_read (const char *name,
        int status;
 
        if (ctx.interval != 0) {
+               /* If ctx.interval is not zero (== use interval_g), we need to
+                * use the "complex" read callback, because only that allows to
+                * specify a different interval. Wrap the callback using
+                * read_cb_wrapper(). */
                struct timespec interval;
                user_data_t user_data;
 
@@ -1999,6 +2004,7 @@ static plugin_ctx_t *plugin_ctx_create (void)
        }
 
        *ctx = ctx_init;
+       assert (plugin_ctx_key_initialized);
        pthread_setspecific (plugin_ctx_key, ctx);
        DEBUG("Created new plugin context.");
        return (ctx);
@@ -2007,12 +2013,14 @@ static plugin_ctx_t *plugin_ctx_create (void)
 void plugin_init_ctx (void)
 {
        pthread_key_create (&plugin_ctx_key, plugin_ctx_destructor);
+       plugin_ctx_key_initialized = 1;
 } /* void plugin_init_ctx */
 
 plugin_ctx_t plugin_get_ctx (void)
 {
        plugin_ctx_t *ctx;
 
+       assert (plugin_ctx_key_initialized);
        ctx = pthread_getspecific (plugin_ctx_key);
 
        if (ctx == NULL) {
@@ -2030,6 +2038,7 @@ plugin_ctx_t plugin_set_ctx (plugin_ctx_t ctx)
        plugin_ctx_t *c;
        plugin_ctx_t old;
 
+       assert (plugin_ctx_key_initialized);
        c = pthread_getspecific (plugin_ctx_key);
 
        if (c == NULL) {
@@ -2045,4 +2054,41 @@ plugin_ctx_t plugin_set_ctx (plugin_ctx_t ctx)
        return (old);
 } /* void plugin_set_ctx */
 
+typedef struct {
+       plugin_ctx_t ctx;
+       void *(*start_routine) (void *);
+       void *arg;
+} plugin_thread_t;
+
+static void *plugin_thread_start (void *arg)
+{
+       plugin_thread_t *plugin_thread = arg;
+
+       void *(*start_routine) (void *) = plugin_thread->start_routine;
+       void *plugin_arg = plugin_thread->arg;
+
+       plugin_set_ctx (plugin_thread->ctx);
+
+       free (plugin_thread);
+
+       return start_routine (plugin_arg);
+} /* void *plugin_thread_start */
+
+int plugin_thread_create (pthread_t *thread, const pthread_attr_t *attr,
+               void *(*start_routine) (void *), void *arg)
+{
+       plugin_thread_t *plugin_thread;
+
+       plugin_thread = malloc (sizeof (*plugin_thread));
+       if (plugin_thread == NULL)
+               return -1;
+
+       plugin_thread->ctx           = plugin_get_ctx ();
+       plugin_thread->start_routine = start_routine;
+       plugin_thread->arg           = arg;
+
+       return pthread_create (thread, attr,
+                       plugin_thread_start, plugin_thread);
+} /* int plugin_thread_create */
+
 /* vim: set sw=8 ts=8 noet fdm=marker : */