LIBTRACEEVENT(3)

NAME
tep_load_plugins, tep_unload_plugins, tep_load_plugins_hook, tep_add_plugin_path, tep_plugin_add_option - Load / unload traceevent plugins.

SYNOPSIS

#include <event-parse.h>

struct tep_plugin_list *tep_load_plugins(struct tep_handle *tep);
void tep_unload_plugins(struct tep_plugin_list *plugin_list, struct tep_handle *tep);
void tep_load_plugins_hook(struct tep_handle *tep, const char *suffix,
                           void (*load_plugin)(struct tep_handle *tep,
                                               const char *path,
                                               const char *name,
                                               void *data),
                           void *data);
int tep_add_plugin_path(struct tep_handle *tep, char *path,
                          enum tep_plugin_load_priority prio);
int tep_plugin_add_option(const char *name, const char *val);

DESCRIPTION

The tep_load_plugins() function loads all plugins, located in the plugin directories. The tep argument is trace event parser context. The plugin directories are :

            - Directories, specified in tep→plugins_dir with priority TEP_PLUGIN_FIRST
            - System’s plugin directory, defined at the library compile time. It
              depends on the library installation prefix and usually is
              (install_preffix)/lib/traceevent/plugins
            - Directory, defined by the environment variable TRACEEVENT_PLUGIN_DIR
            - User’s plugin directory, located at ~/.local/lib/traceevent/plugins
            - Directories, specified in tep→plugins_dir with priority TEP_PLUGIN_LAST

Loading of plugins can be controlled by the tep_flags, using the tep_set_flag() API:

            TEP_DISABLE_SYS_PLUGINS       - do not load plugins, located in
                                            the system’s plugin directory.
            TEP_DISABLE_PLUGINS           - do not load any plugins.

The tep_set_flag() API needs to be called before tep_load_plugins(), if loading of all plugins is not the desired case.

The tep_unload_plugins() function unloads the plugins, previously loaded by tep_load_plugins(). The tep argument is trace event parser context. The plugin_list is the list of loaded plugins, returned by the tep_load_plugins() function.

The tep_load_plugins_hook() function walks through all directories with plugins and calls user specified load_plugin() hook for each plugin file. Only files with given suffix are considered to be plugins. The data is a user specified context, passed to load_plugin(). Directories and the walk order are the same as in tep_load_plugins() API.

The tep_add_plugin_path() functions adds additional directories with plugins in the tep→plugins_dir list. It must be called before tep_load_plugins() in order for the plugins from the new directories to be loaded. The tep argument is the trace event parser context. The path is the full path to the new plugin directory. The prio argument specifies the loading priority order for the new directory of plugins. The loading priority is important in case of different versions of the same plugin located in multiple plugin directories.The last loaded plugin wins. The priority can be:

            TEP_PLUGIN_FIRST      - Load plugins from this directory first
            TEP_PLUGIN_LAST       - Load plugins from this directory last

Where the plugins in TEP_PLUGIN_LAST" will take precedence over the plugins in the other directories.

The tep_plugin_add_option() sets options defined by a plugin. The name is the name of the option to set to val. Plugins can add options to change its behavior and tep_plugin_add_option() is used by the application to make those modifications.

RETURN VALUE

The tep_load_plugins() function returns a list of successfully loaded plugins, or NULL in case no plugins are loaded. The tep_add_plugin_path() function returns -1 in case of an error, 0 otherwise.

EXAMPLE

    #include <event-parse.h>
    ...
    struct tep_handle *tep = tep_alloc();
    ...
    tep_add_plugin_path(tep, "~/dev_plugins", TEP_PLUGIN_LAST);
    ...
    struct tep_plugin_list *plugins = tep_load_plugins(tep);
    if (plugins == NULL) {
            /* no plugins are loaded */
    }
    ...
    tep_unload_plugins(plugins, tep);
    ...
    void print_plugin(struct tep_handle *tep, const char *path,
                      const char *name, void *data)
    {
            pritnf("Found libtraceevent plugin %s/%s\n", path, name);
    }
    ...
    tep_load_plugins_hook(tep, ".so", print_plugin, NULL);
    ...

FILES

    event-parse.h
            Header file to include in order to have access to the library APIs.
    -ltraceevent
            Linker switch to add when building a program that uses the library.

SEE ALSO

libtraceevent(3), trace-cmd(1), tep_set_flag(3)

AUTHOR

    Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
    Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, author of this man page.

REPORTING BUGS

Report bugs to <linux-trace-devel@vger.kernel.org[3]>

LICENSE

libtraceevent is Free Software licensed under the GNU LGPL 2.1

RESOURCES

https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/

NOTES

1.  rostedt@goodmis.org
    mailto:rostedt@goodmis.org

2.  tz.stoyanov@gmail.com
    mailto:tz.stoyanov@gmail.com

3.  linux-trace-devel@vger.kernel.org
    mailto:linux-trace-devel@vger.kernel.org