src/common/plugrack.h

/*****************************************************************************\
 *  plugrack.h - an intelligent container for plugins
 *****************************************************************************
 *  Copyright (C) 2002 The Regents of the University of California.
 *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
 *  Written by Jay Windley <jwindley@lnxi.com>.
 *  CODE-OCEC-09-009. All rights reserved.
 *
 *  This file is part of Slurm, a resource management program.
 *  For details, see <https://slurm.schedmd.com/>.
 *  Please also read the included file: DISCLAIMER.
 *
 *  Slurm is free software; you can redistribute it and/or modify it under
 *  the terms of the GNU General Public License as published by the Free
 *  Software Foundation; either version 2 of the License, or (at your option)
 *  any later version.
 *
 *  In addition, as a special exception, the copyright holders give permission
 *  to link the code of portions of this program with the OpenSSL library under
 *  certain conditions as described in each individual source file, and
 *  distribute linked combinations including the two. You must obey the GNU
 *  General Public License in all respects for all of the code used other than
 *  OpenSSL. If you modify file(s) with this exception, you may extend this
 *  exception to your version of the file(s), but you are not obligated to do
 *  so. If you do not wish to do so, delete this exception statement from your
 *  version.  If you delete this exception statement from all source files in
 *  the program, then also delete it here.
 *
 *  Slurm is distributed in the hope that it will be useful, but WITHOUT ANY
 *  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 *  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 *  details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with Slurm; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA.
\*****************************************************************************/

#ifndef __PLUGRACK_H__
#define __PLUGRACK_H__

#include <sys/types.h>

#include "src/common/plugin.h"
#include "src/common/list.h"

/* Opaque type for plugin rack. */
typedef struct _plugrack plugrack_t;

/*
 * Returns a new plugin rack object for a provided major type.
 */
plugrack_t *plugrack_create(const char *major_type);

/*
 * Destroy a plugin rack.  All the associated plugins are unloaded and
 * all associated memory is deallocated.
 *
 * Returns a Slurm errno.
 */
int plugrack_destroy(plugrack_t *rack);

/*
 * Add plugins to a rack by scanning the given directory.  If a
 * type has been set for this rack, only those plugins whose major type
 * matches the rack's type will be loaded.
 *
 * Returns a Slurm errno.
 */
int plugrack_read_dir(plugrack_t *rack, const char *dir);

/*
 * Find a plugin in the rack which matches the given minor type,
 * load it if necessary, and return a handle to it.
 *
 * Returns PLUGIN_INVALID_HANDLE if a suitable plugin cannot be
 * found or loaded.
 */
plugin_handle_t plugrack_use_by_type(plugrack_t *rack, const char *type);

/*
 * Find a plugin in the rack which matches the given minor type,
 * and unload it if ref count is <= 0.
 */
extern void plugrack_release_by_type(plugrack_t *rack, const char *type);

/*
 * print all MPI plugins in rack
 *
 * Returns a Slurm errno.
 */
int plugrack_print_mpi_plugins(plugrack_t *rack);

/*
 * Call function f for each plugin found in rack
 */
typedef void (*plugrack_foreach_t)(const char *full_type, const char *fq_path,
				   const plugin_handle_t id, void *arg);
extern void plugrack_foreach(plugrack_t *rack, plugrack_foreach_t f, void *arg);

#define PLUGINS_MAGIC 0x3ddfdab5
typedef struct {
	int magic;
	/* array of pointer to function ptr structs */
	void **functions;
	plugin_handle_t *handles;
	char **types;
	size_t count;
	plugrack_t *rack;
} plugins_t;

/*
 * Load a given list of plugins
 * IN/OUT plugins_ptr - ptr to ptr of plugins to populate.
 * 	*ptr may be NULL or will use existing plugins
 * IN major_type - major type of plugin
 * IN plugin_list - comma delimited list of plugins
 * IN listf - callback on each possible plugin if plugin_list="list".
 * 	A "list" request only enumerates. *plugins_ptr is left untouched, so it
 * 	is still NULL on return when it was NULL on entry.
 * RET SLURM_SUCCESS, or an error only when *plugins_ptr was NULL on entry.
 * 	A failed load into an already populated *plugins_ptr calls fatal()
 * 	instead of returning, because the entries the failed call added cannot
 * 	be taken back out of the caller's set.
 */
extern int load_plugins(plugins_t **plugins_ptr, const char *major_type,
			const char *plugin_list, plugrack_foreach_t listf,
			const char **syms, size_t syms_count);
/*
 * unload and release a given list of plugins
 *
 * Call FREE_NULL_PLUGINS() instead
 */
extern void unload_plugins(plugins_t *plugins);

#define FREE_NULL_PLUGINS(_X)               \
	do {                                \
		if (_X)                     \
			unload_plugins(_X); \
		_X = NULL;                  \
	} while (0)

#endif /*__PLUGRACK_H__*/