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/*
* Copyright © 2013-2016 Inria. All rights reserved.
* See COPYING in top-level directory.
*/
/** \file
* \brief Topology differences.
*/
#ifndef HWLOC_DIFF_H
#define HWLOC_DIFF_H
#ifndef HWLOC_H
#error Please include the main hwloc.h instead
#endif
#ifdef __cplusplus
extern "C" {
#elif 0
}
#endif
/** \defgroup hwlocality_diff Topology differences
*
* Applications that manipulate many similar topologies, for instance
* one for each node of a homogeneous cluster, may want to compress
* topologies to reduce the memory footprint.
*
* This file offers a way to manipulate the difference between topologies
* and export/import it to/from XML.
* Compression may therefore be achieved by storing one topology
* entirely while the others are only described by their differences
* with the former.
* The actual topology can be reconstructed when actually needed by
* applying the precomputed difference to the reference topology.
*
* This interface targets very similar nodes.
* Only very simple differences between topologies are actually
* supported, for instance a change in the memory size, the name
* of the object, or some info attribute.
* More complex differences such as adding or removing objects cannot
* be represented in the difference structures and therefore return
* errors.
*
* It means that there is no need to apply the difference when
* looking at the tree organization (how many levels, how many
* objects per level, what kind of objects, CPU and node sets, etc)
* and when binding to objects.
* However the difference must be applied when looking at object
* attributes such as the name, the memory size or info attributes.
*
* @{
*/
/** \brief Type of one object attribute difference.
*/
typedef enum hwloc_topology_diff_obj_attr_type_e {
/** \brief The object local memory is modified.
* The union is a hwloc_topology_diff_obj_attr_u::hwloc_topology_diff_obj_attr_uint64_s
* (and the index field is ignored).
*/
HWLOC_TOPOLOGY_DIFF_OBJ_ATTR_SIZE,
/** \brief The object name is modified.
* The union is a hwloc_topology_diff_obj_attr_u::hwloc_topology_diff_obj_attr_string_s
* (and the name field is ignored).
*/
HWLOC_TOPOLOGY_DIFF_OBJ_ATTR_NAME,
/** \brief the value of an info attribute is modified.
* The union is a hwloc_topology_diff_obj_attr_u::hwloc_topology_diff_obj_attr_string_s.
*/
HWLOC_TOPOLOGY_DIFF_OBJ_ATTR_INFO
} hwloc_topology_diff_obj_attr_type_t;
/** \brief One object attribute difference.
*/
union hwloc_topology_diff_obj_attr_u {
struct hwloc_topology_diff_obj_attr_generic_s {
/* each part of the union must start with these */
hwloc_topology_diff_obj_attr_type_t type;
} generic;
/** \brief Integer attribute modification with an optional index. */
struct hwloc_topology_diff_obj_attr_uint64_s {
/* used for storing integer attributes */
hwloc_topology_diff_obj_attr_type_t type;
hwloc_uint64_t index; /* not used for SIZE */
hwloc_uint64_t oldvalue;
hwloc_uint64_t newvalue;
} uint64;
/** \brief String attribute modification with an optional name */
struct hwloc_topology_diff_obj_attr_string_s {
/* used for storing name and info pairs */
hwloc_topology_diff_obj_attr_type_t type;
char *name; /* not used for NAME */
char *oldvalue;
char *newvalue;
} string;
};
/** \brief Type of one element of a difference list.
*/
typedef enum hwloc_topology_diff_type_e {
/** \brief An object attribute was changed.
* The union is a hwloc_topology_diff_obj_attr_u::hwloc_topology_diff_obj_attr_s.
*/
HWLOC_TOPOLOGY_DIFF_OBJ_ATTR,
/** \brief The difference is too complex,
* it cannot be represented. The difference below
* this object has not been checked.
* hwloc_topology_diff_build() will return 1.
*
* The union is a hwloc_topology_diff_obj_attr_u::hwloc_topology_diff_too_complex_s.
*/
HWLOC_TOPOLOGY_DIFF_TOO_COMPLEX
} hwloc_topology_diff_type_t;
/** \brief One element of a difference list between two topologies.
*/
typedef union hwloc_topology_diff_u {
struct hwloc_topology_diff_generic_s {
/* each part of the union must start with these */
hwloc_topology_diff_type_t type;
union hwloc_topology_diff_u * next; /* pointer to the next element of the list, or NULL */
} generic;
/* A difference in an object attribute. */
struct hwloc_topology_diff_obj_attr_s {
hwloc_topology_diff_type_t type; /* must be ::HWLOC_TOPOLOGY_DIFF_OBJ_ATTR */
union hwloc_topology_diff_u * next;
/* List of attribute differences for a single object */
unsigned obj_depth;
unsigned obj_index;
union hwloc_topology_diff_obj_attr_u diff;
} obj_attr;
/* A difference that is too complex. */
struct hwloc_topology_diff_too_complex_s {
hwloc_topology_diff_type_t type; /* must be ::HWLOC_TOPOLOGY_DIFF_TOO_COMPLEX */
union hwloc_topology_diff_u * next;
/* Where we had to stop computing the diff in the first topology */
unsigned obj_depth;
unsigned obj_index;
} too_complex;
} * hwloc_topology_diff_t;
/** \brief Compute the difference between 2 topologies.
*
* The difference is stored as a list of ::hwloc_topology_diff_t entries
* starting at \p diff.
* It is computed by doing a depth-first traversal of both topology trees
* simultaneously.
*
* If the difference between 2 objects is too complex to be represented
* (for instance if some objects have different types, or different numbers
* of children), a special diff entry of type ::HWLOC_TOPOLOGY_DIFF_TOO_COMPLEX
* is queued.
* The computation of the diff does not continue below these objects.
* So each such diff entry means that the difference between two subtrees
* could not be computed.
*
* \return 0 if the difference can be represented properly.
*
* \return 0 with \p diff pointing to NULL if there is no difference
* between the topologies.
*
* \return 1 if the difference is too complex (see above). Some entries in
* the list will be of type ::HWLOC_TOPOLOGY_DIFF_TOO_COMPLEX.
*
* \return -1 on any other error.
*
* \note \p flags is currently not used. It should be 0.
*
* \note The output diff has to be freed with hwloc_topology_diff_destroy().
*
* \note The output diff can only be exported to XML or passed to
* hwloc_topology_diff_apply() if 0 was returned, i.e. if no entry of type
* ::HWLOC_TOPOLOGY_DIFF_TOO_COMPLEX is listed.
*
* \note The output diff may be modified by removing some entries from
* the list. The removed entries should be freed by passing them to
* to hwloc_topology_diff_destroy() (possible as another list).
*/
HWLOC_DECLSPEC int hwloc_topology_diff_build(hwloc_topology_t topology, hwloc_topology_t newtopology, unsigned long flags, hwloc_topology_diff_t *diff);
/** \brief Flags to be given to hwloc_topology_diff_apply().
*/
enum hwloc_topology_diff_apply_flags_e {
/** \brief Apply topology diff in reverse direction.
* \hideinitializer
*/
HWLOC_TOPOLOGY_DIFF_APPLY_REVERSE = (1UL<<0)
};
/** \brief Apply a topology diff to an existing topology.
*
* \p flags is an OR'ed set of ::hwloc_topology_diff_apply_flags_e.
*
* The new topology is modified in place. hwloc_topology_dup()
* may be used to duplicate it before patching.
*
* If the difference cannot be applied entirely, all previous applied
* elements are unapplied before returning.
*
* \return 0 on success.
*
* \return -N if applying the difference failed while trying
* to apply the N-th part of the difference. For instance -1
* is returned if the very first difference element could not
* be applied.
*/
HWLOC_DECLSPEC int hwloc_topology_diff_apply(hwloc_topology_t topology, hwloc_topology_diff_t diff, unsigned long flags);
/** \brief Destroy a list of topology differences.
*
* \note The \p topology parameter must be a valid topology
* but it is not required that it is related to \p diff.
*/
HWLOC_DECLSPEC int hwloc_topology_diff_destroy(hwloc_topology_t topology, hwloc_topology_diff_t diff);
/** \brief Load a list of topology differences from a XML file.
*
* If not \c NULL, \p refname will be filled with the identifier
* string of the reference topology for the difference file,
* if any was specified in the XML file.
* This identifier is usually the name of the other XML file
* that contains the reference topology.
*
* \note The \p topology parameter must be a valid topology
* but it is not required that it is related to \p diff.
*
* \note the pointer returned in refname should later be freed
* by the caller.
*/
HWLOC_DECLSPEC int hwloc_topology_diff_load_xml(hwloc_topology_t topology, const char *xmlpath, hwloc_topology_diff_t *diff, char **refname);
/** \brief Export a list of topology differences to a XML file.
*
* If not \c NULL, \p refname defines an identifier string
* for the reference topology which was used as a base when
* computing this difference.
* This identifier is usually the name of the other XML file
* that contains the reference topology.
* This attribute is given back when reading the diff from XML.
*
* \note The \p topology parameter must be a valid topology
* but it is not required that it is related to \p diff.
*/
HWLOC_DECLSPEC int hwloc_topology_diff_export_xml(hwloc_topology_t topology, hwloc_topology_diff_t diff, const char *refname, const char *xmlpath);
/** \brief Load a list of topology differences from a XML buffer.
*
* If not \c NULL, \p refname will be filled with the identifier
* string of the reference topology for the difference file,
* if any was specified in the XML file.
* This identifier is usually the name of the other XML file
* that contains the reference topology.
*
* \note The \p topology parameter must be a valid topology
* but it is not required that it is related to \p diff.
*
* \note the pointer returned in refname should later be freed
* by the caller.
*/
HWLOC_DECLSPEC int hwloc_topology_diff_load_xmlbuffer(hwloc_topology_t topology, const char *xmlbuffer, int buflen, hwloc_topology_diff_t *diff, char **refname);
/** \brief Export a list of topology differences to a XML buffer.
*
* If not \c NULL, \p refname defines an identifier string
* for the reference topology which was used as a base when
* computing this difference.
* This identifier is usually the name of the other XML file
* that contains the reference topology.
* This attribute is given back when reading the diff from XML.
*
* \note The XML buffer should later be freed with hwloc_free_xmlbuffer().
*
* \note The \p topology parameter must be a valid topology
* but it is not required that it is related to \p diff.
*/
HWLOC_DECLSPEC int hwloc_topology_diff_export_xmlbuffer(hwloc_topology_t topology, hwloc_topology_diff_t diff, const char *refname, char **xmlbuffer, int *buflen);
/** @} */
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* HWLOC_DIFF_H */
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