Modulemd.Prioritizer: Modulemd Reference Manual

Modulemd.Prioritizer

Modulemd.Prioritizer — Class to aid in merging metadata from multiple repositories.

Stability Level

Stable, unless otherwise indicated

Functions

ModulemdPrioritizer *	modulemd_prioritizer_new ()
void	modulemd_prioritizer_take_index ()
ModulemdModuleIndex *	modulemd_prioritizer_resolve ()

Types and Values

#define	MODULEMD_TYPE_PRIORITIZER
	ModulemdPrioritizer

Description

Prioritizer is used to resolve merges between multiple repository metadata sources, possibly with varying priorities.

It is expected to be used as follows (python example) by tools such as yum:

prioritizer = Modulemd.Prioritizer.new()

prioritizer.take_index(fedora_repo_index, 0)
prioritizer.take_index(updates_repo_index, 0)
prioritizer.take_index(updates_testing_repo_index, 0)

merged_index = prioritizer.resolve()

In the above code, merged_index will be a complete, merged view of the metadata from all of the added ModulemdModuleIndex instances.

When merging module streams, entries will be deduplicated based on whether they share the same module name, stream name, version number, and context. At present, libmodulemd does not interrogate more closely to determine if they have the same content, so if the repository configuration is broken and there exists two ModulemdModuleStream entries that have different content for the same NSVC, the behavior is undefined.

Merging ModulemdDefaults entries behaves as follows:

Any module default that is provided by a single repository is authoritative.
If the repos have different priorities (not common), then the default for this module and stream name coming from the repo of higher priority will be used and the default from the lower-priority repo will not be included.
If the repos have the same priority (such as "fedora" and "updates" in the Fedora Project), the entries will be merged as follows:
- If both repositories specify a default stream for the module, use it.
- If either repository specifies a default stream for the module and the other does not, use the one specified.
- If both repositories specify different streams, this is an unresolvable merge conflict and the merge resolution will fail and report an error.
- If both repositories specify a set of default profiles for a stream and the sets are equivalent, use that set.
- If one repository specifies a set of default profiles for a stream and the other does not, use the one specified.
- If both repositories specify a set of default profiles for a stream and each are providing a different set, this is an unresolvable merge conflict and the merge resolution will fail and report an error.

Merging ModulemdTranslations entries behaves as follows:

For each translated summary, description and profile description, compare the modified value of the Translation document matching this module name and stream. Whichever has the higher value will be used. Any translation containing the empty string will be interpreted as removing the translation. Subsequent processing of a higher modified value may restore it.

Functions

modulemd_prioritizer_new ()

ModulemdPrioritizer *
modulemd_prioritizer_new (void);

Returns

A newly-allocated Modulemd.Prioritizer object.

[transfer full]

Since: 2.0

modulemd_prioritizer_take_index ()

void
modulemd_prioritizer_take_index (ModulemdPrioritizer *self,
                                 ModulemdModuleIndex *index,
                                 guint16 priority);

Enqueues a ModulemdModuleIndex representing the parsed metadata from a repository into this ModulemdPrioritizer for merging and deduplication of other repositories.

Once all repositories have been added, call modulemd_prioritizer_resolve() to perform the merge.

Parameters

self	This ModulemdPrioritizer object.	[in]
index	A ModuleIndex, usually constructed by reading the module metadata from a repository with `modulemd_module_index_update_from_file()`, `modulemd_module_index_update_from_string()`, or `modulemd_module_index_update_from_stream()`. This function assumes ownership of `index` , so the caller must not free it.	[in][transfer full]
priority	The priority of the repository that the entries in `index` came from. This is used to determine when `index` should override rather then merge. In most cases, this will be zero. See the Description section for the ModulemdPrioritizer class for details on the merge logic.	[in]

Since: 2.0

modulemd_prioritizer_resolve ()

ModulemdModuleIndex *
modulemd_prioritizer_resolve (ModulemdPrioritizer *self,
                              GError **error);

Merges all added ModulemdModuleIndex objects according to their priority. The logic of this merge is described in the Description of ModulemdPrioritizer.

Once this function has been called, the internal state of the ModulemdPrioritizer is undefined. The only valid action on it after that point is g_object_unref().

Parameters

self	This ModulemdPrioritizer object.	[in]
error	A GError containing the reason for a failure to resolve the merges.	[out]

Returns

A newly-allocated ModulemdModuleIndex containing the merged results. If this function encounters an unresolvable merge conflict, it will return NULL and set error appropriately.

[transfer full]

Since: 2.0

Types and Values

MODULEMD_TYPE_PRIORITIZER

#define MODULEMD_TYPE_PRIORITIZER (modulemd_prioritizer_get_type ())

ModulemdPrioritizer

typedef struct _ModulemdPrioritizer ModulemdPrioritizer;