Package org.eclipse.aether.util.graph.transformer

Class ConflictResolver

java.lang.Object

org.eclipse.aether.util.graph.transformer.ConflictResolver

All Implemented Interfaces:

DependencyGraphTransformer

public final class ConflictResolver
extends java.lang.Object
implements DependencyGraphTransformer

A dependency graph transformer that resolves version and scope conflicts among dependencies. For a given set of conflicting nodes, one node will be chosen as the winner and the other nodes are removed from the dependency graph. The exact rules by which a winning node and its effective scope are determined are controlled by user-supplied implementations of ConflictResolver.VersionSelector, ConflictResolver.ScopeSelector, ConflictResolver.OptionalitySelector and ConflictResolver.ScopeDeriver.

By default, this graph transformer will turn the dependency graph into a tree without duplicate artifacts. Using the configuration property CONFIG_PROP_VERBOSE, a verbose mode can be enabled where the graph is still turned into a tree but all nodes participating in a conflict are retained. The nodes that were rejected during conflict resolution have no children and link back to the winner node via the NODE_DATA_WINNER key in their custom data. Additionally, the keys NODE_DATA_ORIGINAL_SCOPE and NODE_DATA_ORIGINAL_OPTIONALITY are used to store the original scope and optionality of each node. Obviously, the resulting dependency tree is not suitable for artifact resolution unless a filter is employed to exclude the duplicate dependencies.

This transformer will query the keys TransformationContextKeys.CONFLICT_IDS, TransformationContextKeys.SORTED_CONFLICT_IDS, TransformationContextKeys.CYCLIC_CONFLICT_IDS for existing information about conflict ids. In absence of this information, it will automatically invoke the ConflictIdSorter to calculate it.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ConflictResolver.ConflictContext	A context used to hold information that is relevant for resolving version and scope conflicts.
static class	ConflictResolver.ConflictItem	A conflicting dependency.
(package private) static class	ConflictResolver.NodeInfo
static class	ConflictResolver.OptionalitySelector	An extension point of ConflictResolver that determines the effective optional flag of a dependency from a potentially conflicting set of derived optionalities.
static class	ConflictResolver.ScopeContext	A context used to hold information that is relevant for deriving the scope of a child dependency.
static class	ConflictResolver.ScopeDeriver	An extension point of ConflictResolver that determines the scope of a dependency in relation to the scope of its parent.
static class	ConflictResolver.ScopeSelector	An extension point of ConflictResolver that determines the effective scope of a dependency from a potentially conflicting set of derived scopes.
(package private) class	ConflictResolver.State
static class	ConflictResolver.VersionSelector	An extension point of ConflictResolver that determines the winner among conflicting dependencies.

Field Summary

Fields

Modifier and Type	Field	Description
static java.lang.String	CONFIG_PROP_VERBOSE	The key in the repository session's configuration properties used to store a Boolean flag controlling the transformer's verbose mode.
static java.lang.String	NODE_DATA_ORIGINAL_OPTIONALITY	The key in the dependency node's custom data under which the optional flag of the dependency before derivation and conflict resolution is stored.
static java.lang.String	NODE_DATA_ORIGINAL_SCOPE	The key in the dependency node's custom data under which the scope of the dependency before scope derivation and conflict resolution is stored.
static java.lang.String	NODE_DATA_WINNER	The key in the dependency node's custom data under which a reference to the DependencyNode which has won the conflict is stored.
private ConflictResolver.OptionalitySelector	optionalitySelector
private ConflictResolver.ScopeDeriver	scopeDeriver
private ConflictResolver.ScopeSelector	scopeSelector
private ConflictResolver.VersionSelector	versionSelector

Constructor Summary

Constructors

Constructor	Description
ConflictResolver(ConflictResolver.VersionSelector versionSelector, ConflictResolver.ScopeSelector scopeSelector, ConflictResolver.OptionalitySelector optionalitySelector, ConflictResolver.ScopeDeriver scopeDeriver)	Creates a new conflict resolver instance with the specified hooks.

Method Summary

Modifier and Type	Method	Description
private boolean	gatherConflictItems(DependencyNode node, ConflictResolver.State state)
private void	removeLosers(ConflictResolver.State state)
DependencyNode	transformGraph(DependencyNode node, DependencyGraphTransformationContext context)	Transforms the dependency graph denoted by the specified root node.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CONFIG_PROP_VERBOSE

public static final java.lang.String CONFIG_PROP_VERBOSE

The key in the repository session's configuration properties used to store a Boolean flag controlling the transformer's verbose mode.

See Also:

Constant Field Values

NODE_DATA_WINNER

public static final java.lang.String NODE_DATA_WINNER

The key in the dependency node's custom data under which a reference to the DependencyNode which has won the conflict is stored.

See Also:

Constant Field Values

NODE_DATA_ORIGINAL_SCOPE

public static final java.lang.String NODE_DATA_ORIGINAL_SCOPE

The key in the dependency node's custom data under which the scope of the dependency before scope derivation and conflict resolution is stored.

See Also:

Constant Field Values

NODE_DATA_ORIGINAL_OPTIONALITY

public static final java.lang.String NODE_DATA_ORIGINAL_OPTIONALITY

The key in the dependency node's custom data under which the optional flag of the dependency before derivation and conflict resolution is stored.

See Also:

Constant Field Values

versionSelector

private final ConflictResolver.VersionSelector versionSelector

scopeSelector

private final ConflictResolver.ScopeSelector scopeSelector

scopeDeriver

private final ConflictResolver.ScopeDeriver scopeDeriver

optionalitySelector

private final ConflictResolver.OptionalitySelector optionalitySelector

Constructor Detail

ConflictResolver

public ConflictResolver(ConflictResolver.VersionSelector versionSelector,
                        ConflictResolver.ScopeSelector scopeSelector,
                        ConflictResolver.OptionalitySelector optionalitySelector,
                        ConflictResolver.ScopeDeriver scopeDeriver)

Creates a new conflict resolver instance with the specified hooks.

Parameters:

versionSelector - The version selector to use, must not be null.

scopeSelector - The scope selector to use, must not be null.

optionalitySelector - The optionality selector ot use, must not be null.

scopeDeriver - The scope deriver to use, must not be null.

Method Detail

transformGraph

public DependencyNode transformGraph(DependencyNode node,
                                     DependencyGraphTransformationContext context)
                              throws RepositoryException

Description copied from interface: DependencyGraphTransformer

Transforms the dependency graph denoted by the specified root node. The transformer may directly change the provided input graph or create a new graph, the former is recommended for performance reasons.

Specified by:

transformGraph in interface DependencyGraphTransformer

Parameters:

node - The root node of the (possibly cyclic!) graph to transform, must not be null.

context - The graph transformation context, must not be null.

Returns:

The result graph of the transformation, never null.

Throws:

RepositoryException - If the transformation failed.

gatherConflictItems

private boolean gatherConflictItems(DependencyNode node,
                                    ConflictResolver.State state)
                             throws RepositoryException

Throws:

RepositoryException

removeLosers

private void removeLosers(ConflictResolver.State state)