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

Class ClassicConflictResolver

java.lang.Object

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

org.eclipse.aether.util.graph.transformer.ClassicConflictResolver

All Implemented Interfaces:

DependencyGraphTransformer

public final class ClassicConflictResolver
extends ConflictResolver

A legacy dependency graph transformer that resolves version and scope conflicts among dependencies. This implementation maintains backward compatibility with Maven 3.x and Resolver 1.x behavior but has O(N²) worst-case performance characteristics. For new projects, consider using PathConflictResolver.

For a given set of conflicting nodes, one node will be chosen as the winner. How losing nodes are handled depends on the configured verbosity level: they may be removed entirely, have their children removed, or be left in place with conflict information. 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.

Performance Characteristics:

• Time Complexity: O(N²) worst-case where N is the number of dependency nodes
• Memory Usage: Modifies the dependency graph in-place
• Scalability: Performance degrades significantly on large multi-module projects

Algorithm Overview:

1. Depth-First Traversal: Walks the dependency graph depth-first
2. In-Place Modification: Modifies nodes directly during traversal
3. Conflict Detection: Identifies conflicts by comparing conflict IDs
4. Winner Selection: Uses provided selectors to choose winners
5. Loser Removal: Removes or marks losing nodes during traversal

When to Use:

• Exact backward compatibility with Maven 3.x/Resolver 1.x is required
• Debugging performance differences between old and new algorithms
• Small projects where performance is not a concern
• Testing and validation scenarios

Migration Recommendation: New projects should use PathConflictResolver for better performance. This implementation is retained primarily for compatibility and testing purposes.

Implementation Note: This conflict resolver is identical to the one used in Maven 3/Resolver 1.x. The implementation may produce O(N²) worst-case performance on projects with many small conflict groups (typically one member each), which is common in large multi-module projects.

Since:

2.0.11

See Also:

• PathConflictResolver

Nested Class Summary

Nested classes/interfaces inherited from class org.eclipse.aether.util.graph.transformer.ConflictResolver

ConflictResolver.OptionalitySelector, ConflictResolver.ScopeDeriver, ConflictResolver.ScopeSelector, ConflictResolver.Verbosity, ConflictResolver.VersionSelector

Field Summary

Fields inherited from class org.eclipse.aether.util.graph.transformer.ConflictResolver

CLASSIC_CONFLICT_RESOLVER, CONFIG_PROP_CONFLICT_RESOLVER_IMPL, CONFIG_PROP_VERBOSE, DEFAULT_CONFLICT_RESOLVER_IMPL, NODE_DATA_ORIGINAL_OPTIONALITY, NODE_DATA_ORIGINAL_SCOPE, NODE_DATA_WINNER, PATH_CONFLICT_RESOLVER

Constructor Summary

Constructors

Constructor	Description
ClassicConflictResolver(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
DependencyNode	transformGraph(DependencyNode node, DependencyGraphTransformationContext context)	Transforms the dependency graph denoted by the specified root node.

Methods inherited from class org.eclipse.aether.util.graph.transformer.ConflictResolver

getVerbosity

Methods inherited from class java.lang.Object

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

Constructor Details

ClassicConflictResolver

public ClassicConflictResolver(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 Details

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

Overrides:

transformGraph in class ConflictResolver

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.