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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.eclipse.aether.internal.impl;
20  
21  import javax.inject.Inject;
22  import javax.inject.Named;
23  import javax.inject.Singleton;
24  
25  import java.io.IOException;
26  import java.nio.file.Files;
27  import java.nio.file.Path;
28  import java.nio.file.Paths;
29  import java.util.ArrayList;
30  import java.util.Collection;
31  import java.util.Collections;
32  import java.util.Iterator;
33  import java.util.List;
34  import java.util.Map;
35  import java.util.concurrent.atomic.AtomicBoolean;
36  
37  import org.eclipse.aether.ConfigurationProperties;
38  import org.eclipse.aether.RepositoryEvent;
39  import org.eclipse.aether.RepositoryEvent.EventType;
40  import org.eclipse.aether.RepositorySystemSession;
41  import org.eclipse.aether.RequestTrace;
42  import org.eclipse.aether.SyncContext;
43  import org.eclipse.aether.artifact.Artifact;
44  import org.eclipse.aether.impl.ArtifactResolver;
45  import org.eclipse.aether.impl.OfflineController;
46  import org.eclipse.aether.impl.RemoteRepositoryFilterManager;
47  import org.eclipse.aether.impl.RemoteRepositoryManager;
48  import org.eclipse.aether.impl.RepositoryConnectorProvider;
49  import org.eclipse.aether.impl.RepositoryEventDispatcher;
50  import org.eclipse.aether.impl.UpdateCheck;
51  import org.eclipse.aether.impl.UpdateCheckManager;
52  import org.eclipse.aether.impl.VersionResolver;
53  import org.eclipse.aether.repository.ArtifactRepository;
54  import org.eclipse.aether.repository.LocalArtifactRegistration;
55  import org.eclipse.aether.repository.LocalArtifactRequest;
56  import org.eclipse.aether.repository.LocalArtifactResult;
57  import org.eclipse.aether.repository.LocalRepository;
58  import org.eclipse.aether.repository.LocalRepositoryManager;
59  import org.eclipse.aether.repository.RemoteRepository;
60  import org.eclipse.aether.repository.RepositoryPolicy;
61  import org.eclipse.aether.repository.WorkspaceReader;
62  import org.eclipse.aether.resolution.ArtifactRequest;
63  import org.eclipse.aether.resolution.ArtifactResolutionException;
64  import org.eclipse.aether.resolution.ArtifactResult;
65  import org.eclipse.aether.resolution.ResolutionErrorPolicy;
66  import org.eclipse.aether.resolution.VersionRequest;
67  import org.eclipse.aether.resolution.VersionResolutionException;
68  import org.eclipse.aether.resolution.VersionResult;
69  import org.eclipse.aether.scope.SystemDependencyScope;
70  import org.eclipse.aether.spi.connector.ArtifactDownload;
71  import org.eclipse.aether.spi.connector.RepositoryConnector;
72  import org.eclipse.aether.spi.connector.filter.RemoteRepositoryFilter;
73  import org.eclipse.aether.spi.io.PathProcessor;
74  import org.eclipse.aether.spi.resolution.ArtifactResolverPostProcessor;
75  import org.eclipse.aether.spi.synccontext.SyncContextFactory;
76  import org.eclipse.aether.transfer.ArtifactFilteredOutException;
77  import org.eclipse.aether.transfer.ArtifactNotFoundException;
78  import org.eclipse.aether.transfer.ArtifactTransferException;
79  import org.eclipse.aether.transfer.NoRepositoryConnectorException;
80  import org.eclipse.aether.transfer.RepositoryOfflineException;
81  import org.eclipse.aether.util.ConfigUtils;
82  import org.slf4j.Logger;
83  import org.slf4j.LoggerFactory;
84  
85  import static java.util.Objects.requireNonNull;
86  
87  /**
88   *
89   */
90  @Singleton
91  @Named
92  public class DefaultArtifactResolver implements ArtifactResolver {
93  
94      public static final String CONFIG_PROPS_PREFIX = ConfigurationProperties.PREFIX_AETHER + "artifactResolver.";
95  
96      /**
97       * Configuration to enable "snapshot normalization", downloaded snapshots from remote with timestamped file names
98       * will have file names converted back to baseVersion. It replaces the timestamped snapshot file name with a
99       * filename containing the SNAPSHOT qualifier only. This only affects resolving/retrieving artifacts but not
100      * uploading those.
101      *
102      * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
103      * @configurationType {@link java.lang.Boolean}
104      * @configurationDefaultValue {@link #DEFAULT_SNAPSHOT_NORMALIZATION}
105      */
106     public static final String CONFIG_PROP_SNAPSHOT_NORMALIZATION = CONFIG_PROPS_PREFIX + "snapshotNormalization";
107 
108     public static final boolean DEFAULT_SNAPSHOT_NORMALIZATION = true;
109 
110     /**
111      * Configuration to enable "interoperability" with Simple LRM, but this breaks RRF feature, hence this configuration
112      * is IGNORED when RRF is used, and is warmly recommended to leave it disabled even if no RRF is being used.
113      *
114      * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
115      * @configurationType {@link java.lang.Boolean}
116      * @configurationDefaultValue {@link #DEFAULT_SIMPLE_LRM_INTEROP}
117      */
118     public static final String CONFIG_PROP_SIMPLE_LRM_INTEROP = CONFIG_PROPS_PREFIX + "simpleLrmInterop";
119 
120     public static final boolean DEFAULT_SIMPLE_LRM_INTEROP = false;
121 
122     /**
123      * Configuration to restore the legacy "existence check" behavior for artifacts that are present in the local
124      * repository but were cached from a remote repository unavailable in the current build context: when enabled, a
125      * bare remote existence check (no content transfer, hence no checksum validation) suffices to re-label the cached
126      * bytes as originating from the queried repository. When disabled (the default), the artifact is downloaded again
127      * through the regular transfer path, so the content is validated against the repository's checksum policy before
128      * it is registered with the local repository for that repository. Enabling this trades integrity for bandwidth
129      * and is warmly recommended to leave it disabled.
130      *
131      * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
132      * @configurationType {@link java.lang.Boolean}
133      * @configurationDefaultValue {@link #DEFAULT_EXISTENCE_CHECK_RELABEL}
134      */
135     public static final String CONFIG_PROP_EXISTENCE_CHECK_RELABEL = CONFIG_PROPS_PREFIX + "existenceCheckRelabel";
136 
137     public static final boolean DEFAULT_EXISTENCE_CHECK_RELABEL = false;
138 
139     private static final Logger LOGGER = LoggerFactory.getLogger(DefaultArtifactResolver.class);
140 
141     private final PathProcessor pathProcessor;
142 
143     private final RepositoryEventDispatcher repositoryEventDispatcher;
144 
145     private final VersionResolver versionResolver;
146 
147     private final UpdateCheckManager updateCheckManager;
148 
149     private final RepositoryConnectorProvider repositoryConnectorProvider;
150 
151     private final RemoteRepositoryManager remoteRepositoryManager;
152 
153     private final SyncContextFactory syncContextFactory;
154 
155     private final OfflineController offlineController;
156 
157     private final Map<String, ArtifactResolverPostProcessor> artifactResolverPostProcessors;
158 
159     private final RemoteRepositoryFilterManager remoteRepositoryFilterManager;
160 
161     @SuppressWarnings("checkstyle:parameternumber")
162     @Inject
163     public DefaultArtifactResolver(
164             PathProcessor pathProcessor,
165             RepositoryEventDispatcher repositoryEventDispatcher,
166             VersionResolver versionResolver,
167             UpdateCheckManager updateCheckManager,
168             RepositoryConnectorProvider repositoryConnectorProvider,
169             RemoteRepositoryManager remoteRepositoryManager,
170             SyncContextFactory syncContextFactory,
171             OfflineController offlineController,
172             Map<String, ArtifactResolverPostProcessor> artifactResolverPostProcessors,
173             RemoteRepositoryFilterManager remoteRepositoryFilterManager) {
174         this.pathProcessor = requireNonNull(pathProcessor, "path processor cannot be null");
175         this.repositoryEventDispatcher =
176                 requireNonNull(repositoryEventDispatcher, "repository event dispatcher cannot be null");
177         this.versionResolver = requireNonNull(versionResolver, "version resolver cannot be null");
178         this.updateCheckManager = requireNonNull(updateCheckManager, "update check manager cannot be null");
179         this.repositoryConnectorProvider =
180                 requireNonNull(repositoryConnectorProvider, "repository connector provider cannot be null");
181         this.remoteRepositoryManager =
182                 requireNonNull(remoteRepositoryManager, "remote repository provider cannot be null");
183         this.syncContextFactory = requireNonNull(syncContextFactory, "sync context factory cannot be null");
184         this.offlineController = requireNonNull(offlineController, "offline controller cannot be null");
185         this.artifactResolverPostProcessors =
186                 requireNonNull(artifactResolverPostProcessors, "artifact resolver post-processors cannot be null");
187         this.remoteRepositoryFilterManager =
188                 requireNonNull(remoteRepositoryFilterManager, "remote repository filter manager cannot be null");
189     }
190 
191     @Override
192     public ArtifactResult resolveArtifact(RepositorySystemSession session, ArtifactRequest request)
193             throws ArtifactResolutionException {
194         requireNonNull(session, "session cannot be null");
195         requireNonNull(request, "request cannot be null");
196 
197         return resolveArtifacts(session, Collections.singleton(request)).get(0);
198     }
199 
200     @Override
201     public List<ArtifactResult> resolveArtifacts(
202             RepositorySystemSession session, Collection<? extends ArtifactRequest> requests)
203             throws ArtifactResolutionException {
204         requireNonNull(session, "session cannot be null");
205         requireNonNull(requests, "requests cannot be null");
206         Collection<Artifact> artifacts = new ArrayList<>(requests.size());
207         SystemDependencyScope systemDependencyScope = session.getSystemDependencyScope();
208         for (ArtifactRequest request : requests) {
209             if (systemDependencyScope != null && systemDependencyScope.getSystemPath(request.getArtifact()) != null) {
210                 continue;
211             }
212             artifacts.add(request.getArtifact());
213         }
214 
215         try (SyncContext shared = new CloseOnceSyncContext(syncContextFactory.newInstance(session, true));
216                 SyncContext exclusive = new CloseOnceSyncContext(syncContextFactory.newInstance(session, false))) {
217             return resolve(shared, exclusive, artifacts, session, requests);
218         }
219     }
220 
221     @SuppressWarnings("checkstyle:methodlength")
222     private List<ArtifactResult> resolve(
223             SyncContext shared,
224             SyncContext exclusive,
225             Collection<Artifact> subjects,
226             RepositorySystemSession session,
227             Collection<? extends ArtifactRequest> requests)
228             throws ArtifactResolutionException {
229         SystemDependencyScope systemDependencyScope = session.getSystemDependencyScope();
230         SyncContext current = shared;
231         try {
232             while (true) {
233                 current.acquire(subjects, null);
234 
235                 boolean failures = false;
236                 final List<ArtifactResult> results = new ArrayList<>(requests.size());
237                 final boolean simpleLrmInterop =
238                         ConfigUtils.getBoolean(session, DEFAULT_SIMPLE_LRM_INTEROP, CONFIG_PROP_SIMPLE_LRM_INTEROP);
239                 final LocalRepositoryManager lrm = session.getLocalRepositoryManager();
240                 final WorkspaceReader workspace = session.getWorkspaceReader();
241                 final List<ResolutionGroup> groups = new ArrayList<>();
242                 // filter != null: means "filtering applied", if null no filtering applied (behave as before)
243                 final RemoteRepositoryFilter filter = remoteRepositoryFilterManager.getRemoteRepositoryFilter(session);
244 
245                 for (ArtifactRequest request : requests) {
246                     RequestTrace trace = RequestTrace.newChild(request.getTrace(), request);
247 
248                     ArtifactResult result = new ArtifactResult(request);
249                     results.add(result);
250 
251                     Artifact artifact = request.getArtifact();
252 
253                     if (current == shared) {
254                         artifactResolving(session, trace, artifact);
255                     }
256 
257                     String localPath =
258                             systemDependencyScope != null ? systemDependencyScope.getSystemPath(artifact) : null;
259                     if (localPath != null) {
260                         // unhosted artifact, just validate file
261                         Path path = Paths.get(localPath);
262                         if (!Files.isRegularFile(path)) {
263                             failures = true;
264                             result.addException(
265                                     ArtifactResult.NO_REPOSITORY, new ArtifactNotFoundException(artifact, localPath));
266                         } else {
267                             artifact = artifact.setPath(path);
268                             result.setArtifact(artifact);
269                             artifactResolved(session, trace, artifact, null, result.getExceptions());
270                         }
271                         continue;
272                     }
273 
274                     List<RemoteRepository> remoteRepositories = request.getRepositories();
275                     List<RemoteRepository> filteredRemoteRepositories = new ArrayList<>(remoteRepositories);
276                     if (filter != null) {
277                         for (RemoteRepository repository : remoteRepositories) {
278                             RemoteRepositoryFilter.Result filterResult = filter.acceptArtifact(repository, artifact);
279                             if (!filterResult.isAccepted()) {
280                                 result.addException(
281                                         repository,
282                                         new ArtifactFilteredOutException(
283                                                 artifact, repository, filterResult.reasoning()));
284                                 filteredRemoteRepositories.remove(repository);
285                             }
286                         }
287                     }
288 
289                     VersionResult versionResult;
290                     try {
291                         VersionRequest versionRequest =
292                                 new VersionRequest(artifact, filteredRemoteRepositories, request.getRequestContext());
293                         versionRequest.setTrace(trace);
294                         versionResult = versionResolver.resolveVersion(session, versionRequest);
295                     } catch (VersionResolutionException e) {
296                         if (filteredRemoteRepositories.isEmpty()) {
297                             result.addException(lrm.getRepository(), e);
298                         } else {
299                             filteredRemoteRepositories.forEach(r -> result.addException(r, e));
300                         }
301                         continue;
302                     }
303 
304                     artifact = artifact.setVersion(versionResult.getVersion());
305 
306                     if (versionResult.getRepository() != null) {
307                         if (versionResult.getRepository() instanceof RemoteRepository) {
308                             filteredRemoteRepositories =
309                                     Collections.singletonList((RemoteRepository) versionResult.getRepository());
310                         } else {
311                             filteredRemoteRepositories = Collections.emptyList();
312                         }
313                     }
314 
315                     if (workspace != null) {
316                         Path path = workspace.findArtifactPath(artifact);
317                         if (path != null) {
318                             artifact = artifact.setPath(path);
319                             result.setArtifact(artifact);
320                             result.setRepository(workspace.getRepository());
321                             artifactResolved(session, trace, artifact, result.getRepository(), null);
322                             continue;
323                         }
324                     }
325 
326                     LocalArtifactResult local = lrm.find(
327                             session,
328                             new LocalArtifactRequest(
329                                     artifact, filteredRemoteRepositories, request.getRequestContext()));
330                     result.setLocalArtifactResult(local);
331                     boolean found = (filter != null && local.isAvailable())
332                             || (filter == null && isLocallyInstalled(local, versionResult));
333                     // with filtering: availability drives the logic
334                     // without filtering: simply presence of file drives the logic
335                     // "interop" logic with simple LRM leads to RRF breakage: hence is ignored when filtering in effect
336                     if (found) {
337                         if (local.getRepository() != null) {
338                             result.setRepository(local.getRepository());
339                         } else {
340                             result.setRepository(lrm.getRepository());
341                         }
342 
343                         try {
344                             Path localArtifactPath = local.getPath();
345                             artifact = artifact.setPath(getPath(session, artifact, localArtifactPath));
346                             result.setArtifact(artifact);
347                             if (local.getRepository() != null && !localArtifactPath.equals(artifact.getPath())) {
348                                 /*
349                                  * NOTE: Snapshot normalization materialized a base-version copy next to the tracked
350                                  * timestamped file. The copy must carry the same provenance tracking as its source;
351                                  * otherwise the untracked copy is later treated as locally installed (accepted
352                                  * without any repository/offline checks) by the untracked-file interop logic.
353                                  */
354                                 lrm.add(
355                                         session,
356                                         new LocalArtifactRegistration(
357                                                 artifact.setVersion(artifact.getBaseVersion()),
358                                                 local.getRepository(),
359                                                 Collections.singleton(request.getRequestContext())));
360                             }
361                             artifactResolved(session, trace, artifact, result.getRepository(), null);
362                         } catch (ArtifactTransferException e) {
363                             result.addException(lrm.getRepository(), e);
364                         }
365                         if (filter == null && simpleLrmInterop && !local.isAvailable()) {
366                             /*
367                              * NOTE: Interop with simple local repository: An artifact installed by a simple local repo
368                              * manager will not show up in the repository tracking file of the enhanced local repository.
369                              * If however the maven-metadata-local.xml tells us the artifact was installed locally, we
370                              * sync the repository tracking file.
371                              */
372                             lrm.add(session, new LocalArtifactRegistration(artifact));
373                         }
374 
375                         continue;
376                     }
377 
378                     if (local.getPath() != null) {
379                         LOGGER.info(
380                                 "Artifact {} is present in the local repository, but cached from a remote repository ID that is unavailable in current build context, verifying that is downloadable from {}",
381                                 LogSanitizer.sanitize(String.valueOf(artifact)),
382                                 LogSanitizer.sanitize(String.valueOf(remoteRepositories)));
383                     }
384 
385                     LOGGER.debug(
386                             "Resolving artifact {} from {}",
387                             LogSanitizer.sanitize(String.valueOf(artifact)),
388                             LogSanitizer.sanitize(String.valueOf(remoteRepositories)));
389                     AtomicBoolean resolved = new AtomicBoolean(false);
390                     Iterator<ResolutionGroup> groupIt = groups.iterator();
391                     for (RemoteRepository repo : filteredRemoteRepositories) {
392                         if (!repo.getPolicy(artifact.isSnapshot()).isEnabled()) {
393                             continue;
394                         }
395 
396                         try {
397                             Utils.checkOffline(session, offlineController, repo);
398                         } catch (RepositoryOfflineException e) {
399                             Exception exception = new ArtifactNotFoundException(
400                                     artifact,
401                                     repo,
402                                     "Cannot access " + repo.getId() + " ("
403                                             + repo.getUrl() + ") in offline mode and the artifact " + artifact
404                                             + " has not been downloaded from it before.",
405                                     e);
406                             result.addException(repo, exception);
407                             continue;
408                         }
409 
410                         ResolutionGroup group = null;
411                         while (groupIt.hasNext()) {
412                             ResolutionGroup t = groupIt.next();
413                             if (t.matches(repo)) {
414                                 group = t;
415                                 break;
416                             }
417                         }
418                         if (group == null) {
419                             group = new ResolutionGroup(repo);
420                             groups.add(group);
421                             groupIt = Collections.emptyIterator();
422                         }
423                         group.items.add(new ResolutionItem(trace, artifact, resolved, result, local, repo));
424                     }
425                 }
426 
427                 if (!groups.isEmpty() && current == shared) {
428                     SyncContext sharedContext = current;
429                     current = exclusive;
430                     sharedContext.close();
431                     continue;
432                 }
433 
434                 for (ResolutionGroup group : groups) {
435                     performDownloads(session, group);
436                 }
437 
438                 for (ArtifactResolverPostProcessor artifactResolverPostProcessor :
439                         artifactResolverPostProcessors.values()) {
440                     artifactResolverPostProcessor.postProcess(session, results);
441                 }
442 
443                 for (ArtifactResult result : results) {
444                     ArtifactRequest request = result.getRequest();
445 
446                     Artifact artifact = result.getArtifact();
447                     if (artifact == null || artifact.getPath() == null) {
448                         failures = true;
449                         if (result.getExceptions().isEmpty()) {
450                             Exception exception =
451                                     new ArtifactNotFoundException(request.getArtifact(), (RemoteRepository) null);
452                             // Note: result.getRepository() MAY BE null; in cases when
453                             // the artifact was not even tried by any remote repository (snapshot vs repo policy)
454                             // and local repository does not have it either
455                             result.addException(
456                                     result.getRepository() != null
457                                             ? result.getRepository()
458                                             : ArtifactResult.NO_REPOSITORY,
459                                     exception);
460                         }
461                         RequestTrace trace = RequestTrace.newChild(request.getTrace(), request);
462                         artifactResolved(session, trace, request.getArtifact(), null, result.getExceptions());
463                     }
464                 }
465 
466                 if (failures) {
467                     throw new ArtifactResolutionException(results);
468                 }
469 
470                 return results;
471             }
472         } finally {
473             try {
474                 current.close();
475             } finally {
476                 if (current == shared) {
477                     exclusive.close();
478                 }
479             }
480         }
481     }
482 
483     /**
484      * This is the method that checks local artifact result if no RRF being used. Unlike with RRF, where only
485      * {@link LocalArtifactResult#isAvailable()} is checked, here we perform multiple checks:
486      * <ul>
487      *     <li>if {@link LocalArtifactResult#isAvailable()} is {@code true}, return {@code true}</li>
488      *     <li>if {@link LocalArtifactResult#getRepository()} is instance of {@link LocalRepository}, return {@code true}</li>
489      *     <li>if {@link LocalArtifactResult#getRepository()} is {@code null} and request had zero remote repositories set, return {@code true}</li>
490      * </ul>
491      * Note: the third check is interfering with RRF, as RRF may make list of remote repositories empty,  that was
492      * originally non-empty, by eliminating remote repositories to consider.
493      * Hence, we may use this method ONLY if RRF is inactive.
494      */
495     private boolean isLocallyInstalled(LocalArtifactResult lar, VersionResult vr) {
496         if (lar.isAvailable()) {
497             return true;
498         }
499         if (lar.getPath() != null) {
500             // resolution of version range found locally installed artifact
501             if (vr.getRepository() instanceof LocalRepository) {
502                 // resolution of (snapshot) version found locally installed artifact
503                 return true;
504             } else {
505                 return vr.getRepository() == null
506                         && lar.getRequest().getRepositories().isEmpty();
507             }
508         }
509         return false;
510     }
511 
512     private Path getPath(RepositorySystemSession session, Artifact artifact, Path path)
513             throws ArtifactTransferException {
514         if (artifact.isSnapshot()
515                 && !artifact.getVersion().equals(artifact.getBaseVersion())
516                 && ConfigUtils.getBoolean(
517                         session, DEFAULT_SNAPSHOT_NORMALIZATION, CONFIG_PROP_SNAPSHOT_NORMALIZATION)) {
518             String name = path.getFileName().toString().replace(artifact.getVersion(), artifact.getBaseVersion());
519             Path dst = path.getParent().resolve(name);
520 
521             try {
522                 long pathLastModified = pathProcessor.lastModified(path, 0L);
523                 boolean copy = pathProcessor.size(dst, 0L) != pathProcessor.size(path, 0L)
524                         || pathProcessor.lastModified(dst, 0L) != pathLastModified;
525                 if (copy) {
526                     pathProcessor.copyWithTimestamp(path, dst);
527                 }
528             } catch (IOException e) {
529                 throw new ArtifactTransferException(artifact, null, e);
530             }
531 
532             path = dst;
533         }
534 
535         return path;
536     }
537 
538     private void performDownloads(RepositorySystemSession session, ResolutionGroup group) {
539         List<ArtifactDownload> downloads = gatherDownloads(session, group);
540         if (downloads.isEmpty()) {
541             return;
542         }
543 
544         for (ArtifactDownload download : downloads) {
545             artifactDownloading(session, download.getTrace(), download.getArtifact(), group.repository);
546         }
547 
548         try {
549             try (RepositoryConnector connector =
550                     repositoryConnectorProvider.newRepositoryConnector(session, group.repository)) {
551                 connector.get(downloads, null);
552             }
553         } catch (NoRepositoryConnectorException e) {
554             for (ArtifactDownload download : downloads) {
555                 download.setException(new ArtifactTransferException(download.getArtifact(), group.repository, e));
556             }
557         }
558 
559         evaluateDownloads(session, group);
560     }
561 
562     private List<ArtifactDownload> gatherDownloads(RepositorySystemSession session, ResolutionGroup group) {
563         LocalRepositoryManager lrm = session.getLocalRepositoryManager();
564         final boolean existenceCheckRelabel =
565                 ConfigUtils.getBoolean(session, DEFAULT_EXISTENCE_CHECK_RELABEL, CONFIG_PROP_EXISTENCE_CHECK_RELABEL);
566         List<ArtifactDownload> downloads = new ArrayList<>();
567 
568         for (ResolutionItem item : group.items) {
569             Artifact artifact = item.artifact;
570 
571             if (item.resolved.get()) {
572                 // resolved in previous resolution group
573                 continue;
574             }
575 
576             ArtifactDownload download = new ArtifactDownload();
577             download.setArtifact(artifact);
578             download.setRequestContext(item.request.getRequestContext());
579             download.setListener(SafeTransferListener.wrap(session));
580             download.setTrace(item.trace);
581             if (item.local.getPath() != null && existenceCheckRelabel) {
582                 /*
583                  * NOTE: Legacy behavior, disabled by default: a bare existence check transfers no content, so the
584                  * cached bytes are re-labeled to this repository without ever passing checksum validation.
585                  */
586                 download.setPath(item.local.getPath());
587                 download.setExistenceCheck(true);
588             } else {
589                 /*
590                  * NOTE: Even if the artifact is present in the local repository (cached from a repository unavailable
591                  * in the current build context), download it again so the content passes the repository's checksum
592                  * policy before the artifact is registered with the local repository for this repository.
593                  */
594                 download.setPath(lrm.getAbsolutePathForRemoteArtifact(
595                         artifact, group.repository, item.request.getRequestContext()));
596             }
597 
598             boolean snapshot = artifact.isSnapshot();
599             RepositoryPolicy policy = remoteRepositoryManager.getPolicy(session, group.repository, !snapshot, snapshot);
600 
601             int errorPolicy = Utils.getPolicy(session, artifact, group.repository);
602             if ((errorPolicy & ResolutionErrorPolicy.CACHE_ALL) != 0) {
603                 UpdateCheck<Artifact, ArtifactTransferException> check = new UpdateCheck<>();
604                 check.setItem(artifact);
605                 check.setPath(download.getPath());
606                 check.setFileValid(false);
607                 check.setRepository(group.repository);
608                 check.setArtifactPolicy(policy.getArtifactUpdatePolicy());
609                 check.setMetadataPolicy(policy.getMetadataUpdatePolicy());
610                 item.updateCheck = check;
611                 updateCheckManager.checkArtifact(session, check);
612                 if (!check.isRequired()) {
613                     item.result.addException(group.repository, check.getException());
614                     continue;
615                 }
616             }
617 
618             download.setChecksumPolicy(policy.getChecksumPolicy());
619             download.setRepositories(item.repository.getMirroredRepositories());
620             downloads.add(download);
621             item.download = download;
622         }
623 
624         return downloads;
625     }
626 
627     private void evaluateDownloads(RepositorySystemSession session, ResolutionGroup group) {
628         LocalRepositoryManager lrm = session.getLocalRepositoryManager();
629 
630         for (ResolutionItem item : group.items) {
631             ArtifactDownload download = item.download;
632             if (download == null) {
633                 continue;
634             }
635 
636             Artifact artifact = download.getArtifact();
637             if (download.getException() == null) {
638                 item.resolved.set(true);
639                 item.result.setRepository(group.repository);
640                 try {
641                     artifact = artifact.setPath(getPath(session, artifact, download.getPath()));
642                     item.result.setArtifact(artifact);
643 
644                     lrm.add(
645                             session,
646                             new LocalArtifactRegistration(artifact, group.repository, download.getSupportedContexts()));
647                     if (!download.getPath().equals(artifact.getPath())) {
648                         /*
649                          * NOTE: Snapshot normalization materialized a base-version copy of the downloaded file. Every
650                          * file the resolver derives from remote content must carry the same provenance tracking as
651                          * the download it stems from: register the copy under the same repository, otherwise the
652                          * untracked copy is later treated as locally installed (accepted without any
653                          * repository/offline checks) by the untracked-file interop logic.
654                          */
655                         lrm.add(
656                                 session,
657                                 new LocalArtifactRegistration(
658                                         artifact.setVersion(artifact.getBaseVersion()),
659                                         group.repository,
660                                         download.getSupportedContexts()));
661                     }
662                 } catch (ArtifactTransferException e) {
663                     download.setException(e);
664                     item.result.addException(group.repository, e);
665                 }
666             } else {
667                 item.result.addException(group.repository, download.getException());
668             }
669 
670             /*
671              * NOTE: Touch after registration with local repo to ensure concurrent resolution is not rejected with
672              * "already updated" via session data when actual update to local repo is still pending.
673              */
674             if (item.updateCheck != null) {
675                 item.updateCheck.setException(download.getException());
676                 updateCheckManager.touchArtifact(session, item.updateCheck);
677             }
678 
679             artifactDownloaded(session, download.getTrace(), artifact, group.repository, download.getException());
680             if (download.getException() == null) {
681                 artifactResolved(session, download.getTrace(), artifact, group.repository, null);
682             }
683         }
684     }
685 
686     private void artifactResolving(RepositorySystemSession session, RequestTrace trace, Artifact artifact) {
687         RepositoryEvent.Builder event = new RepositoryEvent.Builder(session, EventType.ARTIFACT_RESOLVING);
688         event.setTrace(trace);
689         event.setArtifact(artifact);
690 
691         repositoryEventDispatcher.dispatch(event.build());
692     }
693 
694     private void artifactResolved(
695             RepositorySystemSession session,
696             RequestTrace trace,
697             Artifact artifact,
698             ArtifactRepository repository,
699             Collection<Exception> exceptions) {
700         RepositoryEvent.Builder event = new RepositoryEvent.Builder(session, EventType.ARTIFACT_RESOLVED);
701         event.setTrace(trace);
702         event.setArtifact(artifact);
703         event.setRepository(repository);
704         event.setExceptions(exceptions != null ? new ArrayList<>(exceptions) : null);
705         if (artifact != null) {
706             event.setPath(artifact.getPath());
707         }
708 
709         repositoryEventDispatcher.dispatch(event.build());
710     }
711 
712     private void artifactDownloading(
713             RepositorySystemSession session, RequestTrace trace, Artifact artifact, RemoteRepository repository) {
714         RepositoryEvent.Builder event = new RepositoryEvent.Builder(session, EventType.ARTIFACT_DOWNLOADING);
715         event.setTrace(trace);
716         event.setArtifact(artifact);
717         event.setRepository(repository);
718 
719         repositoryEventDispatcher.dispatch(event.build());
720     }
721 
722     private void artifactDownloaded(
723             RepositorySystemSession session,
724             RequestTrace trace,
725             Artifact artifact,
726             RemoteRepository repository,
727             Exception exception) {
728         RepositoryEvent.Builder event = new RepositoryEvent.Builder(session, EventType.ARTIFACT_DOWNLOADED);
729         event.setTrace(trace);
730         event.setArtifact(artifact);
731         event.setRepository(repository);
732         event.setException(exception);
733         if (artifact != null) {
734             event.setPath(artifact.getPath());
735         }
736 
737         repositoryEventDispatcher.dispatch(event.build());
738     }
739 
740     static class ResolutionGroup {
741 
742         final RemoteRepository repository;
743 
744         final List<ResolutionItem> items = new ArrayList<>();
745 
746         ResolutionGroup(RemoteRepository repository) {
747             this.repository = repository;
748         }
749 
750         boolean matches(RemoteRepository repo) {
751             return repository.getUrl().equals(repo.getUrl())
752                     && repository.getContentType().equals(repo.getContentType())
753                     && repository.isRepositoryManager() == repo.isRepositoryManager();
754         }
755     }
756 
757     static class ResolutionItem {
758 
759         final RequestTrace trace;
760 
761         final ArtifactRequest request;
762 
763         final ArtifactResult result;
764 
765         final LocalArtifactResult local;
766 
767         final RemoteRepository repository;
768 
769         final Artifact artifact;
770 
771         final AtomicBoolean resolved;
772 
773         ArtifactDownload download;
774 
775         UpdateCheck<Artifact, ArtifactTransferException> updateCheck;
776 
777         ResolutionItem(
778                 RequestTrace trace,
779                 Artifact artifact,
780                 AtomicBoolean resolved,
781                 ArtifactResult result,
782                 LocalArtifactResult local,
783                 RemoteRepository repository) {
784             this.trace = trace;
785             this.artifact = artifact;
786             this.resolved = resolved;
787             this.result = result;
788             this.request = result.getRequest();
789             this.local = local;
790             this.repository = repository;
791         }
792     }
793 }