[MRESOLVER-377] Introduce metadataUpdatePolicy

maven-resolver-api/src/main/java/org/eclipse/aether/AbstractForwardingRepositorySystemSession.java

@@ -87,6 +87,11 @@ public String getUpdatePolicy() {
         return getSession().getUpdatePolicy();
     }
 
+    @Override
+    public String getMetadataUpdatePolicy() {
+        return getSession().getMetadataUpdatePolicy();
+    }
+
     @Override
     public LocalRepository getLocalRepository() {
         return getSession().getLocalRepository();

maven-resolver-api/src/main/java/org/eclipse/aether/DefaultRepositorySystemSession.java

@@ -73,6 +73,8 @@ public final class DefaultRepositorySystemSession implements RepositorySystemSes
 
     private String updatePolicy;
 
+    private String metadataUpdatePolicy;
+
     private LocalRepositoryManager localRepositoryManager;
 
     private FileTransformerManager fileTransformerManager;
@@ -154,6 +156,7 @@ public DefaultRepositorySystemSession(RepositorySystemSession session) {
         setArtifactDescriptorPolicy(session.getArtifactDescriptorPolicy());
         setChecksumPolicy(session.getChecksumPolicy());
         setUpdatePolicy(session.getUpdatePolicy());
+        setMetadataUpdatePolicy(session.getMetadataUpdatePolicy());
         setLocalRepositoryManager(session.getLocalRepositoryManager());
         setWorkspaceReader(session.getWorkspaceReader());
         setRepositoryListener(session.getRepositoryListener());
@@ -293,6 +296,28 @@ public DefaultRepositorySystemSession setUpdatePolicy(String updatePolicy) {
         return this;
     }
 
+    @Override
+    public String getMetadataUpdatePolicy() {
+        return metadataUpdatePolicy;
+    }
+
+    /**
+     * Sets the global metadata update policy. If set, the global update policy overrides the update policies of the remote
+     * repositories being used for resolution.
+     *
+     * @param metadataUpdatePolicy The global update policy, may be {@code null}/empty to apply the per-repository policies.
+     * @return This session for chaining, never {@code null}.
+     * @see RepositoryPolicy#UPDATE_POLICY_ALWAYS
+     * @see RepositoryPolicy#UPDATE_POLICY_DAILY
+     * @see RepositoryPolicy#UPDATE_POLICY_NEVER
+     * @since TBD
+     */
+    public DefaultRepositorySystemSession setMetadataUpdatePolicy(String metadataUpdatePolicy) {
+        verifyStateForMutation();
+        this.metadataUpdatePolicy = metadataUpdatePolicy;
+        return this;
+    }
+
     @Override
     public LocalRepository getLocalRepository() {
         LocalRepositoryManager lrm = getLocalRepositoryManager();

maven-resolver-api/src/main/java/org/eclipse/aether/RepositorySystemSession.java

@@ -94,7 +94,7 @@ public interface RepositorySystemSession {
     String getChecksumPolicy();
 
     /**
-     * Gets the global update policy. If set, the global update policy overrides the update policies of the remote
+     * Gets the global data update policy. If set, the global update policy overrides the update policies of the remote
      * repositories being used for resolution.
      *
      * @return The global update policy or {@code null}/empty if not set and the per-repository policies apply.
@@ -104,6 +104,18 @@ public interface RepositorySystemSession {
      */
     String getUpdatePolicy();
 
+    /**
+     * Gets the global metadata update policy. If set, the global update policy overrides the update policies of the remote
+     * repositories being used for resolution.
+     *
+     * @return The global update policy or {@code null}/empty if not set and the per-repository policies apply.
+     * @see RepositoryPolicy#UPDATE_POLICY_ALWAYS
+     * @see RepositoryPolicy#UPDATE_POLICY_DAILY
+     * @see RepositoryPolicy#UPDATE_POLICY_NEVER
+     * @since TBD
+     */
+    String getMetadataUpdatePolicy();
+
     /**
      * Gets the local repository used during this session. This is a convenience method for
      * {@link LocalRepositoryManager#getRepository()}.

maven-resolver-api/src/main/java/org/eclipse/aether/repository/RepositoryPolicy.java

@@ -62,26 +62,40 @@ public final class RepositoryPolicy {
 
     private final String updatePolicy;
 
+    private final String metadataUpdatePolicy;
+
     private final String checksumPolicy;
 
     /**
      * Creates a new policy with checksum warnings and daily update checks.
      */
     public RepositoryPolicy() {
-        this(true, UPDATE_POLICY_DAILY, CHECKSUM_POLICY_WARN);
+        this(true, UPDATE_POLICY_DAILY, UPDATE_POLICY_DAILY, CHECKSUM_POLICY_WARN);
+    }
+
+    /**
+     * Creates a new policy with the specified settings (uses same update policy for data and metadata, retains old
+     * resolver behaviour).
+     */
+    public RepositoryPolicy(boolean enabled, String updatePolicy, String checksumPolicy) {
+        this(enabled, updatePolicy, updatePolicy, checksumPolicy);
     }
 
     /**
      * Creates a new policy with the specified settings.
      *
      * @param enabled A flag whether the associated repository should be accessed or not.
      * @param updatePolicy The update interval after which locally cached data from the repository is considered stale
-     *            and should be refetched, may be {@code null}.
+     *            and should be re-fetched, may be {@code null}.
+     * @param metadataUpdatePolicy The update interval after which locally cached metadata from the repository is considered stale
+     *            and should be re-fetched, may be {@code null}.
      * @param checksumPolicy The way checksum verification should be handled, may be {@code null}.
+     * @since TBD
      */
-    public RepositoryPolicy(boolean enabled, String updatePolicy, String checksumPolicy) {
+    public RepositoryPolicy(boolean enabled, String updatePolicy, String metadataUpdatePolicy, String checksumPolicy) {
         this.enabled = enabled;
         this.updatePolicy = (updatePolicy != null) ? updatePolicy : "";
+        this.metadataUpdatePolicy = (metadataUpdatePolicy != null) ? metadataUpdatePolicy : "";
         this.checksumPolicy = (checksumPolicy != null) ? checksumPolicy : "";
     }
 
@@ -103,6 +117,16 @@ public String getUpdatePolicy() {
         return updatePolicy;
     }
 
+    /**
+     * Gets the update policy for locally cached metadata from the repository.
+     *
+     * @return The update policy, never {@code null}.
+     * @since TBD
+     */
+    public String getMetadataUpdatePolicy() {
+        return metadataUpdatePolicy;
+    }
+
     /**
      * Gets the policy for checksum validation.
      *
@@ -114,11 +138,10 @@ public String getChecksumPolicy() {
 
     @Override
     public String toString() {
-        StringBuilder buffer = new StringBuilder(256);
-        buffer.append("enabled=").append(isEnabled());
-        buffer.append(", checksums=").append(getChecksumPolicy());
-        buffer.append(", updates=").append(getUpdatePolicy());
-        return buffer.toString();
+        return "enabled=" + isEnabled()
+                + ", checksums=" + getChecksumPolicy()
+                + ", updates=" + getUpdatePolicy()
+                + ", metadataUpdates=" + getMetadataUpdatePolicy();
     }
 
     @Override

maven-resolver-impl/src/main/java/org/eclipse/aether/impl/UpdateCheck.java

@@ -43,6 +43,8 @@ public final class UpdateCheck<T, E extends RepositoryException> {
 
     private String policy;
 
+    private String metadataPolicy;
+
     private RemoteRepository repository;
 
     private RemoteRepository authoritativeRepository;
@@ -147,19 +149,30 @@ public UpdateCheck<T, E> setFileValid(boolean fileValid) {
     }
 
     /**
-     * Gets the policy to use for the check.
+     * Gets the policy to use for the data check.
      *
-     * @return The policy to use for the check.
+     * @return The policy to use for the data check.
      * @see org.eclipse.aether.repository.RepositoryPolicy
      */
     public String getPolicy() {
         return policy;
     }
 
+    /**
+     * Gets the policy to use for the metadata check.
+     *
+     * @return The policy to use for the metadata check.
+     * @see org.eclipse.aether.repository.RepositoryPolicy
+     * @since TBD
+     */
+    public String getMetadataPolicy() {
+        return metadataPolicy;
+    }
+
     /**
      * Sets the policy to use for the check.
      *
-     * @param policy The policy to use for the check, may be {@code null}.
+     * @param policy The policy to use for the data check, may be {@code null}.
      * @return This object for chaining.
      * @see org.eclipse.aether.repository.RepositoryPolicy
      */
@@ -168,6 +181,19 @@ public UpdateCheck<T, E> setPolicy(String policy) {
         return this;
     }
 
+    /**
+     * Sets the policy to use for the check.
+     *
+     * @param metadataPolicy The policy to use for the metadata check, may be {@code null}.
+     * @return This object for chaining.
+     * @see org.eclipse.aether.repository.RepositoryPolicy
+     * @since TBD
+     */
+    public UpdateCheck<T, E> setMetadataPolicy(String metadataPolicy) {
+        this.metadataPolicy = metadataPolicy;
+        return this;
+    }
+
     /**
      * Gets the repository from which a potential update/download will performed.
      *
@@ -256,6 +282,6 @@ public UpdateCheck<T, E> setException(E exception) {
 
     @Override
     public String toString() {
-        return getPolicy() + ": " + getFile() + " < " + getRepository();
+        return getPolicy() + "/" + getMetadataPolicy() + ": " + getFile() + " < " + getRepository();
     }
 }

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/DefaultArtifactResolver.java

@@ -582,6 +582,7 @@ private List<ArtifactDownload> gatherDownloads(RepositorySystemSession session,
                 check.setFileValid(false);
                 check.setRepository(group.repository);
                 check.setPolicy(policy.getUpdatePolicy());
+                check.setMetadataPolicy(policy.getMetadataUpdatePolicy());
                 item.updateCheck = check;
                 updateCheckManager.checkArtifact(session, check);
                 if (!check.isRequired()) {

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/DefaultMetadataResolver.java

@@ -282,6 +282,8 @@ private List<MetadataResult> resolve(
                     List<UpdateCheck<Metadata, MetadataTransferException>> checks = new ArrayList<>();
                     Exception exception = null;
                     for (RemoteRepository repo : repositories) {
+                        RepositoryPolicy policy = getPolicy(session, repo, metadata.getNature());
+
                         UpdateCheck<Metadata, MetadataTransferException> check = new UpdateCheck<>();
                         check.setLocalLastUpdated((localLastUpdate != null) ? localLastUpdate : 0);
                         check.setItem(metadata);
@@ -294,8 +296,8 @@ private List<MetadataResult> resolve(
                         check.setFile(checkFile);
                         check.setRepository(repository);
                         check.setAuthoritativeRepository(repo);
-                        check.setPolicy(
-                                getPolicy(session, repo, metadata.getNature()).getUpdatePolicy());
+                        check.setPolicy(policy.getUpdatePolicy());
+                        check.setMetadataPolicy(policy.getMetadataUpdatePolicy());
 
                         if (lrmResult.isStale()) {
                             checks.add(check);

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/DefaultRemoteRepositoryManager.java

@@ -256,25 +256,41 @@ private RepositoryPolicy merge(
 
         if (policy2 == null) {
             if (globalPolicy) {
-                policy = merge(policy1, session.getUpdatePolicy(), session.getChecksumPolicy());
+                policy = merge(
+                        policy1,
+                        session.getUpdatePolicy(),
+                        session.getMetadataUpdatePolicy(),
+                        session.getChecksumPolicy());
             } else {
                 policy = policy1;
             }
         } else if (policy1 == null) {
             if (globalPolicy) {
-                policy = merge(policy2, session.getUpdatePolicy(), session.getChecksumPolicy());
+                policy = merge(
+                        policy2,
+                        session.getUpdatePolicy(),
+                        session.getMetadataUpdatePolicy(),
+                        session.getChecksumPolicy());
             } else {
                 policy = policy2;
             }
         } else if (!policy2.isEnabled()) {
             if (globalPolicy) {
-                policy = merge(policy1, session.getUpdatePolicy(), session.getChecksumPolicy());
+                policy = merge(
+                        policy1,
+                        session.getUpdatePolicy(),
+                        session.getMetadataUpdatePolicy(),
+                        session.getChecksumPolicy());
             } else {
                 policy = policy1;
             }
         } else if (!policy1.isEnabled()) {
             if (globalPolicy) {
-                policy = merge(policy2, session.getUpdatePolicy(), session.getChecksumPolicy());
+                policy = merge(
+                        policy2,
+                        session.getUpdatePolicy(),
+                        session.getMetadataUpdatePolicy(),
+                        session.getChecksumPolicy());
             } else {
                 policy = policy2;
             }
@@ -296,24 +312,35 @@ private RepositoryPolicy merge(
                 updates = updatePolicyAnalyzer.getEffectiveUpdatePolicy(
                         session, policy1.getUpdatePolicy(), policy2.getUpdatePolicy());
             }
+            String metadataUpdates = session.getMetadataUpdatePolicy();
+            if (globalPolicy && metadataUpdates != null && !metadataUpdates.isEmpty()) {
+                // use global override
+            } else {
+                metadataUpdates = updatePolicyAnalyzer.getEffectiveUpdatePolicy(
+                        session, policy1.getMetadataUpdatePolicy(), policy2.getMetadataUpdatePolicy());
+            }
 
-            policy = new RepositoryPolicy(true, updates, checksums);
+            policy = new RepositoryPolicy(true, updates, metadataUpdates, checksums);
         }
 
         return policy;
     }
 
-    private RepositoryPolicy merge(RepositoryPolicy policy, String updates, String checksums) {
+    private RepositoryPolicy merge(RepositoryPolicy policy, String updates, String metadataUpdates, String checksums) {
         if (policy != null) {
             if (updates == null || updates.isEmpty()) {
                 updates = policy.getUpdatePolicy();
             }
+            if (metadataUpdates == null || metadataUpdates.isEmpty()) {
+                metadataUpdates = policy.getMetadataUpdatePolicy();
+            }
             if (checksums == null || checksums.isEmpty()) {
                 checksums = policy.getChecksumPolicy();
             }
             if (!policy.getUpdatePolicy().equals(updates)
+                    || !policy.getMetadataUpdatePolicy().equals(metadataUpdates)
                     || !policy.getChecksumPolicy().equals(checksums)) {
-                policy = new RepositoryPolicy(policy.isEnabled(), updates, checksums);
+                policy = new RepositoryPolicy(policy.isEnabled(), updates, metadataUpdates, checksums);
             }
         }
         return policy;

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/DefaultUpdateCheckManager.java

@@ -136,8 +136,9 @@ public DefaultUpdateCheckManager setUpdatePolicyAnalyzer(UpdatePolicyAnalyzer up
     public void checkArtifact(RepositorySystemSession session, UpdateCheck<Artifact, ArtifactTransferException> check) {
         requireNonNull(session, "session cannot be null");
         requireNonNull(check, "check cannot be null");
+        final String updatePolicy = check.getPolicy();
         if (check.getLocalLastUpdated() != 0
-                && !isUpdatedRequired(session, check.getLocalLastUpdated(), check.getPolicy())) {
+                && !isUpdatedRequired(session, check.getLocalLastUpdated(), updatePolicy)) {
             LOGGER.debug("Skipped remote request for {}, locally installed artifact up-to-date", check.getItem());
 
             check.setRequired(false);
@@ -187,7 +188,7 @@ public void checkArtifact(RepositorySystemSession session, UpdateCheck<Artifact,
             if (error != null) {
                 check.setException(newException(error, artifact, repository));
             }
-        } else if (isUpdatedRequired(session, lastUpdated, check.getPolicy())) {
+        } else if (isUpdatedRequired(session, lastUpdated, updatePolicy)) {
             check.setRequired(true);
         } else if (fileExists) {
             LOGGER.debug("Skipped remote request for {}, locally cached artifact up-to-date", check.getItem());
@@ -241,8 +242,9 @@ private ArtifactTransferException newException(String error, Artifact artifact,
     public void checkMetadata(RepositorySystemSession session, UpdateCheck<Metadata, MetadataTransferException> check) {
         requireNonNull(session, "session cannot be null");
         requireNonNull(check, "check cannot be null");
+        final String updatePolicy = check.getMetadataPolicy();
         if (check.getLocalLastUpdated() != 0
-                && !isUpdatedRequired(session, check.getLocalLastUpdated(), check.getPolicy())) {
+                && !isUpdatedRequired(session, check.getLocalLastUpdated(), updatePolicy)) {
             LOGGER.debug("Skipped remote request for {} locally installed metadata up-to-date", check.getItem());
 
             check.setRequired(false);
@@ -292,7 +294,7 @@ public void checkMetadata(RepositorySystemSession session, UpdateCheck<Metadata,
             if (error != null) {
                 check.setException(newException(error, metadata, repository));
             }
-        } else if (isUpdatedRequired(session, lastUpdated, check.getPolicy())) {
+        } else if (isUpdatedRequired(session, lastUpdated, updatePolicy)) {
             check.setRequired(true);
         } else if (fileExists) {
             LOGGER.debug("Skipped remote request for {}, locally cached metadata up-to-date", check.getItem());