Expose Maven logging output capabilities in Maven 3.10

maven-core/src/main/java/org/apache/maven/DefaultMaven.java

@@ -47,6 +47,7 @@
 import org.apache.maven.internal.aether.MavenChainedWorkspaceReader;
 import org.apache.maven.lifecycle.internal.ExecutionEventCatapult;
 import org.apache.maven.lifecycle.internal.LifecycleStarter;
+import org.apache.maven.logging.internal.DefaultOutputCapabilities;
 import org.apache.maven.model.Prerequisites;
 import org.apache.maven.model.building.ModelProblem;
 import org.apache.maven.model.building.Result;
@@ -93,6 +94,9 @@ public class DefaultMaven implements Maven {
     @Inject
     private RepositorySystemSessionFactory repositorySessionFactory;
 
+    @Inject
+    private DefaultOutputCapabilities outputCapabilities;
+
     @Inject
     @Named(GraphBuilder.HINT)
     private GraphBuilder graphBuilder;
@@ -102,6 +106,7 @@ public MavenExecutionResult execute(MavenExecutionRequest request) {
         MavenExecutionResult result;
 
         try {
+            request.getData().put(DefaultOutputCapabilities.REQUEST_DATA_KEY, outputCapabilities.asMap());
             result = doExecute(request);
         } catch (OutOfMemoryError e) {
             result = addExceptionToResult(new DefaultMavenExecutionResult(), e);

maven-core/src/main/java/org/apache/maven/logging/OutputCapabilities.java

@@ -0,0 +1,77 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.logging;
+
+import java.nio.charset.Charset;
+import java.util.Optional;
+
+/**
+ * Describes the current destination of Maven logging, including plugin log messages.
+ * The information follows logging configuration and is shared by all projects in a build.
+ * It does not describe files or streams written directly by a plugin.
+ *
+ * <p>Plugins compiled against older Maven APIs can obtain the same information without
+ * referencing this interface through
+ * {@code session.getRequest().getData().get("maven.logging.outputCapabilities")}.
+ * The value is an immutable {@code Map<String, String>}. Its {@code destination}
+ * entry is always present and contains {@code CONSOLE}, {@code FILE}, {@code REDIRECTED},
+ * or {@code UNKNOWN}. Its {@code encoding} entry contains the canonical
+ * {@link Charset#name()} when known and is otherwise absent, independently of destination.
+ * An absent request-data entry means the service is unavailable (for example, on older
+ * Maven versions); a present map with {@code UNKNOWN} means detection is unavailable.
+ * Clients should ignore additional keys and treat unfamiliar destinations as unknown.
+ *
+ * <p>The map captures the logging configuration when
+ * {@link org.apache.maven.Maven#execute(org.apache.maven.execution.MavenExecutionRequest)}
+ * begins, before validation and lifecycle callbacks. The entry is absent before execution
+ * unless it remains from an earlier execution of the same request. Each execution replaces
+ * the entry with a fresh capture, including when the request is copied or reused.
+ * The map and its collection views remain unchanged through logging cleanup,
+ * reconfiguration, and subsequent invocations. A retained map captured while information
+ * is unknown remains unknown. Cleanup does not remove the entry from the request.
+ * Unlike the map, this component's getters describe the current logging configuration
+ * and may therefore differ from a retained request's map after reconfiguration or cleanup.
+ */
+public interface OutputCapabilities {
+    /** The known kind of logging destination. */
+    enum Destination {
+        /** Output is attached to a terminal, independently of whether color is enabled. */
+        CONSOLE,
+        /** Maven or its logging provider opened an explicit file destination. */
+        FILE,
+        /** Output is not attached to a terminal; its final destination is not known. */
+        REDIRECTED,
+        /** The logging destination could not be determined. */
+        UNKNOWN
+    }
+
+    /**
+     * Returns the known kind of logging destination.
+     * @return the destination, never {@code null}
+     */
+    Destination getDestination();
+
+    /**
+     * Returns the charset selected for the logging output route, if known.
+     * Encoding may be known even when the destination is unknown. It does not imply
+     * support for terminal control sequences or guarantee that a font contains a glyph.
+     * @return the output charset, or an empty optional when it cannot be determined
+     */
+    Optional<Charset> getEncoding();
+}

maven-core/src/main/java/org/apache/maven/logging/internal/DefaultOutputCapabilities.java

@@ -0,0 +1,110 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.logging.internal;
+
+import javax.inject.Named;
+import javax.inject.Singleton;
+
+import java.nio.charset.Charset;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+
+import org.apache.maven.logging.OutputCapabilities;
+
+/**
+ * Internal bridge between logging setup and the read-only component exposed to plugins.
+ * Publication and restoration follow the logging lifecycle, not the build session.
+ */
+@Named
+@Singleton
+public class DefaultOutputCapabilities implements OutputCapabilities {
+    public static final String REQUEST_DATA_KEY = "maven.logging.outputCapabilities";
+
+    public static final OutputCapabilities UNKNOWN = snapshot(Destination.UNKNOWN, null);
+
+    private volatile Snapshot current = (Snapshot) UNKNOWN;
+
+    /** Internal access to an immutable description of the current logging configuration. */
+    public Map<String, String> asMap() {
+        return current.properties;
+    }
+
+    @Override
+    public Destination getDestination() {
+        return current.getDestination();
+    }
+
+    @Override
+    public Optional<Charset> getEncoding() {
+        return current.getEncoding();
+    }
+
+    /** Creates an immutable description for transport from logging setup to the container. */
+    public static OutputCapabilities snapshot(Destination destination, Charset encoding) {
+        return new Snapshot(Objects.requireNonNull(destination), encoding);
+    }
+
+    /**
+     * Installs the current output description and returns its logging-lifecycle cleanup.
+     * An obsolete cleanup must not overwrite a subsequently installed configuration.
+     */
+    public synchronized AutoCloseable install(OutputCapabilities capabilities) {
+        Snapshot previous = current;
+        Snapshot installed = new Snapshot(
+                capabilities.getDestination(), capabilities.getEncoding().orElse(null));
+        current = installed;
+        return () -> {
+            synchronized (DefaultOutputCapabilities.this) {
+                if (current == installed) {
+                    current = previous;
+                }
+            }
+        };
+    }
+
+    private static final class Snapshot implements OutputCapabilities {
+        private final Destination destination;
+        private final Optional<Charset> encoding;
+        private final Map<String, String> properties;
+
+        private Snapshot(Destination destination, Charset encoding) {
+            this.destination = destination;
+            this.encoding = Optional.ofNullable(encoding);
+            Map<String, String> values = new LinkedHashMap<>();
+            values.put("destination", destination.name());
+            if (encoding != null) {
+                values.put("encoding", encoding.name());
+            }
+            this.properties = Collections.unmodifiableMap(values);
+        }
+
+        @Override
+        public Destination getDestination() {
+            return destination;
+        }
+
+        @Override
+        public Optional<Charset> getEncoding() {
+            return encoding;
+        }
+    }
+}

maven-core/src/main/resources/META-INF/maven/extension.xml

@@ -32,6 +32,7 @@ under the License.
     <exportedPackage>org.apache.maven.execution.scope</exportedPackage>
     <exportedPackage>org.apache.maven.graph</exportedPackage>
     <exportedPackage>org.apache.maven.lifecycle</exportedPackage>
+    <exportedPackage>org.apache.maven.logging.*</exportedPackage>
     <exportedPackage>org.apache.maven.model</exportedPackage>
     <exportedPackage>org.apache.maven.monitor</exportedPackage>
     <exportedPackage>org.apache.maven.plugin</exportedPackage>