Rework how artifact-compare works

Fix #1871

tycho-artifactcomparator/src/main/java/org/eclipse/tycho/artifactcomparator/ArtifactDelta.java

@@ -19,20 +19,25 @@
  */
 public interface ArtifactDelta {
 
+    /**
+     * A delta that represents no difference was found
+     */
+    public static final ArtifactDelta NO_DIFFERENCE = null;
+
     /**
      * a default instance that indicates there is a difference but can't tell any further details
      */
-    public static final SimpleArtifactDelta DEFAULT = new SimpleArtifactDelta("different");
+    public static final ArtifactDelta DEFAULT = new SimpleArtifactDelta("different");
 
     /**
      * a default instance that indicate an item is only present in the baseline but no more details
      */
-    public static final SimpleArtifactDelta BASELINE_ONLY = new SimpleArtifactDelta("present in baseline only");
+    public static final ArtifactDelta BASELINE_ONLY = new SimpleArtifactDelta("present in baseline only");
 
     /**
      * a default instance that indicate an item is missing from what is found in the baseline
      */
-    public static final SimpleArtifactDelta MISSING_FROM_BASELINE = new SimpleArtifactDelta("not present in baseline");
+    public static final ArtifactDelta MISSING_FROM_BASELINE = new SimpleArtifactDelta("not present in baseline");
 
     /**
      * @return description of the delta, never null.

tycho-artifactcomparator/src/main/java/org/eclipse/tycho/artifactcomparator/ComparatorInputStream.java

@@ -0,0 +1,88 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Christoph Läubrich and others.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ * 
+ * Contributors:
+ *     Christoph Läubrich - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.tycho.artifactcomparator;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.Charset;
+import java.util.Arrays;
+
+import org.apache.commons.io.IOUtils;
+
+/**
+ * Input stream to carry some important information for comparison and allows direct access to the
+ * underlying buffer.
+ * 
+ * @author christoph
+ *
+ */
+public class ComparatorInputStream extends ByteArrayInputStream {
+
+    private final byte[] content;
+    private final String name;
+
+    public ComparatorInputStream(InputStream stream, String name) throws IOException {
+        this(IOUtils.toByteArray(stream), name);
+    }
+
+    public ComparatorInputStream(byte[] content, String name) {
+        super(content);
+        this.content = content;
+        this.name = name;
+    }
+
+    /**
+     * 
+     * @return the total number of bytes of this stream
+     */
+    public int size() {
+        return content.length;
+    }
+
+    /**
+     * @return a new stream backed by this stream data that could be read independently
+     */
+    public InputStream asNewStream() {
+        return new ByteArrayInputStream(content);
+    }
+
+    /**
+     * @param charset
+     * @return the content of this stream as a string with the given charset
+     */
+
+    public String asString(Charset charset) {
+        return new String(content, charset);
+    }
+
+    public byte[] asBytes() {
+        return content.clone();
+    }
+
+    /**
+     * Compares this stream directly to another stream on a by-by-byte basis, this is independent of
+     * the state of the streams, e.g number of bytes read, closing or mark state.
+     * 
+     * @param other
+     * @return {@link ArtifactDelta#DEFAULT} if there is any difference or <code>null</code>
+     *         otherwise.
+     */
+    public ArtifactDelta compare(ComparatorInputStream other) {
+        if (Arrays.equals(content, other.content)) {
+            return null;
+        }
+        return ArtifactDelta.DEFAULT;
+    }
+
+}

tycho-artifactcomparator/src/main/java/org/eclipse/tycho/zipcomparator/internal/ClassfileComparator.java

@@ -13,17 +13,16 @@
 package org.eclipse.tycho.zipcomparator.internal;
 
 import java.io.IOException;
-import java.io.InputStream;
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
 import org.codehaus.plexus.component.annotations.Component;
 import org.eclipse.tycho.artifactcomparator.ArtifactComparator.ComparisonData;
 import org.eclipse.tycho.artifactcomparator.ArtifactDelta;
+import org.eclipse.tycho.artifactcomparator.ComparatorInputStream;
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.tree.ClassNode;
@@ -40,24 +39,20 @@ public class ClassfileComparator implements ContentsComparator {
     // which is not exported, so can't use this either.
 
     @Override
-    public ArtifactDelta getDelta(InputStream baseline, InputStream reactor, ComparisonData data) throws IOException {
-        byte[] baselineBytes = baseline.readAllBytes();
-        byte[] reactorBytes = reactor.readAllBytes();
-
-        String baselineDisassemble = null;
-        String reactorDisassemble = null;
-
+    public ArtifactDelta getDelta(ComparatorInputStream baseline, ComparatorInputStream reactor, ComparisonData data)
+            throws IOException {
         boolean equal;
         try {
-            baselineDisassemble = disassemble(baselineBytes);
-            reactorDisassemble = disassemble(reactorBytes);
-            equal = baselineDisassemble.equals(reactorDisassemble);
+            String baselineDisassemble = disassemble(baseline.asBytes());
+            String reactorDisassemble = disassemble(reactor.asBytes());
+            if (baselineDisassemble.equals(reactorDisassemble)) {
+                return ArtifactDelta.NO_DIFFERENCE;
+            }
+            return new SimpleArtifactDelta("different", baselineDisassemble, reactorDisassemble);
         } catch (RuntimeException e) {
-            // asm could not disassemble one of the classes, fallback to byte-to-byte comparison
-            equal = Arrays.equals(baselineBytes, reactorBytes);
+            return baseline.compare(reactor);
         }
 
-        return !equal ? new SimpleArtifactDelta("different", baselineDisassemble, reactorDisassemble) : null;
     }
 
     private String disassemble(byte[] bytes) {

tycho-artifactcomparator/src/main/java/org/eclipse/tycho/zipcomparator/internal/ContentsComparator.java

@@ -17,7 +17,23 @@
 
 import org.eclipse.tycho.artifactcomparator.ArtifactComparator.ComparisonData;
 import org.eclipse.tycho.artifactcomparator.ArtifactDelta;
+import org.eclipse.tycho.artifactcomparator.ComparatorInputStream;
 
 public interface ContentsComparator {
-    public ArtifactDelta getDelta(InputStream baseline, InputStream reactor, ComparisonData data) throws IOException;
+
+    /**
+     * Computes the delta for the given {@link InputStream}s, the streams passed will support
+     * mark/reset for repeated reads.
+     * 
+     * @param baseline
+     *            the baseline data
+     * @param reactor
+     *            the reactor data or current project state
+     * @param data
+     * @return the {@link ArtifactDelta} or {@link ArtifactDelta#NO_DIFFERENCE} if the content is
+     *         semantically the same
+     * @throws IOException
+     */
+    public ArtifactDelta getDelta(ComparatorInputStream baseline, ComparatorInputStream reactor, ComparisonData data)
+            throws IOException;
 }

tycho-artifactcomparator/src/main/java/org/eclipse/tycho/zipcomparator/internal/DefaultContentsComparator.java

@@ -13,21 +13,21 @@
 package org.eclipse.tycho.zipcomparator.internal;
 
 import java.io.IOException;
-import java.io.InputStream;
 
 import org.codehaus.plexus.component.annotations.Component;
-import org.codehaus.plexus.util.IOUtil;
 import org.eclipse.tycho.artifactcomparator.ArtifactComparator.ComparisonData;
 import org.eclipse.tycho.artifactcomparator.ArtifactDelta;
+import org.eclipse.tycho.artifactcomparator.ComparatorInputStream;
 
 @Component(role = ContentsComparator.class, hint = DefaultContentsComparator.TYPE)
 public class DefaultContentsComparator implements ContentsComparator {
 
     public static final String TYPE = "default";
 
     @Override
-    public ArtifactDelta getDelta(InputStream baseline, InputStream reactor, ComparisonData data) throws IOException {
-        return !IOUtil.contentEquals(baseline, reactor) ? ArtifactDelta.DEFAULT : null;
+    public ArtifactDelta getDelta(ComparatorInputStream baseline, ComparatorInputStream reactor, ComparisonData data)
+            throws IOException {
+        return baseline.compare(reactor);
     }
 
 }

tycho-artifactcomparator/src/main/java/org/eclipse/tycho/zipcomparator/internal/ManifestComparator.java

@@ -13,7 +13,6 @@
 package org.eclipse.tycho.zipcomparator.internal;
 
 import java.io.IOException;
-import java.io.InputStream;
 import java.util.LinkedHashSet;
 import java.util.Set;
 import java.util.TreeMap;
@@ -24,6 +23,7 @@
 import org.codehaus.plexus.component.annotations.Component;
 import org.eclipse.tycho.artifactcomparator.ArtifactComparator.ComparisonData;
 import org.eclipse.tycho.artifactcomparator.ArtifactDelta;
+import org.eclipse.tycho.artifactcomparator.ComparatorInputStream;
 
 @Component(role = ContentsComparator.class, hint = ManifestComparator.TYPE)
 public class ManifestComparator implements ContentsComparator {
@@ -45,7 +45,8 @@ public class ManifestComparator implements ContentsComparator {
     // TODO make it possible to disable default ignores and add custom ignore
 
     @Override
-    public ArtifactDelta getDelta(InputStream baseline, InputStream reactor, ComparisonData data) throws IOException {
+    public ArtifactDelta getDelta(ComparatorInputStream baseline, ComparatorInputStream reactor, ComparisonData data)
+            throws IOException {
         TreeMap<String, ArtifactDelta> result = new TreeMap<>();
 
         Manifest manifest = new Manifest(baseline);
@@ -76,7 +77,7 @@ public ArtifactDelta getDelta(InputStream baseline, InputStream reactor, Compari
             }
         }
 
-        return !result.isEmpty() ? new CompoundArtifactDelta("different", result) : null;
+        return !result.isEmpty() ? new CompoundArtifactDelta("different", result) : ArtifactDelta.NO_DIFFERENCE;
     }
 
     private void addDelta(TreeMap<String, ArtifactDelta> result, Name key, String message) {

tycho-artifactcomparator/src/main/java/org/eclipse/tycho/zipcomparator/internal/NestedZipComparator.java

@@ -13,7 +13,6 @@
 package org.eclipse.tycho.zipcomparator.internal;
 
 import java.io.IOException;
-import java.io.InputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardCopyOption;
@@ -23,6 +22,7 @@
 import org.eclipse.tycho.artifactcomparator.ArtifactComparator;
 import org.eclipse.tycho.artifactcomparator.ArtifactComparator.ComparisonData;
 import org.eclipse.tycho.artifactcomparator.ArtifactDelta;
+import org.eclipse.tycho.artifactcomparator.ComparatorInputStream;
 
 @Component(role = ContentsComparator.class, hint = NestedZipComparator.TYPE)
 public class NestedZipComparator implements ContentsComparator {
@@ -32,7 +32,8 @@ public class NestedZipComparator implements ContentsComparator {
     private ArtifactComparator zipComparator;
 
     @Override
-    public ArtifactDelta getDelta(InputStream baseline, InputStream reactor, ComparisonData data) throws IOException {
+    public ArtifactDelta getDelta(ComparatorInputStream baseline, ComparatorInputStream reactor, ComparisonData data)
+            throws IOException {
         Path baselineZip = Files.createTempFile("baseline", ".zip");
         Path reactorZip = Files.createTempFile("reactor", ".zip");
         try {

tycho-artifactcomparator/src/main/java/org/eclipse/tycho/zipcomparator/internal/PropertiesComparator.java

@@ -13,7 +13,6 @@
 package org.eclipse.tycho.zipcomparator.internal;
 
 import java.io.IOException;
-import java.io.InputStream;
 import java.util.LinkedHashSet;
 import java.util.Map.Entry;
 import java.util.Properties;
@@ -23,13 +22,15 @@
 import org.codehaus.plexus.component.annotations.Component;
 import org.eclipse.tycho.artifactcomparator.ArtifactComparator.ComparisonData;
 import org.eclipse.tycho.artifactcomparator.ArtifactDelta;
+import org.eclipse.tycho.artifactcomparator.ComparatorInputStream;
 
 @Component(role = ContentsComparator.class, hint = PropertiesComparator.TYPE)
 public class PropertiesComparator implements ContentsComparator {
     public static final String TYPE = "properties";
 
     @Override
-    public ArtifactDelta getDelta(InputStream baseline, InputStream reactor, ComparisonData data) throws IOException {
+    public ArtifactDelta getDelta(ComparatorInputStream baseline, ComparatorInputStream reactor, ComparisonData data)
+            throws IOException {
         TreeMap<String, ArtifactDelta> result = new TreeMap<>();
 
         Properties props = new Properties();