reftable: move AutoCloseable to ReftableReader

MergedReftable is not used as an AutoCloseable, because closing tables
is currently handled by DfsReftableStack#close.

Encode that a MergedReftable is a list of ReftableReaders. The previous
code suggested that we could form nested trees of MergedReftables,
which is not how we use reftables.

Change-Id: Icbe2fee8a5a12373f45fc5f97d8b1a2b14231c96
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/MergedReftableTest.java

@@ -414,7 +414,7 @@ public class MergedReftableTest {
 	}
 
 	private static MergedReftable merge(byte[]... table) {
-		List<Reftable> stack = new ArrayList<>(table.length);
+		List<ReftableReader> stack = new ArrayList<>(table.length);
 		for (byte[] b : table) {
 			stack.add(read(b));
 		}

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReftableStack.java

@@ -48,11 +48,11 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
-import org.eclipse.jgit.internal.storage.reftable.Reftable;
+import org.eclipse.jgit.internal.storage.reftable.ReftableReader;
 
 /**
  * Tracks multiple open
- * {@link org.eclipse.jgit.internal.storage.reftable.Reftable} instances.
+ * {@link org.eclipse.jgit.internal.storage.reftable.ReftableReader} instances.
  */
 public class DfsReftableStack implements AutoCloseable {
 	/**
@@ -86,7 +86,7 @@ public class DfsReftableStack implements AutoCloseable {
 	}
 
 	private final List<DfsReftable> files;
-	private final List<Reftable> tables;
+	private final List<ReftableReader> tables;
 
 	private DfsReftableStack(int tableCnt) {
 		this.files = new ArrayList<>(tableCnt);
@@ -109,14 +109,14 @@ public class DfsReftableStack implements AutoCloseable {
 	 * @return unmodifiable list of tables, in the same order the files were
 	 *         passed to {@link #open(DfsReader, List)}.
 	 */
-	public List<Reftable> readers() {
+	public List<ReftableReader> readers() {
 		return Collections.unmodifiableList(tables);
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void close() {
-		for (Reftable t : tables) {
+		for (ReftableReader t : tables) {
 			try {
 				t.close();
 			} catch (IOException e) {

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/ReftableBatchRefUpdate.java

@@ -406,7 +406,7 @@ public class ReftableBatchRefUpdate extends BatchRefUpdate {
 	private boolean canCompactTopOfStack(ReftableConfig cfg)
 			throws IOException {
 		DfsReftableStack stack = refdb.stack();
-		List<Reftable> readers = stack.readers();
+		List<ReftableReader> readers = stack.readers();
 		if (readers.isEmpty()) {
 			return false;
 		}
@@ -427,10 +427,10 @@ public class ReftableBatchRefUpdate extends BatchRefUpdate {
 
 	private ReftableWriter.Stats compactTopOfStack(OutputStream out,
 			ReftableConfig cfg, byte[] newTable) throws IOException {
-		List<Reftable> stack = refdb.stack().readers();
-		Reftable last = stack.get(stack.size() - 1);
+		List<ReftableReader> stack = refdb.stack().readers();
+		ReftableReader last = stack.get(stack.size() - 1);
 
-		List<Reftable> tables = new ArrayList<>(2);
+		List<ReftableReader> tables = new ArrayList<>(2);
 		tables.add(last);
 		tables.add(new ReftableReader(BlockSource.from(newTable)));
 

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/MergedReftable.java

@@ -67,13 +67,11 @@ import org.eclipse.jgit.lib.ReflogEntry;
  * A {@code MergedReftable} is not thread-safe.
  */
 public class MergedReftable extends Reftable {
-	private final Reftable[] tables;
+	private final ReftableReader[] tables;
 
 	/**
 	 * Initialize a merged table reader.
 	 * <p>
-	 * The tables in {@code tableStack} will be closed when this
-	 * {@code MergedReftable} is closed.
 	 *
 	 * @param tableStack
 	 *            stack of tables to read from. The base of the stack is at
@@ -81,12 +79,12 @@ public class MergedReftable extends Reftable {
 	 *            {@code tableStack.size() - 1}. The top of the stack (higher
 	 *            index) shadows the base of the stack (lower index).
 	 */
-	public MergedReftable(List<Reftable> tableStack) {
-		tables = tableStack.toArray(new Reftable[0]);
+	public MergedReftable(List<ReftableReader> tableStack) {
+		tables = tableStack.toArray(new ReftableReader[0]);
 
 		// Tables must expose deletes to this instance to correctly
 		// shadow references from lower tables.
-		for (Reftable t : tables) {
+		for (ReftableReader t : tables) {
 			t.setIncludeDeletes(true);
 		}
 	}
@@ -161,14 +159,6 @@ public class MergedReftable extends Reftable {
 		return m;
 	}
 
-	/** {@inheritDoc} */
-	@Override
-	public void close() throws IOException {
-		for (Reftable t : tables) {
-			t.close();
-		}
-	}
-
 	int queueSize() {
 		return Math.max(1, tables.length);
 	}

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/Reftable.java

@@ -58,7 +58,7 @@ import org.eclipse.jgit.lib.SymbolicRef;
 /**
  * Abstract table of references.
  */
-public abstract class Reftable implements AutoCloseable {
+public abstract class Reftable {
 	/**
 	 * References to convert into a reftable
 	 *
@@ -295,8 +295,4 @@ public abstract class Reftable implements AutoCloseable {
 		}
 		return new SymbolicRef(ref.getName(), dst, ref.getUpdateIndex());
 	}
-
-	/** {@inheritDoc} */
-	@Override
-	public abstract void close() throws IOException;
 }

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableCompactor.java

@@ -69,7 +69,7 @@ import org.eclipse.jgit.lib.ReflogEntry;
  */
 public class ReftableCompactor {
 	private final ReftableWriter writer;
-	private final ArrayDeque<Reftable> tables = new ArrayDeque<>();
+	private final ArrayDeque<ReftableReader> tables = new ArrayDeque<>();
 
 	private long compactBytesLimit;
 	private long bytesToCompact;
@@ -188,12 +188,10 @@ public class ReftableCompactor {
 	 * @throws java.io.IOException
 	 *             update indexes of a reader cannot be accessed.
 	 */
-	public void addAll(List<? extends Reftable> readers) throws IOException {
-		tables.addAll(readers);
-		for (Reftable r : readers) {
-			if (r instanceof ReftableReader) {
-				adjustUpdateIndexes((ReftableReader) r);
-			}
+	public void addAll(List<ReftableReader> readers) throws IOException {
+		for (ReftableReader r : readers) {
+			tables.add(r);
+			adjustUpdateIndexes(r);
 		}
 	}
 

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableReader.java

@@ -78,7 +78,7 @@ import org.eclipse.jgit.util.NB;
  * {@code ReftableReader} is not thread-safe. Concurrent readers need their own
  * instance to read from the same file.
  */
-public class ReftableReader extends Reftable {
+public class ReftableReader extends Reftable implements AutoCloseable {
 	private final BlockSource src;
 
 	private int blockSize = -1;