move constants into Page, cleanup

h2/src/main/org/h2/engine/Session.java

@@ -30,7 +30,6 @@ import org.h2.jdbc.JdbcConnection;
 import org.h2.message.DbException;
 import org.h2.message.Trace;
 import org.h2.message.TraceSystem;
-import org.h2.mvstore.MVStore;
 import org.h2.mvstore.db.MVTable;
 import org.h2.mvstore.db.MVTableEngine;
 import org.h2.mvstore.db.TransactionStore.Change;

h2/src/main/org/h2/mvstore/DataUtils.java

@@ -138,20 +138,6 @@ public final class DataUtils {
      */
     public static final long COMPRESSED_VAR_LONG_MAX = 0x1ffffffffffffL;
 
-    /**
-     * The estimated number of bytes used per page object.
-     */
-    public static final int PAGE_MEMORY = Constants.MEMORY_OBJECT + 2 * Constants.MEMORY_POINTER + 22; //128;
-    public static final int PAGE_LEAF_MEMORY = PAGE_MEMORY + Constants.MEMORY_POINTER;
-    public static final int PAGE_NODE_MEMORY = PAGE_MEMORY + Constants.MEMORY_POINTER + 8;
-    public static final int PAGE_LEAF_EMPTY_MEMORY = PAGE_LEAF_MEMORY + 2 * Constants.MEMORY_ARRAY;
-    public static final int PAGE_NODE_EMPTY_MEMORY = PAGE_NODE_MEMORY + Constants.MEMORY_ARRAY;
-
-    /**
-     * The estimated number of bytes used per child entry.
-     */
-    public static final int PAGE_MEMORY_CHILD = 16;
-
     /**
      * The marker size of a very large page.
      */

h2/src/main/org/h2/mvstore/MVMapConcurrent.java

-/*
- * Copyright 2004-2018 H2 Group. Multiple-Licensed under the MPL 2.0,
- * and the EPL 1.0 (http://h2database.com/html/license.html).
- * Initial Developer: H2 Group
- */
-package org.h2.mvstore;
-
-import org.h2.mvstore.type.DataType;
-import org.h2.mvstore.type.ObjectDataType;
-
-import java.util.Map;
-
-/**
- * A class used for backward compatibility.
- *
- * @param <K> the key type
- * @param <V> the value type
- */
-public class MVMapConcurrent<K, V> extends MVMap<K, V> {
-
-    public MVMapConcurrent(Map<String, Object> config) {
-        super(config);
-    }
-
-    /**
-     * A builder for this class.
-     *
-     * @param <K> the key type
-     * @param <V> the value type
-     */
-    public static class Builder<K, V> extends MVMap.Builder<K,V> {
-        /**
-         * Create a new builder with the default key and value data types.
-         */
-        public Builder() {
-            // ignore
-        }
-
-        /**
-         * Set the key data type.
-         *
-         * @param keyType the key type
-         * @return this
-         */
-        public Builder<K, V> keyType(DataType keyType) {
-            setKeyType(keyType);
-            return this;
-        }
-
-        /**
-         * Set the key data type.
-         *
-         * @param valueType the key type
-         * @return this
-         */
-        public Builder<K, V> valueType(DataType valueType) {
-            setValueType(valueType);
-            return this;
-        }
-
-        @Override
-        protected MVMapConcurrent<K, V> create(Map<String, Object> config) {
-            return new MVMapConcurrent<>(config);
-        }
-    }
-}

h2/src/main/org/h2/mvstore/MVStore.java

@@ -226,7 +226,7 @@ public final class MVStore {
 
     private Compressor compressorHigh;
 
-    public final UncaughtExceptionHandler backgroundExceptionHandler;
+    private final UncaughtExceptionHandler backgroundExceptionHandler;
 
     private volatile long currentVersion;
 
@@ -235,8 +235,19 @@ public final class MVStore {
      */
     private long lastStoredVersion = INITIAL_VERSION;
 
+    /**
+     * Oldest store version in use. All version beyond this can be safely dropped
+     */
     private final AtomicLong oldestVersionToKeep = new AtomicLong();
+
+    /**
+     * Collection of all versions used by currently open transactions.
+     */
     private final Deque<TxCounter> versions = new LinkedList<>();
+
+    /**
+     * Counter of open transactions for the latest (current) store version
+     */
     private volatile TxCounter currentTxCounter = new TxCounter(currentVersion);
 
     /**
@@ -2819,6 +2830,11 @@ public final class MVStore {
         setOldestVersionToKeep(txCounter != null ? txCounter.version : currentTxCounter.version);
     }
 
+    /**
+     * Class TxCounter is a simple data structure to hold version of the store
+     * along with the counter of open transactions,
+     * which are still operating on this version.
+     */
     public static final class TxCounter {
         public final long version;
         public final AtomicInteger counter = new AtomicInteger();

h2/src/main/org/h2/mvstore/Page.java

@@ -65,6 +65,18 @@ public abstract class Page implements Cloneable
      */
     private volatile boolean removedInMemory;
 
+    /**
+     * The estimated number of bytes used per page object.
+     */
+    private static final int PAGE_MEMORY = Constants.MEMORY_OBJECT + 2 * Constants.MEMORY_POINTER + Constants.MEMORY_ARRAY + 17;
+    protected static final int PAGE_NODE_MEMORY = PAGE_MEMORY + Constants.MEMORY_POINTER + 8 + Constants.MEMORY_ARRAY;
+    protected static final int PAGE_LEAF_MEMORY = PAGE_MEMORY + Constants.MEMORY_POINTER + Constants.MEMORY_ARRAY;
+
+    /**
+     * The estimated number of bytes used per child entry.
+     */
+    protected static final int PAGE_MEMORY_CHILD = Constants.MEMORY_POINTER + 16; //  16 = two longs
+
     /**
      * An empty object array.
      */
@@ -100,13 +112,13 @@ public abstract class Page implements Cloneable
      */
     static Page createEmptyLeaf(MVMap<?, ?> map) {
         Page page = new Leaf(map, EMPTY_OBJECT_ARRAY, EMPTY_OBJECT_ARRAY);
-        page.initMemoryAccount(DataUtils.PAGE_LEAF_EMPTY_MEMORY);
+        page.initMemoryAccount(PAGE_LEAF_MEMORY);
         return page;
     }
 
     public static Page createEmptyNode(MVMap<?, ?> map) {
         Page page = new NonLeaf(map, EMPTY_OBJECT_ARRAY, SINGLE_EMPTY, 0);
-        page.initMemoryAccount(DataUtils.PAGE_NODE_EMPTY_MEMORY);
+        page.initMemoryAccount(PAGE_NODE_MEMORY);
         return page;
     }
 
@@ -775,7 +787,7 @@ public abstract class Page implements Cloneable
 
     protected void recalculateMemory() {
         assert isPersistent();
-        int mem = Constants.MEMORY_ARRAY;
+        int mem = 0;
         DataType keyType = map.getKeyType();
         for (Object key : keys) {
             mem += Constants.MEMORY_POINTER + keyType.getMemory(key);
@@ -999,7 +1011,7 @@ public abstract class Page implements Cloneable
 
             totalCount += childPage.getTotalCount();
             if (isPersistent()) {
-                addMemory(Constants.MEMORY_POINTER + DataUtils.PAGE_MEMORY_CHILD);
+                addMemory(PAGE_MEMORY_CHILD);
             }
         }
 
@@ -1008,7 +1020,7 @@ public abstract class Page implements Cloneable
             int childCount = getRawChildPageCount();
             super.remove(index);
             if(isPersistent()) {
-                addMemory(-(Constants.MEMORY_POINTER + DataUtils.PAGE_MEMORY_CHILD));
+                addMemory(-PAGE_MEMORY_CHILD);
             }
             totalCount -= children[index].count;
             PageReference newChildren[] = new PageReference[childCount - 1];
@@ -1116,8 +1128,8 @@ public abstract class Page implements Cloneable
         @Override
         protected void recalculateMemory() {
             super.recalculateMemory();
-            int mem = DataUtils.PAGE_NODE_MEMORY + Constants.MEMORY_ARRAY +
-                    getRawChildPageCount() * (Constants.MEMORY_POINTER + DataUtils.PAGE_MEMORY_CHILD);
+            int mem = PAGE_NODE_MEMORY +
+                    getRawChildPageCount() * PAGE_MEMORY_CHILD;
             addMemory(mem);
         }
 
@@ -1310,7 +1322,7 @@ public abstract class Page implements Cloneable
         @Override
         protected void recalculateMemory() {
             super.recalculateMemory();
-            int mem = DataUtils.PAGE_LEAF_MEMORY + Constants.MEMORY_ARRAY;
+            int mem = PAGE_LEAF_MEMORY;
             DataType valueType = map.getValueType();
             for (Object value : values) {
                 mem += valueType.getMemory(value);