A persistent tree map (work in progress).

h2/src/test/org/h2/test/store/TestBtreeMapStore.java

@@ -29,6 +29,7 @@ public class TestBtreeMapStore extends TestBase {
     }
 
     public void test() {
+        testTruncateFile();
         testFastDelete();
         testRollbackInMemory();
         testRollbackStored();
@@ -43,6 +44,29 @@ public class TestBtreeMapStore extends TestBase {
         testSimple();
     }
 
+    private void testTruncateFile() {
+        String fileName = getBaseDir() + "/testMeta.h3";
+        FileUtils.delete(fileName);
+        BtreeMapStore s;
+        BtreeMap<Integer, String> m;
+        s = openStore(fileName);
+        m = s.openMap("data", Integer.class, String.class);
+        for (int i = 0; i < 1000; i++) {
+            m.put(i, "Hello World");
+        }
+        s.store();
+        s.close();
+        long len = FileUtils.size(fileName);
+        s = openStore(fileName);
+        m = s.openMap("data", Integer.class, String.class);
+        m.clear();
+        s.store();
+        s.compact(100);
+        s.close();
+        long len2 = FileUtils.size(fileName);
+        assertTrue(len2 < len);
+    }
+
     private void testFastDelete() {
         String fileName = getBaseDir() + "/testMeta.h3";
         FileUtils.delete(fileName);
@@ -53,7 +77,9 @@ public class TestBtreeMapStore extends TestBase {
         m = s.openMap("data", Integer.class, String.class);
         for (int i = 0; i < 1000; i++) {
             m.put(i, "Hello World");
+            assertEquals(i + 1, m.size());
         }
+        assertEquals(1000, m.size());
         s.store();
         assertEquals(3, s.getWriteCount());
         s.close();
@@ -61,6 +87,7 @@ public class TestBtreeMapStore extends TestBase {
         s = openStore(fileName);
         m = s.openMap("data", Integer.class, String.class);
         m.clear();
+        assertEquals(0, m.size());
         s.store();
         // ensure only nodes are read, but not leaves
         assertEquals(4, s.getReadCount());
@@ -76,7 +103,7 @@ public class TestBtreeMapStore extends TestBase {
         assertEquals(-1, s.getRetainChunk());
         s.setRetainChunk(0);
         assertEquals(0, s.getRetainChunk());
-        assertEquals(0, s.getCurrentVersion());
+        assertEquals(1, s.getCurrentVersion());
         assertFalse(s.hasUnsavedChanges());
         BtreeMap<String, String> m = s.openMap("data", String.class, String.class);
         assertTrue(s.hasUnsavedChanges());
@@ -86,12 +113,14 @@ public class TestBtreeMapStore extends TestBase {
         s.rollbackTo(1);
         assertEquals("Hello", m.get("1"));
         long v2 = s.store();
+        assertEquals(2, v2);
+        assertEquals(3, s.getCurrentVersion());
         assertFalse(s.hasUnsavedChanges());
         s.close();
 
         s = openStore(fileName);
+        assertEquals(3, s.getCurrentVersion());
         s.setRetainChunk(0);
-        assertEquals(2, s.getCurrentVersion());
         meta = s.getMetaMap();
         m = s.openMap("data", String.class, String.class);
         m0 = s.openMap("data0", String.class, String.class);
@@ -101,6 +130,7 @@ public class TestBtreeMapStore extends TestBase {
         m1.put("1", "Hallo");
         assertEquals("Hallo", m.get("1"));
         assertEquals("Hallo", m1.get("1"));
+        assertTrue(s.hasUnsavedChanges());
         s.rollbackTo(v2);
         assertFalse(s.hasUnsavedChanges());
         assertNull(meta.get("map.data1"));
@@ -111,7 +141,7 @@ public class TestBtreeMapStore extends TestBase {
 
         s = openStore(fileName);
         s.setRetainChunk(0);
-        assertEquals(2, s.getCurrentVersion());
+        assertEquals(3, s.getCurrentVersion());
         meta = s.getMetaMap();
         assertTrue(meta.get("map.data") != null);
         assertTrue(meta.get("map.data0") != null);
@@ -123,10 +153,10 @@ public class TestBtreeMapStore extends TestBase {
         assertFalse(m0.isReadOnly());
         m.put("1",  "Hallo");
         s.commit();
-        assertEquals(3, s.getCurrentVersion());
+        assertEquals(4, s.getCurrentVersion());
         long v4 = s.store();
         assertEquals(4, v4);
-        assertEquals(4, s.getCurrentVersion());
+        assertEquals(5, s.getCurrentVersion());
         s.close();
 
         s = openStore(fileName);
@@ -155,8 +185,14 @@ public class TestBtreeMapStore extends TestBase {
         String fileName = getBaseDir() + "/testMeta.h3";
         FileUtils.delete(fileName);
         BtreeMapStore s = openStore(fileName);
+        assertEquals(1, s.getCurrentVersion());
         s.setMaxPageSize(5);
         BtreeMap<String, String> m = s.openMap("data", String.class, String.class);
+        s.rollbackTo(0);
+        assertTrue(m.isClosed());
+        assertEquals(1, s.getCurrentVersion());
+        m = s.openMap("data", String.class, String.class);
+
         BtreeMap<String, String> m0 = s.openMap("data0", String.class, String.class);
         BtreeMap<String, String> m2 = s.openMap("data2", String.class, String.class);
         m.put("1", "Hello");
@@ -165,6 +201,7 @@ public class TestBtreeMapStore extends TestBase {
         }
         long v1 = s.commit();
         assertEquals(1, v1);
+        assertEquals(2, s.getCurrentVersion());
         BtreeMap<String, String> m1 = s.openMap("data1", String.class, String.class);
         assertEquals("Test", m2.get("1"));
         m.put("1", "Hallo");
@@ -174,6 +211,7 @@ public class TestBtreeMapStore extends TestBase {
         assertEquals("Hallo", m.get("1"));
         assertEquals("Hallo", m1.get("1"));
         s.rollbackTo(v1);
+        assertEquals(2, s.getCurrentVersion());
         for (int i = 0; i < 10; i++) {
             assertEquals("Test", m2.get("" + i));
         }
@@ -195,11 +233,11 @@ public class TestBtreeMapStore extends TestBase {
         data.put("1", "Hello");
         data.put("2", "World");
         s.store();
-        assertEquals("1/0//", m.get("map.data"));
+        assertEquals("1/1//", m.get("map.data"));
         assertTrue(m.containsKey("chunk.1"));
         data.put("1", "Hallo");
         s.store();
-        assertEquals("1/0//", m.get("map.data"));
+        assertEquals("1/1//", m.get("map.data"));
         assertTrue(m.get("root.1").length() > 0);
         assertTrue(m.containsKey("chunk.1"));
         assertTrue(m.containsKey("chunk.2"));
@@ -295,7 +333,7 @@ public class TestBtreeMapStore extends TestBase {
                 m.put(j + i, "Hello " + j);
             }
             s.store();
-            s.compact();
+            s.compact(80);
             s.close();
             long len = FileUtils.size(fileName);
             // System.out.println("   len:" + len);
@@ -313,13 +351,13 @@ public class TestBtreeMapStore extends TestBase {
             m.remove(i);
         }
         s.store();
-        s.compact();
+        s.compact(80);
         s.close();
         // len = FileUtils.size(fileName);
         // System.out.println("len1: " + len);
         s = openStore(fileName);
         m = s.openMap("data", Integer.class, String.class);
-        s.compact();
+        s.compact(80);
         s.close();
         // len = FileUtils.size(fileName);
         // System.out.println("len2: " + len);

h2/src/tools/org/h2/dev/store/btree/BtreeMap.java

@@ -6,7 +6,9 @@
  */
 package org.h2.dev.store.btree;
 
+import java.util.AbstractSet;
 import java.util.Iterator;
+import java.util.Set;
 import java.util.TreeMap;
 
 /**
@@ -22,6 +24,11 @@ public class BtreeMap<K, V> {
     private final DataType keyType;
     private final DataType valueType;
     private final long createVersion;
+
+    /**
+     * The map of old roots. The key is the new version, the value is the root
+     * before this version.
+     */
     private final TreeMap<Long, Page> oldRoots = new TreeMap<Long, Page>();
     private BtreeMapStore store;
     private Page root;
@@ -45,7 +52,11 @@ public class BtreeMap<K, V> {
     public void put(K key, V data) {
         checkWrite();
         Page oldRoot = root;
-        root = Page.put(this, root, store.getCurrentVersion(), key, data);
+        if (containsKey(key)) {
+            root = Page.set(this, root, store.getCurrentVersion(), key, data);
+        } else {
+            root = Page.add(this, root, store.getCurrentVersion(), key, data);
+        }
         markChanged(oldRoot);
     }
 
@@ -56,7 +67,7 @@ public class BtreeMap<K, V> {
      * @return the value, or null if not found
      */
     @SuppressWarnings("unchecked")
-    public V get(K key) {
+    public V get(Object key) {
         checkOpen();
         if (root == null) {
             return null;
@@ -64,7 +75,7 @@ public class BtreeMap<K, V> {
         return (V) root.find(key);
     }
 
-    public boolean containsKey(K key) {
+    public boolean containsKey(Object key) {
         return get(key) != null;
     }
 
@@ -102,7 +113,7 @@ public class BtreeMap<K, V> {
         if (root != null) {
             root.removeAllRecursive();
         }
-        store.removeMap(id);
+        store.removeMap(name);
         close();
     }
 
@@ -118,22 +129,25 @@ public class BtreeMap<K, V> {
     }
 
     /**
-     * Remove a key-value pair.
+     * Remove a key-value pair, if the key exists.
      *
      * @param key the key
      */
     public void remove(K key) {
         checkWrite();
-        if (root != null) {
+        if (containsKey(key)) {
             Page oldRoot = root;
-            root = Page.remove(root, store.getCurrentVersion(), key);
+            root = Page.removeExisting(root, store.getCurrentVersion(), key);
             markChanged(oldRoot);
         }
     }
 
     private void markChanged(Page oldRoot) {
         if (oldRoot != root) {
-            oldRoots.put(store.getCurrentVersion(), oldRoot);
+            long v = store.getCurrentVersion();
+            if (!oldRoots.containsKey(v)) {
+                oldRoots.put(v, oldRoot);
+            }
             store.markChanged(this);
         }
     }
@@ -201,6 +215,28 @@ public class BtreeMap<K, V> {
         return new Cursor<K>(root, from);
     }
 
+    public Set<K> keySet() {
+        checkOpen();
+        return new AbstractSet<K>() {
+
+            @Override
+            public Iterator<K> iterator() {
+                return new Cursor<K>(getRoot(), null);
+            }
+
+            @Override
+            public int size() {
+                return BtreeMap.this.size();
+            }
+
+            @Override
+            public boolean contains(Object o) {
+                return BtreeMap.this.containsKey(o);
+            }
+
+        };
+    }
+
     /**
      * Get the root page.
      *
@@ -229,7 +265,7 @@ public class BtreeMap<K, V> {
 
     void rollbackTo(long version) {
         checkWrite();
-        if (version <= createVersion) {
+        if (version < createVersion) {
             remove();
         } else {
             // iterating in ascending order, and pick the last version -
@@ -238,7 +274,7 @@ public class BtreeMap<K, V> {
             Long newestOldVersion = null;
             for (Iterator<Long> it = oldRoots.keySet().iterator(); it.hasNext();) {
                 Long x = it.next();
-                if (x >= version) {
+                if (x > version) {
                     if (newestOldVersion == null) {
                         newestOldVersion = x;
                         root = oldRoots.get(x);
@@ -249,6 +285,10 @@ public class BtreeMap<K, V> {
         }
     }
 
+    void stored() {
+        oldRoots.clear();
+    }
+
     public void setReadOnly(boolean readOnly) {
         this.readOnly = readOnly;
     }
@@ -286,6 +326,15 @@ public class BtreeMap<K, V> {
         return id;
     }
 
+    public int size() {
+        long size = getSize();
+        return size > Integer.MAX_VALUE ? Integer.MAX_VALUE : (int) size;
+    }
+
+    public long getSize() {
+        return root == null ? 0 : root.getTotalSize();
+    }
+
     public boolean equals(Object o) {
         return this == o;
     }

h2/src/tools/org/h2/dev/store/btree/DataUtils.java

@@ -35,6 +35,11 @@ public class DataUtils {
      */
     public static final int MAX_VAR_INT_LEN = 5;
 
+    /**
+     * The maximum length of a variable size long.
+     */
+    public static final int MAX_VAR_LONG_LEN = 10;
+
     /**
      * Get the length of the variable size int.
      *