MVStore: maps can now be renamed.

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

@@ -62,7 +62,8 @@ public class MVMap<K, V> extends AbstractMap<K, V>
     public void open(MVStore store, HashMap<String, String> config) {
         this.store = store;
         this.id = Integer.parseInt(config.get("id"));
-        this.createVersion = Long.parseLong(config.get("createVersion"));
+        String x = config.get("createVersion");
+        this.createVersion = x == null ? 0 : Long.parseLong(x);
     }
 
     /**
@@ -799,7 +800,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         checkWrite();
         removeUnusedOldVersions();
         if (version <= createVersion) {
-            removeMap();
+            // the map is removed later
         } else if (root.getVersion() >= version) {
             // iterating in descending order -
             // this is not terribly efficient if there are many versions
@@ -997,24 +998,38 @@ public class MVMap<K, V> extends AbstractMap<K, V>
      * @return the map type
      */
     public String getType() {
-        return "btree";
+        return null;
     }
 
     /**
      * Get the map metadata as a string.
      *
+     * @param name the map name (or null)
      * @return the string
      */
-    public String asString() {
+    public String asString(String name) {
         StringBuilder buff = new StringBuilder();
-        DataUtils.appendMap(buff, "id", id);
-        DataUtils.appendMap(buff, "type", getType());
-        DataUtils.appendMap(buff, "createVersion", createVersion);
+        if (name != null) {
+            DataUtils.appendMap(buff, "name", name);
+        }
+        if (createVersion != 0) {
+            DataUtils.appendMap(buff, "createVersion", createVersion);
+        }
+        String type = getType();
+        if (type != null) {
+            DataUtils.appendMap(buff, "type", type);
+        }
         if (keyType != null) {
-            DataUtils.appendMap(buff, "key", keyType.asString());
+            String k = keyType.asString();
+            if (k.length() > 0) {
+                DataUtils.appendMap(buff, "key", k);
+            }
         }
         if (valueType != null) {
-            DataUtils.appendMap(buff, "value", valueType.asString());
+            String v = valueType.asString();
+            if (v.length() > 0) {
+                DataUtils.appendMap(buff, "value", v);
+            }
         }
         return buff.toString();
     }
@@ -1024,13 +1039,13 @@ public class MVMap<K, V> extends AbstractMap<K, V>
      *
      * @param newMapName the name name
      */
-    public void rename(String newMapName) {
+    public void renameMap(String newMapName) {
         checkWrite();
         store.renameMap(this, newMapName);
     }
 
     public String toString() {
-        return asString();
+        return asString(null);
     }
 
 }

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

@@ -44,9 +44,7 @@ H:3,...
 
 TODO:
 
-- after rollback: is a regular save ok?
 - cache: change API to better match guava / Android
-- rename a map
 - MVStore: improved API thanks to Simo Tripodi
 - implement table engine for H2
 - automated 'kill process' and 'power failure' test
@@ -154,8 +152,7 @@ public class MVStore {
     private final HashMap<Long, HashMap<Integer, Chunk>> freedChunks = New.hashMap();
 
     private MVMap<String, String> meta;
-    private final HashMap<String, MVMap<?, ?>> maps = New.hashMap();
-    private final HashMap<Integer, String> mapIdName = New.hashMap();
+    private final HashMap<Integer, MVMap<?, ?>> maps = New.hashMap();
 
     /**
      * The set of maps with potentially unsaved changes.
@@ -291,34 +288,37 @@ public class MVStore {
     @SuppressWarnings("unchecked")
     public <T extends MVMap<K, V>, K, V> T openMap(String name, T template) {
         checkOpen();
-        MVMap<K, V> m = (MVMap<K, V>) maps.get(name);
-        if (m != null) {
-            return (T) m;
-        }
-        m = template;
-        String config = meta.get("map." + name);
-        long root;
+        MVMap<K, V> m;
+        String x = meta.get("name." + name);
         int id;
+        long root;
         HashMap<String, String> c;
-        if (config == null) {
+        if (x != null) {
+            id = Integer.parseInt(x);
+            m = (MVMap<K, V>) maps.get(id);
+            if (m != null) {
+                return (T) m;
+            }
+            m = template;
+            String config = meta.get("map." + x);
+            c = DataUtils.parseMap(config);
+            c.put("id", x);
+            m.open(this, c);
+            String r = meta.get("root." + id);
+            root = r == null ? 0 : Long.parseLong(r);
+        } else {
             c = New.hashMap();
             id = ++lastMapId;
             c.put("id", Integer.toString(id));
-            c.put("name", name);
             c.put("createVersion", Long.toString(currentVersion));
+            m = template;
             m.open(this, c);
-            meta.put("map." + name, m.asString());
+            meta.put("map." + id, m.asString(name));
+            meta.put("name." + name, Integer.toString(id));
             root = 0;
-        } else {
-            c = DataUtils.parseMap(config);
-            id = Integer.parseInt(c.get("id"));
-            String r = meta.get("root." + id);
-            root = r == null ? 0 : Long.parseLong(r);
         }
-        m.open(this, c);
         m.setRootPos(root, -1);
-        mapIdName.put(id, name);
-        maps.put(name, m);
+        maps.put(id, m);
         return (T) m;
     }
 
@@ -370,12 +370,12 @@ public class MVStore {
      * @param id the map id
      */
     void removeMap(int id) {
-        String name = mapIdName.get(id);
-        meta.remove("map." + name);
+        String name = getMapName(id);
+        meta.remove("map." + id);
+        meta.remove("name." + name);
         meta.remove("root." + id);
         mapsChanged.remove(id);
-        mapIdName.remove(id);
-        maps.remove(name);
+        maps.remove(id);
     }
 
     private DataType getDataType(Class<?> clazz) {
@@ -402,7 +402,6 @@ public class MVStore {
         meta = new MVMap<String, String>(StringDataType.INSTANCE, StringDataType.INSTANCE);
         HashMap<String, String> c = New.hashMap();
         c.put("id", "0");
-        c.put("name", "meta");
         c.put("createVersion", Long.toString(currentVersion));
         meta.open(this, c);
         if (fileName == null) {
@@ -572,7 +571,6 @@ public class MVStore {
                 chunks.clear();
                 cache.clear();
                 maps.clear();
-                mapIdName.clear();
                 mapsChanged.clear();
             } catch (Exception e) {
                 throw DataUtils.illegalStateException("Closing failed for file " + fileName, e);
@@ -1004,7 +1002,7 @@ public class MVStore {
         if (mapId == 0) {
             return meta;
         }
-        return maps.get(mapIdName.get(mapId));
+        return maps.get(mapId);
     }
 
     /**
@@ -1250,7 +1248,6 @@ public class MVStore {
         if (!isKnownVersion(version)) {
             throw DataUtils.illegalArgumentException("Unknown version: " + version);
         }
-        // TODO could remove newer temporary pages on rollback
         for (MVMap<?, ?> m : mapsChanged.values()) {
             m.rollbackTo(version);
         }
@@ -1286,12 +1283,11 @@ public class MVStore {
                 readMeta();
             }
         }
-        int todoRollbackMapNames;
-        for (MVMap<?, ?> m : maps.values()) {
+        for (MVMap<?, ?> m : New.arrayList(maps.values())) {
             int id = m.getId();
             if (m.getCreateVersion() >= version) {
                 m.close();
-                removeMap(id);
+                maps.remove(id);
             } else {
                 if (loadFromFile) {
                     String r = meta.get("root." + id);
@@ -1389,20 +1385,20 @@ public class MVStore {
         if (map.getName().equals(newName)) {
             return;
         }
-        if (meta.containsKey("map." + newName)) {
+        if (meta.containsKey("name." + newName)) {
             throw DataUtils.illegalArgumentException("A map named " + newName + " already exists");
         }
         int id = map.getId();
-        String oldName = mapIdName.remove(id);
-        maps.remove(oldName);
-        String value = meta.remove("map." + oldName);
-        meta.put("map." + newName, value);
-        maps.put(newName, map);
-        mapIdName.put(id, newName);
+        String oldName = getMapName(id);
+        meta.remove("map." + id);
+        meta.remove("name." + oldName);
+        meta.put("map." + id, map.asString(newName));
+        meta.put("name." + newName, Integer.toString(id));
     }
 
     String getMapName(int id) {
-        return mapIdName.get(id);
+        String m = meta.get("map." + id);
+        return DataUtils.parseMap(m).get("name");
     }
 
 }

h2/src/main/org/h2/mvstore/db/MVPrimaryIndex.java

@@ -55,7 +55,7 @@ public class MVPrimaryIndex extends BaseIndex {
 
     public void renameTable(String newName) {
         rename(newName + "_DATA");
-        map.rename(newName + "_DATA_" + getId());
+        map.renameMap(newName + "_DATA_" + getId());
     }
 
     public String getCreateSQL() {

h2/src/main/org/h2/mvstore/db/MVSecondaryIndex.java

@@ -73,7 +73,7 @@ public class MVSecondaryIndex extends BaseIndex {
     }
 
     public void rename(String newName) {
-        map.rename(newName + "_" + getId());
+        map.renameMap(newName + "_" + getId());
         super.rename(newName);
     }
 

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

@@ -42,6 +42,7 @@ public class TestMVStore extends TestBase {
 
     public void test() throws Exception {
         FileUtils.deleteRecursive(getBaseDir(), true);
+        testRenameMapRollback();
         testCustomMapType();
         testCacheSize();
         testConcurrentOpen();
@@ -73,11 +74,24 @@ public class TestMVStore extends TestBase {
         testSimple();
     }
 
+    private void testRenameMapRollback() {
+        MVStore s = openStore(null);
+        MVMap<Integer, Integer> map;
+        map = s.openMap("hello");
+        map.put(1, 10);
+        long old = s.incrementVersion();
+        map.renameMap("world");
+        map.put(2, 20);
+        assertEquals("world", map.getName());
+        s.rollbackTo(old);
+        assertEquals("hello", map.getName());
+        s.close();
+    }
+
     private void testCustomMapType() {
         String fileName = getBaseDir() + "/testMapType.h3";
         FileUtils.delete(fileName);
-        MVStore s;
-        s = openStore(fileName);
+        MVStore s = openStore(fileName);
         SequenceMap seq = new SequenceMap();
         seq = s.openMap("data", seq);
         StringBuilder buff = new StringBuilder();
@@ -634,7 +648,7 @@ public class TestMVStore extends TestBase {
         assertTrue(s.hasUnsavedChanges());
         s.rollbackTo(v2);
         assertFalse(s.hasUnsavedChanges());
-        assertNull(meta.get("map.data1"));
+        assertNull(meta.get("name.data1"));
         assertNull(m0.get("1"));
         assertEquals("Hello", m.get("1"));
         assertEquals(2, s.store());
@@ -643,9 +657,9 @@ public class TestMVStore extends TestBase {
         s = openStore(fileName);
         assertEquals(2, s.getCurrentVersion());
         meta = s.getMetaMap();
-        assertTrue(meta.get("map.data") != null);
-        assertTrue(meta.get("map.data0") != null);
-        assertNull(meta.get("map.data1"));
+        assertTrue(meta.get("name.data") != null);
+        assertTrue(meta.get("name.data0") != null);
+        assertNull(meta.get("name.data1"));
         m = s.openMap("data", String.class, String.class);
         m0 = s.openMap("data0", String.class, String.class);
         assertNull(m0.get("1"));
@@ -735,17 +749,16 @@ public class TestMVStore extends TestBase {
         assertTrue(m.containsKey("chunk.1"));
         assertFalse(m.containsKey("chunk.2"));
 
-        assertEquals("id:1,type:btree,createVersion:0,key:,value:",
-                m.get("map.data"));
+        String id = s.getMetaMap().get("name.data");
+        assertEquals("name:data", m.get("map." + id));
         assertTrue(m.containsKey("chunk.1"));
         assertEquals("Hello", data.put("1", "Hallo"));
         s.store();
-        assertEquals("id:1,type:btree,createVersion:0,key:,value:",
-                m.get("map.data"));
+        assertEquals("name:data", m.get("map." + id));
         assertTrue(m.get("root.1").length() > 0);
         assertTrue(m.containsKey("chunk.1"));
-        assertEquals("id:1,length:271,maxLength:288,maxLengthLive:0," +
-                "metaRoot:274877910924,pageCount:2," +
+        assertEquals("id:1,length:246,maxLength:224,maxLengthLive:0," +
+                "metaRoot:274877910922,pageCount:2," +
                 "start:8192,time:0,version:1", m.get("chunk.1"));
 
         assertTrue(m.containsKey("chunk.2"));