Merge pull request #553 from andreitokar/mem_optimization

eliminate memory estimations for "mem:" case

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

@@ -72,7 +72,6 @@ public class MVMap<K, V> extends AbstractMap<K, V>
     protected MVMap(DataType keyType, DataType valueType) {
         this.keyType = keyType;
         this.valueType = valueType;
-        this.root = Page.createEmpty(this,  -1);
     }
 
     /**
@@ -106,6 +105,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         this.id = DataUtils.readHexInt(config, "id", 0);
         this.createVersion = DataUtils.readHexLong(config, "createVersion", 0);
         this.writeVersion = store.getCurrentVersion();
+        this.root = Page.createEmpty(this,  -1);
     }
 
     /**

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

@@ -120,7 +120,7 @@ MVStore:
 /**
  * A persistent storage for maps.
  */
-public class MVStore {
+public final class MVStore {
 
     /**
      * Whether assertions are enabled.
@@ -292,12 +292,21 @@ public class MVStore {
         Object o = config.get("compress");
         this.compressionLevel = o == null ? 0 : (Integer) o;
         String fileName = (String) config.get("fileName");
+        fileStore = (FileStore) config.get("fileStore");
+        fileStoreIsProvided = fileStore != null;
+        if(fileStore == null && fileName != null) {
+            fileStore = new FileStore();
+        }
         o = config.get("pageSplitSize");
-        if (o == null) {
-            pageSplitSize = fileName == null ? 4 * 1024 : 16 * 1024;
+        int pgSplitSize;
+        if (o != null) {
+            pgSplitSize = (Integer) o;
+        } else if(fileStore != null) {
+            pgSplitSize = 16 * 1024;
         } else {
-            pageSplitSize = (Integer) o;
+            pgSplitSize = 48; // number of keys per page in that case
         }
+        pageSplitSize = pgSplitSize;
         o = config.get("backgroundExceptionHandler");
         this.backgroundExceptionHandler = (UncaughtExceptionHandler) o;
         meta = new MVMap<String, String>(StringDataType.INSTANCE,
@@ -306,18 +315,11 @@ public class MVStore {
         c.put("id", 0);
         c.put("createVersion", currentVersion);
         meta.init(this, c);
-        fileStore = (FileStore) config.get("fileStore");
-        if (fileName == null && fileStore == null) {
+        if (fileStore == null) {
             cache = null;
             cacheChunkRef = null;
             return;
         }
-        if (fileStore == null) {
-            fileStoreIsProvided = false;
-            fileStore = new FileStore();
-        } else {
-            fileStoreIsProvided = true;
-        }
         retentionTime = fileStore.getDefaultRetentionTime();
         boolean readOnly = config.containsKey("readOnly");
         o = config.get("cacheSize");
@@ -995,7 +997,7 @@ public class MVStore {
      *
      * @return the new version
      */
-    public long commit() {
+    public synchronized long commit() {
         if (fileStore != null) {
             return commitAndSave();
         }

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

@@ -36,6 +36,7 @@ public class Page {
      * An empty object array.
      */
     public static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
+    private static final int IN_MEMORY = Integer.MIN_VALUE;
 
     private final MVMap<?, ?> map;
     private long version;
@@ -52,7 +53,7 @@ public class Page {
     private int cachedCompare;
 
     /**
-     * The estimated memory used.
+     * The estimated memory used in persistent case, IN_MEMORY marker value otherwise.
      */
     private int memory;
 
@@ -125,13 +126,15 @@ public class Page {
         p.values = values;
         p.children = children;
         p.totalCount = totalCount;
-        if (memory == 0) {
+        MVStore store = map.store;
+        if(store.getFileStore() == null) {
+            p.memory = IN_MEMORY;
+        } else if (memory == 0) {
             p.recalculateMemory();
         } else {
             p.addMemory(memory);
         }
-        MVStore store = map.store;
-        if (store != null) {
+        if(store.getFileStore() != null) {
             store.registerUnsavedPage(p.memory);
         }
         return p;
@@ -146,18 +149,8 @@ public class Page {
      * @return the page
      */
     public static Page create(MVMap<?, ?> map, long version, Page source) {
-        Page p = new Page(map, version);
-        // the position is 0
-        p.keys = source.keys;
-        p.values = source.values;
-        p.children = source.children;
-        p.totalCount = source.totalCount;
-        p.memory = source.memory;
-        MVStore store = map.store;
-        if (store != null) {
-            store.registerUnsavedPage(p.memory);
-        }
-        return p;
+        return create(map, version, source.keys, source.values, source.children,
+                source.totalCount, source.memory);
     }
 
     /**
@@ -302,7 +295,7 @@ public class Page {
         Page newPage = create(map, version,
                 keys, values,
                 children, totalCount,
-                getMemory());
+                memory);
         // mark the old as deleted
         removePage();
         newPage.cachedCompare = cachedCompare;
@@ -368,7 +361,11 @@ public class Page {
      * @return the page with the entries after the split index
      */
     Page split(int at) {
-        return isLeaf() ? splitLeaf(at) : splitNode(at);
+        Page page = isLeaf() ? splitLeaf(at) : splitNode(at);
+        if(isPersistent()) {
+            recalculateMemory();
+        }
+        return page;
     }
 
     private Page splitLeaf(int at) {
@@ -388,9 +385,7 @@ public class Page {
         Page newPage = create(map, version,
                 bKeys, bValues,
                 null,
-                bKeys.length, 0);
-        recalculateMemory();
-        newPage.recalculateMemory();
+                b, 0);
         return newPage;
     }
 
@@ -422,8 +417,6 @@ public class Page {
                 bKeys, null,
                 bChildren,
                 t, 0);
-        recalculateMemory();
-        newPage.recalculateMemory();
         return newPage;
     }
 
@@ -498,6 +491,7 @@ public class Page {
         // this is slightly slower:
         // keys = Arrays.copyOf(keys, keys.length);
         keys = keys.clone();
+        if(isPersistent()) {
             Object old = keys[index];
             DataType keyType = map.getKeyType();
             int mem = keyType.getMemory(key);
@@ -505,6 +499,7 @@ public class Page {
                 mem -= keyType.getMemory(old);
             }
             addMemory(mem);
+        }
         keys[index] = key;
     }
 
@@ -521,8 +516,10 @@ public class Page {
         // values = Arrays.copyOf(values, values.length);
         values = values.clone();
         DataType valueType = map.getValueType();
+        if(isPersistent()) {
             addMemory(valueType.getMemory(value) -
                     valueType.getMemory(old));
+        }
         values[index] = value;
         return old;
     }
@@ -569,9 +566,11 @@ public class Page {
         keys[index] = key;
         values[index] = value;
         totalCount++;
+        if(isPersistent()) {
             addMemory(map.getKeyType().getMemory(key) +
                     map.getValueType().getMemory(value));
         }
+    }
 
     /**
      * Insert a child page into this node.
@@ -595,9 +594,11 @@ public class Page {
         children = newChildren;
 
         totalCount += childPage.totalCount;
+        if(isPersistent()) {
             addMemory(map.getKeyType().getMemory(key) +
                     DataUtils.PAGE_MEMORY_CHILD);
         }
+    }
 
     /**
      * Remove the key and value (or child) at the given index.
@@ -607,22 +608,28 @@ public class Page {
     public void remove(int index) {
         int keyLength = keys.length;
         int keyIndex = index >= keyLength ? index - 1 : index;
+        if(isPersistent()) {
             Object old = keys[keyIndex];
             addMemory(-map.getKeyType().getMemory(old));
+        }
         Object[] newKeys = new Object[keyLength - 1];
         DataUtils.copyExcept(keys, newKeys, keyLength, keyIndex);
         keys = newKeys;
 
         if (values != null) {
-            old = values[index];
+            if(isPersistent()) {
+                Object old = values[index];
                 addMemory(-map.getValueType().getMemory(old));
+            }
             Object[] newValues = new Object[keyLength - 1];
             DataUtils.copyExcept(values, newValues, keyLength, index);
             values = newValues;
             totalCount--;
         }
         if (children != null) {
+            if(isPersistent()) {
                 addMemory(-DataUtils.PAGE_MEMORY_CHILD);
+            }
             long countOffset = children[index].count;
 
             int childCount = children.length;
@@ -887,7 +894,12 @@ public class Page {
         return pos != 0 ? (int) (pos | (pos >>> 32)) : super.hashCode();
     }
 
+    private boolean isPersistent() {
+        return memory != IN_MEMORY;
+    }
+
     public int getMemory() {
+        if (isPersistent()) {
             if (MVStore.ASSERT) {
                 int mem = memory;
                 recalculateMemory();
@@ -898,6 +910,8 @@ public class Page {
             }
             return memory;
         }
+        return getKeyCount();
+    }
 
     private void addMemory(int mem) {
         memory += mem;
@@ -928,12 +942,14 @@ public class Page {
      * Remove the page.
      */
     public void removePage() {
+        if(isPersistent()) {
             long p = pos;
             if (p == 0) {
                 removedInMemory = true;
             }
             map.removePage(p, memory);
         }
+    }
 
     /**
      * A pointer to a page, either in-memory or using a page position.

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

@@ -1416,7 +1416,9 @@ public class TestMVStore extends TestBase {
             assertEquals(i + 1, m.size());
         }
         assertEquals(1000, m.size());
-        assertEquals(131896, s.getUnsavedMemory());
+        // previously (131896) we fail to account for initial root page for every map
+        // there are two of them here (meta and "data"), hence lack of 256 bytes
+        assertEquals(132152, s.getUnsavedMemory());
         s.commit();
         assertEquals(2, s.getFileStore().getWriteCount());
         s.close();