LIRS replacement algorithm

h2/src/test/org/h2/test/TestBase.java

@@ -848,7 +848,9 @@ public abstract class TestBase {
      * @throws AssertionError if the condition is false
      */
     public void assertNull(Object obj) {
-        assertTrue("Expected: null got: " + obj, obj == null);
+        if (obj != null) {
+            fail("Expected: null got: " + obj);
+        }
     }
 
     /**

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

@@ -16,12 +16,12 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.Map;
 import java.util.Properties;
 import org.h2.dev.store.FilePathCache;
 import org.h2.store.fs.FilePath;
 import org.h2.store.fs.FileUtils;
 import org.h2.util.New;
-import org.h2.util.SmallLRUCache;
 import org.h2.util.StringUtils;
 
 /*
@@ -45,10 +45,10 @@ data ...
 
 todo:
 
-- garbage collection
 - use page checksums
 - compress chunks
 - possibly encode the length in pos (1=32, 2=128, 3=512,...)
+- rollback feature
 
 - floating header (avoid duplicate header)
     for each chunk, store chunk (a counter)
@@ -67,26 +67,29 @@ public class BtreeMapStore {
     private final String fileName;
     private final DataTypeFactory typeFactory;
 
+    private int readCacheSize = 2 * 1024 * 1024;
+
+    private int maxPageSize = 30;
+
     private FileChannel file;
     private int blockSize = 4 * 1024;
     private long rootChunkPos;
-    private HashMap<Long, Page> cache = SmallLRUCache.newInstance(5000);
-    private HashMap<Long, Page> temp = New.hashMap();
-    private HashMap<Integer, Chunk> chunks = New.hashMap();
-    private HashMap<String, BtreeMap<?, ?>> maps = New.hashMap();
-    private HashMap<String, BtreeMap<?, ?>> mapsChanged = New.hashMap();
-    private BtreeMap<String, String> meta;
 
-    // TODO use an int instead? (with rollover to 0)
-    private long transaction;
-    private long tempPageId;
+    private int tempPageId;
+    private Map<Long, Page> cache = CacheLIRS.newInstance(readCacheSize, 2048);
+    private HashMap<Long, Page> temp = New.hashMap();
 
     private int lastChunkId;
+    private HashMap<Integer, Chunk> chunks = New.hashMap();
 
     // TODO use bit set, and integer instead of long
+    private BtreeMap<String, String> meta;
     private long lastMapId;
+    private HashMap<String, BtreeMap<?, ?>> maps = New.hashMap();
+    private HashMap<String, BtreeMap<?, ?>> mapsChanged = New.hashMap();
 
-    private int maxPageSize = 30;
+    // TODO use an int instead? (with rollover to 0)
+    private long transaction;
 
     // TODO support reading metadata to support quota (per map, per storage)
     // TODO support r-tree

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

@@ -30,7 +30,7 @@ public class Page {
     }
 
     /**
-     * Create a new page.
+     * Create a new page. The arrays are not cloned.
      *
      * @param map the map
      * @param keys the keys
@@ -71,10 +71,10 @@ public class Page {
             return this;
         }
         map.removePage(id);
-        Page p2 = create(map, keys, values, children);
-        p2.transaction = t;
-        p2.cachedCompare = cachedCompare;
-        return p2;
+        Page newPage = create(map, keys, values, children);
+        newPage.transaction = t;
+        newPage.cachedCompare = cachedCompare;
+        return newPage;
     }
 
     public String toString() {
@@ -323,7 +323,7 @@ public class Page {
         int parentIndex = 0;
         while (true) {
             if (parent != null) {
-                parent.children[parentIndex] = p.id;
+                parent.setChild(parentIndex, p.id);
             }
             if (!p.isLeaf()) {
                 if (p.keyCount() >= map.getMaxPageSize()) {
@@ -345,12 +345,7 @@ public class Page {
             int index = p.findKey(key);
             if (p.isLeaf()) {
                 if (index >= 0) {
-                    // create a copy
-                    // TODO might not be required, but needs a "modified" flag
-                    Object[] v2 = new Object[p.values.length];
-                    System.arraycopy(p.values, 0, v2, 0, v2.length);
-                    p.values = v2;
-                    p.values[index] = value;
+                    p.setValue(index, value);
                     break;
                 }
                 index = -index - 1;
@@ -382,6 +377,22 @@ public class Page {
         return top;
     }
 
+    private void setChild(int index, long value) {
+        long[] newChildren = new long[children.length];
+        System.arraycopy(children, 0, newChildren, 0, newChildren.length);
+        newChildren[index] = value;
+        children = newChildren;
+    }
+
+    private void setValue(int index, Object value) {
+        // create a copy - not always required, but avoid unnecessary cloning
+        // would require a "modified" flag
+        Object[] newValues = new Object[values.length];
+        System.arraycopy(values, 0, newValues, 0, newValues.length);
+        newValues[index] = value;
+        values = newValues;
+    }
+
     /**
      * Remove this page and all child pages.
      */
@@ -436,7 +447,7 @@ public class Page {
             }
         } else {
             p = p.copyOnWrite();
-            p.children[index] = c2.id;
+            p.setChild(index, c2.id);
         }
         return p;
     }
@@ -485,8 +496,8 @@ public class Page {
             throw new RuntimeException("Page map id mismatch, expected " + map.getId() + " got " + id);
         }
         boolean node = buff.get() == 1;
-        if (node) {
         int len = DataUtils.readVarInt(buff);
+        if (node) {
             children = new long[len];
             keys = new Object[len - 1];
             for (int i = 0; i < len; i++) {
@@ -496,7 +507,6 @@ public class Page {
                 keys[i] = map.getKeyType().read(buff);
             }
         } else {
-            int len = DataUtils.readVarInt(buff);
             keys = new Object[len];
             values = new Object[len];
             for (int i = 0; i < len; i++) {