MVRTreeMap: never free a page twice

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

@@ -74,7 +74,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
 
     /**
      * Create a copy of a page, if the write version is higher than the current
-     * version.
+     * version. If a copy is created, the old page is marked as deleted.
      *
      * @param p the page
      * @param writeVersion the write version
@@ -674,7 +674,7 @@ public class MVMap<K, V> extends AbstractMap<K, V>
             if (p.getKeyCount() == 0) {
                 p.setChild(index, c);
                 p.setCounts(index, c);
-                removePage(p.getPos());
+                p.removePage();
             } else {
                 p.remove(index);
             }

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

@@ -273,7 +273,7 @@ public class Page {
      * @return a page with the given version
      */
     public Page copy(long version) {
-        map.removePage(pos);
+        removePage();
         Page newPage = create(map, version,
                 keyCount, keys, values, children, childrenPages,
                 counts, totalCount,
@@ -552,7 +552,7 @@ public class Page {
                 }
             }
         }
-        map.removePage(pos);
+        removePage();
     }
 
     /**
@@ -934,4 +934,11 @@ public class Page {
         this.version = version;
     }
 
+    /**
+     * Remove the page.
+     */
+    public void removePage() {
+        map.removePage(pos);
+    }
+
 }

h2/src/main/org/h2/mvstore/rtree/MVRTreeMap.java

@@ -155,7 +155,7 @@ public class MVRTreeMap<V> extends MVMap<SpatialKey, V> {
                     result = p.getValue(i);
                     p.remove(i);
                     if (p.getKeyCount() == 0) {
-                        removePage(p.getPos());
+                        p.removePage();
                     }
                     break;
                 }
@@ -165,9 +165,14 @@ public class MVRTreeMap<V> extends MVMap<SpatialKey, V> {
         for (int i = 0; i < p.getKeyCount(); i++) {
             if (contains(p, i, key)) {
                 Page cOld = p.getChildPage(i);
+                // this will mark the old page as deleted
+                // so we need to update the parent in any case
+                // (otherwise the old page might be deleted again)
                 Page c = copyOnWrite(cOld, writeVersion);
                 long oldSize = c.getTotalCount();
                 result = remove(c, writeVersion, key);
+                p.setChild(i, c);
+                p.setCounts(i, c);
                 if (oldSize == c.getTotalCount()) {
                     continue;
                 }
@@ -175,7 +180,7 @@ public class MVRTreeMap<V> extends MVMap<SpatialKey, V> {
                     // this child was deleted
                     p.remove(i);
                     if (p.getKeyCount() == 0) {
-                        removePage(p.getPos());
+                        p.removePage();
                     }
                     break;
                 }
@@ -183,8 +188,6 @@ public class MVRTreeMap<V> extends MVMap<SpatialKey, V> {
                 if (!keyType.isInside(key, oldBounds)) {
                     p.setKey(i, getBounds(c));
                 }
-                p.setChild(i, c);
-                p.setCounts(i, c);
                 break;
             }
         }