MVStore: closing a map and making it read-only is now only a marker and not…

MVStore: closing a map and making it read-only is now only a marker and not enforced, to allow concurrent store operations

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

@@ -529,15 +529,11 @@ public class MVMap<K, V> extends AbstractMap<K, V>
     }
 
     /**
-     * Close the map, making it read only and release the memory. This method
-     * may only be called when closing the store or when removing the map, as
-     * further writes are not possible.
+     * Close the map. Accessing the data is still possible (to allow concurrent
+     * reads), but it is marked as closed.
      */
     void close() {
         closed = true;
-        readOnly = true;
-        removeAllOldVersions();
-        root = null;
     }
 
     public boolean isClosed() {
@@ -873,15 +869,6 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         }
     }
 
-    /**
-     * Forget all old versions.
-     */
-    private void removeAllOldVersions() {
-        // create a new instance
-        // because another thread might iterate over it
-        oldRoots = new ArrayList<Page>();
-    }
-
     /**
      * Forget those old versions that are no longer needed.
      */
@@ -906,10 +893,6 @@ public class MVMap<K, V> extends AbstractMap<K, V>
         oldRoots = list;
     }
 
-    public void setReadOnly(boolean readOnly) {
-        this.readOnly = readOnly;
-    }
-
     public boolean isReadOnly() {
         return readOnly;
     }

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

@@ -35,7 +35,6 @@ public class SequenceMap extends MVMap<Long, Long> {
     @Override
     public void init(MVStore store, HashMap<String, String> config) {
         super.init(store, config);
-        setReadOnly(true);
     }
 
     @Override

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

@@ -44,6 +44,7 @@ public class TestConcurrent extends TestMVStore {
         FileUtils.deleteRecursive(getBaseDir(), true);
         FileUtils.createDirectories(getBaseDir());
 
+        testConcurrentStoreAndRemoveMap();
         testConcurrentStoreAndClose();
         testConcurrentOnlineBackup();
         testConcurrentMap();
@@ -51,6 +52,33 @@ public class TestConcurrent extends TestMVStore {
         testConcurrentWrite();
         testConcurrentRead();
     }
+    
+    private void testConcurrentStoreAndRemoveMap() throws InterruptedException {
+        String fileName = getBaseDir() + "/testConcurrentStoreAndRemoveMap.h3";
+        final MVStore s = openStore(fileName);
+        int count = 100;
+        for (int i = 0; i < count; i++) {
+            MVMap<Integer, Integer> m = s.openMap("d" + i);
+            m.put(1, 1);
+        }
+        Task task = new Task() {
+            @Override
+            public void call() throws Exception {
+                while (!stop) {
+                    s.store();
+                }
+            }
+        };
+        task.execute();
+        Thread.sleep(1);
+        for (int i = 0; i < count; i++) {
+            MVMap<Integer, Integer> m = s.openMap("d" + i);
+            m.put(1, 10);
+            m.removeMap();
+        }
+        task.get();
+        s.close();
+    }
 
     private void testConcurrentStoreAndClose() throws InterruptedException {
         String fileName = getBaseDir() + "/testConcurrentStoreAndClose.h3";

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

@@ -1231,7 +1231,6 @@ public class TestMVStore extends TestBase {
         assertNull(m0.get("1"));
         assertTrue(m1.isClosed());
         assertFalse(m0.isReadOnly());
-        assertTrue(m1.isReadOnly());
         s.close();
     }