Multi-Version Concurrency (MVCC) may no longer be used when using the…

Multi-Version Concurrency (MVCC) may no longer be used when using the multi-threaded kernel feature (MULTI_THREADED).

h2/src/main/org/h2/engine/Database.java

@@ -132,7 +132,6 @@ public class Database implements DataHandler {
     private boolean logIndexChanges;
     private int logLevel = 1;
     private int maxLengthInplaceLob = Constants.DEFAULT_MAX_LENGTH_INPLACE_LOB;
-    private long biggestFileSize;
     private int allowLiterals = Constants.DEFAULT_ALLOW_LITERALS;
 
     private int powerOffCount = initialPowerOffCount;
@@ -198,6 +197,7 @@ public class Database implements DataHandler {
             this.recovery = true;
         }
         this.multiVersion = ci.removeProperty("MVCC", false);
+        checkMultiThreadedAllowed();
         boolean closeAtVmShutdown = ci.removeProperty("DB_CLOSE_ON_EXIT", true);
         int traceLevelFile = ci.getIntProperty(SetTypes.TRACE_LEVEL_FILE, TraceSystem.DEFAULT_TRACE_LEVEL_FILE);
         int traceLevelSystemOut = ci.getIntProperty(SetTypes.TRACE_LEVEL_SYSTEM_OUT,
@@ -1749,7 +1749,6 @@ public class Database implements DataHandler {
         case Constants.LOCK_MODE_READ_COMMITTED:
         case Constants.LOCK_MODE_TABLE:
         case Constants.LOCK_MODE_TABLE_GC:
-        case Constants.LOCK_MODE_ROW:
             break;
         default:
             throw Message.getInvalidValueException("lock mode", "" + lockMode);
@@ -1860,30 +1859,17 @@ public class Database implements DataHandler {
     }
     
     /**
-     * Called when the size if the data or index file has been changed. The log
-     * file size is at least 10% of the largest file.
+     * Called when the size if the data or index file has been changed.
      * 
      * @param length the new file size
      */
     public void notifyFileSize(long length) {
-        if (length > biggestFileSize) {
-            biggestFileSize = length;
-            setMaxLogSize(0);
-        }
+        // ignore
     }
     
     public synchronized void setMaxLogSize(long value) {
-        long minLogSize = biggestFileSize / Constants.LOG_SIZE_DIVIDER;
-        minLogSize = Math.max(value, minLogSize);
-        long currentLogSize = getLog().getMaxLogSize();
-        if (minLogSize > currentLogSize || (value > 0 && minLogSize > value)) {
-            // works for currentLogSize <= 0 as well
-            value = minLogSize;
-        }
-        if (value > 0) {
         getLog().setMaxLogSize(value);
     }    
-    }
 
     public void setAllowLiterals(int value) {
         this.allowLiterals = value;
@@ -1970,10 +1956,19 @@ public class Database implements DataHandler {
         return multiThreaded;
     }
 
-    public void setMultiThreaded(boolean multiThreaded) {
+    public void setMultiThreaded(boolean multiThreaded) throws SQLException {
         this.multiThreaded = multiThreaded;
+        checkMultiThreadedAllowed();
     }
     
+    private void checkMultiThreadedAllowed() throws SQLException {
+        if (multiThreaded && multiVersion) {
+            multiVersion = false;
+            throw Message.getSQLException(ErrorCode.CANNOT_CHANGE_SETTING_WHEN_OPEN_1, "MVCC & MULTI_THREADED");
+        }
+    }
+
+
     public void setMaxOperationMemory(int maxOperationMemory) {
         this.maxOperationMemory  = maxOperationMemory;
     }

h2/src/test/org/h2/test/mvcc/TestMvccMultiThreaded.java

+/*
+ * Copyright 2004-2008 H2 Group. Multiple-Licensed under the H2 License, 
+ * Version 1.0, and under the Eclipse Public License, Version 1.0
+ * (http://h2database.com/html/license.html).
+ * Initial Developer: H2 Group
+ */
+package org.h2.test.mvcc;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+import org.h2.test.TestBase;
+
+/**
+ * Multi-threaded MVCC (multi version concurrency) test cases.
+ */
+public class TestMvccMultiThreaded extends TestBase {
+
+    public void test() throws Exception {
+        if (!config.mvcc) {
+            return;
+        }
+        if (config.mvcc) {
+            // not supported at this time
+            return;
+        }
+        deleteDb("mvccMultiThreaded");
+        int len = 2;
+        final Connection[] connList = new Connection[len];
+        for (int i = 0; i < len; i++) {
+            connList[i] = getConnection("mvccMultiThreaded;MULTI_THREADED=TRUE");
+        }
+        Connection conn = connList[0];
+        conn.createStatement().execute("create table test(id int primary key, value int)");
+        conn.createStatement().execute("insert into test values(0, 0)");
+        final SQLException[] ex = new SQLException[1];
+        final int count = 1000;
+        Thread[] threads = new Thread[len];
+        for (int i = 0; i < len; i++) {
+            final int x = i;
+            threads[i] = new Thread() {
+                public void run() {
+                    for (int a = 0; a < count; a++) {
+                        try {
+                            connList[x].createStatement().execute("update test set value=value+1");
+                        } catch (SQLException e) {
+                            ex[0] = e;
+                        }
+                    }
+                }
+            };
+            threads[i].start();
+        }
+        for (int i = 0; i < len; i++) {
+            threads[i].join();
+        }
+        if (ex[0] != null) {
+            throw ex[0];
+        }
+        ResultSet rs = conn.createStatement().executeQuery("select value from test");
+        rs.next();
+        assertEquals(count * len, rs.getInt(1));
+        for (int i = 0; i < len; i++) {
+            connList[i].close();
+        }
+    }
+
+}