[401763] Make CDO Server more robust against data dictionary changes

https://bugs.eclipse.org/bugs/show_bug.cgi?id=401763

4 files changed, 7 insertions, 99 deletions

diff --git a/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/db/IDBStore.java b/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/db/IDBStore.java
index c95999e648..b779c3f49f 100644
--- a/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/db/IDBStore.java
+++ b/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/db/IDBStore.java
@@ -46,6 +46,11 @@ public interface IDBStore extends IStore, IDBConnectionProvider, CanHandleClient
    */
   public IIDHandler getIDHandler();
 
+  /**
+   * @since 4.2
+   */
+  // public IDBDatabase getDatabase();
+
   public IDBAdapter getDBAdapter();
 
   public IDBSchema getDBSchema();
diff --git a/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/db/IPreparedStatementCache.java b/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/db/IPreparedStatementCache.java
index 0c36a68023..5cd4634393 100644
--- a/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/db/IPreparedStatementCache.java
+++ b/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/db/IPreparedStatementCache.java
@@ -31,11 +31,6 @@ public interface IPreparedStatementCache
   public void releasePreparedStatement(PreparedStatement ps);
 
   /**
-   * @since 4.2
-   */
-  public void invalidate();
-
-  /**
    * An enum for the degree of probability to which a prepared statement is reused later on. This is used for managing
    * the cache of prepared statements so that statements which are more likely reused are kept in the cache longer. Rule
    * of thumb:
diff --git a/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/internal/db/DBStore.java b/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/internal/db/DBStore.java
index 3a02869bde..626d4d7cb9 100644
--- a/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/internal/db/DBStore.java
+++ b/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/internal/db/DBStore.java
@@ -67,8 +67,6 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.Timer;
-import java.util.concurrent.locks.ReadWriteLock;
-import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 /**
  * @author Eike Stepper
@@ -117,26 +115,14 @@ public class DBStore extends Store implements IDBStore, CDOAllRevisionsProvider
 
   private IMappingStrategy mappingStrategy;
 
+  // private IDBDatabase database;
+
   private IDBSchema dbSchema;
 
   private IDBAdapter dbAdapter;
 
   private IDBConnectionProvider dbConnectionProvider;
 
-  /**
-   * A global database-level lock to secure data read/write operations against data dictionary changes (DML vs. DDL).
-   *
-   * @see DBStoreAccessor#doWrite
-   * @see DBStoreAccessor#doCommit
-   * @see DBStoreAccessor#doRollback
-   */
-  private ReentrantReadWriteLock dbSchemaLock;
-
-  /**
-   * A transient version number that accessors rely upon to determine whether they need to invalidate their prepared statement caches.
-   */
-  private int dbSchemaModCount;
-
   @ExcludeFromDump
   private transient ProgressDistributor accessorWriteDistributor = new ProgressDistributor.Geometric()
   {
@@ -277,21 +263,6 @@ public class DBStore extends Store implements IDBStore, CDOAllRevisionsProvider
     return dbSchema;
   }
 
-  public ReadWriteLock getDBSchemaLock()
-  {
-    return dbSchemaLock;
-  }
-
-  public int getDBSchemaModCount()
-  {
-    return dbSchemaModCount;
-  }
-
-  public int incDBSchemaModCount()
-  {
-    return ++dbSchemaModCount;
-  }
-
   public void visitAllTables(Connection connection, IDBStore.TableVisitor visitor)
   {
     for (String name : DBUtil.getAllTableNames(connection, getRepository().getName()))
@@ -654,8 +625,6 @@ public class DBStore extends Store implements IDBStore, CDOAllRevisionsProvider
     }
 
     dbSchema = createSchema();
-    dbSchemaLock = new ReentrantReadWriteLock();
-    dbSchemaModCount = 1;
 
     LifecycleUtil.activate(idHandler);
     LifecycleUtil.activate(metaDataManager);
diff --git a/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/internal/db/DBStoreAccessor.java b/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/internal/db/DBStoreAccessor.java
index d36f911576..d679abdec8 100644
--- a/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/internal/db/DBStoreAccessor.java
+++ b/plugins/org.eclipse.emf.cdo.server.db/src/org/eclipse/emf/cdo/server/internal/db/DBStoreAccessor.java
@@ -106,7 +106,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.TimerTask;
-import java.util.concurrent.locks.Lock;
 
 /**
  * @author Eike Stepper
@@ -125,10 +124,6 @@ public class DBStoreAccessor extends StoreAccessor implements IDBStoreAccessor,
 
   private CDOID maxID = CDOID.NULL;
 
-  private Lock dbSchemaLock;
-
-  private int dbSchemaModCount;
-
   public DBStoreAccessor(DBStore store, ISession session) throws DBException
   {
     super(store, session);
@@ -691,13 +686,6 @@ public class DBStoreAccessor extends StoreAccessor implements IDBStoreAccessor,
   }
 
   @Override
-  protected void doWrite(InternalCommitContext context, OMMonitor monitor)
-  {
-    lockSchema(context);
-    super.doWrite(context, monitor);
-  }
-
-  @Override
   protected final void doCommit(OMMonitor monitor)
   {
     if (TRACER.isEnabled())
@@ -736,7 +724,6 @@ public class DBStoreAccessor extends StoreAccessor implements IDBStoreAccessor,
     }
     finally
     {
-      unlockSchema();
       monitor.done();
     }
   }
@@ -762,46 +749,6 @@ public class DBStoreAccessor extends StoreAccessor implements IDBStoreAccessor,
     {
       throw new DBException(ex);
     }
-    finally
-    {
-      unlockSchema();
-    }
-  }
-
-  private void lockSchema(InternalCommitContext context)
-  {
-    DBStore store = getStore();
-
-    InternalCDOPackageUnit[] newPackageUnits = context.getNewPackageUnits();
-    if (!ObjectUtil.isEmpty(newPackageUnits))
-    {
-      // This transaction will possibly execute DDL, so we need an exclusive lock
-      dbSchemaLock = store.getDBSchemaLock().writeLock();
-    }
-    else
-    {
-      // No DDL, so we are ok with a simple concurrent lock
-      dbSchemaLock = store.getDBSchemaLock().readLock();
-    }
-
-    dbSchemaLock.lock();
-
-    // Check if our prepared statement cache is still usable
-    int storeModCount = store.getDBSchemaModCount();
-    if (dbSchemaModCount != storeModCount)
-    {
-      statementCache.invalidate();
-      dbSchemaModCount = storeModCount;
-    }
-  }
-
-  private void unlockSchema()
-  {
-    if (dbSchemaLock != null)
-    {
-      dbSchemaLock.unlock();
-      dbSchemaLock = null;
-    }
   }
 
   @Override
@@ -828,8 +775,6 @@ public class DBStoreAccessor extends StoreAccessor implements IDBStoreAccessor,
     statementCache = CDODBUtil.createStatementCache();
     statementCache.setConnection(connection);
     LifecycleUtil.activate(statementCache);
-
-    dbSchemaModCount = store.getDBSchemaModCount();
   }
 
   @Override
@@ -885,12 +830,6 @@ public class DBStoreAccessor extends StoreAccessor implements IDBStoreAccessor,
     }
     finally
     {
-      // most likely, we have modified the database definition structure. So, we
-      // reflect this by incrementing the version which forces all other DBStoreAccessors
-      // to invalidate their statementCache, and we invalidate ours, too.
-      statementCache.invalidate();
-      dbSchemaModCount = getStore().incDBSchemaModCount();
-
       monitor.done();
     }
   }