Track session states (aws#729)

wrapper/src/main/java/software/amazon/jdbc/PluginService.java

@@ -27,6 +27,7 @@
 import software.amazon.jdbc.dialect.Dialect;
 import software.amazon.jdbc.exceptions.ExceptionHandler;
 import software.amazon.jdbc.hostavailability.HostAvailability;
+import software.amazon.jdbc.states.SessionDirtyFlag;
 import software.amazon.jdbc.util.telemetry.TelemetryFactory;
 
 /**
@@ -47,6 +48,18 @@ EnumSet<NodeChangeOptions> setCurrentConnection(
       @Nullable ConnectionPlugin skipNotificationForThisPlugin)
       throws SQLException;
 
+  EnumSet<SessionDirtyFlag> getCurrentConnectionState();
+
+  void setCurrentConnectionState(SessionDirtyFlag flag);
+
+  void resetCurrentConnectionState(SessionDirtyFlag flag);
+
+  void resetCurrentConnectionStates();
+
+  boolean getAutoCommit();
+
+  void setAutoCommit(final boolean autoCommit);
+
   List<HostSpec> getHosts();
 
   HostSpec getInitialConnectionHostSpec();

wrapper/src/main/java/software/amazon/jdbc/PluginServiceImpl.java

@@ -43,6 +43,7 @@
 import software.amazon.jdbc.hostavailability.HostAvailability;
 import software.amazon.jdbc.hostavailability.HostAvailabilityStrategyFactory;
 import software.amazon.jdbc.hostlistprovider.StaticHostListProvider;
+import software.amazon.jdbc.states.SessionDirtyFlag;
 import software.amazon.jdbc.util.CacheMap;
 import software.amazon.jdbc.util.Messages;
 import software.amazon.jdbc.util.telemetry.TelemetryFactory;
@@ -68,6 +69,8 @@ public class PluginServiceImpl implements PluginService, CanReleaseResources,
   private final ExceptionManager exceptionManager;
   protected final DialectProvider dialectProvider;
   protected Dialect dialect;
+  protected EnumSet<SessionDirtyFlag> currentConnectionSessionState = EnumSet.noneOf(SessionDirtyFlag.class);
+  protected boolean isAutoCommit = false;
 
   public PluginServiceImpl(
       @NonNull final ConnectionPluginManager pluginManager,
@@ -568,4 +571,27 @@ public String getTargetName() {
     return this.pluginManager.getDefaultConnProvider().getTargetName();
   }
 
+  public EnumSet<SessionDirtyFlag> getCurrentConnectionState() {
+    return this.currentConnectionSessionState.clone();
+  }
+
+  public void setCurrentConnectionState(SessionDirtyFlag flag) {
+    this.currentConnectionSessionState.add(flag);
+  }
+
+  public void resetCurrentConnectionState(SessionDirtyFlag flag) {
+    this.currentConnectionSessionState.remove(flag);
+  }
+
+  public void resetCurrentConnectionStates() {
+    this.currentConnectionSessionState.clear();
+  }
+
+  public boolean getAutoCommit() {
+    return this.isAutoCommit;
+  }
+
+  public void setAutoCommit(final boolean autoCommit) {
+    this.isAutoCommit = autoCommit;
+  }
 }

wrapper/src/main/java/software/amazon/jdbc/plugin/failover/FailoverConnectionPlugin.java

@@ -42,6 +42,10 @@
 import software.amazon.jdbc.hostavailability.HostAvailability;
 import software.amazon.jdbc.plugin.AbstractConnectionPlugin;
 import software.amazon.jdbc.plugin.staledns.AuroraStaleDnsHelper;
+import software.amazon.jdbc.states.RestoreSessionStateCallable;
+import software.amazon.jdbc.states.SessionDirtyFlag;
+import software.amazon.jdbc.states.SessionStateHelper;
+import software.amazon.jdbc.states.SessionStateTransferCallable;
 import software.amazon.jdbc.util.Messages;
 import software.amazon.jdbc.util.RdsUrlType;
 import software.amazon.jdbc.util.RdsUtils;
@@ -85,6 +89,10 @@ public class FailoverConnectionPlugin extends AbstractConnectionPlugin {
   static final String METHOD_ABORT = "Connection.abort";
   static final String METHOD_CLOSE = "Connection.close";
   static final String METHOD_IS_CLOSED = "Connection.isClosed";
+
+  protected static SessionStateTransferCallable sessionStateTransferCallable;
+  protected static RestoreSessionStateCallable restoreSessionStateCallable;
+
   private final PluginService pluginService;
   protected final Properties properties;
   protected boolean enableFailoverSetting;
@@ -199,6 +207,22 @@ public FailoverConnectionPlugin(final PluginService pluginService, final Propert
     this.failoverReaderFailedCounter = telemetryFactory.createCounter("readerFailover.completed.failed.count");
   }
 
+  public static void setSessionStateTransferFunc(SessionStateTransferCallable callable) {
+    sessionStateTransferCallable = callable;
+  }
+
+  public static void resetSessionStateTransferFunc() {
+    sessionStateTransferCallable = null;
+  }
+
+  public static void setRestoreSessionStateFunc(RestoreSessionStateCallable callable) {
+    restoreSessionStateCallable = callable;
+  }
+
+  public static void resetRestoreSessionStateFunc() {
+    restoreSessionStateCallable = null;
+  }
+
   @Override
   public Set<String> getSubscribedMethods() {
     return subscribedMethods;
@@ -521,9 +545,10 @@ private boolean shouldAttemptReaderConnection() {
    */
   private void switchCurrentConnectionTo(final HostSpec host, final Connection connection) throws SQLException {
     Connection currentConnection = this.pluginService.getCurrentConnection();
+    HostSpec currentHostSpec = this.pluginService.getCurrentHostSpec();
 
     if (currentConnection != connection) {
-      transferSessionState(currentConnection, connection);
+      transferSessionState(currentConnection, currentHostSpec, connection, host);
       invalidateCurrentConnection();
     }
 
@@ -535,46 +560,73 @@ private void switchCurrentConnectionTo(final HostSpec host, final Connection con
   }
 
   /**
-   * Transfers basic session state from one connection to another.
+   * Transfers session state from one connection to another.
    *
-   * @param from The connection to transfer state from
-   * @param to   The connection to transfer state to
+   * @param src The connection to transfer state from
+   * @param srcHostSpec The connection {@link HostSpec} to transfer state from
+   * @param dest   The connection to transfer state to
+   * @param destHostSpec The connection {@link HostSpec} to transfer state to
    * @throws SQLException if a database access error occurs, this method is called on a closed connection, this
    *                      method is called during a distributed transaction, or this method is called during a
    *                      transaction
    */
   protected void transferSessionState(
-      final Connection from,
-      final Connection to) throws SQLException {
+      final Connection src,
+      final HostSpec srcHostSpec,
+      final Connection dest,
+      final HostSpec destHostSpec) throws SQLException {
 
-    if (from == null || to == null) {
+    if (src == null || dest == null) {
       return;
     }
 
-    to.setReadOnly(from.isReadOnly());
-    to.setAutoCommit(from.getAutoCommit());
-    to.setTransactionIsolation(from.getTransactionIsolation());
+    EnumSet<SessionDirtyFlag> sessionState = this.pluginService.getCurrentConnectionState();
+
+    SessionStateTransferCallable callableCopy = sessionStateTransferCallable;
+    if (callableCopy != null) {
+      final boolean isHandled = callableCopy.transferSessionState(sessionState, src, srcHostSpec, dest, destHostSpec);
+      if (isHandled) {
+        // Custom function has handled session transfer
+        return;
+      }
+    }
+
+    // Otherwise, lets run default logic.
+    sessionState = this.pluginService.getCurrentConnectionState();
+    final SessionStateHelper helper = new SessionStateHelper();
+    helper.transferSessionState(sessionState, src, dest);
   }
 
   /**
    * Restores partial session state from saved values to a connection.
    *
-   * @param to   The connection to transfer state to
+   * @param dest   The connection to transfer state to
    * @throws SQLException if a database access error occurs, this method is called on a closed connection, this
    *                      method is called during a distributed transaction, or this method is called during a
    *                      transaction
    */
-  protected void restoreSessionState(final Connection to) throws SQLException {
-    if (to == null) {
+  protected void restoreSessionState(final Connection dest) throws SQLException {
+    if (dest == null) {
       return;
     }
 
-    if (savedReadOnlyStatus != null) {
-      to.setReadOnly(savedReadOnlyStatus);
-    }
-    if (savedAutoCommitStatus != null) {
-      to.setAutoCommit(savedAutoCommitStatus);
+    final RestoreSessionStateCallable callableCopy = restoreSessionStateCallable;
+    if (callableCopy != null) {
+      final boolean isHandled = callableCopy.restoreSessionState(
+          this.pluginService.getCurrentConnectionState(),
+          dest,
+          this.savedReadOnlyStatus,
+          this.savedAutoCommitStatus
+      );
+      if (isHandled) {
+        // Custom function has handled everything.
+        return;
+      }
     }
+
+    // Otherwise, lets run default logic.
+    final SessionStateHelper helper = new SessionStateHelper();
+    helper.restoreSessionState(dest, this.savedReadOnlyStatus, this.savedAutoCommitStatus);
   }
 
   private <E extends Exception> void dealWithOriginalException(

wrapper/src/main/java/software/amazon/jdbc/plugin/readwritesplitting/ReadWriteSplittingPlugin.java

@@ -40,6 +40,9 @@
 import software.amazon.jdbc.cleanup.CanReleaseResources;
 import software.amazon.jdbc.plugin.AbstractConnectionPlugin;
 import software.amazon.jdbc.plugin.failover.FailoverSQLException;
+import software.amazon.jdbc.states.SessionDirtyFlag;
+import software.amazon.jdbc.states.SessionStateHelper;
+import software.amazon.jdbc.states.SessionStateTransferCallable;
 import software.amazon.jdbc.util.Messages;
 import software.amazon.jdbc.util.SqlState;
 import software.amazon.jdbc.util.WrapperUtils;
@@ -61,6 +64,9 @@ public class ReadWriteSplittingPlugin extends AbstractConnectionPlugin
   static final String METHOD_SET_READ_ONLY = "Connection.setReadOnly";
   static final String METHOD_CLEAR_WARNINGS = "Connection.clearWarnings";
 
+  protected static SessionStateTransferCallable sessionStateTransferCallable;
+
+
   private final PluginService pluginService;
   private final Properties properties;
   private final String readerSelectorStrategy;
@@ -105,6 +111,14 @@ public class ReadWriteSplittingPlugin extends AbstractConnectionPlugin
     this.readerConnection = readerConnection;
   }
 
+  public static void setSessionStateTransferFunc(SessionStateTransferCallable callable) {
+    sessionStateTransferCallable = callable;
+  }
+
+  public static void resetSessionStateTransferFunc() {
+    sessionStateTransferCallable = null;
+  }
+
   @Override
   public Set<String> getSubscribedMethods() {
     return subscribedMethods;
@@ -408,7 +422,7 @@ private void switchCurrentConnectionTo(
       return;
     }
 
-    transferSessionStateOnReadWriteSplit(newConnection);
+    transferSessionStateOnReadWriteSplit(newConnection, newConnectionHost);
     this.pluginService.setCurrentConnection(newConnection, newConnectionHost);
     LOGGER.finest(() -> Messages.get(
         "ReadWriteSplittingPlugin.settingCurrentConnection",
@@ -421,19 +435,41 @@ private void switchCurrentConnectionTo(
    * status. This method is only called when setReadOnly is being called; the read-only status
    * will be updated when the setReadOnly call continues down the plugin chain
    *
-   * @param to The connection to transfer state to
+   * @param dest The destination connection to transfer state to
+   * @param destHostSpec The destination connection {@link HostSpec}
    * @throws SQLException if a database access error occurs, this method is called on a closed
    *                      connection, or this method is called during a distributed transaction
    */
   protected void transferSessionStateOnReadWriteSplit(
-      final Connection to) throws SQLException {
-    final Connection from = this.pluginService.getCurrentConnection();
-    if (from == null || to == null) {
+      final Connection dest,
+      final HostSpec destHostSpec)
+      throws SQLException {
+
+    final Connection src = this.pluginService.getCurrentConnection();
+    if (src == null || dest == null) {
       return;
     }
 
-    to.setAutoCommit(from.getAutoCommit());
-    to.setTransactionIsolation(from.getTransactionIsolation());
+    EnumSet<SessionDirtyFlag> sessionState = this.pluginService.getCurrentConnectionState();
+
+    SessionStateTransferCallable callableCopy = sessionStateTransferCallable;
+    if (callableCopy != null) {
+      final boolean isHandled = callableCopy.transferSessionState(
+          sessionState,
+          src,
+          this.pluginService.getCurrentHostSpec(),
+          dest,
+          destHostSpec);
+      if (isHandled) {
+        // Custom function has handled session transfer
+        return;
+      }
+    }
+
+    sessionState = this.pluginService.getCurrentConnectionState();
+    sessionState.remove(SessionDirtyFlag.READONLY); // We don't want to change READONLY flag of the connection
+    final SessionStateHelper helper = new SessionStateHelper();
+    helper.transferSessionState(sessionState, src, dest);
   }
 
   private synchronized void switchToReaderConnection(final List<HostSpec> hosts)

wrapper/src/main/java/software/amazon/jdbc/states/RestoreSessionStateCallable.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package software.amazon.jdbc.states;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.EnumSet;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public interface RestoreSessionStateCallable {
+  /**
+   * Restores partial session state from saved values to a connection.
+   *
+   * @param sessionState Session state flags for from-connection
+   * @param dest   The destination connection to transfer state to
+   * @param readOnly ReadOnly flag to set to
+   * @param autoCommit AutoCommit flag to set to
+   * @return true, if session state is restored successful and no default logic should be executed after.
+   *          False, if default logic should be executed.
+   */
+  boolean restoreSessionState(
+      final @NonNull EnumSet<SessionDirtyFlag> sessionState,
+      final @NonNull Connection dest,
+      final @Nullable Boolean readOnly,
+      final @Nullable Boolean autoCommit)
+      throws SQLException;
+}

wrapper/src/main/java/software/amazon/jdbc/states/SessionDirtyFlag.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package software.amazon.jdbc.states;
+
+
+import java.util.EnumSet;
+
+public enum SessionDirtyFlag {
+  READONLY,
+  AUTO_COMMIT,
+  TRANSACTION_ISOLATION,
+  CATALOG,
+  NETWORK_TIMEOUT,
+  SCHEMA,
+  TYPE_MAP,
+  HOLDABILITY;
+
+  public static final EnumSet<SessionDirtyFlag> ALL = EnumSet.allOf(SessionDirtyFlag.class);
+}