Add TransactionMonitor.

3 files changed, 89 insertions, 4 deletions

diff --git a/src/main/java/com/amazon/carbonado/txn/TransactionManager.java b/src/main/java/com/amazon/carbonado/txn/TransactionManager.java
index dcd9671..19aec4d 100644
--- a/src/main/java/com/amazon/carbonado/txn/TransactionManager.java
+++ b/src/main/java/com/amazon/carbonado/txn/TransactionManager.java
@@ -39,15 +39,21 @@ public abstract class TransactionManager<Txn> {
 

     private final ThreadLocal<TransactionScope<Txn>> mLocalScope;

     private final Map<TransactionScope<Txn>, ?> mAllScopes;

+    private final TransactionMonitor mMonitor;

 

     private int mState;

 

     public TransactionManager() {

+        this(null);

+    }

+ 

+    public TransactionManager(TransactionMonitor monitor) {

         mLocalScope = new ThreadLocal<TransactionScope<Txn>>();

         mAllScopes = new WeakIdentityMap();

+        mMonitor = monitor;

     }

 

-    /**

+   /**

      * Returns the thread-local TransactionScope, creating it if needed.

      */

     public TransactionScope<Txn> localScope() {

@@ -108,6 +114,22 @@ public abstract class TransactionManager<Txn> {
         return false;

     }

 

+    // Called by TransactionScope.

+    void entered(Transaction txn, Transaction parent) {

+        TransactionMonitor monitor = mMonitor;

+        if (monitor != null) {

+            monitor.entered(txn, parent);

+        }

+    }

+

+    // Called by TransactionScope.

+    void exited(Transaction txn, Transaction active) {

+        TransactionMonitor monitor = mMonitor;

+        if (monitor != null) {

+            monitor.exited(txn, active);

+        }

+    }

+

     /**

      * Closes all transaction scopes. Should be called only when repository is

      * closed.

diff --git a/src/main/java/com/amazon/carbonado/txn/TransactionMonitor.java b/src/main/java/com/amazon/carbonado/txn/TransactionMonitor.java
new file mode 100644
index 0000000..2604dac
--- /dev/null
+++ b/src/main/java/com/amazon/carbonado/txn/TransactionMonitor.java
@@ -0,0 +1,47 @@
+/*

+ * Copyright 2011 Amazon Technologies, Inc. or its affiliates.

+ * Amazon, Amazon.com and Carbonado are trademarks or registered trademarks

+ * of Amazon Technologies, 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 com.amazon.carbonado.txn;

+

+import com.amazon.carbonado.Transaction;

+

+/**

+ * Is notified as transactions enter and exit. Implementation must be thread-safe.

+ *

+ * @author Brian S O'Neill

+ * @see TransactionManager

+ */

+public interface TransactionMonitor {

+    /**

+     * Called by a thread which has just entered a transaction.

+     *

+     * @param entered transaction just entered

+     * @param parent optional parent of transaction; is null for top level transactions

+     */

+    public abstract void entered(Transaction entered, Transaction parent);

+

+    /**

+     * Called by a thread which has just exited a transaction. Only the first

+     * invocation of the exit method is passed to this monitor.

+     *

+     * @param exited transaction just exited

+     * @param active optional transaction which is now active; is null if the

+     * outermost transaction scope exited

+     */

+    public abstract void exited(Transaction exited, Transaction active);

+}

diff --git a/src/main/java/com/amazon/carbonado/txn/TransactionScope.java b/src/main/java/com/amazon/carbonado/txn/TransactionScope.java
index 7cf4903..2110ff6 100644
--- a/src/main/java/com/amazon/carbonado/txn/TransactionScope.java
+++ b/src/main/java/com/amazon/carbonado/txn/TransactionScope.java
@@ -90,7 +90,12 @@ public class TransactionScope<Txn> {
                 }

             }

 

-            return mActive = new TransactionImpl<Txn>(this, parent, false, actualLevel);

+            TransactionImpl<Txn> txn = new TransactionImpl<Txn>(this, parent, false, actualLevel);

+            mActive = txn;

+

+            mTxnMgr.entered(txn, parent);

+

+            return txn;

         } finally {

             mLock.unlock();

         }

@@ -113,12 +118,23 @@ public class TransactionScope<Txn> {
                     ("Desired isolation level not supported: " + level);

             }

 

-            return mActive = new TransactionImpl<Txn>(this, mActive, true, actualLevel);

+            TransactionImpl<Txn> txn = new TransactionImpl<Txn>(this, mActive, true, actualLevel);

+            mActive = txn;

+

+            mTxnMgr.entered(txn, null);

+

+            return txn;

         } finally {

             mLock.unlock();

         }

     }

 

+    // Called by TransactionImpl with lock held.

+    void exited(TransactionImpl<Txn> txn, TransactionImpl<Txn> active) {

+        mActive = active;

+        mTxnMgr.exited(txn, active);

+    }

+

     /**

      * Registers the given cursor against the active transaction, allowing it

      * to be closed on transaction exit or transaction manager close. If there

@@ -494,8 +510,8 @@ public class TransactionScope<Txn> {
                         }

                     }

                 } finally {

-                    scope.mActive = mParent;

                     mState = EXITED;

+                    scope.exited(this, mParent);

                     if (exception != null) {

                         throw ExceptionTransformer.getInstance().toPersistException(exception);

                     }