From 312018c6ef5a3231c260e4ecdcd4c83588b56479 Mon Sep 17 00:00:00 2001
From: "Brian S. O'Neill" <bronee@gmail.com>
Date: Wed, 10 Aug 2011 17:39:53 +0000
Subject: Fix thread-local memory leaks.

---
 .../amazon/carbonado/repo/map/MapRepository.java   |  5 ++++
 .../amazon/carbonado/txn/TransactionManager.java   | 31 ++++++++++++++++++++++
 .../com/amazon/carbonado/txn/TransactionScope.java | 14 ++++++++--
 3 files changed, 48 insertions(+), 2 deletions(-)

(limited to 'src/main/java/com/amazon/carbonado')

diff --git a/src/main/java/com/amazon/carbonado/repo/map/MapRepository.java b/src/main/java/com/amazon/carbonado/repo/map/MapRepository.java
index 7fbe16a..ac847f1 100644
--- a/src/main/java/com/amazon/carbonado/repo/map/MapRepository.java
+++ b/src/main/java/com/amazon/carbonado/repo/map/MapRepository.java
@@ -89,6 +89,11 @@ class MapRepository extends AbstractRepository<MapTransaction>
         return ((MapStorage) storageFor(storableType)).getIndexInfo();
     }
 
+    @Override
+    protected void finalize() {
+        close();
+    }
+
     @Override
     protected Log getLog() {
         return null;
diff --git a/src/main/java/com/amazon/carbonado/txn/TransactionManager.java b/src/main/java/com/amazon/carbonado/txn/TransactionManager.java
index 19aec4d..6ae3b2e 100644
--- a/src/main/java/com/amazon/carbonado/txn/TransactionManager.java
+++ b/src/main/java/com/amazon/carbonado/txn/TransactionManager.java
@@ -157,6 +157,9 @@ public abstract class TransactionManager<Txn> {
         for (TransactionScope<?> scope : mAllScopes.keySet()) {
             scope.close();
         }
+
+        mAllScopes.clear();
+        mLocalScope.remove();
     }
 
     public synchronized boolean isClosed() {
@@ -270,4 +273,32 @@ public abstract class TransactionManager<Txn> {
      * Aborts and closes the given internal transaction.
      */
     protected abstract void abortTxn(Txn txn) throws PersistException;
+
+    static class Closed extends TransactionManager<Object> {
+        static final Closed THE = new Closed();
+
+        @Override
+        protected IsolationLevel selectIsolationLevel(Transaction parent, IsolationLevel level) {
+            return IsolationLevel.SERIALIZABLE;
+        }
+
+        @Override
+        protected boolean supportsForUpdate() {
+            return true;
+        }
+
+        @Override
+        protected Object createTxn(Object parent, IsolationLevel level) throws Exception {
+            throw new IllegalStateException("Transaction manager is closed");
+        }
+
+        @Override
+        protected boolean commitTxn(Object txn) throws PersistException {
+            return false;
+        }
+
+        @Override
+        protected void abortTxn(Object txn) throws PersistException {
+        }
+    }
 }
diff --git a/src/main/java/com/amazon/carbonado/txn/TransactionScope.java b/src/main/java/com/amazon/carbonado/txn/TransactionScope.java
index 2110ff6..7ff5997 100644
--- a/src/main/java/com/amazon/carbonado/txn/TransactionScope.java
+++ b/src/main/java/com/amazon/carbonado/txn/TransactionScope.java
@@ -43,9 +43,16 @@ import com.amazon.carbonado.spi.ExceptionTransformer;
  * @see TransactionManager
  */
 public class TransactionScope<Txn> {
-    final TransactionManager<Txn> mTxnMgr;
     final Lock mLock;
 
+    // Note: Cannot be final because it needs to be replaced by close
+    // method. Access doesn't need to be synchronized, because only one thread
+    // ever accesses scope instances. The close method might be called by a
+    // separate thread, in which case the closed transaction manager reference
+    // might not be immediately visible by the thread which needs it. This is
+    // not harmful.
+    TransactionManager<Txn> mTxnMgr;
+
     TransactionImpl<Txn> mActive;
 
     // Tracks all registered cursors by storage type.
@@ -55,8 +62,8 @@ public class TransactionScope<Txn> {
     private boolean mDetached;
 
     TransactionScope(TransactionManager<Txn> txnMgr, boolean closed) {
-        mTxnMgr = txnMgr;
         mLock = new ReentrantLock(true);
+        mTxnMgr = txnMgr;
         if (closed) {
             mLock.lock();
             try {
@@ -332,6 +339,9 @@ public class TransactionScope<Txn> {
             }
         } finally {
             mClosed = true;
+            // Swap TransactionManager out with a dummy one, to allow the
+            // original one to get freed.
+            mTxnMgr = (TransactionManager<Txn>) TransactionManager.Closed.THE;
             mLock.unlock();
         }
     }
-- 
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