diff options
Diffstat (limited to 'src/main/java/com/amazon/carbonado/spi')
3 files changed, 638 insertions, 611 deletions
diff --git a/src/main/java/com/amazon/carbonado/spi/AbstractRepository.java b/src/main/java/com/amazon/carbonado/spi/AbstractRepository.java index 0dc1e74..7150f56 100644 --- a/src/main/java/com/amazon/carbonado/spi/AbstractRepository.java +++ b/src/main/java/com/amazon/carbonado/spi/AbstractRepository.java @@ -28,8 +28,6 @@ import java.util.concurrent.locks.ReentrantReadWriteLock; import org.apache.commons.logging.Log;
-import org.cojen.util.WeakIdentityMap;
-
import com.amazon.carbonado.IsolationLevel;
import com.amazon.carbonado.Repository;
import com.amazon.carbonado.RepositoryException;
@@ -56,13 +54,9 @@ public abstract class AbstractRepository<Txn> implements Repository, ShutdownCapability, SequenceCapability
{
private final String mName;
+ private final TransactionManager<Txn> mTxnMgr;
private final ReadWriteLock mShutdownLock;
- private final ThreadLocal<TransactionManager<Txn>> mCurrentTxnMgr;
-
- // Weakly tracks all TransactionManager instances for shutdown hook.
- private final Map<TransactionManager<Txn>, ?> mAllTxnMgrs;
-
private final StoragePool mStoragePool;
private final SequenceValueProducerPool mSequencePool;
@@ -74,10 +68,9 @@ public abstract class AbstractRepository<Txn> if (name == null) {
throw new IllegalArgumentException("Repository name cannot be null");
}
+
mName = name;
mShutdownLock = new ReentrantReadWriteLock();
- mCurrentTxnMgr = new ThreadLocal<TransactionManager<Txn>>();
- mAllTxnMgrs = new WeakIdentityMap();
mStoragePool = new StoragePool() {
protected <S extends Storable> Storage<S> createStorage(Class<S> type)
@@ -104,6 +97,8 @@ public abstract class AbstractRepository<Txn> }
}
};
+
+ mTxnMgr = createTransactionManager();
}
public String getName() {
@@ -117,19 +112,19 @@ public abstract class AbstractRepository<Txn> }
public Transaction enterTransaction() {
- return localTransactionManager().enter(null);
+ return mTxnMgr.localTransactionScope().enter(null);
}
public Transaction enterTransaction(IsolationLevel level) {
- return localTransactionManager().enter(level);
+ return mTxnMgr.localTransactionScope().enter(level);
}
public Transaction enterTopTransaction(IsolationLevel level) {
- return localTransactionManager().enterTop(level);
+ return mTxnMgr.localTransactionScope().enterTop(level);
}
public IsolationLevel getTransactionIsolationLevel() {
- return localTransactionManager().getIsolationLevel();
+ return mTxnMgr.localTransactionScope().getIsolationLevel();
}
/**
@@ -212,21 +207,17 @@ public abstract class AbstractRepository<Txn> }
/**
- * Returns the thread-local TransactionManager, creating it if needed.
+ * Returns the TransactionManager which was passed into the constructor.
*/
- protected TransactionManager<Txn> localTransactionManager() {
- TransactionManager<Txn> txnMgr = mCurrentTxnMgr.get();
- if (txnMgr == null) {
- lockoutShutdown();
- try {
- txnMgr = createTransactionManager();
- mCurrentTxnMgr.set(txnMgr);
- mAllTxnMgrs.put(txnMgr, null);
- } finally {
- unlockoutShutdown();
- }
- }
- return txnMgr;
+ protected TransactionManager<Txn> transactionManager() {
+ return mTxnMgr;
+ }
+
+ /**
+ * Returns the thread-local TransactionScope, creating it if needed.
+ */
+ protected TransactionScope<Txn> localTransactionScope() {
+ return mTxnMgr.localTransactionScope();
}
/**
@@ -279,11 +270,6 @@ public abstract class AbstractRepository<Txn> protected abstract Log getLog();
/**
- * Called upon to create a new thread-local TransactionManager instance.
- */
- protected abstract TransactionManager<Txn> createTransactionManager();
-
- /**
* Called upon to create a new Storage instance.
*/
protected abstract <S extends Storable> Storage<S> createStorage(Class<S> type)
@@ -295,6 +281,11 @@ public abstract class AbstractRepository<Txn> protected abstract SequenceValueProducer createSequenceValueProducer(String name)
throws RepositoryException;
+ /**
+ * Called upon to create a new TransactionManager instance.
+ */
+ protected abstract TransactionManager<Txn> createTransactionManager();
+
void info(String message) {
Log log = getLog();
if (log != null) {
@@ -345,19 +336,10 @@ public abstract class AbstractRepository<Txn> // Return unused sequence values.
repository.mSequencePool.returnReservedValues(null);
- // Close transactions and cursors.
- for (TransactionManager<?> txnMgr : repository.mAllTxnMgrs.keySet()) {
- if (suspendThreads) {
- // Lock transaction manager but don't release it. This
- // prevents other threads from beginning work during
- // shutdown, which will likely fail along the way.
- txnMgr.getLock().lock();
- }
- try {
- txnMgr.close();
- } catch (Throwable e) {
- repository.error("Failed to close TransactionManager", e);
- }
+ try {
+ repository.mTxnMgr.close(suspendThreads);
+ } catch (Throwable e) {
+ repository.error("Failed to close TransactionManager", e);
}
repository.shutdownHook();
diff --git a/src/main/java/com/amazon/carbonado/spi/TransactionManager.java b/src/main/java/com/amazon/carbonado/spi/TransactionManager.java index fe08a01..8820974 100644 --- a/src/main/java/com/amazon/carbonado/spi/TransactionManager.java +++ b/src/main/java/com/amazon/carbonado/spi/TransactionManager.java @@ -18,280 +18,82 @@ package com.amazon.carbonado.spi;
-import java.util.IdentityHashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
-import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReentrantLock;
-import com.amazon.carbonado.Cursor;
-import com.amazon.carbonado.FetchException;
+import org.cojen.util.WeakIdentityMap;
+
import com.amazon.carbonado.IsolationLevel;
import com.amazon.carbonado.PersistException;
import com.amazon.carbonado.RepositoryException;
-import com.amazon.carbonado.Storable;
import com.amazon.carbonado.Transaction;
/**
- * Generic transaction manager for repositories. Repositories should only have
- * thread local instances.
+ * Generic transaction manager for repositories.
*
+ * @param <Txn> Transaction type
* @author Brian S O'Neill
*/
public abstract class TransactionManager<Txn> {
+ private static final int NOT_CLOSED = 0, CLOSED = 1, SUSPENDED = 2;
- final Lock mLock;
- final ExceptionTransformer mExTransformer;
-
- TransactionImpl<Txn> mCurrent;
-
- // Tracks all registered cursors by storage type.
- private Map<Class<?>, CursorList<TransactionImpl<Txn>>> mCursors;
+ private final ThreadLocal<TransactionScope<Txn>> mCurrentScope;
+ private final Map<TransactionScope<Txn>, ?> mAllScopes;
- private boolean mClosed;
-
- /**
- * @deprecated
- */
- public TransactionManager(ExceptionTransformer exTransformer) {
- // The use of a fair lock is essential for shutdown hooks that attempt
- // to acquire the locks of all TransactionManagers. Otherwise, the
- // shutdown can take a long time.
- mLock = new ReentrantLock(true);
- mExTransformer = exTransformer;
- }
+ private int mClosedState;
public TransactionManager() {
- this(null);
- }
-
- /**
- * Returns the exception transformer in use.
- *
- * @deprecated
- */
- public ExceptionTransformer getExceptionTransformer() {
- return mExTransformer;
- }
-
- /**
- * Enters a new transaction scope.
- *
- * @param level desired isolation level (may be null)
- * @throws UnsupportedOperationException if isolation level higher than
- * supported by repository
- */
- public Transaction enter(IsolationLevel level) {
- mLock.lock();
- try {
- TransactionImpl<Txn> parent = mCurrent;
- IsolationLevel actualLevel = selectIsolationLevel(parent, level);
- if (actualLevel == null) {
- if (parent == null) {
- throw new UnsupportedOperationException
- ("Desired isolation level not supported: " + level);
- } else {
- throw new UnsupportedOperationException
- ("Desired isolation level not supported: " + level
- + "; parent isolation level: " + parent.getIsolationLevel());
- }
- }
-
- return mCurrent = new TransactionImpl<Txn>(this, parent, false, actualLevel);
- } finally {
- mLock.unlock();
- }
+ mCurrentScope = new ThreadLocal<TransactionScope<Txn>>();
+ mAllScopes = new WeakIdentityMap();
}
/**
- * Enters a new top-level transaction scope.
- *
- * @param level desired isolation level (may be null)
- * @throws UnsupportedOperationException if isolation level higher than
- * supported by repository
+ * Returns the thread-local TransactionScope, creating it if needed.
*/
- public Transaction enterTop(IsolationLevel level) {
- mLock.lock();
- try {
- IsolationLevel actualLevel = selectIsolationLevel(null, level);
- if (actualLevel == null) {
- throw new UnsupportedOperationException
- ("Desired isolation level not supported: " + level);
+ public TransactionScope<Txn> localTransactionScope() {
+ TransactionScope<Txn> scope = mCurrentScope.get();
+ if (scope == null) {
+ int closedState;
+ synchronized (this) {
+ closedState = mClosedState;
+ scope = new TransactionScope<Txn>(this, closedState != NOT_CLOSED);
+ mAllScopes.put(scope, null);
}
-
- return mCurrent = new TransactionImpl<Txn>(this, mCurrent, true, actualLevel);
- } finally {
- mLock.unlock();
- }
- }
-
- /**
- * Registers the given cursor against the current transaction, allowing
- * it to be closed on transaction exit or transaction manager close. If
- * there is no current transaction scope, the cursor is registered as not
- * part of a transaction. Cursors should register when created.
- */
- public <S extends Storable> void register(Class<S> type, Cursor<S> cursor) {
- mLock.lock();
- try {
- checkState();
- if (mCursors == null) {
- mCursors = new IdentityHashMap<Class<?>, CursorList<TransactionImpl<Txn>>>();
+ mCurrentScope.set(scope);
+ if (closedState == SUSPENDED) {
+ // Immediately suspend new scope.
+ scope.getLock().lock();
}
-
- CursorList<TransactionImpl<Txn>> cursorList = mCursors.get(type);
- if (cursorList == null) {
- cursorList = new CursorList<TransactionImpl<Txn>>();
- mCursors.put(type, cursorList);
- }
-
- cursorList.register(cursor, mCurrent);
-
- if (mCurrent != null) {
- mCurrent.register(cursor);
- }
- } finally {
- mLock.unlock();
}
+ return scope;
}
/**
- * Unregisters a previously registered cursor. Cursors should unregister
- * when closed.
- */
- public <S extends Storable> void unregister(Class<S> type, Cursor<S> cursor) {
- mLock.lock();
- try {
- if (mCursors != null) {
- CursorList<TransactionImpl<Txn>> cursorList = mCursors.get(type);
- if (cursorList != null) {
- TransactionImpl<Txn> txnImpl = cursorList.unregister(cursor);
- if (txnImpl != null) {
- txnImpl.unregister(cursor);
- }
- }
- }
- } finally {
- mLock.unlock();
- }
- }
-
- /**
- * Returns the count of registered cursors of a specific type.
- */
- public <S extends Storable> int getRegisteredCount(Class<S> type) {
- mLock.lock();
- try {
- if (mCursors != null) {
- CursorList<TransactionImpl<Txn>> cursorList = mCursors.get(type);
- if (cursorList != null) {
- return cursorList.size();
- }
- }
- } finally {
- mLock.unlock();
- }
- return 0;
- }
-
- /**
- * Returns a registered cursor of the given type, or null if none at given index.
- */
- @SuppressWarnings("unchecked")
- public <S extends Storable> Cursor<S> getRegisteredCursor(Class<S> type, int index) {
- mLock.lock();
- try {
- if (mCursors != null) {
- CursorList<TransactionImpl<Txn>> cursorList = mCursors.get(type);
- if (cursorList != null) {
- if (index < cursorList.size()) {
- return (Cursor<S>) cursorList.getCursor(index);
- }
- }
- }
- } finally {
- mLock.unlock();
- }
- return null;
- }
-
- /**
- * Returns lock used by TransactionManager. While holding lock, operations
- * are suspended.
- */
- public Lock getLock() {
- return mLock;
- }
-
- /**
- * Exits all transactions and closes all cursors. Should be called only
- * when repository is closed.
- */
- public void close() throws RepositoryException {
- mLock.lock();
- try {
- if (!mClosed) {
- while (mCurrent != null) {
- mCurrent.exit();
- }
- if (mCursors != null) {
- for (CursorList<TransactionImpl<Txn>> cursorList : mCursors.values()) {
- cursorList.closeCursors();
- }
- }
- }
- } finally {
- mClosed = true;
- mLock.unlock();
- }
- }
-
- /**
- * Returns null if no transaction is in progress.
+ * Closes all transaction scopes. Should be called only when repository is
+ * closed.
*
- * @throws Exception thrown by createTxn or reuseTxn
+ * @param suspend when true, indefinitely suspend all threads interacting
+ * with transactions
*/
- public Txn getTxn() throws Exception {
- mLock.lock();
- try {
- checkState();
- return mCurrent == null ? null : mCurrent.getTxn();
- } finally {
- mLock.unlock();
+ public synchronized void close(boolean suspend) throws RepositoryException {
+ if (mClosedState == SUSPENDED) {
+ // If suspended, attempting to close again will likely deadlock.
+ return;
}
- }
- /**
- * Returns true if a transaction is in progress and it is for update.
- */
- public boolean isForUpdate() {
- mLock.lock();
- try {
- return (mClosed || mCurrent == null) ? false : mCurrent.isForUpdate();
- } finally {
- mLock.unlock();
+ if (suspend) {
+ for (TransactionScope<?> scope : mAllScopes.keySet()) {
+ // Lock scope but don't release it. This prevents other threads
+ // from beginning work during shutdown, which will likely fail
+ // along the way.
+ scope.getLock().lock();
+ }
}
- }
- /**
- * Returns the isolation level of the current transaction, or null if there
- * is no transaction in the current thread.
- */
- public IsolationLevel getIsolationLevel() {
- mLock.lock();
- try {
- return (mClosed || mCurrent == null) ? null : mCurrent.getIsolationLevel();
- } finally {
- mLock.unlock();
- }
- }
+ mClosedState = suspend ? SUSPENDED : CLOSED;
- /**
- * Caller must hold mLock.
- */
- private void checkState() {
- if (mClosed) {
- throw new IllegalStateException("Repository is closed");
+ for (TransactionScope<?> scope : mAllScopes.keySet()) {
+ scope.close();
}
}
@@ -306,6 +108,13 @@ public abstract class TransactionManager<Txn> { IsolationLevel level);
/**
+ * Return true if transactions support "for update" mode.
+ *
+ * @since 1.2
+ */
+ protected abstract boolean supportsForUpdate();
+
+ /**
* Creates an internal transaction representation, with the optional parent
* transaction. If parent is not null and real nested transactions are not
* supported, simply return parent transaction for supporting fake nested
@@ -363,330 +172,4 @@ public abstract class TransactionManager<Txn> { * Aborts and closes the given internal transaction.
*/
protected abstract void abortTxn(Txn txn) throws PersistException;
-
- private static class TransactionImpl<Txn> implements Transaction {
- private final TransactionManager<Txn> mTxnMgr;
- private final TransactionImpl<Txn> mParent;
- private final boolean mTop;
- private final IsolationLevel mLevel;
-
- private boolean mForUpdate;
- private int mDesiredLockTimeout;
- private TimeUnit mTimeoutUnit;
-
- private TransactionImpl<Txn> mChild;
- private boolean mExited;
- private Txn mTxn;
-
- // Tracks all registered cursors.
- private CursorList<?> mCursorList;
-
- TransactionImpl(TransactionManager<Txn> txnMgr,
- TransactionImpl<Txn> parent,
- boolean top,
- IsolationLevel level) {
- mTxnMgr = txnMgr;
- mParent = parent;
- mTop = top;
- mLevel = level;
- if (!top && parent != null) {
- parent.mChild = this;
- mDesiredLockTimeout = parent.mDesiredLockTimeout;
- mTimeoutUnit = parent.mTimeoutUnit;
- }
- }
-
- public void commit() throws PersistException {
- TransactionManager<Txn> txnMgr = mTxnMgr;
- txnMgr.mLock.lock();
- try {
- if (!mExited) {
- if (mChild != null) {
- mChild.commit();
- }
-
- closeCursors();
-
- if (mTxn != null) {
- if (mParent == null || mParent.mTxn != mTxn) {
- try {
- if (!txnMgr.commitTxn(mTxn)) {
- mTxn = null;
- }
- } catch (Throwable e) {
- mTxn = null;
- if (txnMgr.mExTransformer != null) {
- throw txnMgr.mExTransformer.toPersistException(e);
- }
- throw ExceptionTransformer.getInstance().toPersistException(e);
- }
- } else {
- // Indicate fake nested transaction committed.
- mTxn = null;
- }
- }
- }
- } finally {
- txnMgr.mLock.unlock();
- }
- }
-
- public void exit() throws PersistException {
- TransactionManager<Txn> txnMgr = mTxnMgr;
- txnMgr.mLock.lock();
- try {
- if (!mExited) {
- if (mChild != null) {
- mChild.exit();
- }
-
- closeCursors();
-
- if (mTxn != null) {
- try {
- if (mParent == null || mParent.mTxn != mTxn) {
- try {
- txnMgr.abortTxn(mTxn);
- } catch (Throwable e) {
- if (txnMgr.mExTransformer != null) {
- throw txnMgr.mExTransformer.toPersistException(e);
- }
- throw ExceptionTransformer.getInstance().toPersistException(e);
- }
- }
- } finally {
- mTxn = null;
- }
- }
-
- txnMgr.mCurrent = mParent;
-
- mExited = true;
- }
- } finally {
- txnMgr.mLock.unlock();
- }
- }
-
- public void setForUpdate(boolean forUpdate) {
- mForUpdate = forUpdate;
- }
-
- public boolean isForUpdate() {
- return mForUpdate;
- }
-
- public void setDesiredLockTimeout(int timeout, TimeUnit unit) {
- TransactionManager<Txn> txnMgr = mTxnMgr;
- txnMgr.mLock.lock();
- try {
- if (timeout < 0) {
- mDesiredLockTimeout = 0;
- mTimeoutUnit = null;
- } else {
- mDesiredLockTimeout = timeout;
- mTimeoutUnit = unit;
- }
- } finally {
- txnMgr.mLock.unlock();
- }
- }
-
- public IsolationLevel getIsolationLevel() {
- return mLevel;
- }
-
- // Caller must hold mLock.
- <S extends Storable> void register(Cursor<S> cursor) {
- if (mCursorList == null) {
- mCursorList = new CursorList<Object>();
- }
- mCursorList.register(cursor, null);
- }
-
- // Caller must hold mLock.
- <S extends Storable> void unregister(Cursor<S> cursor) {
- if (mCursorList != null) {
- mCursorList.unregister(cursor);
- }
- }
-
- // Caller must hold mLock.
- Txn getTxn() throws Exception {
- TransactionManager<Txn> txnMgr = mTxnMgr;
- if (mTxn != null) {
- txnMgr.reuseTxn(mTxn);
- } else {
- Txn parentTxn;
- if (mParent == null || mTop) {
- parentTxn = null;
- } else if ((parentTxn = mParent.mTxn) == null) {
- // No point in creating nested transaction if parent
- // has never been used. Create parent transaction
- // and use it in child transaction, just like a fake
- // nested transaction.
- if ((parentTxn = mParent.getTxn()) != null) {
- return mTxn = parentTxn;
- }
- // Isolation level of parent is none, so proceed to create
- // a real transaction.
- }
- if (mTimeoutUnit == null) {
- mTxn = txnMgr.createTxn(parentTxn, mLevel);
- } else {
- mTxn = txnMgr.createTxn(parentTxn, mLevel, mDesiredLockTimeout, mTimeoutUnit);
- }
- }
- return mTxn;
- }
-
- // Caller must hold mLock.
- private void closeCursors() throws PersistException {
- if (mCursorList != null) {
- mCursorList.closeCursors();
- }
- }
- }
-
- /**
- * Simple fast list/map for holding a small amount of cursors.
- */
- static class CursorList<V> {
- private int mSize;
- private Cursor<?>[] mCursors;
- private V[] mValues;
-
- CursorList() {
- mCursors = new Cursor[8];
- }
-
- /**
- * @param value optional value to associate
- */
- @SuppressWarnings("unchecked")
- void register(Cursor<?> cursor, V value) {
- int size = mSize;
- Cursor<?>[] cursors = mCursors;
-
- if (size == cursors.length) {
- int newLength = size << 1;
-
- Cursor<?>[] newCursors = new Cursor[newLength];
- System.arraycopy(cursors, 0, newCursors, 0, size);
- mCursors = cursors = newCursors;
-
- if (mValues != null) {
- V[] newValues = (V[]) new Object[newLength];
- System.arraycopy(mValues, 0, newValues, 0, size);
- mValues = newValues;
- }
- }
-
- cursors[size] = cursor;
-
- if (value != null) {
- V[] values = mValues;
- if (values == null) {
- mValues = values = (V[]) new Object[cursors.length];
- }
- values[size] = value;
- }
-
- mSize = size + 1;
- }
-
- V unregister(Cursor<?> cursor) {
- // Assuming that cursors are opened and closed in LIFO order
- // (stack order), search backwards to optimize.
- Cursor<?>[] cursors = mCursors;
- int size = mSize;
- int i = size;
- search: {
- while (--i >= 0) {
- if (cursors[i] == cursor) {
- break search;
- }
- }
- // Not found.
- return null;
- }
-
- V[] values = mValues;
- V value;
-
- if (values == null) {
- value = null;
- if (i == size - 1) {
- // Clear reference so that it can be garbage collected.
- cursors[i] = null;
- } else {
- // Shift array elements down.
- System.arraycopy(cursors, i + 1, cursors, i, size - i - 1);
- }
- } else {
- value = values[i];
- if (i == size - 1) {
- // Clear references so that they can be garbage collected.
- cursors[i] = null;
- values[i] = null;
- } else {
- // Shift array elements down.
- System.arraycopy(cursors, i + 1, cursors, i, size - i - 1);
- System.arraycopy(values, i + 1, values, i, size - i - 1);
- }
- }
-
- mSize = size - 1;
- return value;
- }
-
- int size() {
- return mSize;
- }
-
- Cursor<?> getCursor(int index) {
- return mCursors[index];
- }
-
- V getValue(int index) {
- V[] values = mValues;
- return values == null ? null : values[index];
- }
-
- /**
- * Closes all cursors and resets the size of this list to 0.
- */
- void closeCursors() throws PersistException {
- // Note: Iteration must be in reverse order. Calling close on the
- // cursor should cause it to unregister from this list. This will
- // cause only a modification to the end of the list, which is no
- // longer needed by this method.
- try {
- Cursor<?>[] cursors = mCursors;
- V[] values = mValues;
- int i = mSize;
- if (values == null) {
- while (--i >= 0) {
- Cursor<?> cursor = cursors[i];
- if (cursor != null) {
- cursor.close();
- cursors[i] = null;
- }
- }
- } else {
- while (--i >= 0) {
- Cursor<?> cursor = cursors[i];
- if (cursor != null) {
- cursor.close();
- cursors[i] = null;
- values[i] = null;
- }
- }
- }
- } catch (FetchException e) {
- throw e.toPersistException();
- }
- mSize = 0;
- }
- }
}
diff --git a/src/main/java/com/amazon/carbonado/spi/TransactionScope.java b/src/main/java/com/amazon/carbonado/spi/TransactionScope.java new file mode 100644 index 0000000..2031d68 --- /dev/null +++ b/src/main/java/com/amazon/carbonado/spi/TransactionScope.java @@ -0,0 +1,562 @@ +/*
+ * Copyright 2008 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.spi;
+
+import java.util.IdentityHashMap;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+import com.amazon.carbonado.Cursor;
+import com.amazon.carbonado.FetchException;
+import com.amazon.carbonado.IsolationLevel;
+import com.amazon.carbonado.PersistException;
+import com.amazon.carbonado.RepositoryException;
+import com.amazon.carbonado.Storable;
+import com.amazon.carbonado.Transaction;
+
+/**
+ * Container of thread local, scoped transactions.
+ *
+ * @param <Txn> Transaction type
+ * @author Brian S O'Neill
+ * @since 1.2
+ * @see TransactionManager
+ */
+public class TransactionScope<Txn> {
+ final TransactionManager<Txn> mTxnMgr;
+ final Lock mLock;
+
+ TransactionImpl<Txn> mCurrent;
+
+ // Tracks all registered cursors by storage type.
+ private Map<Class<?>, CursorList<TransactionImpl<Txn>>> mCursors;
+
+ private boolean mClosed;
+
+ TransactionScope(TransactionManager<Txn> txnMgr, boolean closed) {
+ mTxnMgr = txnMgr;
+ mLock = new ReentrantLock(true);
+ mClosed = closed;
+ }
+
+ /**
+ * Enters a new transaction scope.
+ *
+ * @param level desired isolation level (may be null)
+ * @throws UnsupportedOperationException if isolation level higher than
+ * supported by repository
+ */
+ public Transaction enter(IsolationLevel level) {
+ mLock.lock();
+ try {
+ TransactionImpl<Txn> parent = mCurrent;
+ IsolationLevel actualLevel = mTxnMgr.selectIsolationLevel(parent, level);
+ if (actualLevel == null) {
+ if (parent == null) {
+ throw new UnsupportedOperationException
+ ("Desired isolation level not supported: " + level);
+ } else {
+ throw new UnsupportedOperationException
+ ("Desired isolation level not supported: " + level
+ + "; parent isolation level: " + parent.getIsolationLevel());
+ }
+ }
+
+ return mCurrent = new TransactionImpl<Txn>(this, parent, false, actualLevel);
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Enters a new top-level transaction scope.
+ *
+ * @param level desired isolation level (may be null)
+ * @throws UnsupportedOperationException if isolation level higher than
+ * supported by repository
+ */
+ public Transaction enterTop(IsolationLevel level) {
+ mLock.lock();
+ try {
+ IsolationLevel actualLevel = mTxnMgr.selectIsolationLevel(null, level);
+ if (actualLevel == null) {
+ throw new UnsupportedOperationException
+ ("Desired isolation level not supported: " + level);
+ }
+
+ return mCurrent = new TransactionImpl<Txn>(this, mCurrent, true, actualLevel);
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Registers the given cursor against the current transaction, allowing
+ * it to be closed on transaction exit or transaction manager close. If
+ * there is no current transaction scope, the cursor is registered as not
+ * part of a transaction. Cursors should register when created.
+ */
+ public <S extends Storable> void register(Class<S> type, Cursor<S> cursor) {
+ mLock.lock();
+ try {
+ checkState();
+ if (mCursors == null) {
+ mCursors = new IdentityHashMap<Class<?>, CursorList<TransactionImpl<Txn>>>();
+ }
+
+ CursorList<TransactionImpl<Txn>> cursorList = mCursors.get(type);
+ if (cursorList == null) {
+ cursorList = new CursorList<TransactionImpl<Txn>>();
+ mCursors.put(type, cursorList);
+ }
+
+ cursorList.register(cursor, mCurrent);
+
+ if (mCurrent != null) {
+ mCurrent.register(cursor);
+ }
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Unregisters a previously registered cursor. Cursors should unregister
+ * when closed.
+ */
+ public <S extends Storable> void unregister(Class<S> type, Cursor<S> cursor) {
+ mLock.lock();
+ try {
+ if (mCursors != null) {
+ CursorList<TransactionImpl<Txn>> cursorList = mCursors.get(type);
+ if (cursorList != null) {
+ TransactionImpl<Txn> txnImpl = cursorList.unregister(cursor);
+ if (txnImpl != null) {
+ txnImpl.unregister(cursor);
+ }
+ }
+ }
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Returns lock used by TransactionScope. While holding lock, operations
+ * are suspended.
+ */
+ public Lock getLock() {
+ return mLock;
+ }
+
+ /**
+ * Exits all transactions and closes all cursors. Should be called only
+ * when repository is closed.
+ */
+ public void close() throws RepositoryException {
+ mLock.lock();
+ try {
+ if (!mClosed) {
+ while (mCurrent != null) {
+ mCurrent.exit();
+ }
+ if (mCursors != null) {
+ for (CursorList<TransactionImpl<Txn>> cursorList : mCursors.values()) {
+ cursorList.closeCursors();
+ }
+ }
+ }
+ } finally {
+ mClosed = true;
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Returns null if no transaction is in progress.
+ *
+ * @throws Exception thrown by createTxn or reuseTxn
+ */
+ public Txn getTxn() throws Exception {
+ mLock.lock();
+ try {
+ checkState();
+ return mCurrent == null ? null : mCurrent.getTxn();
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Returns true if a transaction is in progress and it is for update.
+ */
+ public boolean isForUpdate() {
+ mLock.lock();
+ try {
+ return (mClosed || mCurrent == null) ? false : mCurrent.isForUpdate();
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Returns the isolation level of the current transaction, or null if there
+ * is no transaction in the current thread.
+ */
+ public IsolationLevel getIsolationLevel() {
+ mLock.lock();
+ try {
+ return (mClosed || mCurrent == null) ? null : mCurrent.getIsolationLevel();
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Caller must hold mLock.
+ */
+ private void checkState() {
+ if (mClosed) {
+ throw new IllegalStateException("Repository is closed");
+ }
+ }
+
+ private static class TransactionImpl<Txn> implements Transaction {
+ private final TransactionScope<Txn> mScope;
+ private final TransactionImpl<Txn> mParent;
+ private final boolean mTop;
+ private final IsolationLevel mLevel;
+
+ private boolean mForUpdate;
+ private int mDesiredLockTimeout;
+ private TimeUnit mTimeoutUnit;
+
+ private TransactionImpl<Txn> mChild;
+ private boolean mExited;
+ private Txn mTxn;
+
+ // Tracks all registered cursors.
+ private CursorList<?> mCursorList;
+
+ TransactionImpl(TransactionScope<Txn> scope,
+ TransactionImpl<Txn> parent,
+ boolean top,
+ IsolationLevel level) {
+ mScope = scope;
+ mParent = parent;
+ mTop = top;
+ mLevel = level;
+ if (!top && parent != null) {
+ parent.mChild = this;
+ mDesiredLockTimeout = parent.mDesiredLockTimeout;
+ mTimeoutUnit = parent.mTimeoutUnit;
+ }
+ }
+
+ public void commit() throws PersistException {
+ TransactionScope<Txn> scope = mScope;
+ scope.mLock.lock();
+ try {
+ if (!mExited) {
+ if (mChild != null) {
+ mChild.commit();
+ }
+
+ closeCursors();
+
+ if (mTxn != null) {
+ if (mParent == null || mParent.mTxn != mTxn) {
+ try {
+ if (!scope.mTxnMgr.commitTxn(mTxn)) {
+ mTxn = null;
+ }
+ } catch (Throwable e) {
+ mTxn = null;
+ throw ExceptionTransformer.getInstance().toPersistException(e);
+ }
+ } else {
+ // Indicate fake nested transaction committed.
+ mTxn = null;
+ }
+ }
+ }
+ } finally {
+ scope.mLock.unlock();
+ }
+ }
+
+ public void exit() throws PersistException {
+ TransactionScope<Txn> scope = mScope;
+ scope.mLock.lock();
+ try {
+ if (!mExited) {
+ if (mChild != null) {
+ mChild.exit();
+ }
+
+ closeCursors();
+
+ if (mTxn != null) {
+ try {
+ if (mParent == null || mParent.mTxn != mTxn) {
+ try {
+ scope.mTxnMgr.abortTxn(mTxn);
+ } catch (Throwable e) {
+ throw ExceptionTransformer.getInstance().toPersistException(e);
+ }
+ }
+ } finally {
+ mTxn = null;
+ }
+ }
+
+ scope.mCurrent = mParent;
+
+ mExited = true;
+ }
+ } finally {
+ scope.mLock.unlock();
+ }
+ }
+
+ public void setForUpdate(boolean forUpdate) {
+ mForUpdate = forUpdate && mScope.mTxnMgr.supportsForUpdate();
+ }
+
+ public boolean isForUpdate() {
+ return mForUpdate;
+ }
+
+ public void setDesiredLockTimeout(int timeout, TimeUnit unit) {
+ TransactionScope<Txn> scope = mScope;
+ scope.mLock.lock();
+ try {
+ if (timeout < 0) {
+ mDesiredLockTimeout = 0;
+ mTimeoutUnit = null;
+ } else {
+ mDesiredLockTimeout = timeout;
+ mTimeoutUnit = unit;
+ }
+ } finally {
+ scope.mLock.unlock();
+ }
+ }
+
+ public IsolationLevel getIsolationLevel() {
+ return mLevel;
+ }
+
+ // Caller must hold mLock.
+ <S extends Storable> void register(Cursor<S> cursor) {
+ if (mCursorList == null) {
+ mCursorList = new CursorList<Object>();
+ }
+ mCursorList.register(cursor, null);
+ }
+
+ // Caller must hold mLock.
+ <S extends Storable> void unregister(Cursor<S> cursor) {
+ if (mCursorList != null) {
+ mCursorList.unregister(cursor);
+ }
+ }
+
+ // Caller must hold mLock.
+ Txn getTxn() throws Exception {
+ TransactionScope<Txn> scope = mScope;
+ if (mTxn != null) {
+ scope.mTxnMgr.reuseTxn(mTxn);
+ } else {
+ Txn parentTxn;
+ if (mParent == null || mTop) {
+ parentTxn = null;
+ } else if ((parentTxn = mParent.mTxn) == null) {
+ // No point in creating nested transaction if parent
+ // has never been used. Create parent transaction
+ // and use it in child transaction, just like a fake
+ // nested transaction.
+ if ((parentTxn = mParent.getTxn()) != null) {
+ return mTxn = parentTxn;
+ }
+ // Isolation level of parent is none, so proceed to create
+ // a real transaction.
+ }
+ if (mTimeoutUnit == null) {
+ mTxn = scope.mTxnMgr.createTxn(parentTxn, mLevel);
+ } else {
+ mTxn = scope.mTxnMgr.createTxn(parentTxn, mLevel,
+ mDesiredLockTimeout, mTimeoutUnit);
+ }
+ }
+ return mTxn;
+ }
+
+ // Caller must hold mLock.
+ private void closeCursors() throws PersistException {
+ if (mCursorList != null) {
+ mCursorList.closeCursors();
+ }
+ }
+ }
+
+ /**
+ * Simple fast list/map for holding a small amount of cursors.
+ */
+ static class CursorList<V> {
+ private int mSize;
+ private Cursor<?>[] mCursors;
+ private V[] mValues;
+
+ CursorList() {
+ mCursors = new Cursor[8];
+ }
+
+ /**
+ * @param value optional value to associate
+ */
+ @SuppressWarnings("unchecked")
+ void register(Cursor<?> cursor, V value) {
+ int size = mSize;
+ Cursor<?>[] cursors = mCursors;
+
+ if (size == cursors.length) {
+ int newLength = size << 1;
+
+ Cursor<?>[] newCursors = new Cursor[newLength];
+ System.arraycopy(cursors, 0, newCursors, 0, size);
+ mCursors = cursors = newCursors;
+
+ if (mValues != null) {
+ V[] newValues = (V[]) new Object[newLength];
+ System.arraycopy(mValues, 0, newValues, 0, size);
+ mValues = newValues;
+ }
+ }
+
+ cursors[size] = cursor;
+
+ if (value != null) {
+ V[] values = mValues;
+ if (values == null) {
+ mValues = values = (V[]) new Object[cursors.length];
+ }
+ values[size] = value;
+ }
+
+ mSize = size + 1;
+ }
+
+ V unregister(Cursor<?> cursor) {
+ // Assuming that cursors are opened and closed in LIFO order
+ // (stack order), search backwards to optimize.
+ Cursor<?>[] cursors = mCursors;
+ int size = mSize;
+ int i = size;
+ search: {
+ while (--i >= 0) {
+ if (cursors[i] == cursor) {
+ break search;
+ }
+ }
+ // Not found.
+ return null;
+ }
+
+ V[] values = mValues;
+ V value;
+
+ if (values == null) {
+ value = null;
+ if (i == size - 1) {
+ // Clear reference so that it can be garbage collected.
+ cursors[i] = null;
+ } else {
+ // Shift array elements down.
+ System.arraycopy(cursors, i + 1, cursors, i, size - i - 1);
+ }
+ } else {
+ value = values[i];
+ if (i == size - 1) {
+ // Clear references so that they can be garbage collected.
+ cursors[i] = null;
+ values[i] = null;
+ } else {
+ // Shift array elements down.
+ System.arraycopy(cursors, i + 1, cursors, i, size - i - 1);
+ System.arraycopy(values, i + 1, values, i, size - i - 1);
+ }
+ }
+
+ mSize = size - 1;
+ return value;
+ }
+
+ int size() {
+ return mSize;
+ }
+
+ Cursor<?> getCursor(int index) {
+ return mCursors[index];
+ }
+
+ V getValue(int index) {
+ V[] values = mValues;
+ return values == null ? null : values[index];
+ }
+
+ /**
+ * Closes all cursors and resets the size of this list to 0.
+ */
+ void closeCursors() throws PersistException {
+ // Note: Iteration must be in reverse order. Calling close on the
+ // cursor should cause it to unregister from this list. This will
+ // cause only a modification to the end of the list, which is no
+ // longer needed by this method.
+ try {
+ Cursor<?>[] cursors = mCursors;
+ V[] values = mValues;
+ int i = mSize;
+ if (values == null) {
+ while (--i >= 0) {
+ Cursor<?> cursor = cursors[i];
+ if (cursor != null) {
+ cursor.close();
+ cursors[i] = null;
+ }
+ }
+ } else {
+ while (--i >= 0) {
+ Cursor<?> cursor = cursors[i];
+ if (cursor != null) {
+ cursor.close();
+ cursors[i] = null;
+ values[i] = null;
+ }
+ }
+ }
+ } catch (FetchException e) {
+ throw e.toPersistException();
+ }
+ mSize = 0;
+ }
+ }
+}
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