diff options
Diffstat (limited to 'src/main/java/com/amazon/carbonado/txn/TransactionScope.java')
| -rw-r--r-- | src/main/java/com/amazon/carbonado/txn/TransactionScope.java | 621 |
1 files changed, 621 insertions, 0 deletions
diff --git a/src/main/java/com/amazon/carbonado/txn/TransactionScope.java b/src/main/java/com/amazon/carbonado/txn/TransactionScope.java new file mode 100644 index 0000000..62b62a3 --- /dev/null +++ b/src/main/java/com/amazon/carbonado/txn/TransactionScope.java @@ -0,0 +1,621 @@ +/*
+ * 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.txn;
+
+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;
+
+import com.amazon.carbonado.spi.ExceptionTransformer;
+
+/**
+ * Container of thread local, scoped transactions.
+ *
+ * @param <Txn> Transaction implementation
+ * @author Brian S O'Neill
+ * @since 1.2
+ * @see TransactionManager
+ */
+public class TransactionScope<Txn> {
+ final TransactionManager<Txn> mTxnMgr;
+ final Lock mLock;
+
+ TransactionImpl<Txn> mActive;
+
+ // Tracks all registered cursors by storage type.
+ private Map<Class<?>, CursorList<TransactionImpl<Txn>>> mCursors;
+
+ private boolean mClosed;
+ private boolean mDetached;
+
+ TransactionScope(TransactionManager<Txn> txnMgr, boolean closed) {
+ mTxnMgr = txnMgr;
+ mLock = new ReentrantLock(true);
+ }
+
+ /**
+ * Enters a new transaction scope which becomes the active transaction.
+ *
+ * @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 = mActive;
+ 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 mActive = new TransactionImpl<Txn>(this, parent, false, actualLevel);
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Enters a new top-level transaction scope which becomes the active
+ * transaction.
+ *
+ * @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 mActive = new TransactionImpl<Txn>(this, mActive, true, actualLevel);
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Registers the given cursor against the active transaction, allowing it
+ * to be closed on transaction exit or transaction manager close. If there
+ * is no active transaction in 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 {
+ checkClosed();
+ 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, mActive);
+
+ if (mActive != null) {
+ mActive.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;
+ }
+
+ /**
+ * Returns the implementation for the active transaction, or null if there
+ * is no active transaction.
+ *
+ * @throws Exception thrown by createTxn or reuseTxn
+ */
+ public Txn getTxn() throws Exception {
+ mLock.lock();
+ try {
+ checkClosed();
+ return mActive == null ? null : mActive.getTxn();
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Returns true if an active transaction exists and it is for update.
+ */
+ public boolean isForUpdate() {
+ mLock.lock();
+ try {
+ return (mClosed || mActive == null) ? false : mActive.isForUpdate();
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Returns the isolation level of the active transaction, or null if there
+ * is no active transaction.
+ */
+ public IsolationLevel getIsolationLevel() {
+ mLock.lock();
+ try {
+ return (mClosed || mActive == null) ? null : mActive.getIsolationLevel();
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Attach this scope to the current thread, if it has been {@link
+ * TransactionManager#detachLocalScope detached}.
+ *
+ * @throws IllegalStateException if current thread has a different
+ * transaction already attached
+ */
+ public void attach() {
+ mLock.lock();
+ try {
+ if (mTxnMgr.setLocalScope(this, mDetached)) {
+ mDetached = false;
+ } else if (!mDetached) {
+ throw new IllegalStateException("Transaction scope is not detached");
+ } else {
+ throw new IllegalStateException
+ ("Current thread has a different transaction already attached");
+ }
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ // Called by TransactionImpl.
+ void detach() {
+ mLock.lock();
+ try {
+ if (mDetached || mTxnMgr.removeLocalScope(this)) {
+ mDetached = true;
+ } else {
+ throw new IllegalStateException("Transaction is attached to a different thread");
+ }
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ // Called by TransactionManager.
+ void markDetached() {
+ mLock.lock();
+ try {
+ mDetached = true;
+ } finally {
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Exits all transactions and closes all cursors. Should be called only
+ * when repository is closed.
+ */
+ void close() throws RepositoryException {
+ mLock.lock();
+ try {
+ if (!mClosed) {
+ while (mActive != null) {
+ mActive.exit();
+ }
+ if (mCursors != null) {
+ for (CursorList<TransactionImpl<Txn>> cursorList : mCursors.values()) {
+ cursorList.closeCursors();
+ }
+ }
+ }
+ } finally {
+ mClosed = true;
+ mLock.unlock();
+ }
+ }
+
+ /**
+ * Caller must hold mLock.
+ */
+ private void checkClosed() {
+ 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.mActive = 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;
+ }
+
+ public void detach() {
+ mScope.detach();
+ }
+
+ public void attach() {
+ mScope.attach();
+ }
+
+ // 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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