CacheTransactionManager (GemFire Java API Documentation)

```
public interface CacheTransactionManager
```
The CacheTransactionManager interface allows applications to manage transactions on a per Cache basis.
The life cycle of a GemFire transaction starts with a begin operation. The life cycle ends with either a commit or rollback operation. Between the begin and the commit/rollback are typically Region operations. In general, those that either create, destroy, invalidate or update Region.Entry are considered transactional, that is they modify transactional state.
A GemFire transaction may involve operations on multiple regions, each of which may have different attributes.
While a GemFire transaction and its operations are invoked in the local VM, the resulting transaction state is distributed to other VM's at commit time as per the attributes of each participant Region.
A transaction can have no more than one thread associated with it and conversely a thread can only operate on one transaction at any given time. Child threads will not inherit the existing transaction.
Each of the following methods operate on the current thread. All methods throw CacheClosedException if the Cache is closed.
GemFire Transactions currently only support Read Committed isolation. In addition, they are optimistic transactions in that write locking and conflict checks are performed as part of the commit operation.
For guaranteed Read Committed isolation, avoid making "in place" changes, because such changes will be "seen" by other transactions and break the Read Committed isolation guarantee. e.g.
```
    CacheTransactionManager txMgr = cache.getCacheTransactionManager();
    txMgr.begin();
    StringBuffer s = (StringBuffer) r.get("stringBuf");
    s.append("Changes seen before commit. NOT Read Committed!");
    r.put("stringBuf", s);
    txMgr.commit();
  
```
To aid in creating copies, the "copy on read" Cache attribute and the CopyHelper.copy(T) method are provided. The following is a Read Committed safe example using the CopyHelper.copy method.
```
    CacheTransactionManager txMgr = cache.getCacheTransactionManager();
    txMgr.begin();
    Object o = r.get("stringBuf");
    StringBuffer s = (StringBuffer) CopyHelper.copy(o);
    s.append("Changes unseen before commit. Read Committed.");
    r.put("stringBuf", s);
    txMgr.commit();
  
```
Its important to note that creating copies can negatively impact both performance and memory consumption.
Partitioned Regions, Distributed No Ack and Distributed Ack Regions are supported (see AttributesFactory for Scope). For both scopes, a consistent configuration (per VM) is enforced.
Global Regions, client Regions (see com.gemstone.gemfire.cache.client) and persistent Regions (see DiskWriteAttributes) do not support transactions.
When PartitionedRegions are involved in a transaction, all data in the transaction must be colocated together on one data node. See the GemFire Developer Guide for details on using transactions with Partitioned Regions.
Since:

4.0

See Also:
Cache

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`addListener(TransactionListener aListener)` Adds a transaction listener to the end of the list of transaction listeners on this cache.
`void`	`begin()` Creates a new transaction and associates it with the current thread.
`void`	`commit()` Commit the transaction associated with the current thread.
`boolean`	`exists()` Reports the existence of a Transaction for this thread
`boolean`	`exists(TransactionId transactionId)` Reports the existence of a transaction for the given transactionId.
`TransactionListener`	`getListener()` Deprecated. as of GemFire 5.0, use `getListeners()` instead
`TransactionListener[]`	`getListeners()` Returns an array of all the transaction listeners on this cache.
`TransactionId`	`getTransactionId()` Returns the transaction identifier for the current thread
`TransactionWriter`	`getWriter()` Returns the current `TransactionWriter`
`void`	`initListeners(TransactionListener[] newListeners)` Removes all transaction listeners, calling `CacheCallback.close()` on each of them, and then adds each listener in the specified array.
`boolean`	`isSuspended(TransactionId transactionId)` This method can be used to determine if a transaction with the given transaction identifier is currently suspended locally.
`void`	`removeListener(TransactionListener aListener)` Removes a transaction listener from the list of transaction listeners on this cache.
`void`	`resume(TransactionId transactionId)` On the current thread, resumes a transaction that was previously suspended using `suspend()`
`void`	`rollback()` Roll back the transaction associated with the current thread.
`TransactionListener`	`setListener(TransactionListener newListener)` Deprecated. as of GemFire 5.0, use `addListener(com.gemstone.gemfire.cache.TransactionListener)` or `initListeners(com.gemstone.gemfire.cache.TransactionListener[])` instead.
`void`	`setWriter(TransactionWriter writer)` Set the TransactionWriter for the cache
`TransactionId`	`suspend()` Suspends the transaction on the current thread.
`boolean`	`tryResume(TransactionId transactionId)` On the current thread, resumes a transaction that was previously suspended using `suspend()`.
`boolean`	`tryResume(TransactionId transactionId, long time, TimeUnit unit)` On the current thread, resumes a transaction that was previously suspended using `suspend()`, or waits for the specified timeout interval if the transaction has not been suspended.

- Method Detail
  - begin
```
void begin()
```
    Creates a new transaction and associates it with the current thread.
    
    Throws:
    
    IllegalStateException - if the thread is already associated with a transaction
    Since:
    
    4.0
  - commit
```
void commit()
            throws CommitConflictException
```
    Commit the transaction associated with the current thread. If the commit operation fails due to a conflict it will destroy the transaction state and throw a CommitConflictException. If the commit operation succeeds, it returns after the transaction state has been merged with committed state. When this method completes, the thread is no longer associated with a transaction.
    
    Throws:
    
    IllegalStateException - if the thread is not associated with a transaction
    
    CommitConflictException - if the commit operation fails due to a write conflict.
    
    TransactionDataNodeHasDepartedException - if the node hosting the transaction data has departed. This is only relevant for transaction that involve PartitionedRegions.
    
    TransactionDataNotColocatedException - if at commit time, the data involved in the transaction has moved away from the transaction hosting node. This can only happen if rebalancing/recovery happens during a transaction that involves a PartitionedRegion.
    
    TransactionInDoubtException - when GemFire cannot tell which nodes have applied the transaction and which have not. This only occurs if nodes fail mid-commit, and only then in very rare circumstances.
  - rollback
```
void rollback()
```
    Roll back the transaction associated with the current thread. When this method completes, the thread is no longer associated with a transaction and the transaction context is destroyed.
    
    Throws:
    
    IllegalStateException - if the thread is not associated with a transaction
    Since:
    
    4.0
  - suspend
```
TransactionId suspend()
```
    Suspends the transaction on the current thread. All subsequent operations performed by this thread will be non-transactional. The suspended transaction can be resumed by calling resume(TransactionId)
    
    Returns:
    the transaction identifier of the suspended transaction or null if the thread was not associated with a transaction
    Since:
    
    6.6.2
  - resume
```
void resume(TransactionId transactionId)
```
    On the current thread, resumes a transaction that was previously suspended using suspend()
    
    Parameters:
    transactionId - the transaction to resume
    
    Throws:
    
    IllegalStateException - if the thread is associated with a transaction or if isSuspended(TransactionId) would return false for the given transactionId
    Since:
    
    6.6.2
    
    See Also:
    tryResume(TransactionId)
  - isSuspended
```
boolean isSuspended(TransactionId transactionId)
```
    This method can be used to determine if a transaction with the given transaction identifier is currently suspended locally. This method does not check other members for transaction status.
    
    Parameters:
    transactionId -
    
    Returns:
    true if the transaction is in suspended state, false otherwise
    Since:
    
    6.6.2
    
    See Also:
    exists(TransactionId)
  - tryResume
```
boolean tryResume(TransactionId transactionId)
```
    On the current thread, resumes a transaction that was previously suspended using suspend(). This method is equivalent to
```
 if (isSuspended(txId)) {
   resume(txId);
 }
 
```
    except that this action is performed atomically
    Parameters:
    transactionId - the transaction to resume
    
    Returns:
    true if the transaction was resumed, false otherwise
    Since:
    
    6.6.2
  - tryResume
```
boolean tryResume(TransactionId transactionId,
                long time,
                TimeUnit unit)
```
    On the current thread, resumes a transaction that was previously suspended using suspend(), or waits for the specified timeout interval if the transaction has not been suspended. This method will return if:
    - Another thread suspends the transaction
    - Another thread calls commit/rollback on the transaction
    - This thread has waited for the specified timeout
    This method returns immediately if exists(TransactionId) returns false.
    Parameters:
    transactionId - the transaction to resume
    time - the maximum time to wait
    unit - the time unit of the time argument
    
    Returns:
    true if the transaction was resumed, false otherwise
    Since:
    
    6.6.2
    
    See Also:
    tryResume(TransactionId)
  - exists
```
boolean exists(TransactionId transactionId)
```
    Reports the existence of a transaction for the given transactionId. This method can be used to determine if a transaction with the given transaction identifier is currently in progress locally.
    
    Parameters:
    transactionId - the given transaction identifier
    
    Returns:
    true if the transaction is in progress, false otherwise.
    Since:
    
    6.6.2
    
    See Also:
    isSuspended(TransactionId)
  - exists
```
boolean exists()
```
    Reports the existence of a Transaction for this thread
    
    Returns:
    true if a transaction exists, false otherwise
    Since:
    
    4.0
  - getTransactionId
```
TransactionId getTransactionId()
```
    Returns the transaction identifier for the current thread
    
    Returns:
    the transaction identifier or null if no transaction exists
    Since:
    
    4.0
  - getListener
```
@Deprecated
TransactionListener getListener()
```
    Deprecated. as of GemFire 5.0, use getListeners() instead
    
    Gets the transaction listener for this Cache.
    
    Returns:
    The TransactionListener instance or null if no listener.
    
    Throws:
    
    IllegalStateException - if more than one listener exists on this cache
  - getListeners
```
TransactionListener[] getListeners()
```
    Returns an array of all the transaction listeners on this cache. Modifications to the returned array will not effect what listeners are on this cache.
    
    Returns:
    the cache's TransactionListeners; an empty array if no listeners
    Since:
    
    5.0
  - setListener
```
@Deprecated
TransactionListener setListener(TransactionListener newListener)
```
    Deprecated. as of GemFire 5.0, use addListener(com.gemstone.gemfire.cache.TransactionListener) or initListeners(com.gemstone.gemfire.cache.TransactionListener[]) instead.
    
    Sets the transaction listener for this Cache.
    
    Parameters:
    newListener - the TransactionListener to register with the Cache. Use a null to deregister the current listener without registering a new one.
    
    Returns:
    the previous TransactionListener
    
    Throws:
    
    IllegalStateException - if more than one listener exists on this cache
  - addListener
```
void addListener(TransactionListener aListener)
```
    Adds a transaction listener to the end of the list of transaction listeners on this cache.
    
    Parameters:
    aListener - the user defined transaction listener to add to the cache.
    
    Throws:
    
    IllegalArgumentException - if aListener is null
    Since:
    
    5.0
  - removeListener
```
void removeListener(TransactionListener aListener)
```
    Removes a transaction listener from the list of transaction listeners on this cache. Does nothing if the specified listener has not been added. If the specified listener has been added then CacheCallback.close() will be called on it; otherwise does nothing.
    
    Parameters:
    aListener - the transaction listener to remove from the cache.
    
    Throws:
    
    IllegalArgumentException - if aListener is null
    Since:
    
    5.0
  - initListeners
```
void initListeners(TransactionListener[] newListeners)
```
    Removes all transaction listeners, calling CacheCallback.close() on each of them, and then adds each listener in the specified array.
    
    Parameters:
    newListeners - a possibly null or empty array of listeners to add to this cache.
    
    Throws:
    
    IllegalArgumentException - if the newListeners array has a null element
    Since:
    
    5.0
  - setWriter
```
void setWriter(TransactionWriter writer)
```
    Set the TransactionWriter for the cache
    
    Parameters:
    writer -
    Since:
    
    6.5
    
    See Also:
    TransactionWriter
  - getWriter
```
TransactionWriter getWriter()
```
    Returns the current TransactionWriter
    
    Returns:
    the current TransactionWriter
    Since:
    
    6.5
    
    See Also:
    setWriter(TransactionWriter)

Interface CacheTransactionManager

Method Summary

Method Detail

begin

commit

rollback

suspend

resume

isSuspended

tryResume

tryResume

exists

exists

getTransactionId

getListener

getListeners

setListener

addListener

removeListener

initListeners

setWriter

getWriter