GridCacheTx (gridgain-core 6.1.9 API)

All Superinterfaces:

AutoCloseable, GridMetadataAware, Serializable

All Known Subinterfaces:

GridCacheTxEx<K,V>, GridCacheTxLocalEx<K,V>, GridCacheTxProxy, GridCacheTxRemoteEx<K,V>

All Known Implementing Classes:

GridCacheTxAdapter, GridCacheTxLocalAdapter, GridCacheTxProxyImpl, GridDhtColocatedTxLocal, GridDhtTxLocal, GridDhtTxLocalAdapter, GridDhtTxRemote, GridDistributedTxRemoteAdapter, GridNearTxRemote
```
public interface GridCacheTx
extends GridMetadataAware, AutoCloseable
```
Grid cache transaction. Cache transactions have a default 2PC (two-phase-commit) behavior and can be plugged into ongoing JTA transaction by properly implementing GridCacheTmLookup interface. Cache transactions can also be started explicitly directly from GridCacheProjection API via any of the 'GridCacheProjection.txStart(..)' methods.
Cache transactions support the following isolation levels:
- GridCacheTxIsolation.READ_COMMITTED isolation level means that always a committed value will be provided for read operations. With this isolation level values are always read from cache global memory or persistent store every time a value is accessed. In other words, if the same key is accessed more than once within the same transaction, it may have different value every time since global cache memory may be updated concurrently by other threads.
- GridCacheTxIsolation.REPEATABLE_READ isolation level means that if a value was read once within transaction, then all consecutive reads will provide the same in-transaction value. With this isolation level accessed values are stored within in-transaction memory, so consecutive access to the same key within the same transaction will always return the value that was previously read or updated within this transaction. If concurrency is GridCacheTxConcurrency.PESSIMISTIC, then a lock on the key will be acquired prior to accessing the value.
- GridCacheTxIsolation.SERIALIZABLE isolation level means that all transactions occur in a completely isolated fashion, as if all transactions in the system had executed serially, one after the other. Read access with this level happens the same way as with GridCacheTxIsolation.REPEATABLE_READ level. However, in GridCacheTxConcurrency.OPTIMISTIC mode, if some transactions cannot be serially isolated from each other, then one winner will be picked and the other transactions in conflict will result in GridCacheTxOptimisticException being thrown.
Cache transactions support the following concurrency models:
- GridCacheTxConcurrency.OPTIMISTIC - in this mode all cache operations are not distributed to other nodes until commit() or commitAsync() are called. In this mode one 'PREPARE' message will be sent to participating cache nodes to start acquiring per-transaction locks, and once all nodes reply 'OK' (i.e. Phase 1 completes successfully), a one-way' 'COMMIT' message is sent without waiting for reply. If it is necessary to know whenever remote nodes have committed as well, synchronous commit or synchronous rollback should be enabled via GridCacheConfiguration.setWriteSynchronizationMode(org.gridgain.grid.cache.GridCacheWriteSynchronizationMode) or by setting proper flags on cache projection, such as GridCacheFlag.SYNC_COMMIT.
  Note that in this mode, optimistic failures are only possible in conjunction with GridCacheTxIsolation.SERIALIZABLE isolation level. In all other cases, optimistic transactions will never fail optimistically and will always be identically ordered on all participating grid nodes.
- GridCacheTxConcurrency.PESSIMISTIC - in this mode a lock is acquired on all cache operations with exception of read operations in GridCacheTxIsolation.READ_COMMITTED mode. All optional filters passed into cache operations will be evaluated after successful lock acquisition. Whenever commit() or commitAsync() is called, a single one-way 'COMMIT' message is sent to participating cache nodes without waiting for reply. Note that there is no reason for distributed 'PREPARE' step, as all locks have been already acquired. Just like with optimistic mode, it is possible to configure synchronous commit or rollback and wait till transaction commits on all participating remote nodes.
Cache Atomicity Mode
In addition to standard GridCacheAtomicityMode.TRANSACTIONAL behavior, GridGain also supports a lighter GridCacheAtomicityMode.ATOMIC mode as well. In this mode distributed transactions and distributed locking are not supported. Disabling transactions and locking allows to achieve much higher performance and throughput ratios. It is recommended that GridCacheAtomicityMode.ATOMIC mode is used whenever full ACID-compliant transactions are not needed.

Usage
You can use cache transactions as follows:
```
 GridCache<String, Integer> cache = GridGain.grid().cache();

 try (GridCacheTx tx = cache.txStart()) {
     // Perform transactional operations.
     Integer v1 = cache.get("k1");

     // Check if v1 satisfies some condition before doing a put.
     if (v1 != null && v1 > 0)
         cache.putx("k1", 2);

     cache.removex("k2");

     // Commit the transaction.
     tx.commit();
 }
 
```

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`close()` Ends the transaction.
`void`	`commit()` Commits this transaction by initiating `two-phase-commit` process.
`GridFuture<GridCacheTx>`	`commitAsync()` Asynchronously commits this transaction by initiating `two-phase-commit` process.
`GridCacheTxConcurrency`	`concurrency()` Cache transaction concurrency mode.
`boolean`	`implicit()` Flag indicating whether transaction was started automatically by the system or not.
`boolean`	`isInvalidate()` Get invalidation flag for this transaction.
`GridCacheTxIsolation`	`isolation()` Cache transaction isolation level.
`boolean`	`isRollbackOnly()` If transaction was marked as rollback-only.
`UUID`	`nodeId()` ID of the node on which this transaction started.
`void`	`rollback()` Rolls back this transaction.
`boolean`	`setRollbackOnly()` Modify the transaction associated with the current thread such that the only possible outcome of the transaction is to roll back the transaction.
`long`	`startTime()` Start time of this transaction.
`GridCacheTxState`	`state()` Gets current transaction state value.
`long`	`threadId()` ID of the thread in which this transaction started.
`long`	`timeout()` Gets timeout value in milliseconds for this transaction.
`long`	`timeout(long timeout)` Sets transaction timeout value.
`GridUuid`	`xid()` Gets unique identifier for this transaction.

Methods inherited from interface org.gridgain.grid.GridMetadataAware
addMeta, addMetaIfAbsent, addMetaIfAbsent, allMeta, copyMeta, copyMeta, hasMeta, hasMeta, meta, putMetaIfAbsent, putMetaIfAbsent, removeMeta, removeMeta, replaceMeta

- Method Detail
  - xid
```
GridUuid xid()
```
    Gets unique identifier for this transaction.
    
    Returns:
    Transaction UID.
  - nodeId
```
UUID nodeId()
```
    ID of the node on which this transaction started.
    
    Returns:
    Originating node ID.
  - threadId
```
long threadId()
```
    ID of the thread in which this transaction started.
    
    Returns:
    Thread ID.
  - startTime
```
long startTime()
```
    Start time of this transaction.
    
    Returns:
    Start time of this transaction on this node.
  - isolation
```
GridCacheTxIsolation isolation()
```
    Cache transaction isolation level.
    
    Returns:
    Isolation level.
  - concurrency
```
GridCacheTxConcurrency concurrency()
```
    Cache transaction concurrency mode.
    
    Returns:
    Concurrency mode.
  - implicit
```
boolean implicit()
```
    Flag indicating whether transaction was started automatically by the system or not. System will start transactions implicitly whenever any cache put(..) or remove(..) operation is invoked outside of transaction.
    
    Returns:
    True if transaction was started implicitly.
  - isInvalidate
```
boolean isInvalidate()
```
    Get invalidation flag for this transaction. If set to true, then remote values will be invalidated (set to null) instead of updated.
    Invalidation messages don't carry new values, so they are a lot lighter than update messages. However, when a value is accessed on a node after it's been invalidated, it must be loaded from persistent store.
    
    Returns:
    Invalidation flag.
  - state
```
GridCacheTxState state()
```
    Gets current transaction state value.
    
    Returns:
    Current transaction state.
  - timeout
```
long timeout()
```
    Gets timeout value in milliseconds for this transaction. If transaction times out prior to it's completion, GridCacheTxTimeoutException will be thrown.
    
    Returns:
    Transaction timeout value.
  - timeout
```
long timeout(long timeout)
```
    Sets transaction timeout value. This value can be set only before a first operation on transaction has been performed.
    
    Parameters:
    timeout - Transaction timeout value.
    
    Returns:
    Previous timeout.
  - setRollbackOnly
```
boolean setRollbackOnly()
```
    Modify the transaction associated with the current thread such that the only possible outcome of the transaction is to roll back the transaction.
    
    Returns:
    True if rollback-only flag was set as a result of this operation, false if it was already set prior to this call or could not be set because transaction is already finishing up committing or rolling back.
  - isRollbackOnly
```
boolean isRollbackOnly()
```
    If transaction was marked as rollback-only.
    
    Returns:
    True if transaction can only be rolled back.
  - commit
```
void commit()
            throws GridException
```
    Commits this transaction by initiating two-phase-commit process.
    
    Throws:
    
    GridException - If commit failed.
  - close
```
void close()
           throws GridException
```
    Ends the transaction. Transaction will be rolled back if it has not been committed.
    
    Specified by:
    
    close in interface AutoCloseable
    
    Throws:
    
    GridException - If transaction could not be gracefully ended.
  - commitAsync
```
GridFuture<GridCacheTx> commitAsync()
```
    Asynchronously commits this transaction by initiating two-phase-commit process.
    
    Returns:
    Future for commit operation.
  - rollback
```
void rollback()
              throws GridException
```
    Rolls back this transaction.
    
    Throws:
    
    GridException - If rollback failed.

Interface GridCacheTx

Cache Atomicity Mode

Usage

Method Summary

Methods inherited from interface org.gridgain.grid.GridMetadataAware

Method Detail

xid

nodeId

threadId

startTime

isolation

concurrency

implicit

isInvalidate

state

timeout

timeout

setRollbackOnly

isRollbackOnly

commit

close

commitAsync

rollback