co.cask.tephra.inmemory

Class DetachedTxSystemClient

java.lang.Object

co.cask.tephra.inmemory.DetachedTxSystemClient

All Implemented Interfaces:

TransactionSystemClient

public class DetachedTxSystemClient
extends Object
implements TransactionSystemClient

Implementation of the tx system client that doesn't talk to any global service and tries to do its best to meet the tx system requirements/expectations. In fact it implements enough logic to support running flows (when each flowlet uses its own detached tx system client, without talking to each other and sharing any state) with "process exactly once" guarantee if no failures happen. NOTE: Will NOT detect conflicts. May leave inconsistent state when process crashes. Does NOT provide even read isolation guarantees. Good for performance testing. For demoing high throughput. For use-cases with relaxed tx guarantees.

Constructor Summary

Constructors

Constructor and Description
DetachedTxSystemClient()

Method Summary

Methods

Modifier and Type	Method and Description
void	abort(Transaction tx) Makes transaction visible.
boolean	canCommit(Transaction tx, Collection<byte[]> changeIds) Checks if transaction with the set of changes can be committed.
Transaction	checkpoint(Transaction tx) Performs a checkpoint operation on the current transaction, returning a new Transaction instance with the updated state.
boolean	commit(Transaction tx) Makes transaction visible.
int	getInvalidSize()
InputStream	getSnapshotInputStream() Retrieves the state of the transaction manager and send it as a stream.
boolean	invalidate(long tx) Makes transaction invalid.
void	resetState() Resets the state of the transaction manager.
Transaction	startLong() Starts new long transaction.
Transaction	startShort() Starts new short transaction.
Transaction	startShort(int timeout) Starts new short transaction.
String	status() Return the status of the transaction Manager
boolean	truncateInvalidTx(Set<Long> invalidTxIds) Removes the given transaction ids from the invalid list.
boolean	truncateInvalidTxBefore(long time) Removes all transaction ids started before the given time from invalid list.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DetachedTxSystemClient

public DetachedTxSystemClient()

Method Detail

startShort

public Transaction startShort()

Description copied from interface: TransactionSystemClient

Starts new short transaction.

Specified by:

startShort in interface TransactionSystemClient

Returns:

instance of Transaction

startShort

public Transaction startShort(int timeout)

Description copied from interface: TransactionSystemClient

Starts new short transaction.

Specified by:

startShort in interface TransactionSystemClient

Parameters:

timeout - the timeout for the transaction

Returns:

instance of Transaction

startLong

public Transaction startLong()

Description copied from interface: TransactionSystemClient

Starts new long transaction.

Specified by:

startLong in interface TransactionSystemClient

Returns:

instance of Transaction

canCommit

public boolean canCommit(Transaction tx,
                Collection<byte[]> changeIds)

Description copied from interface: TransactionSystemClient

Checks if transaction with the set of changes can be committed. E.g. it can check conflicts with other changes and refuse commit if there are conflicts. It is assumed that no other changes will be done in between this method call and TransactionSystemClient.commit(Transaction) which may check conflicts again to avoid races.

Since we do conflict detection at commit time as well, this may seem redundant. The idea is to check for conflicts before we persist changes to avoid rollback in case of conflicts as much as possible. NOTE: in some situations we may want to skip this step to save on RPC with a risk of many rollback ops. So by default we take safe path.

Specified by:

canCommit in interface TransactionSystemClient

Parameters:

tx - transaction to verify

changeIds - ids of changes made by transaction

Returns:

true if transaction can be committed otherwise false

commit

public boolean commit(Transaction tx)

Description copied from interface: TransactionSystemClient

Makes transaction visible. It will again check conflicts of changes submitted previously with TransactionSystemClient.canCommit(Transaction, java.util.Collection)

Specified by:

commit in interface TransactionSystemClient

Parameters:

tx - transaction to make visible.

Returns:

true if transaction can be committed otherwise false

abort

public void abort(Transaction tx)

Description copied from interface: TransactionSystemClient

Makes transaction visible. You should call it only when all changes of this tx are undone. NOTE: it will not throw TransactionNotInProgressException if transaction has timed out.

Specified by:

abort in interface TransactionSystemClient

Parameters:

tx - transaction to make visible.

invalidate

public boolean invalidate(long tx)

Description copied from interface: TransactionSystemClient

Makes transaction invalid. You should call it if not all changes of this tx could be undone. NOTE: it will not throw TransactionNotInProgressException if transaction has timed out.

Specified by:

invalidate in interface TransactionSystemClient

Parameters:

tx - transaction id to invalidate.

Returns:

true if transaction has been successfully invalidated

checkpoint

public Transaction checkpoint(Transaction tx)

Description copied from interface: TransactionSystemClient

Performs a checkpoint operation on the current transaction, returning a new Transaction instance with the updated state. A checkpoint operation assigns a new write pointer for the current transaction.

Specified by:

checkpoint in interface TransactionSystemClient

Parameters:

tx - the current transaction to checkpoint

Returns:

an updated transaction instance with the new write pointer

getSnapshotInputStream

public InputStream getSnapshotInputStream()
                                   throws TransactionCouldNotTakeSnapshotException

Description copied from interface: TransactionSystemClient

Retrieves the state of the transaction manager and send it as a stream. The snapshot will not be persisted.

Specified by:

getSnapshotInputStream in interface TransactionSystemClient

Returns:

an input stream containing an encoded snapshot of the transaction manager

Throws:

TransactionCouldNotTakeSnapshotException

status

public String status()

Description copied from interface: TransactionSystemClient

Return the status of the transaction Manager

Specified by:

status in interface TransactionSystemClient

Returns:

a String which denotes the status of txManager

resetState

public void resetState()

Description copied from interface: TransactionSystemClient

Resets the state of the transaction manager.

Specified by:

resetState in interface TransactionSystemClient

truncateInvalidTx

public boolean truncateInvalidTx(Set<Long> invalidTxIds)

Description copied from interface: TransactionSystemClient

Removes the given transaction ids from the invalid list.

Specified by:

truncateInvalidTx in interface TransactionSystemClient

Parameters:

invalidTxIds - transaction ids

Returns:

true if invalid list got changed, false otherwise

truncateInvalidTxBefore

public boolean truncateInvalidTxBefore(long time)
                                throws InvalidTruncateTimeException

Description copied from interface: TransactionSystemClient

Removes all transaction ids started before the given time from invalid list.

Specified by:

truncateInvalidTxBefore in interface TransactionSystemClient

Parameters:

time - time in milliseconds

Returns:

true if invalid list got changed, false otherwise

Throws:

InvalidTruncateTimeException - if there are any in-progress transactions started before given time

getInvalidSize

public int getInvalidSize()

Specified by:

getInvalidSize in interface TransactionSystemClient

Returns:

the size of invalid list