co.cask.cdap.data2.dataset2

Class SingleThreadDatasetCache

java.lang.Object

co.cask.cdap.data2.dataset2.DynamicDatasetCache

co.cask.cdap.data2.dataset2.SingleThreadDatasetCache

All Implemented Interfaces:

co.cask.cdap.api.data.DatasetContext, com.google.common.base.Supplier<co.cask.tephra.TransactionContext>

public class SingleThreadDatasetCache
extends DynamicDatasetCache

Implementation of DatasetContext that allows to dynamically load datasets into a started TransactionContext. Datasets acquired from this context are distinct from any Datasets instantiated outside this class.

Nested Class Summary

Nested classes/interfaces inherited from class co.cask.cdap.data2.dataset2.DynamicDatasetCache

DynamicDatasetCache.DatasetCacheKey

Field Summary

Fields inherited from class co.cask.cdap.data2.dataset2.DynamicDatasetCache

instantiator, metricsContext, namespace, runtimeArguments, txClient

Constructor Summary

Constructors

Constructor and Description
SingleThreadDatasetCache(SystemDatasetInstantiator instantiator, co.cask.tephra.TransactionSystemClient txClient, NamespaceId namespace, Map<String,String> runtimeArguments, MetricsContext metricsContext, Map<String,Map<String,String>> staticDatasets) See DynamicDatasetCache.

Method Summary

Methods

Modifier and Type	Method and Description
void	addExtraTransactionAware(co.cask.tephra.TransactionAware txAware) Add an extra transaction aware to the static datasets.
void	close() Close and dismiss all datasets that were obtained through this factory, and destroy the factory.
void	discardDataset(co.cask.cdap.api.dataset.Dataset dataset)
void	discardSafely(Object dataset) Discard a dataset when it is known that no transaction is going on.
void	dismissTransactionContext() Dismiss the current transaction context.
<T extends co.cask.cdap.api.dataset.Dataset> T	getDataset(DynamicDatasetCache.DatasetCacheKey key, boolean bypass) To be implemented by subclasses.
Iterable<co.cask.tephra.TransactionAware>	getStaticTransactionAwares()
Iterable<co.cask.tephra.TransactionAware>	getTransactionAwares()
void	invalidate() Close and dismiss all datasets that were obtained through this factory.
co.cask.tephra.TransactionContext	newTransactionContext() Return a new transaction context for the current thread.
void	removeExtraTransactionAware(co.cask.tephra.TransactionAware txAware) Remove a transaction-aware that was added via DynamicDatasetCache.addExtraTransactionAware(TransactionAware).

Methods inherited from class co.cask.cdap.data2.dataset2.DynamicDatasetCache

get, getDataset, getDataset, getDataset, releaseDataset

Methods inherited from class java.lang.Object

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

Constructor Detail

SingleThreadDatasetCache

public SingleThreadDatasetCache(SystemDatasetInstantiator instantiator,
                        co.cask.tephra.TransactionSystemClient txClient,
                        NamespaceId namespace,
                        Map<String,String> runtimeArguments,
                        @Nullable
                        MetricsContext metricsContext,
                        @Nullable
                        Map<String,Map<String,String>> staticDatasets)

See DynamicDatasetCache.

Parameters:

staticDatasets - if non-null, a map from dataset name to runtime arguments. These datasets will be instantiated immediately, and they will participate in every transaction started through newTransactionContext().

Method Detail

getDataset

public <T extends co.cask.cdap.api.dataset.Dataset> T getDataset(DynamicDatasetCache.DatasetCacheKey key,
                                                        boolean bypass)
                                                      throws co.cask.cdap.api.data.DatasetInstantiationException

Description copied from class: DynamicDatasetCache

To be implemented by subclasses.

Specified by:

getDataset in class DynamicDatasetCache

bypass - if true, bypass the dataset cache, and do not add this to the transaction.

Throws:

co.cask.cdap.api.data.DatasetInstantiationException

discardDataset

public void discardDataset(co.cask.cdap.api.dataset.Dataset dataset)

discardSafely

public void discardSafely(Object dataset)

Discard a dataset when it is known that no transaction is going on.

Parameters:

dataset - this is an Object because we need to pass in TransactionAware or Dataset

newTransactionContext

public co.cask.tephra.TransactionContext newTransactionContext()

Description copied from class: DynamicDatasetCache

Return a new transaction context for the current thread. All transaction-aware static datasets and all extra transaction-awares are added to this transaction initially. Also, any transaction-aware that was previously dynamically acquired, and that has not been garbage-collected, is added to the transaction. Any transaction-aware datasets that will subsequently be obtained via (@link #getDataset()) will then also be added to this transaction context and thus participate in its transaction. These datasets can also be retrieved using DynamicDatasetCache.getTransactionAwares().

Specified by:

newTransactionContext in class DynamicDatasetCache

Returns:

a new transaction context

dismissTransactionContext

public void dismissTransactionContext()

Description copied from class: DynamicDatasetCache

Dismiss the current transaction context. This releases the references to the context's transaction-aware datasets so that they can be collected by the garbage collector (if no one else is holding a reference to them). The static datasets and the extra transaction-awares, however, will not be made available to garbage collection, and will participate in the next transaction (created by DynamicDatasetCache.newTransactionContext()).

Specified by:

dismissTransactionContext in class DynamicDatasetCache

getStaticTransactionAwares

public Iterable<co.cask.tephra.TransactionAware> getStaticTransactionAwares()

Specified by:

getStaticTransactionAwares in class DynamicDatasetCache

Returns:

the static datasets that are transaction-aware. This is the same independent of whether a transaction context was started using DynamicDatasetCache.newTransactionContext().

getTransactionAwares

public Iterable<co.cask.tephra.TransactionAware> getTransactionAwares()

Specified by:

getTransactionAwares in class DynamicDatasetCache

Returns:

the transaction-aware datasets that participate in the current transaction. If DynamicDatasetCache.newTransactionContext() has not been called (or DynamicDatasetCache.dismissTransactionContext() has been called), then there is no transaction and this will return an empty iterable.

addExtraTransactionAware

public void addExtraTransactionAware(co.cask.tephra.TransactionAware txAware)

Description copied from class: DynamicDatasetCache

Add an extra transaction aware to the static datasets. This is a transaction aware that is not instantiated through this factory, but needs to participate in every transaction. Note that if a transaction is in progress, then this transaction aware will join that transaction.

Specified by:

addExtraTransactionAware in class DynamicDatasetCache

removeExtraTransactionAware

public void removeExtraTransactionAware(co.cask.tephra.TransactionAware txAware)

Description copied from class: DynamicDatasetCache

Remove a transaction-aware that was added via DynamicDatasetCache.addExtraTransactionAware(TransactionAware). Note that if a transaction is in progress, then this transaction aware will leave that transaction.

Specified by:

removeExtraTransactionAware in class DynamicDatasetCache

invalidate

public void invalidate()

Description copied from class: DynamicDatasetCache

Close and dismiss all datasets that were obtained through this factory. This can be used to ensure that all resources held by datasets are released, even though the factory may be still be used for subsequent execution.

Specified by:

invalidate in class DynamicDatasetCache

close

public void close()

Description copied from class: DynamicDatasetCache

Close and dismiss all datasets that were obtained through this factory, and destroy the factory. If an extra transaction-awares were added to this cache (and not removed), then they will also be closed.

Overrides:

close in class DynamicDatasetCache