com.graphaware.runtime.module

Interface TxDrivenModule<T>

Type Parameters:

T - The type of a state object that the module can use to pass information from the beforeCommit(com.graphaware.tx.event.improved.api.ImprovedTransactionData) method to the afterCommit(Object) method.

All Superinterfaces:

RuntimeModule

All Known Subinterfaces:

TxAndTimerDrivenModule<T,C>

All Known Implementing Classes:

BaseTxDrivenModule, DefaultThirdPartyIntegrationModule, ThirdPartyIntegrationModule, WriterBasedThirdPartyIntegrationModule

public interface TxDrivenModule<T>
extends RuntimeModule

A RuntimeModule module performing some useful work based on about-to-be-committed transaction data.

Method Summary

Modifier and Type	Method and Description
void	afterCommit(T state) Perform the core business logic of this module after a transaction commits.
void	afterRollback(T state) Cleanup if needed after a transaction rolled back.
T	beforeCommit(ImprovedTransactionData transactionData) Perform the core business logic of this module before a transaction commits.
TxDrivenModuleConfiguration	getConfiguration() Return the configuration of this module.
void	initialize(org.neo4j.graphdb.GraphDatabaseService database) Initialize this module.
void	reinitialize(org.neo4j.graphdb.GraphDatabaseService database, TxDrivenModuleMetadata oldMetadata) Re-initialize this module.
void	start(org.neo4j.graphdb.GraphDatabaseService database) Start the module.

Methods inherited from interface com.graphaware.runtime.module.RuntimeModule

getId, shutdown

Method Detail

beforeCommit

T beforeCommit(ImprovedTransactionData transactionData)
        throws DeliberateTransactionRollbackException

Perform the core business logic of this module before a transaction commits. If the framework determines by looking at getConfiguration() that the module isn't interested in this transaction, this method will not be called.

Note that in case this method throws RuntimeException (including NeedsInitializationException), afterCommit(Object) will be called with a null argument.

Note that in case this method throws DeliberateTransactionRollbackException, afterRollback(Object) will be called with a null argument.

Parameters:

transactionData - data about the soon-to-be-committed transaction. It is already filtered based on getConfiguration().

Returns:

a state object (or null) that will be passed on to afterCommit(Object) of this object. Only return null if you do nothing in afterCommit(Object).

Throws:

NeedsInitializationException - if it detects data is out of sync. initialize(org.neo4j.graphdb.GraphDatabaseService) will be called next time the GraphAwareRuntime is started. Until then, the module should perform on best-effort basis.

DeliberateTransactionRollbackException - if the module wants to prevent the transaction from committing.

afterCommit

void afterCommit(T state)

Perform the core business logic of this module after a transaction commits.

Parameters:

state - returned by beforeCommit(com.graphaware.tx.event.improved.api.ImprovedTransactionData). Will be null if beforeCommit(com.graphaware.tx.event.improved.api.ImprovedTransactionData) threw an exception but the transaction still committed. This is the case for all exceptions except DeliberateTransactionRollbackException.

afterRollback

void afterRollback(T state)

Cleanup if needed after a transaction rolled back. Will only be called if this module's beforeCommit(com.graphaware.tx.event.improved.api.ImprovedTransactionData) method was called.

Parameters:

state - returned by beforeCommit(com.graphaware.tx.event.improved.api.ImprovedTransactionData). Will be null if it is this module that caused the rollback by throwing DeliberateTransactionRollbackException. Will also be null if beforeCommit(com.graphaware.tx.event.improved.api.ImprovedTransactionData) threw a non-rollback-causing exception, but some other module caused rollback after that.

getConfiguration

TxDrivenModuleConfiguration getConfiguration()

Return the configuration of this module. Each module must encapsulate its entire configuration in an instance of a TxDrivenModuleConfiguration implementation. Use NullTxDrivenModuleConfiguration if this module needs no configuration.

Returns:

module configuration.

start

void start(org.neo4j.graphdb.GraphDatabaseService database)

Start the module. This method must bring the module to a usable state, i.e. after it returns, the module must be able to handle multi-threaded requests. This method is guaranteed to be called exactly once every time the runtime/database starts.

Parameters:

database - to start this module against.

initialize

void initialize(org.neo4j.graphdb.GraphDatabaseService database)

Initialize this module. This method must bring the module to a state equivalent to a state of the same module that has been registered at all times since the database was empty. It can perform global-graph operations to achieve this. It must manage its own transactions.

For example, a module that performs some in-graph caching needs to write information into the graph so that when the method returns, the graph is in the same state as it would be if the module has been running all the time since the graph was empty.

Parameters:

database - to initialize this module for.

reinitialize

void reinitialize(org.neo4j.graphdb.GraphDatabaseService database,
                  TxDrivenModuleMetadata oldMetadata)

Re-initialize this module. This method must remove all metadata written to the graph by this module and bring the module to a state equivalent to a state of the same module that has been registered at all times since the database was empty. It can perform global-graph operations to achieve this. It must manage its own transactions.

Parameters:

database - to re-initialize this module for.

oldMetadata - metadata stored for this module from its previous run. Can be null in case metadata was corrupt or there was no metadata.