Package uk.gov.gchq.gaffer.graph.hook

Interface GraphHook

All Known Subinterfaces:

GetFromCacheHook

All Known Implementing Classes:

AddOperationsToChain, FunctionAuthoriser, GraphHookPath, Log4jLogger, NamedOperationResolver, NamedViewResolver, OperationAuthoriser, OperationChainLimiter, SchemaMigration, UpdateViewHook

public interface GraphHook

A GraphHook can be registered with a Graph and will be triggered before and after operation chains are executed on the graph.

If an error occurs whilst running the operation chain the onFailure method will be triggered.

The OperationChain parameter that is given to the graph hook is a clone of the original and can be adapted or optimised in any GraphHook implementation. So please note that if you want to access the original operation chain without modifications then you can access if from Context.getOriginalOpChain(). This original operation chain should not be modified.

Method Summary

Modifier and Type	Method	Description
default <T> T	onFailure(T result, OperationChain<?> opChain, Context context, Exception e)	Called from Graph if an error occurs whilst executing the OperationChain.
default <T> T	postExecute(T result, OperationChain<?> opChain, Context context)	Called from Graph after an OperationChain is executed.
default void	preExecute(OperationChain<?> opChain, Context context)	Called from Graph before an OperationChain is executed.

Method Detail

preExecute

default void preExecute(OperationChain<?> opChain,
                        Context context)

Called from Graph before an OperationChain is executed.

Parameters:

opChain - the OperationChain being executed. This can be modified/optimised in any GraphHook.

context - the Context in which the operation chain was executed. The context also holds a reference to the original operation chain.

postExecute

default <T> T postExecute(T result,
                          OperationChain<?> opChain,
                          Context context)

Called from Graph after an OperationChain is executed.

Type Parameters:

T - the result type

Parameters:

result - the result from the operation chain

opChain - the OperationChain that was executed. This can be modified/optimised in any GraphHook.

context - the Context in which the operation chain was executed. The context also holds a reference to the original operation chain.

Returns:

result object

onFailure

default <T> T onFailure(T result,
                        OperationChain<?> opChain,
                        Context context,
                        Exception e)

Called from Graph if an error occurs whilst executing the OperationChain.

Type Parameters:

T - the result type

Parameters:

result - the result from the operation chain - likely to be null.

opChain - the OperationChain that was executed. This can be modified/optimised in any GraphHook.

context - the Context in which the operation chain was executed. The context also holds a reference to the original operation chain.

e - the exception

Returns:

result object