org.apache.tinkerpop.gremlin.process.computer

Interface Memory

All Known Subinterfaces:

Memory.Admin

All Known Implementing Classes:

EmptyMemory, GiraphMemory, ImmutableMemory, MapMemory, PassThroughMemory, SparkMemory, TinkerMemory

public interface Memory

The Memory of a GraphComputer is a global data structure where by vertices can communicate information with one another. Moreover, it also contains global information about the state of the computation such as runtime and the current iteration. The Memory data is logically updated in parallel using associative/commutative methods which have embarrassingly parallel implementations.

Author:

Marko A. Rodriguez (http://markorodriguez.com)

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	Memory.Admin The Admin interface is used by the GraphComputer to update the Memory.
static class	Memory.Exceptions

Method Summary

Modifier and Type	Method and Description
void	add(String key, Object value) Set the value of the provided key.
default Map<String,Object>	asMap() A helper method that generates a Map of the memory key/values.
default boolean	exists(String key) Whether the key exists in the memory.
<R> R	get(String key) Get the value associated with the provided key.
int	getIteration() Get the current iteration number.
long	getRuntime() Get the amount of milliseconds the GraphComputer has been executing thus far.
default boolean	isInitialIteration() A helper method that states whether the current iteration is 0.
Set<String>	keys() The set of keys currently associated with this memory.
void	set(String key, Object value)

Method Detail

exists

default boolean exists(String key)

Whether the key exists in the memory.

Parameters:

key - key to search the memory for.

Returns:

whether the key exists

keys

Set<String> keys()

The set of keys currently associated with this memory.

Returns:

the memory's key set.

get

<R> R get(String key)
   throws IllegalArgumentException

Get the value associated with the provided key.

Type Parameters:

R - the type of the value

Parameters:

key - the key of the value

Returns:

the value

Throws:

IllegalArgumentException - is thrown if the key does not exist

set

void set(String key,
         Object value)
  throws IllegalArgumentException,
         IllegalStateException

Throws:

IllegalArgumentException

IllegalStateException

add

void add(String key,
         Object value)
  throws IllegalArgumentException,
         IllegalStateException

Set the value of the provided key. This is typically called in setup() and/or terminate() of the VertexProgram. If this is called during execute(), there is no guarantee as to the ultimately stored value as call order is indeterminate.

Parameters:

key - they key to set a value for

value - the value to set for the key

Throws:

IllegalArgumentException

IllegalStateException

asMap

default Map<String,Object> asMap()

A helper method that generates a Map of the memory key/values.

Returns:

the map representation of the memory key/values

getIteration

int getIteration()

Get the current iteration number.

Returns:

the current iteration

getRuntime

long getRuntime()

Get the amount of milliseconds the GraphComputer has been executing thus far.

Returns:

the total time in milliseconds

isInitialIteration

default boolean isInitialIteration()

A helper method that states whether the current iteration is 0.

Returns:

whether this is the first iteration