org.protelis.vm.impl

Class AbstractExecutionContext<S extends AbstractExecutionContext<S>>

java.lang.Object

org.protelis.vm.impl.AbstractExecutionContext<S>

Type Parameters:

S - self-type. Subclasses must parameterize AbstractExecutionContext with themselves, and return themselves in instance(). This forces a compiler check on the type of instanced contexts, ensuring (if no foolish cast is used) that restricted contexts have all the methods available in the main ExecutionContext. For instance, if your class is MyContext, it should be written as MyContext extends AbstractExecutionContext.

All Implemented Interfaces:

ExecutionContext

public abstract class AbstractExecutionContext<S extends AbstractExecutionContext<S>>
extends java.lang.Object
implements ExecutionContext

Partial implementation of ExecutionContext, containing functionality expected to be shared between most implementations. Instantiations of Protelis should generally extend this class.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractExecutionContext(ExecutionEnvironment execenv, NetworkManager netmgr) Create a new AbstractExecutionContext with a default, time-efficient code path factory.
protected	AbstractExecutionContext(ExecutionEnvironment execenv, NetworkManager netmgr, CodePathFactory codePathFactory) Create a new AbstractExecutionContext with the specified CodePathFactory.

Method Summary

Modifier and Type	Method and Description
<T,R> Field<R>	buildField(java.util.function.Function<T,R> computeValue, T localValue) Builds a new Field, fetching data from all the aligned neighbors.
<T,R> Field<R>	buildFieldDeferred(java.util.function.Function<T,R> computeValue, T currentLocal, java.util.function.Supplier<T> toBeSent) Builds a new Field, fetching data from all the aligned neighbors.
void	commit() Called just after the VM is executed, to finalize information of the execution for the environment.
protected void	commitRecursively() recursively commits on restricted contexts.
java.lang.Number	getDeltaTime()
ExecutionEnvironment	getExecutionEnvironment()
protected java.util.Map<Reference,?>	getFunctions() Support for first-class functions by returning the set of currently accessible functions.
protected NetworkManager	getNetworkManager() Accessor for abstract network interface.
java.lang.Object	getVariable(Reference name) Look up the value of a variable from the local environment.
protected abstract S	instance() Produce a child execution context, for encapsulated evaluation of sub-programs.
void	newCallStackFrame(byte... id)
void	newCallStackFrame(int... id)
void	putMultipleVariables(java.util.Map<Reference,?> map) Pushes multiple variables.
void	putVariable(Reference name, java.lang.Object value) Puts a variable value, overwriting the previous one, if any.
S	restrictDomain(Field<?> f) Give a field, returns a new ExecutionContext whose domain is the same of the field one.
void	returnFromCallFrame() returns from the last frame.
void	setGloballyAvailableReferences(java.util.Map<Reference,?> knownFunctions) Used internally to support first-class functions by make the functions of a program accessible for reflection at runtime.
void	setup() Called just before the VM is executed, to enable and preparations needed in the environment.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.protelis.vm.ExecutionContext

getCurrentTime, getDeviceUID, nextRandomDouble

Constructor Detail

AbstractExecutionContext

protected AbstractExecutionContext(ExecutionEnvironment execenv,
                                   NetworkManager netmgr)

Create a new AbstractExecutionContext with a default, time-efficient code path factory.

Parameters:

execenv - The execution environment

netmgr - Abstract network interface to be used

AbstractExecutionContext

protected AbstractExecutionContext(ExecutionEnvironment execenv,
                                   NetworkManager netmgr,
                                   CodePathFactory codePathFactory)

Create a new AbstractExecutionContext with the specified CodePathFactory. Subclasses which want to use hashing or other means to encode CodePaths can call this constructor, e.g.:

 super(execenv, netmgr, new HashingCodePathFactory(Hashing.sha256()));
 

Parameters:

execenv - The execution environment

netmgr - Abstract network interface to be used

codePathFactory - The code path factory to use

Method Detail

buildField

public final <T,R> Field<R> buildField(java.util.function.Function<T,R> computeValue,
                                       T localValue)

Description copied from interface: ExecutionContext

Builds a new Field, fetching data from all the aligned neighbors. A neighbor is considered to be aligned it it has reached the exact same DefaultTimeEfficientCodePath. The field will always contain at least one value, namely the value of the local device.

Specified by:

buildField in interface ExecutionContext

Type Parameters:

T - the type of the input

R - the type of the output

Parameters:

computeValue - a function that will be applied to localValue and the equivalents shared from neighbors in the process of constructing this field: the field consists of the values returned from applying computeValue to each of device's value

localValue - the local value for this field

Returns:

a new Field containing the local device value and the values for any of the aligned neighbors

buildFieldDeferred

public final <T,R> Field<R> buildFieldDeferred(java.util.function.Function<T,R> computeValue,
                                               T currentLocal,
                                               java.util.function.Supplier<T> toBeSent)

Description copied from interface: ExecutionContext

Builds a new Field, fetching data from all the aligned neighbors. A neighbor is considered to be aligned it it has reached the exact same DefaultTimeEfficientCodePath. The field will always contain at least one value, namely the value of the local device. The deferred version does not immediately schedule the local value for being sent away. Rather, it schedules the provided Supplier to be executed at the end of the round for obtaining the value to be shared. This function is the base upon which the ShareCall is built.

Specified by:

buildFieldDeferred in interface ExecutionContext

Type Parameters:

T - the type of the input

R - the type of the output

Parameters:

computeValue - a function that will be applied to localValue and the equivalents shared from neighbors in the process of constructing this field: the field consists of the values returned from applying computeValue to each of device's value

currentLocal - the value to be used as local for this field

toBeSent - a java8.util.function.Supplier which will be used to compute the local value for this field that will get exported at the end of the round

Returns:

a new Field containing the local device value and the values for any of the aligned neighbors

commit

public final void commit()

Description copied from interface: ExecutionContext

Called just after the VM is executed, to finalize information of the execution for the environment.

Specified by:

commit in interface ExecutionContext

commitRecursively

protected final void commitRecursively()

recursively commits on restricted contexts.

getDeltaTime

public java.lang.Number getDeltaTime()

Specified by:

getDeltaTime in interface ExecutionContext

Returns:

the current time, relative to last round

getExecutionEnvironment

public final ExecutionEnvironment getExecutionEnvironment()

Specified by:

getExecutionEnvironment in interface ExecutionContext

Returns:

The current ExecutionEnvironment

getFunctions

protected final java.util.Map<Reference,?> getFunctions()

Support for first-class functions by returning the set of currently accessible functions.

Returns:

Map from function name to function objects

getNetworkManager

protected final NetworkManager getNetworkManager()

Accessor for abstract network interface.

Returns:

Current abstract network interface

getVariable

public final java.lang.Object getVariable(Reference name)

Description copied from interface: ExecutionContext

Look up the value of a variable from the local environment.

Specified by:

getVariable in interface ExecutionContext

Parameters:

name - The variable to be looked up

Returns:

Value of the variable, or null if it cannot be found.

instance

protected abstract S instance()

Produce a child execution context, for encapsulated evaluation of sub-programs.

Returns:

Child execution context

newCallStackFrame

public final void newCallStackFrame(byte... id)

Specified by:

newCallStackFrame in interface ExecutionContext

Parameters:

id - stack frame type

newCallStackFrame

public final void newCallStackFrame(int... id)

Specified by:

newCallStackFrame in interface ExecutionContext

Parameters:

id - stack frame type

putMultipleVariables

public final void putMultipleVariables(java.util.Map<Reference,?> map)

Description copied from interface: ExecutionContext

Pushes multiple variables.

Specified by:

putMultipleVariables in interface ExecutionContext

Parameters:

map - the variables to push

putVariable

public final void putVariable(Reference name,
                              java.lang.Object value)

Description copied from interface: ExecutionContext

Puts a variable value, overwriting the previous one, if any.

Specified by:

putVariable in interface ExecutionContext

Parameters:

name - variable reference

value - variable value

restrictDomain

public final S restrictDomain(@Nonnull
                              Field<?> f)

Description copied from interface: ExecutionContext

Give a field, returns a new ExecutionContext whose domain is the same of the field one.

Specified by:

restrictDomain in interface ExecutionContext

Parameters:

f - the field

Returns:

the restricted domain

returnFromCallFrame

public final void returnFromCallFrame()

Description copied from interface: ExecutionContext

returns from the last frame.

Specified by:

returnFromCallFrame in interface ExecutionContext

setGloballyAvailableReferences

public final void setGloballyAvailableReferences(java.util.Map<Reference,?> knownFunctions)

Description copied from interface: ExecutionContext

Used internally to support first-class functions by make the functions of a program accessible for reflection at runtime.

Specified by:

setGloballyAvailableReferences in interface ExecutionContext

Parameters:

knownFunctions - Collection of accessible functions, associating function name and value.

setup

public final void setup()

Description copied from interface: ExecutionContext

Called just before the VM is executed, to enable and preparations needed in the environment.

Specified by:

setup in interface ExecutionContext