HashingCodePathFactory (Protelis unspecified Javadoc API)

java.lang.Object
- org.protelis.vm.impl.HashingCodePathFactory

All Implemented Interfaces:

java.io.Serializable, CodePathFactory
```
public class HashingCodePathFactory
extends java.lang.Object
implements CodePathFactory
```
A hash-based CodePath factory. It allows for predictable packet sizes, as codepath length is no affected by the evaluation tree depth at which the field was built. It is arguably more secure than the default option (if a cryptographic hashing function is used) as receivers cannot deduce the code that generated some values. The provided factory is configurable by using an HashFunction from Guava. Being hash based, it has a non-zero probability of collision. Using decent hash functions (e.g. SHA) should however make the event very unlikely. In any case, there is a trade-off between collision probability and packet size. Implementations of AbstractExecutionContext can use it by passing the factory instance in the super constructor call, e.g.:
```
 super(execenv, netmgr, new HashingCodePathFactory(Hashing.sha256()));
 
```
See Also:

Serialized Form

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`static interface`	`HashingCodePathFactory.HasherSupplier`	Serializable supplier, because Java 8 lambdas are not.
`static class`	`HashingCodePathFactory.HashingCodePath`	Hash-based `CodePath`.

Constructor Summary

Constructors
Constructor	Description
`HashingCodePathFactory(com.google.common.hash.HashFunction hashFunction)`
`HashingCodePathFactory(HashingCodePathFactory.HasherSupplier hashFunction)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`CodePath`	`createCodePath(gnu.trove.list.TIntList callStackIdentifiers, gnu.trove.stack.TIntStack callStackSizes)`	Creates a `CodePath` for the current stack status.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - HashingCodePathFactory
```
public HashingCodePathFactory(HashingCodePathFactory.HasherSupplier hashFunction)
```
    Parameters:
    
    hashFunction - the hashing algorithm to use
  - HashingCodePathFactory
```
public HashingCodePathFactory(com.google.common.hash.HashFunction hashFunction)
```
    Parameters:
    
    hashFunction - the hashing algorithm to use
- Method Detail
  - createCodePath
```
public final CodePath createCodePath(gnu.trove.list.TIntList callStackIdentifiers,
                                     gnu.trove.stack.TIntStack callStackSizes)
```
    Description copied from interface: CodePathFactory
    
    Creates a CodePath for the current stack status.
    
    Specified by:
    
    createCodePath in interface CodePathFactory
    
    Parameters:
    
    callStackIdentifiers - the stack frames identifiers
    
    callStackSizes - the stack frame sizes, by frame
    
    Returns:
    
    a new CodePath