gov.nasa.jpf.vm

Class HashedAllocationContext

java.lang.Object

gov.nasa.jpf.vm.HashedAllocationContext

All Implemented Interfaces:

AllocationContext

public class HashedAllocationContext
extends Object
implements AllocationContext

an AllocationContext that uses a hash value for comparison. This is lossy - heap implementations using this class have to check/handle collisions. However, given that we have very good hash data (search global object references), the probability of collisions is low enough that heap implementations might simply report this as a problem requiring a non-lossy AllocationContext. Ideally, we would like to hash the host VM thread context too (esp. for system allocations), but host VM stack traces are expensive, and it is arguable if would be too strict (e.g. when using a dedicated allocator method called from alternative branches of the caller) note - this is a HashMap key type which has to obey the hashCode/equals contract

Field Summary

Fields

Modifier and Type	Field and Description
protected int	id

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	HashedAllocationContext(int id)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Object o) default implementation is just an identity check
AllocationContext	extend(ClassInfo ci, int anchor)
static AllocationContext	getSUTAllocationContext(ClassInfo ci, ThreadInfo ti) this one is for allocations that should depend on the SUT thread context (such as all explicit NEW executions)
static AllocationContext	getSystemAllocationContext(ClassInfo ci, ThreadInfo ti, int anchor) this one is for allocations that should NOT depend on the SUT thread context (such as automatic allocation of java.lang.Class objects by the VM)
int	hashCode()
static boolean	init(Config conf)

Methods inherited from class java.lang.Object

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

Field Detail

id

protected final int id

Constructor Detail

HashedAllocationContext

protected HashedAllocationContext(int id)

Method Detail

getSUTAllocationContext

public static AllocationContext getSUTAllocationContext(ClassInfo ci,
                                        ThreadInfo ti)

this one is for allocations that should depend on the SUT thread context (such as all explicit NEW executions)

getSystemAllocationContext

public static AllocationContext getSystemAllocationContext(ClassInfo ci,
                                           ThreadInfo ti,
                                           int anchor)

this one is for allocations that should NOT depend on the SUT thread context (such as automatic allocation of java.lang.Class objects by the VM)

Parameters:

anchor - a value that can be used to provide a context that is heap graph specific (such as a classloader or class object reference)

init

public static boolean init(Config conf)

equals

public boolean equals(Object o)

Description copied from class: Object

default implementation is just an identity check

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

extend

public AllocationContext extend(ClassInfo ci,
                       int anchor)

Specified by:

extend in interface AllocationContext