Interface MemorySegment.Scope

Enclosing interface:

MemorySegment

public static sealed interface MemorySegment.Scope

A scope models the lifetime of all the memory segments associated with it.

That is, a memory segment cannot be accessed if its associated scope is not alive. Scope instances can be compared for equality. That is, two scopes are considered equal if they denote the same lifetime.

The lifetime of a memory segment can be either unbounded or bounded. An unbounded lifetime is modeled with the global scope. The global scope is always alive. As such, a segment associated with the global scope features trivial temporal bounds and is always accessible. Segments associated with the global scope are:

• Segments obtained from the global arena;
• Segments obtained from a raw address, using the MemorySegment.ofAddress(long) factory; and
• Zero-length memory segments.

Conversely, a bounded lifetime is modeled with a segment scope that can be invalidated, either explicitly, or automatically, by the garbage collector. A segment scope that is invalidated automatically is an automatic scope. An automatic scope is always alive as long as it is reachable. Segments associated with an automatic scope are:

• Segments obtained from an automatic arena;
• Segments obtained from a Java array, e.g. using the MemorySegment.ofArray(int[]) factory;
• Segments obtained from a buffer, using the MemorySegment.ofBuffer(Buffer) factory; and
• Segments obtained from loader lookup.

If two memory segments are obtained from the same buffer or array, the automatic scopes associated with said segments are considered equal, as the two segments have the same lifetime:

byte[] arr = new byte[10];
MemorySegment segment1 = MemorySegment.ofArray(arr);
MemorySegment segment2 = MemorySegment.ofArray(arr);
assert segment1.scope().equals(segment2.scope());

Since:

22

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object that)	Returns true, if the provided object is also a scope, which models the same lifetime as that modeled by this scope.
int	hashCode()	Returns the hash code of this scope object.
boolean	isAlive()	Returns true, if the regions of memory backing the memory segments associated with this scope are still valid.

Method Details

isAlive

boolean isAlive()

Returns true, if the regions of memory backing the memory segments associated with this scope are still valid.

Returns:

true, if the regions of memory backing the memory segments associated with this scope are still valid

equals

boolean equals(Object that)

Returns true, if the provided object is also a scope, which models the same lifetime as that modeled by this scope.. In that case, it is always the case that this.isAlive() == ((Scope)that).isAlive().

Overrides:

equals in class Object

Parameters:

that - the object to be tested

Returns:

true, if the provided object is also a scope, which models the same lifetime as that modeled by this scope

See Also:

• Object.hashCode()
• HashMap

hashCode

int hashCode()

Returns the hash code of this scope object.

Overrides:

hashCode in class Object

Implementation Requirements:

Implementations of this method obey the general contract of Object.hashCode().

Returns:

the hash code of this scope object

See Also:

• equals(Object)