public final class SwitchPointInvalidator
extends ObjectLazily allocates a SwitchPoint and retires it on demand.
Call sites install the switch point returned by getSwitchPoint() in
guardWithTest chains. invalidate() retires the live switch
point so linked sites fall back and re-link; the next getSwitchPoint()
allocates a fresh one.
Bulk paths (category enter/leave, custom MetaClass events) should prefer detachLive() and a single SwitchPoint.invalidateAll over many individual invalidate() calls.
There is no permanent failover: stock invalidation is scoped to a single class, so deopt storms from a process-wide SwitchPoint do not apply and a simple replace-on-invalidate model is sufficient.
A process-wide registry tracks every live SwitchPoint so bulk retirement is O(live domains), and is skipped entirely while the registry is empty — e.g. classic-only bytecode never links an indy MOP guard. Registration precedes publication, so an empty (or entry-less) observation proves no guard chain holds a live SwitchPoint that the observer could have needed to retire.
Registry entries hold their invalidator strongly; the invalidator's owner is
responsible for retiring the domain when it is discarded (see the reclaim
anchor on ClassInfo's class-level domain), which is what removes the
entry. A guard chain keeps only the SwitchPoint's internal invoker alive,
not the SwitchPoint object, so the registry entry is what keeps a
still-installed guard retirable until its domain is explicitly retired.
| Constructor and description |
|---|
SwitchPointInvalidator()Creates an invalidator with no live SwitchPoint until the first getSwitchPoint() call. |
| Type Params | Return Type | Name and description |
|---|---|---|
|
public SwitchPoint |
detachLive()Atomically detaches the live switch point for bulk SwitchPoint.invalidateAll without invalidating it yet. |
|
public int |
getRetirementCount()Returns how many live switch points have been retired. |
|
public SwitchPoint |
getSwitchPoint()Returns a live switch point to install in a call-site guard chain. |
|
public void |
invalidate()Invalidates the current live switch point (if any) so linked sites re-link. |
|
public static void |
invalidateIfLive(SwitchPoint sp)Invalidates sp when non-null and still valid. |
|
public void |
setReclaimAnchor(Object anchor)Parks anchor so it stays strongly reachable while this
invalidator is reachable. |
Creates an invalidator with no live SwitchPoint until the first getSwitchPoint() call. Field initializers own all state.
Atomically detaches the live switch point for bulk SwitchPoint.invalidateAll without invalidating it yet. The caller must invalidate any non-null return value.
null if none was liveReturns how many live switch points have been retired.
Returns a live switch point to install in a call-site guard chain. Lazily allocates on first use after construction or after retirement.
null)Invalidates the current live switch point (if any) so linked sites re-link. A subsequent getSwitchPoint() allocates a fresh switch point.
Invalidates sp when non-null and still valid.
sp - candidate switch point (may be null) Parks anchor so it stays strongly reachable while this
invalidator is reachable. See reclaimAnchor.
anchor - the object to keep reachable (may be null to clear)Copyright © 2003-2026 The Apache Software Foundation. All rights reserved.