Package org.apache.groovy.runtime.indy

Class SwitchPointInvalidator

java.lang.Object
org.apache.groovy.runtime.indy.SwitchPointInvalidator
public final class SwitchPointInvalidator extends Object
Lazily 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(SwitchPoint[]) 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.

Since:
6.0.0

  • Constructor Details

    • SwitchPointInvalidator

      public SwitchPointInvalidator()
      Creates an invalidator with no live SwitchPoint until the first getSwitchPoint() call. Field initializers own all state.

  • Method Details

    • setReclaimAnchor

      public void setReclaimAnchor(Object anchor)
      Parks anchor so it stays strongly reachable while this invalidator is reachable. See reclaimAnchor.
      Parameters:
      anchor - the object to keep reachable (may be null to clear)

    • getSwitchPoint

      public SwitchPoint getSwitchPoint()
      Returns a live switch point to install in a call-site guard chain. Lazily allocates on first use after construction or after retirement.
      Returns:
      a live switch point (never null)

    • invalidate

      public void invalidate()
      Invalidates the current live switch point (if any) so linked sites re-link. A subsequent getSwitchPoint() allocates a fresh switch point.

    • detachLive

      public SwitchPoint detachLive()
      Atomically detaches the live switch point for bulk SwitchPoint.invalidateAll(java.lang.invoke.SwitchPoint[]) without invalidating it yet. The caller must invalidate any non-null return value.
      Returns:
      the detached live switch point, or null if none was live

    • getRetirementCount

      public int getRetirementCount()
      Returns how many live switch points have been retired.
      Returns:
      the retirement count

    • invalidateIfLive

      public static void invalidateIfLive(SwitchPoint sp)
      Invalidates sp when non-null and still valid.
      Parameters:
      sp - candidate switch point (may be null)