//
//
+ /**
+ * Local knowledge of {@link #refcount} values up to statement root. We use this field to prevent recursive lookups
+ * in {@link #noParentRefs(StatementContextBase)} -- once we discover a parent reference once, we keep that
+ * knowledge and update it when {@link #sweep()} is invoked.
+ */
+ private byte parentRef = PARENTREF_UNKNOWN;
+ private static final byte PARENTREF_UNKNOWN = -1;
+ private static final byte PARENTREF_ABSENT = 0;
+ private static final byte PARENTREF_PRESENT = 1;
+
/**
* Acquire a reference on this context. As long as there is at least one reference outstanding,
* {@link #buildEffective()} will not result in {@link #effectiveSubstatements()} being discarded.
refcount = current - 1;
LOG.trace("Refcount {} on {}", refcount, this);
- if (isSweepable()) {
+
+ if (refcount == REFCOUNT_NONE) {
+ lastDecRef();
+ }
+ }
+
+ private void lastDecRef() {
+ if (noImplictRef()) {
// We are no longer guarded by effective instance
sweepOnDecrement();
+ return;
+ }
+
+ final byte prevRefs = parentRef;
+ if (prevRefs == PARENTREF_ABSENT) {
+ // We are the last reference towards root, any children who observed PARENTREF_PRESENT from us need to be
+ // updated
+ markNoParentRef();
+ } else if (prevRefs == PARENTREF_UNKNOWN) {
+ // Noone observed our parentRef, just update it
+ loadParentRefcount();
}
}
- /**
- * Sweep this statement context as a result of {@link #sweepSubstatements()}, i.e. when parent is also being swept.
- */
- private void sweep() {
- if (isSweepable()) {
- LOG.trace("Releasing {}", this);
- sweepState();
+ static final void markNoParentRef(final Collection<? extends ReactorStmtCtx<?, ?, ?>> substatements) {
+ for (ReactorStmtCtx<?, ?, ?> stmt : substatements) {
+ final byte prevRef = stmt.parentRef;
+ stmt.parentRef = PARENTREF_ABSENT;
+ if (prevRef == PARENTREF_PRESENT && stmt.refcount == REFCOUNT_NONE) {
+ // Child thinks it is pinned down, update its perspective
+ stmt.markNoParentRef();
+ }
}
}
+ abstract void markNoParentRef();
+
static final void sweep(final Collection<? extends ReactorStmtCtx<?, ?, ?>> substatements) {
for (ReactorStmtCtx<?, ?, ?> stmt : substatements) {
stmt.sweep();
}
}
+ /**
+ * Sweep this statement context as a result of {@link #sweepSubstatements()}, i.e. when parent is also being swept.
+ */
+ private void sweep() {
+ parentRef = PARENTREF_ABSENT;
+ if (refcount == REFCOUNT_NONE && noImplictRef()) {
+ LOG.trace("Releasing {}", this);
+ sweepState();
+ }
+ }
+
static final int countUnswept(final Collection<? extends ReactorStmtCtx<?, ?, ?>> substatements) {
int result = 0;
for (ReactorStmtCtx<?, ?, ?> stmt : substatements) {
// Called when this statement does not have an implicit reference and have reached REFCOUNT_NONE
private void sweepOnDecrement() {
LOG.trace("Sweeping on decrement {}", this);
- if (noParentRefcount()) {
+ if (noParentRef()) {
// No further parent references, sweep our state.
sweepState();
}
}
// parent is potentially reclaimable
- if (noParentRefcount()) {
+ if (noParentRef()) {
LOG.trace("Cleanup {} of parent {}", refcount, this);
if (sweepState()) {
final ReactorStmtCtx<?, ?, ?> parent = getParentContext();
return effectiveInstance != null || !isSupportedToBuildEffective();
}
- // FIXME: cache the resolution of this
- private boolean noParentRefcount() {
+ private boolean noParentRef() {
+ return parentRefcount() == PARENTREF_ABSENT;
+ }
+
+ private byte parentRefcount() {
+ final byte refs;
+ return (refs = parentRef) != PARENTREF_UNKNOWN ? refs : loadParentRefcount();
+ }
+
+ private byte loadParentRefcount() {
+ return parentRef = calculateParentRefcount();
+ }
+
+ private byte calculateParentRefcount() {
final ReactorStmtCtx<?, ?, ?> parent = getParentContext();
- if (parent != null) {
- // There are three possibilities:
- // - REFCOUNT_NONE, in which case we need to search next parent
- // - negative (< REFCOUNT_NONE), meaning parent is in some stage of sweeping, hence it does not have
- // a reference to us
- // - positive (> REFCOUNT_NONE), meaning parent has an explicit refcount which is holding us down
- final int refs = parent.refcount;
- return refs == REFCOUNT_NONE ? parent.noParentRefcount() : refs < REFCOUNT_NONE;
+ if (parent == null) {
+ return PARENTREF_ABSENT;
+ }
+ // There are three possibilities:
+ // - REFCOUNT_NONE, in which case we need to search next parent
+ // - negative (< REFCOUNT_NONE), meaning parent is in some stage of sweeping, hence it does not have
+ // a reference to us
+ // - positive (> REFCOUNT_NONE), meaning parent has an explicit refcount which is holding us down
+ final int refs = parent.refcount;
+ if (refs == REFCOUNT_NONE) {
+ return parent.parentRefcount();
}
- return true;
+ return refs < REFCOUNT_NONE ? PARENTREF_ABSENT : PARENTREF_PRESENT;
}
private boolean isAwaitingChildren() {
return refcount > REFCOUNT_SWEEPING && refcount < REFCOUNT_NONE;
}
- private boolean isSweepable() {
- return refcount == REFCOUNT_NONE && noImplictRef();
- }
-
private void sweepOnChildDone() {
LOG.trace("Sweeping on child done {}", this);
final int current = refcount;