2 * Copyright (c) 2020 PANTHEON.tech, s.r.o. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.yangtools.yang.parser.stmt.reactor;
10 import static com.google.common.base.Preconditions.checkArgument;
11 import static com.google.common.base.Verify.verify;
13 import com.google.common.base.MoreObjects;
14 import com.google.common.base.MoreObjects.ToStringHelper;
15 import com.google.common.base.VerifyException;
16 import java.util.Collection;
18 import java.util.Optional;
20 import java.util.stream.Stream;
21 import org.eclipse.jdt.annotation.NonNull;
22 import org.eclipse.jdt.annotation.Nullable;
23 import org.opendaylight.yangtools.yang.common.Empty;
24 import org.opendaylight.yangtools.yang.common.QName;
25 import org.opendaylight.yangtools.yang.common.QNameModule;
26 import org.opendaylight.yangtools.yang.common.YangVersion;
27 import org.opendaylight.yangtools.yang.model.api.meta.DeclaredStatement;
28 import org.opendaylight.yangtools.yang.model.api.meta.EffectiveStatement;
29 import org.opendaylight.yangtools.yang.model.api.meta.StatementDefinition;
30 import org.opendaylight.yangtools.yang.model.api.stmt.AugmentStatement;
31 import org.opendaylight.yangtools.yang.model.api.stmt.ConfigEffectiveStatement;
32 import org.opendaylight.yangtools.yang.model.api.stmt.DeviationStatement;
33 import org.opendaylight.yangtools.yang.model.api.stmt.RefineStatement;
34 import org.opendaylight.yangtools.yang.model.api.stmt.SchemaNodeIdentifier;
35 import org.opendaylight.yangtools.yang.model.api.stmt.UsesStatement;
36 import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
37 import org.opendaylight.yangtools.yang.parser.spi.ParserNamespaces;
38 import org.opendaylight.yangtools.yang.parser.spi.meta.CopyType;
39 import org.opendaylight.yangtools.yang.parser.spi.meta.EffectiveStatementState;
40 import org.opendaylight.yangtools.yang.parser.spi.meta.EffectiveStmtCtx.Current;
41 import org.opendaylight.yangtools.yang.parser.spi.meta.InferenceException;
42 import org.opendaylight.yangtools.yang.parser.spi.meta.ModelActionBuilder;
43 import org.opendaylight.yangtools.yang.parser.spi.meta.ModelProcessingPhase;
44 import org.opendaylight.yangtools.yang.parser.spi.meta.ModelProcessingPhase.ExecutionOrder;
45 import org.opendaylight.yangtools.yang.parser.spi.meta.NamespaceBehaviour.Registry;
46 import org.opendaylight.yangtools.yang.parser.spi.meta.ParserNamespace;
47 import org.opendaylight.yangtools.yang.parser.spi.meta.StatementFactory;
48 import org.opendaylight.yangtools.yang.parser.spi.meta.StmtContext;
49 import org.opendaylight.yangtools.yang.parser.spi.meta.StmtContext.Mutable;
50 import org.opendaylight.yangtools.yang.parser.spi.meta.StmtContextUtils;
51 import org.opendaylight.yangtools.yang.parser.spi.source.SourceException;
52 import org.slf4j.Logger;
53 import org.slf4j.LoggerFactory;
56 * Real "core" reactor statement implementation of {@link Mutable}, supporting basic reactor lifecycle.
58 * @param <A> Argument type
59 * @param <D> Declared Statement representation
60 * @param <E> Effective Statement representation
62 abstract class ReactorStmtCtx<A, D extends DeclaredStatement<A>, E extends EffectiveStatement<A, D>>
63 extends NamespaceStorageSupport implements Mutable<A, D, E>, Current<A, D> {
64 private static final Logger LOG = LoggerFactory.getLogger(ReactorStmtCtx.class);
67 * Substatement refcount tracking. This mechanics deals with retaining substatements for the purposes of
68 * instantiating their lazy copies in InferredStatementContext. It works in concert with {@link #buildEffective()}
69 * and {@link #declared()}: declared/effective statement views hold an implicit reference and refcount-based
70 * sweep is not activated until they are done (or this statement is not {@link #isSupportedToBuildEffective}).
73 * Reference count is hierarchical in that parent references also pin down their child statements and do not allow
77 * The counter's positive values are tracking incoming references via {@link #incRef()}/{@link #decRef()} methods.
78 * Once we transition to sweeping, this value becomes negative counting upwards to {@link #REFCOUNT_NONE} based on
79 * {@link #sweepOnChildDone()}. Once we reach that, we transition to {@link #REFCOUNT_SWEPT}.
81 private int refcount = REFCOUNT_NONE;
83 * No outstanding references, this statement is a potential candidate for sweeping, provided it has populated its
84 * declared and effective views and {@link #parentRef} is known to be absent.
86 private static final int REFCOUNT_NONE = 0;
88 * Reference count overflow or some other recoverable logic error. Do not rely on refcounts and do not sweep
92 * Note on value assignment:
93 * This allow our incRef() to naturally progress to being saturated. Others jump there directly.
94 * It also makes it it impossible to observe {@code Interger.MAX_VALUE} children, which we take advantage of for
95 * {@link #REFCOUNT_SWEEPING}.
97 private static final int REFCOUNT_DEFUNCT = Integer.MAX_VALUE;
99 * This statement is being actively swept. This is a transient value set when we are sweeping our children, so that
100 * we prevent re-entering this statement.
103 * Note on value assignment:
104 * The value is lower than any legal child refcount due to {@link #REFCOUNT_DEFUNCT} while still being higher than
105 * {@link #REFCOUNT_SWEPT}.
107 private static final int REFCOUNT_SWEEPING = -Integer.MAX_VALUE;
109 * This statement, along with its entire subtree has been swept and we positively know all our children have reached
110 * this state. We {@link #sweepNamespaces()} upon reaching this state.
113 * Note on value assignment:
114 * This is the lowest value observable, making it easier on checking others on equality.
116 private static final int REFCOUNT_SWEPT = Integer.MIN_VALUE;
119 * Effective instance built from this context. This field as dual types. Under normal circumstances in matches the
120 * {@link #buildEffective()} instance. If this context is reused, it can be inflated to {@link EffectiveInstances}
121 * and also act as a common instance reuse site.
123 private @Nullable Object effectiveInstance;
125 // Master flag controlling whether this context can yield an effective statement
126 // FIXME: investigate the mechanics that are being supported by this, as it would be beneficial if we can get rid
127 // of this flag -- eliminating the initial alignment shadow used by below gap-filler fields.
128 private boolean isSupportedToBuildEffective = true;
130 // EffectiveConfig mapping
131 private static final int MASK_CONFIG = 0x03;
132 private static final int HAVE_CONFIG = 0x04;
133 // Effective instantiation mechanics for StatementContextBase: if this flag is set all substatements are known not
134 // change when instantiated. This includes context-independent statements as well as any statements which are
135 // ignored during copy instantiation.
136 private static final int ALL_INDEPENDENT = 0x08;
137 // Flag bit assignments
138 private static final int IS_SUPPORTED_BY_FEATURES = 0x10;
139 private static final int HAVE_SUPPORTED_BY_FEATURES = 0x20;
140 private static final int IS_IGNORE_IF_FEATURE = 0x40;
141 private static final int HAVE_IGNORE_IF_FEATURE = 0x80;
142 // Have-and-set flag constants, also used as masks
143 private static final int SET_SUPPORTED_BY_FEATURES = HAVE_SUPPORTED_BY_FEATURES | IS_SUPPORTED_BY_FEATURES;
144 private static final int SET_IGNORE_IF_FEATURE = HAVE_IGNORE_IF_FEATURE | IS_IGNORE_IF_FEATURE;
146 private static final EffectiveConfig[] EFFECTIVE_CONFIGS;
149 final EffectiveConfig[] values = EffectiveConfig.values();
150 final int length = values.length;
151 verify(length == 4, "Unexpected EffectiveConfig cardinality %s", length);
152 EFFECTIVE_CONFIGS = values;
155 // Flags for use with SubstatementContext. These are hiding in the alignment shadow created by above boolean and
156 // hence improve memory layout.
163 ReactorStmtCtx(final ReactorStmtCtx<A, D, E> original) {
164 isSupportedToBuildEffective = original.isSupportedToBuildEffective;
165 flags = original.flags;
168 // Used by ReplicaStatementContext only
169 ReactorStmtCtx(final ReactorStmtCtx<A, D, E> original, final Void dummy) {
170 isSupportedToBuildEffective = original.isSupportedToBuildEffective;
171 flags = original.flags;
176 // Common public interface contracts with simple mechanics. Please keep this in one logical block, so we do not end
177 // up mixing concerns and simple details with more complex logic.
182 public abstract StatementContextBase<?, ?, ?> getParentContext();
185 public abstract RootStatementContext<?, ?, ?> getRoot();
188 public abstract Collection<? extends @NonNull StatementContextBase<?, ?, ?>> mutableDeclaredSubstatements();
191 public final Registry getBehaviourRegistry() {
192 return getRoot().getBehaviourRegistryImpl();
196 public final YangVersion yangVersion() {
197 return getRoot().getRootVersionImpl();
201 public final void setRootVersion(final YangVersion version) {
202 getRoot().setRootVersionImpl(version);
206 public final void addRequiredSource(final SourceIdentifier dependency) {
207 getRoot().addRequiredSourceImpl(dependency);
211 public final void setRootIdentifier(final SourceIdentifier identifier) {
212 getRoot().setRootIdentifierImpl(identifier);
216 public final ModelActionBuilder newInferenceAction(final ModelProcessingPhase phase) {
217 return getRoot().getSourceContext().newInferenceAction(phase);
221 public final StatementDefinition publicDefinition() {
222 return definition().getPublicView();
226 public final Parent effectiveParent() {
227 return getParentContext();
231 public final QName moduleName() {
232 final var root = getRoot();
233 return QName.create(StmtContextUtils.getModuleQName(root), root.getRawArgument());
237 // In the next two methods we are looking for an effective statement. If we already have an effective instance,
238 // defer to it's implementation of the equivalent search. Otherwise we search our substatement contexts.
240 // Note that the search function is split, so as to allow InferredStatementContext to do its own thing first.
244 public final <X, Z extends EffectiveStatement<X, ?>> @NonNull Optional<X> findSubstatementArgument(
245 final @NonNull Class<Z> type) {
246 final E existing = effectiveInstance();
247 return existing != null ? existing.findFirstEffectiveSubstatementArgument(type)
248 : findSubstatementArgumentImpl(type);
252 public final boolean hasSubstatement(final @NonNull Class<? extends EffectiveStatement<?, ?>> type) {
253 final E existing = effectiveInstance();
254 return existing != null ? existing.findFirstEffectiveSubstatement(type).isPresent() : hasSubstatementImpl(type);
257 private E effectiveInstance() {
258 final Object existing = effectiveInstance;
259 return existing != null ? EffectiveInstances.local(existing) : null;
262 // Visible due to InferredStatementContext's override. At this point we do not have an effective instance available.
263 <X, Z extends EffectiveStatement<X, ?>> @NonNull Optional<X> findSubstatementArgumentImpl(
264 final @NonNull Class<Z> type) {
265 return allSubstatementsStream()
266 .filter(ctx -> ctx.isSupportedToBuildEffective() && ctx.producesEffective(type))
268 .map(ctx -> (X) ctx.getArgument());
271 // Visible due to InferredStatementContext's override. At this point we do not have an effective instance available.
272 boolean hasSubstatementImpl(final @NonNull Class<? extends EffectiveStatement<?, ?>> type) {
273 return allSubstatementsStream()
274 .anyMatch(ctx -> ctx.isSupportedToBuildEffective() && ctx.producesEffective(type));
279 @SuppressWarnings("unchecked")
280 public final <Z extends EffectiveStatement<A, D>> StmtContext<A, D, Z> caerbannog() {
281 return (StmtContext<A, D, Z>) this;
285 public final String toString() {
286 return addToStringAttributes(MoreObjects.toStringHelper(this).omitNullValues()).toString();
289 protected ToStringHelper addToStringAttributes(final ToStringHelper toStringHelper) {
290 return toStringHelper.add("definition", definition()).add("argument", argument()).add("refCount", refString());
293 private String refString() {
294 final int current = refcount;
295 return switch (current) {
296 case REFCOUNT_DEFUNCT -> "DEFUNCT";
297 case REFCOUNT_SWEEPING -> "SWEEPING";
298 case REFCOUNT_SWEPT -> "SWEPT";
299 default -> String.valueOf(refcount);
304 * Return the context in which this statement was defined.
306 * @return statement definition
308 abstract @NonNull StatementDefinitionContext<A, D, E> definition();
312 // NamespaceStorageSupport/Mutable integration methods. Keep these together.
317 public final <K, V, T extends K> V namespaceItem(final ParserNamespace<K, V> type, final T key) {
318 return getBehaviourRegistry().getNamespaceBehaviour(type).getFrom(this, key);
322 public final <K, V> Map<K, V> namespace(final ParserNamespace<K, V> type) {
323 return getNamespace(type);
327 public final <K, V> Map<K, V> localNamespacePortion(final ParserNamespace<K, V> type) {
328 return getLocalNamespace(type);
332 protected <K, V> void onNamespaceElementAdded(final ParserNamespace<K, V> type, final K key, final V value) {
333 // definition().onNamespaceElementAdded(this, type, key, value);
337 * Return the effective statement view of a copy operation. This method may return one of:
339 * <li>{@code this}, when the effective view did not change</li>
340 * <li>an InferredStatementContext, when there is a need for inference-equivalent copy</li>
341 * <li>{@code null}, when the statement failed to materialize</li>
344 * @param parent Proposed new parent
345 * @param type Copy operation type
346 * @param targetModule New target module
347 * @return {@link ReactorStmtCtx} holding effective view
349 abstract @Nullable ReactorStmtCtx<?, ?, ?> asEffectiveChildOf(StatementContextBase<?, ?, ?> parent, CopyType type,
350 QNameModule targetModule);
353 public final ReplicaStatementContext<A, D, E> replicaAsChildOf(final Mutable<?, ?, ?> parent) {
354 checkArgument(parent instanceof StatementContextBase, "Unsupported parent %s", parent);
355 final var ret = replicaAsChildOf((StatementContextBase<?, ?, ?>) parent);
356 definition().onStatementAdded(ret);
360 abstract @NonNull ReplicaStatementContext<A, D, E> replicaAsChildOf(@NonNull StatementContextBase<?, ?, ?> parent);
364 // Statement build entry points -- both public and package-private.
369 public final E buildEffective() {
370 final Object existing;
371 return (existing = effectiveInstance) != null ? EffectiveInstances.local(existing) : loadEffective();
374 private @NonNull E loadEffective() {
375 final E ret = createEffective();
376 effectiveInstance = ret;
377 // we have called createEffective(), substatements are no longer guarded by us. Let's see if we can clear up
379 if (refcount == REFCOUNT_NONE) {
385 abstract @NonNull E createEffective();
388 * Routing of the request to build an effective statement from {@link InferredStatementContext} towards the original
389 * definition site. This is needed to pick the correct instantiation method: for declared statements we will
390 * eventually land in {@link AbstractResumedStatement}, for underclared statements that will be
391 * {@link UndeclaredStmtCtx}.
393 * @param factory Statement factory
394 * @param ctx Inferred statement context, i.e. where the effective statement is instantiated
395 * @return Built effective stateue
397 abstract @NonNull E createInferredEffective(@NonNull StatementFactory<A, D, E> factory,
398 @NonNull InferredStatementContext<A, D, E> ctx, Stream<? extends ReactorStmtCtx<?, ?, ?>> declared,
399 Stream<? extends ReactorStmtCtx<?, ?, ?>> effective);
402 * Attach an effective copy of this statement. This essentially acts as a map, where we make a few assumptions:
404 * <li>{@code copy} and {@code this} statement share {@link #getOriginalCtx()} if it exists</li>
405 * <li>{@code copy} did not modify any statements relative to {@code this}</li>
408 * @param state effective statement state, acting as a lookup key
409 * @param stmt New copy to append
410 * @return {@code stmt} or a previously-created instances with the same {@code state}
412 @SuppressWarnings("unchecked")
413 final @NonNull E attachEffectiveCopy(final @NonNull EffectiveStatementState state, final @NonNull E stmt) {
414 final Object local = effectiveInstance;
415 final EffectiveInstances<E> instances;
416 if (local instanceof EffectiveInstances) {
417 instances = (EffectiveInstances<E>) local;
419 effectiveInstance = instances = new EffectiveInstances<>((E) local);
421 return instances.attachCopy(state, stmt);
425 * Walk this statement's copy history and return the statement closest to original which has not had its effective
426 * statements modified. This statement and returned substatement logically have the same set of substatements, hence
427 * share substatement-derived state.
429 * @return Closest {@link ReactorStmtCtx} with equivalent effective substatements
431 abstract @NonNull ReactorStmtCtx<A, D, E> unmodifiedEffectiveSource();
434 public final ModelProcessingPhase getCompletedPhase() {
435 return ModelProcessingPhase.ofExecutionOrder(executionOrder());
438 abstract byte executionOrder();
441 * Try to execute current {@link ModelProcessingPhase} of source parsing. If the phase has already been executed,
442 * this method does nothing. This must not be called with {@link ExecutionOrder#NULL}.
444 * @param phase to be executed (completed)
445 * @return true if phase was successfully completed
446 * @throws SourceException when an error occurred in source parsing
448 final boolean tryToCompletePhase(final byte executionOrder) {
449 return executionOrder() >= executionOrder || doTryToCompletePhase(executionOrder);
452 abstract boolean doTryToCompletePhase(byte targetOrder);
456 // Flags-based mechanics. These include public interfaces as well as all the crud we have lurking in our alignment
461 // Non-final for ImplicitStmtCtx/InferredStatementContext
463 public boolean isSupportedToBuildEffective() {
464 return isSupportedToBuildEffective;
468 public final void setUnsupported() {
469 this.isSupportedToBuildEffective = false;
473 public final boolean isSupportedByFeatures() {
474 final int fl = flags & SET_SUPPORTED_BY_FEATURES;
476 return fl == SET_SUPPORTED_BY_FEATURES;
478 if (isIgnoringIfFeatures()) {
479 flags |= SET_SUPPORTED_BY_FEATURES;
484 * If parent is supported, we need to check if-features statements of this context.
486 if (isParentSupportedByFeatures()) {
487 // If the set of supported features has not been provided, all features are supported by default.
488 final Set<QName> supportedFeatures = getFromNamespace(ParserNamespaces.SUPPORTED_FEATURES,
490 if (supportedFeatures == null || StmtContextUtils.checkFeatureSupport(this, supportedFeatures)) {
491 flags |= SET_SUPPORTED_BY_FEATURES;
496 // Either parent is not supported or this statement is not supported
497 flags |= HAVE_SUPPORTED_BY_FEATURES;
501 protected abstract boolean isParentSupportedByFeatures();
504 * Config statements are not all that common which means we are performing a recursive search towards the root
505 * every time {@link #effectiveConfig()} is invoked. This is quite expensive because it causes a linear search
506 * for the (usually non-existent) config statement.
509 * This method maintains a resolution cache, so once we have returned a result, we will keep on returning the same
510 * result without performing any lookups, solely to support {@link #effectiveConfig()}.
513 * Note: use of this method implies that {@link #isIgnoringConfig()} is realized with
514 * {@link #isIgnoringConfig(StatementContextBase)}.
516 final @NonNull EffectiveConfig effectiveConfig(final ReactorStmtCtx<?, ?, ?> parent) {
517 return (flags & HAVE_CONFIG) != 0 ? EFFECTIVE_CONFIGS[flags & MASK_CONFIG] : loadEffectiveConfig(parent);
520 private @NonNull EffectiveConfig loadEffectiveConfig(final ReactorStmtCtx<?, ?, ?> parent) {
521 final EffectiveConfig parentConfig = parent.effectiveConfig();
523 final EffectiveConfig myConfig;
524 if (parentConfig != EffectiveConfig.IGNORED && !definition().support().isIgnoringConfig()) {
525 final Optional<Boolean> optConfig = findSubstatementArgument(ConfigEffectiveStatement.class);
526 if (optConfig.isPresent()) {
527 if (optConfig.orElseThrow()) {
528 // Validity check: if parent is config=false this cannot be a config=true
529 InferenceException.throwIf(parentConfig == EffectiveConfig.FALSE, this,
530 "Parent node has config=false, this node must not be specifed as config=true");
531 myConfig = EffectiveConfig.TRUE;
533 myConfig = EffectiveConfig.FALSE;
536 // If "config" statement is not specified, the default is the same as the parent's "config" value.
537 myConfig = parentConfig;
540 myConfig = EffectiveConfig.IGNORED;
543 flags = (byte) (flags & ~MASK_CONFIG | HAVE_CONFIG | myConfig.ordinal());
547 protected abstract boolean isIgnoringConfig();
550 * This method maintains a resolution cache for ignore config, so once we have returned a result, we will
551 * keep on returning the same result without performing any lookups. Exists only to support
552 * {@link SubstatementContext#isIgnoringConfig()}.
555 * Note: use of this method implies that {@link #isConfiguration()} is realized with
556 * {@link #effectiveConfig(StatementContextBase)}.
558 final boolean isIgnoringConfig(final StatementContextBase<?, ?, ?> parent) {
559 return EffectiveConfig.IGNORED == effectiveConfig(parent);
562 protected abstract boolean isIgnoringIfFeatures();
565 * This method maintains a resolution cache for ignore if-feature, so once we have returned a result, we will
566 * keep on returning the same result without performing any lookups. Exists only to support
567 * {@link SubstatementContext#isIgnoringIfFeatures()}.
569 final boolean isIgnoringIfFeatures(final StatementContextBase<?, ?, ?> parent) {
570 final int fl = flags & SET_IGNORE_IF_FEATURE;
572 return fl == SET_IGNORE_IF_FEATURE;
574 if (definition().support().isIgnoringIfFeatures() || parent.isIgnoringIfFeatures()) {
575 flags |= SET_IGNORE_IF_FEATURE;
579 flags |= HAVE_IGNORE_IF_FEATURE;
583 // These two exist only for StatementContextBase. Since we are squeezed for size, with only a single bit available
584 // in flags, we default to 'false' and only set the flag to true when we are absolutely sure -- and all other cases
585 // err on the side of caution by taking the time to evaluate each substatement separately.
586 final boolean allSubstatementsContextIndependent() {
587 return (flags & ALL_INDEPENDENT) != 0;
590 final void setAllSubstatementsContextIndependent() {
591 flags |= ALL_INDEPENDENT;
596 // Various functionality from AbstractTypeStatementSupport. This used to work on top of SchemaPath, now it still
597 // lives here. Ultimate future is either proper graduation or (more likely) move to AbstractTypeStatementSupport.
602 public final QName argumentAsTypeQName() {
603 // FIXME: This may yield illegal argument exceptions
604 return StmtContextUtils.qnameFromArgument(getOriginalCtx().orElse(this), getRawArgument());
608 public final QNameModule effectiveNamespace() {
609 if (StmtContextUtils.isUnknownStatement(this)) {
610 return publicDefinition().getStatementName().getModule();
612 if (producesDeclared(UsesStatement.class)) {
613 return coerceParent().effectiveNamespace();
616 final Object argument = argument();
617 if (argument instanceof QName qname) {
618 return qname.getModule();
620 if (argument instanceof String str) {
621 // FIXME: This may yield illegal argument exceptions
622 return StmtContextUtils.qnameFromArgument(getOriginalCtx().orElse(this), str).getModule();
624 if (argument instanceof SchemaNodeIdentifier sni
625 && (producesDeclared(AugmentStatement.class) || producesDeclared(RefineStatement.class)
626 || producesDeclared(DeviationStatement.class))) {
627 return sni.lastNodeIdentifier().getModule();
630 return coerceParent().effectiveNamespace();
633 private ReactorStmtCtx<?, ?, ?> coerceParent() {
634 return (ReactorStmtCtx<?, ?, ?>) coerceParentContext();
639 // Reference counting mechanics start. Please keep these methods in one block for clarity. Note this does not
640 // contribute to state visible outside of this package.
645 * Local knowledge of {@link #refcount} values up to statement root. We use this field to prevent recursive lookups
646 * in {@link #noParentRefs(StatementContextBase)} -- once we discover a parent reference once, we keep that
647 * knowledge and update it when {@link #sweep()} is invoked.
649 private byte parentRef = PARENTREF_UNKNOWN;
650 private static final byte PARENTREF_UNKNOWN = -1;
651 private static final byte PARENTREF_ABSENT = 0;
652 private static final byte PARENTREF_PRESENT = 1;
655 * Acquire a reference on this context. As long as there is at least one reference outstanding,
656 * {@link #buildEffective()} will not result in {@link #effectiveSubstatements()} being discarded.
658 * @throws VerifyException if {@link #effectiveSubstatements()} has already been discarded
660 final void incRef() {
661 final int current = refcount;
662 verify(current >= REFCOUNT_NONE, "Attempted to access reference count of %s", this);
663 if (current != REFCOUNT_DEFUNCT) {
664 // Note: can end up becoming REFCOUNT_DEFUNCT on overflow
665 refcount = current + 1;
667 LOG.debug("Disabled refcount increment of {}", this);
672 * Release a reference on this context. This call may result in {@link #effectiveSubstatements()} becoming
675 final void decRef() {
676 final int current = refcount;
677 if (current == REFCOUNT_DEFUNCT) {
679 LOG.debug("Disabled refcount decrement of {}", this);
682 if (current <= REFCOUNT_NONE) {
683 // Underflow, become defunct
684 // FIXME: add a global 'warn once' flag
685 LOG.warn("Statement refcount underflow, reference counting disabled for {}", this, new Throwable());
686 refcount = REFCOUNT_DEFUNCT;
690 refcount = current - 1;
691 LOG.trace("Refcount {} on {}", refcount, this);
693 if (refcount == REFCOUNT_NONE) {
699 * Return {@code true} if this context has no outstanding references.
701 * @return True if this context has no outstanding references.
703 final boolean noRefs() {
704 final int local = refcount;
705 return local < REFCOUNT_NONE || local == REFCOUNT_NONE && noParentRef();
708 private void lastDecRef() {
709 if (noImplictRef()) {
710 // We are no longer guarded by effective instance
715 final byte prevRefs = parentRef;
716 if (prevRefs == PARENTREF_ABSENT) {
717 // We are the last reference towards root, any children who observed PARENTREF_PRESENT from us need to be
720 } else if (prevRefs == PARENTREF_UNKNOWN) {
721 // Noone observed our parentRef, just update it
722 loadParentRefcount();
726 static final void markNoParentRef(final Collection<? extends ReactorStmtCtx<?, ?, ?>> substatements) {
727 for (ReactorStmtCtx<?, ?, ?> stmt : substatements) {
728 final byte prevRef = stmt.parentRef;
729 stmt.parentRef = PARENTREF_ABSENT;
730 if (prevRef == PARENTREF_PRESENT && stmt.refcount == REFCOUNT_NONE) {
731 // Child thinks it is pinned down, update its perspective
732 stmt.markNoParentRef();
737 abstract void markNoParentRef();
739 static final void sweep(final Collection<? extends ReactorStmtCtx<?, ?, ?>> substatements) {
740 for (ReactorStmtCtx<?, ?, ?> stmt : substatements) {
746 * Sweep this statement context as a result of {@link #sweepSubstatements()}, i.e. when parent is also being swept.
748 private void sweep() {
749 parentRef = PARENTREF_ABSENT;
750 if (refcount == REFCOUNT_NONE && noImplictRef()) {
751 LOG.trace("Releasing {}", this);
756 static final int countUnswept(final Collection<? extends ReactorStmtCtx<?, ?, ?>> substatements) {
758 for (ReactorStmtCtx<?, ?, ?> stmt : substatements) {
759 if (stmt.refcount > REFCOUNT_NONE || !stmt.noImplictRef()) {
767 * Implementation-specific sweep action. This is expected to perform a recursive {@link #sweep(Collection)} on all
768 * {@link #declaredSubstatements()} and {@link #effectiveSubstatements()} and report the result of the sweep
772 * {@link #effectiveSubstatements()} as well as namespaces may become inoperable as a result of this operation.
774 * @return True if the entire tree has been completely swept, false otherwise.
776 abstract int sweepSubstatements();
778 // Called when this statement does not have an implicit reference and have reached REFCOUNT_NONE
779 private void sweepOnDecrement() {
780 LOG.trace("Sweeping on decrement {}", this);
782 // No further parent references, sweep our state.
786 // Propagate towards parent if there is one
790 private void sweepParent() {
791 final ReactorStmtCtx<?, ?, ?> parent = getParentContext();
792 if (parent != null) {
793 parent.sweepOnChildDecrement();
797 // Called from child when it has lost its final reference
798 private void sweepOnChildDecrement() {
799 if (isAwaitingChildren()) {
800 // We are a child for which our parent is waiting. Notify it and we are done.
805 // Check parent reference count
806 final int refs = refcount;
807 if (refs > REFCOUNT_NONE || refs <= REFCOUNT_SWEEPING || !noImplictRef()) {
812 // parent is potentially reclaimable
814 LOG.trace("Cleanup {} of parent {}", refs, this);
821 private boolean noImplictRef() {
822 return effectiveInstance != null || !isSupportedToBuildEffective();
825 private boolean noParentRef() {
826 return parentRefcount() == PARENTREF_ABSENT;
829 private byte parentRefcount() {
831 return (refs = parentRef) != PARENTREF_UNKNOWN ? refs : loadParentRefcount();
834 private byte loadParentRefcount() {
835 return parentRef = calculateParentRefcount();
838 private byte calculateParentRefcount() {
839 final ReactorStmtCtx<?, ?, ?> parent = getParentContext();
840 return parent == null ? PARENTREF_ABSENT : parent.refcountForChild();
843 private byte refcountForChild() {
844 // A slight wrinkle here is that our machinery handles only PRESENT -> ABSENT invalidation and we can reach here
845 // while inference is still ongoing and hence we may not have a complete picture about existing references. We
846 // could therefore end up caching an ABSENT result and then that information becoming stale as a new reference
848 if (executionOrder() < ExecutionOrder.EFFECTIVE_MODEL) {
849 return PARENTREF_UNKNOWN;
852 // There are three possibilities:
853 // - REFCOUNT_NONE, in which case we need to check if this statement or its parents are holding a reference
854 // - negative (< REFCOUNT_NONE), meaning parent is in some stage of sweeping, hence it does not have
856 // - positive (> REFCOUNT_NONE), meaning parent has an explicit refcount which is holding us down
857 final int refs = refcount;
858 if (refs == REFCOUNT_NONE) {
859 return noImplictRef() && noParentRef() ? PARENTREF_ABSENT : PARENTREF_PRESENT;
861 return refs < REFCOUNT_NONE ? PARENTREF_ABSENT : PARENTREF_PRESENT;
864 private boolean isAwaitingChildren() {
865 return refcount > REFCOUNT_SWEEPING && refcount < REFCOUNT_NONE;
868 private void sweepOnChildDone() {
869 LOG.trace("Sweeping on child done {}", this);
870 final int current = refcount;
871 if (current >= REFCOUNT_NONE) {
872 // no-op, perhaps we want to handle some cases differently?
873 LOG.trace("Ignoring child sweep of {} for {}", this, current);
876 verify(current != REFCOUNT_SWEPT, "Attempt to sweep a child of swept %s", this);
878 refcount = current + 1;
879 LOG.trace("Child refcount {}", refcount);
880 if (refcount == REFCOUNT_NONE) {
882 final ReactorStmtCtx<?, ?, ?> parent = getParentContext();
883 LOG.trace("Propagating to parent {}", parent);
884 if (parent != null && parent.isAwaitingChildren()) {
885 parent.sweepOnChildDone();
890 private void sweepDone() {
891 LOG.trace("Sweep done for {}", this);
892 refcount = REFCOUNT_SWEPT;
896 private boolean sweepState() {
897 refcount = REFCOUNT_SWEEPING;
898 final int childRefs = sweepSubstatements();
899 if (childRefs == 0) {
903 if (childRefs < 0 || childRefs >= REFCOUNT_DEFUNCT) {
904 // FIXME: add a global 'warn once' flag
905 LOG.warn("Negative child refcount {} cannot be stored, reference counting disabled for {}", childRefs, this,
907 refcount = REFCOUNT_DEFUNCT;
909 LOG.trace("Still {} outstanding children of {}", childRefs, this);
910 refcount = -childRefs;