Java tutorial
/* * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.yangtools.yang.data.impl.schema.tree; import com.google.common.base.Optional; import com.google.common.base.Preconditions; import com.google.common.base.Predicate; import java.util.Collection; import java.util.Map; import javax.annotation.Nonnull; import javax.annotation.concurrent.NotThreadSafe; import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument; import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode; import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNodeContainer; import org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType; import org.opendaylight.yangtools.yang.data.api.schema.tree.StoreTreeNode; import org.opendaylight.yangtools.yang.data.api.schema.tree.spi.TreeNode; import org.opendaylight.yangtools.yang.data.api.schema.tree.spi.TreeNodeFactory; import org.opendaylight.yangtools.yang.data.api.schema.tree.spi.Version; /** * Node Modification Node and Tree * * Tree which structurally resembles data tree and captures client modifications to the data store tree. This tree is * lazily created and populated via {@link #modifyChild(PathArgument, ModificationApplyOperation, Version)} and * {@link TreeNode} which represents original state as tracked by {@link #getOriginal()}. * * The contract is that the state information exposed here preserves the temporal ordering of whatever modifications * were executed. A child's effects pertain to data node as modified by its ancestors. This means that in order to * reconstruct the effective data node presentation, it is sufficient to perform a depth-first pre-order traversal of * the tree. */ @NotThreadSafe final class ModifiedNode extends NodeModification implements StoreTreeNode<ModifiedNode> { static final Predicate<ModifiedNode> IS_TERMINAL_PREDICATE = input -> { Preconditions.checkNotNull(input); switch (input.getOperation()) { case DELETE: case MERGE: case WRITE: return true; case TOUCH: case NONE: return false; } throw new IllegalArgumentException(String.format("Unhandled modification type %s", input.getOperation())); }; private final Map<PathArgument, ModifiedNode> children; private final Optional<TreeNode> original; private final PathArgument identifier; private LogicalOperation operation = LogicalOperation.NONE; private Optional<TreeNode> snapshotCache; private NormalizedNode<?, ?> value; private ModificationType modType; // Alternative history introduced in WRITE nodes. Instantiated when we touch any child underneath such a node. private TreeNode writtenOriginal; // Internal cache for TreeNodes created as part of validation private SchemaAwareApplyOperation validatedOp; private Optional<TreeNode> validatedCurrent; private TreeNode validatedNode; private ModifiedNode(final PathArgument identifier, final Optional<TreeNode> original, final ChildTrackingPolicy childPolicy) { this.identifier = identifier; this.original = original; this.children = childPolicy.createMap(); } @Override public PathArgument getIdentifier() { return identifier; } @Override LogicalOperation getOperation() { return operation; } @Override Optional<TreeNode> getOriginal() { return original; } /** * Return the value which was written to this node. The returned object is only valid for * {@link LogicalOperation#MERGE} and {@link LogicalOperation#WRITE}. * operations. It should only be consulted when this modification is going to end up being * {@link ModificationType#WRITE}. * * @return Currently-written value */ NormalizedNode<?, ?> getWrittenValue() { return value; } /** * * Returns child modification if child was modified * * @return Child modification if direct child or it's subtree * was modified. * */ @Override public Optional<ModifiedNode> getChild(final PathArgument child) { return Optional.fromNullable(children.get(child)); } private Optional<TreeNode> metadataFromSnapshot(@Nonnull final PathArgument child) { return original.isPresent() ? original.get().getChild(child) : Optional.absent(); } private Optional<TreeNode> metadataFromData(@Nonnull final PathArgument child, final Version modVersion) { if (writtenOriginal == null) { // Lazy instantiation, as we do not want do this for all writes. We are using the modification's version // here, as that version is what the SchemaAwareApplyOperation will see when dealing with the resulting // modifications. writtenOriginal = TreeNodeFactory.createTreeNode(value, modVersion); } return writtenOriginal.getChild(child); } /** * Determine the base tree node we are going to apply the operation to. This is not entirely trivial because * both DELETE and WRITE operations unconditionally detach their descendants from the original snapshot, so we need * to take the current node's operation into account. * * @param child Child we are looking to modify * @param modVersion Version allocated by the calling {@link InMemoryDataTreeModification} * @return Before-image tree node as observed by that child. */ private Optional<TreeNode> findOriginalMetadata(@Nonnull final PathArgument child, final Version modVersion) { switch (operation) { case DELETE: // DELETE implies non-presence return Optional.absent(); case NONE: case TOUCH: case MERGE: return metadataFromSnapshot(child); case WRITE: // WRITE implies presence based on written data return metadataFromData(child, modVersion); } throw new IllegalStateException("Unhandled node operation " + operation); } /** * * Returns child modification if child was modified, creates {@link ModifiedNode} * for child otherwise. * * If this node's {@link ModificationType} is {@link ModificationType#UNMODIFIED} * changes modification type to {@link ModificationType#SUBTREE_MODIFIED} * * @param child child identifier, may not be null * @param childOper Child operation * @param modVersion Version allocated by the calling {@link InMemoryDataTreeModification} * @return {@link ModifiedNode} for specified child, with {@link #getOriginal()} * containing child metadata if child was present in original data. */ ModifiedNode modifyChild(@Nonnull final PathArgument child, @Nonnull final ModificationApplyOperation childOper, @Nonnull final Version modVersion) { clearSnapshot(); if (operation == LogicalOperation.NONE) { updateOperationType(LogicalOperation.TOUCH); } final ModifiedNode potential = children.get(child); if (potential != null) { return potential; } final Optional<TreeNode> currentMetadata = findOriginalMetadata(child, modVersion); final ModifiedNode newlyCreated = new ModifiedNode(child, currentMetadata, childOper.getChildPolicy()); if (operation == LogicalOperation.MERGE && value != null) { /* * We are attempting to modify a previously-unmodified part of a MERGE node. If the * value contains this component, we need to materialize it as a MERGE modification. */ @SuppressWarnings({ "rawtypes", "unchecked" }) final Optional<NormalizedNode<?, ?>> childData = ((NormalizedNodeContainer) value).getChild(child); if (childData.isPresent()) { childOper.mergeIntoModifiedNode(newlyCreated, childData.get(), modVersion); } } children.put(child, newlyCreated); return newlyCreated; } /** * Returns all recorded direct child modification * * @return all recorded direct child modifications */ @Override Collection<ModifiedNode> getChildren() { return children.values(); } /** * Records a delete for associated node. */ void delete() { final LogicalOperation newType; switch (operation) { case DELETE: case NONE: // We need to record this delete. newType = LogicalOperation.DELETE; break; case MERGE: // In case of merge - delete needs to be recored and must not to be changed into // NONE, because lazy expansion of parent MERGE node would reintroduce it // again. newType = LogicalOperation.DELETE; break; case TOUCH: case WRITE: /* * We are canceling a previous modification. This is a bit tricky, * as the original write may have just introduced the data, or it * may have modified it. * * As documented in BUG-2470, a delete of data introduced in this * transaction needs to be turned into a no-op. */ newType = original.isPresent() ? LogicalOperation.DELETE : LogicalOperation.NONE; break; default: throw new IllegalStateException("Unhandled deletion of node with " + operation); } clearSnapshot(); children.clear(); this.value = null; updateOperationType(newType); } /** * Records a write for associated node. * * @param value */ void write(final NormalizedNode<?, ?> value) { updateValue(LogicalOperation.WRITE, value); children.clear(); } /** * Seal the modification node and prune any children which has not been modified. * * @param schema */ void seal(final ModificationApplyOperation schema, final Version version) { clearSnapshot(); writtenOriginal = null; switch (operation) { case TOUCH: // A TOUCH node without any children is a no-op if (children.isEmpty()) { updateOperationType(LogicalOperation.NONE); } break; case WRITE: // A WRITE can collapse all of its children if (!children.isEmpty()) { value = schema.apply(this, getOriginal(), version).get().getData(); children.clear(); } schema.verifyStructure(value, true); break; default: break; } } private void clearSnapshot() { snapshotCache = null; } Optional<TreeNode> getSnapshot() { return snapshotCache; } Optional<TreeNode> setSnapshot(final Optional<TreeNode> snapshot) { snapshotCache = Preconditions.checkNotNull(snapshot); return snapshot; } void updateOperationType(final LogicalOperation type) { operation = type; modType = null; // Make sure we do not reuse previously-instantiated data-derived metadata writtenOriginal = null; clearSnapshot(); } @Override public String toString() { return "NodeModification [identifier=" + identifier + ", modificationType=" + operation + ", childModification=" + children + "]"; } void resolveModificationType(@Nonnull final ModificationType type) { modType = type; } /** * Update this node's value and operation type without disturbing any of its child modifications. * * @param type New operation type * @param value New node value */ void updateValue(final LogicalOperation type, final NormalizedNode<?, ?> value) { this.value = Preconditions.checkNotNull(value); updateOperationType(type); } /** * Return the physical modification done to data. May return null if the * operation has not been applied to the underlying tree. This is different * from the logical operation in that it can actually be a no-op if the * operation has no side-effects (like an empty merge on a container). * * @return Modification type. */ ModificationType getModificationType() { return modType; } public static ModifiedNode createUnmodified(final TreeNode metadataTree, final ChildTrackingPolicy childPolicy) { return new ModifiedNode(metadataTree.getIdentifier(), Optional.of(metadataTree), childPolicy); } void setValidatedNode(final SchemaAwareApplyOperation op, final Optional<TreeNode> current, final TreeNode node) { this.validatedOp = Preconditions.checkNotNull(op); this.validatedCurrent = Preconditions.checkNotNull(current); this.validatedNode = Preconditions.checkNotNull(node); } TreeNode getValidatedNode(final SchemaAwareApplyOperation op, final Optional<TreeNode> current) { return op.equals(validatedOp) && current.equals(validatedCurrent) ? validatedNode : null; } }