Examples of org.apache.jackrabbit.oak.spi.state.NodeState

Package org.apache.jackrabbit.oak.spi.state

Examples of org.apache.jackrabbit.oak.spi.state.NodeState

org.apache.jackrabbit.oak.spi.state.NodeState
A node in a content tree consists of child nodes and properties, each of which evolves through different states during its lifecycle. This interface represents a specific, immutable state of a node. The state consists of an unordered set of name -> item mappings, where each item is either a property or a child node.
Depending on context, a NodeState instance can be interpreted as representing the state of just that node, of the subtree starting at that node, or of an entire tree in case it's a root node.
The crucial difference between this interface and the similarly named class in Jackrabbit 2.x is that this interface represents a specific, immutable state of a node, whereas the Jackrabbit 2.x class represented the current state of a node.
Immutability and thread-safety

As mentioned above, all node and property states are always immutable. Thus repeating a method call is always guaranteed to produce the same result as before unless some internal error occurs (see below). This immutability only applies to a specific state instance. Different states of a node can obviously be different, and in some cases even different instances of the same state may behave slightly differently. For example due to performance optimization or other similar changes the iteration order of properties or child nodes may be different for two instances of the same state.
In addition to being immutable, a specific state instance guaranteed to be fully thread-safe. Possible caching or other internal changes need to be properly synchronized so that any number of concurrent clients can safely access a state instance.
Persistence and error-handling

A node state can be (and often is) backed by local files or network resources. All IO operations or related concerns like caching should be handled transparently below this interface. Potential IO problems and recovery attempts like retrying a timed-out network access need to be handled below this interface, and only hard errors should be thrown up as {@link RuntimeException unchecked exceptions} that higher level codeis not expected to be able to recover from.
Since this interface exposes no higher level constructs like locking, node types or even path parsing, there's no way for content access to fail because of such concerns. Such functionality and related checked exceptions or other control flow constructs should be implemented on a higher level above this interface. On the other hand read access controls can be implemented below this interface, in which case some content that would otherwise be accessible might not show up through such an implementation.
Existence and iterability of node states

The {@link #getChildNode(String)} method is special in that itnever returns a {@code null} value, even if the named childnode does not exist. Instead a client should use the {@link #exists()}method on the returned child state to check whether that node exists. The purpose of this separation of concerns is to allow an implementation to lazily load content only when it's actually read instead of just traversed. It also simplifies client code by avoiding the need for many {@code null} checks when traversing paths.
The iterability of a node is a related concept to the above-mentioned existence. A node state is iterable if it is included in the return values of the {@link #getChildNodeCount(long)}, {@link #getChildNodeNames()} and {@link #getChildNodeEntries()} methods.An iterable node is guaranteed to exist, though not all existing nodes are necessarily iterable.
Furthermore, a non-existing node is guaranteed to contain no properties or iterable child nodes. It can, however contain non-iterable children. Such scenarios are typically the result of access control restrictions.
Decoration and virtual content

Not all content exposed by this interface needs to be backed by actual persisted data. An implementation may want to provide derived data, like for example the aggregate size of the entire subtree as an extra virtual property. A virtualization, sharding or caching layer could provide a composite view over multiple underlying trees. Or a an access control layer could decide to hide certain content based on specific rules. All such features need to be implemented according to the API contract of this interface. A separate higher level interface needs to be used if an implementation can't for example guarantee immutability of exposed content as discussed above.
Equality and hash codes

Two node states are considered equal if and only if their existence, properties and iterable child nodes match, regardless of ordering. The {@link Object#equals(Object)} method needs to be implemented so that itcomplies with this definition. And while node states are not meant for use as hash keys, the {@link Object#hashCode()} method should still beimplemented according to this equality contract.

    private class WrapChildEntryFunction implements Function<ChildNodeEntry, ChildNodeEntry> {
        @Nonnull
        @Override
        public ChildNodeEntry apply(@Nonnull ChildNodeEntry input) {
            String name = input.getName();
            NodeState child = input.getNodeState();
            TreePermission childContext = treePermission.getChildPermission(name, child);
            SecureNodeState secureChild = new SecureNodeState(child, childContext);
            if (child.getChildNodeCount(1) == 0
                    && secureChild.treePermission.canRead()
                    && secureChild.treePermission.canReadProperties()) {
                // Since this is an accessible leaf node whose all properties
                // are readable, we don't need the SecureNodeState wrapper
                // TODO: A further optimization would be to return the raw

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        return name;
    }


    @Override @CheckForNull
    public NodeState retrieve(@Nonnull String checkpoint) {
        NodeState cp = head.get().getChildNode(checkpoint).getChildNode(ROOT);
        if (cp.exists()) {
            return cp;
        }
        return null;
    }

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            throws IOException {
        long s = System.currentTimeMillis();


        // 1. create a new checkpoint with the current state
        String checkpoint = store.checkpoint(DEFAULT_LIFETIME);
        NodeState current = store.retrieve(checkpoint);
        if (current == null) {
            // unable to retrieve the checkpoint; use root state instead
            current = store.getRoot();
        }


        // 2. init filestore
        FileStore backup = new FileStore(destination, MAX_FILE_SIZE, false);
        try {
            Journal journal = backup.getJournal("root");


            SegmentNodeState state = new SegmentNodeState(
                    backup.getWriter().getDummySegment(), journal.getHead());
            SegmentNodeBuilder builder = state.builder();


            String beforeCheckpoint = state.getString("checkpoint");
            if (beforeCheckpoint == null) {
                // 3.1 no stored checkpoint, so do the initial full backup
                builder.setChildNode("root", current);
            } else {
                // 3.2 try to retrieve the previously backed up checkpoint
                NodeState before = store.retrieve(beforeCheckpoint);
                if (before != null) {
                    // the previous checkpoint is no longer available,
                    // so use the backed up state as the basis of the
                    // incremental backup diff
                    before = state.getChildNode("root");

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    public boolean isIndexed(String propertyName, String path, Filter filter) {
        if (PathUtils.denotesRoot(path)) {
            return getIndexNode(root, propertyName, filter) != null;
        }


        NodeState node = root;
        Iterator<String> it = PathUtils.elements(path).iterator();
        while (it.hasNext()) {
            if (getIndexNode(node, propertyName, filter) != null) {
                return true;
            }
            node = node.getChildNode(it.next());
        }
        return false;
    }

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        }
        return false;
    }


    public Iterable<String> query(Filter filter, String propertyName, PropertyValue value) {
        NodeState indexMeta = getIndexNode(root, propertyName, filter);
        if (indexMeta == null) {
            throw new IllegalArgumentException("No index for " + propertyName);
        }
        return getStrategy(indexMeta).query(filter, propertyName, indexMeta, encode(value));
    }

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        }
        return MIRROR;
    }


    public double getCost(Filter filter, String propertyName, PropertyValue value) {
        NodeState indexMeta = getIndexNode(root, propertyName, filter);
        if (indexMeta == null) {
            return Double.POSITIVE_INFINITY;
        }
        return getStrategy(indexMeta).count(indexMeta, encode(value), MAX_COST);
    }

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    @Nullable
    private static NodeState getIndexNode(
            NodeState node, String propertyName, Filter filter) {
        // keep a fallback to a matching index def that has *no* node type constraints
        // (initially, there is no fallback)
        NodeState fallback = null;


        NodeState state = node.getChildNode(INDEX_DEFINITIONS_NAME);
        for (ChildNodeEntry entry : state.getChildNodeEntries()) {
            NodeState index = entry.getNodeState();
            PropertyState type = index.getProperty(TYPE_PROPERTY_NAME);
            if (type == null || type.isArray() || !TYPE.equals(type.getValue(Type.STRING))) {
                continue;
            }
            if (contains(index.getNames(PROPERTY_NAMES), propertyName)) {
                NodeState indexContent = index.getChildNode(INDEX_CONTENT_NODE_NAME);
                if (!indexContent.exists()) {
                    continue;
                }
                Set<String> supertypes = getSuperTypes(filter);
                if (index.hasProperty(DECLARING_NODE_TYPES)) {
                    if (supertypes != null) {

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    @Override
    public synchronized void run() {
        log.debug("Running background index task {}", name);
        String checkpoint = store.checkpoint(lifetime);
        NodeState after = store.retrieve(checkpoint);
        if (after == null) {
            log.debug("Unable to retrieve checkpoint {}", checkpoint);
            return;
        }


        if(isAlreadyRunning(store)){
            log.debug("Async job found to be already running. Skipping");
            return;
        }


        NodeBuilder builder = store.getRoot().builder();
        NodeBuilder async = builder.child(ASYNC);


        NodeState before = null;
        final PropertyState state = async.getProperty(name);
        if (state != null && state.getType() == STRING) {
            before = store.retrieve(state.getValue(STRING));
        }
        if (before == null) {
            before = MISSING_NODE;
        }


        AsyncUpdateCallback callback = new AsyncUpdateCallback();
        IndexUpdate indexUpdate = new IndexUpdate(provider, name, after,
                builder, callback);


        CommitFailedException exception = EditorDiff.process(indexUpdate,
                before, after);
        if (exception == null && callback.dirty) {
            async.setProperty(name, checkpoint);
            try {
                store.merge(builder, new CommitHook() {
                    @Override @Nonnull
                    public NodeState processCommit(NodeState before,
                            NodeState after) throws CommitFailedException {
                        // check for concurrent updates by this async task
                        PropertyState stateAfterRebase = before
                                .getChildNode(ASYNC).getProperty(name);
                        if (Objects.equal(state, stateAfterRebase)) {
                            return postAsyncRunStatus(after.builder(), indexStats)
                                    .getNodeState();
                        } else {

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        else {
            NodeConflictHandler nodeConflictHandler = nodeConflictHandlers.get(conflictType);
            if (nodeConflictHandler != null) {
                for (ChildNodeEntry oursCNE : conflictInfo.getChildNodeEntries()) {
                    String name = oursCNE.getName();
                    NodeState ours = oursCNE.getNodeState();
                    NodeState theirs = parent.getChildNode(name);
                    Resolution resolution = nodeConflictHandler.resolve(name, ours, theirs);
                    applyResolution(resolution, conflictType, name, ours);
                }
            }
            else {

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        preAsyncRunStatus(builder, stats);
        store.merge(builder, EmptyHook.INSTANCE, null);
    }


    private static boolean isAlreadyRunning(NodeStore store) {
        NodeState indexState = store.getRoot().getChildNode(IndexConstants.INDEX_DEFINITIONS_NAME);


        //Probably the first run
        if (!indexState.exists()) {
            return false;
        }


        //Check if already running or timed out
        if (STATUS_RUNNING.equals(indexState.getString("async-status"))) {
            PropertyState startTime = indexState.getProperty("async-start");
            Calendar start = Conversions.convert(startTime.getValue(Type.DATE)).toCalendar();
            Calendar now = Calendar.getInstance();
            long delta = now.getTimeInMillis() - start.getTimeInMillis();


            //Check if the job has timed out and we need to take over

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org.apache.jackrabbit.oak.core.RootImpl

org.apache.jackrabbit.oak.core.SecureNodeBuilder

org.apache.jackrabbit.oak.core.SecureNodeState

org.apache.jackrabbit.oak.core.TreeImpl

org.apache.jackrabbit.oak.explorer.NodeStoreTree

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Examples of org.apache.jackrabbit.oak.spi.state.NodeState

Immutability and thread-safety

Persistence and error-handling

Existence and iterability of node states

Decoration and virtual content

Equality and hash codes

Related Classes of org.apache.jackrabbit.oak.spi.state.NodeState