org.apache.jackrabbit.oak.composite

Class CompositeNodeStore

java.lang.Object

org.apache.jackrabbit.oak.composite.CompositeNodeStore

All Implemented Interfaces:

Observable, NodeStore

public class CompositeNodeStore
extends java.lang.Object
implements NodeStore, Observable

A NodeStore implementation that combines other NodeStore instances mounted under paths defined by Mount.

The main objective of this implementation is to proxy operations working on at most single read-write store with any number of read-only stores. While the composition would technically work at the NodeStore level there are several less-than-obvious issues which prevent it:

1. Thread safety of the write operation can be quite costly, and will come on top of the thread safety measures already put in place by the composite node stores.
2. Many JCR subsystems require global state, e.g. the versioning store. This global state can become corrupt if multiple mounts operate on it or if mounts are added and removed.

As such, the only supported configuration is at most a single write-enabled store.

Because of the limitation described above, right now the only correct way to use CompositeNodeStore is to create a normal repository, split it into parts using oak-upgrade --{include,exclude}-paths and then configure this node store implementation to composite split parts together.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CompositeNodeStore.Builder

Method Summary

Modifier and Type	Method and Description
java.io.Closeable	addObserver(Observer observer) Register a new Observer.
java.lang.String	checkpoint(long lifetime) Creates a new checkpoint of the latest root of the tree.
java.lang.String	checkpoint(long lifetime, java.util.Map<java.lang.String,java.lang.String> properties) Creates a new checkpoint of the latest root of the tree.
java.util.Map<java.lang.String,java.lang.String>	checkpointInfo(java.lang.String checkpoint) Retrieve the properties associated with a checkpoint.
java.lang.Iterable<java.lang.String>	checkpoints() Returns all valid checkpoints.
Blob	createBlob(java.io.InputStream inputStream) Create a Blob from the given input stream.
Blob	getBlob(java.lang.String reference) Get a blob by its reference.
NodeState	getRoot() Returns the latest state of the tree.
NodeState	merge(NodeBuilder builder, CommitHook commitHook, CommitInfo info) Merges the changes between the base and head states of the given builder to this store.
NodeState	rebase(NodeBuilder builder) Rebases the changes between the base and head states of the given builder on top of the current root state.
boolean	release(java.lang.String checkpoint) Releases the provided checkpoint.
NodeState	reset(NodeBuilder builder) Reset the passed builder by throwing away all its changes and setting its base state to the current root state.
NodeState	retrieve(java.lang.String checkpoint) Retrieves the root node from a previously created repository checkpoint.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getRoot

public NodeState getRoot()

Description copied from interface: NodeStore

Returns the latest state of the tree.

Specified by:

getRoot in interface NodeStore

Returns:

root node state

merge

public NodeState merge(NodeBuilder builder,
                       CommitHook commitHook,
                       CommitInfo info)
                throws CommitFailedException

Description copied from interface: NodeStore

Merges the changes between the base and head states of the given builder to this store.

Specified by:

merge in interface NodeStore

Parameters:

builder - the builder whose changes to apply

commitHook - the commit hook to apply while merging changes

info - commit info associated with this merge operation

Returns:

the node state resulting from the merge.

Throws:

CommitFailedException - if the merge failed

rebase

public NodeState rebase(NodeBuilder builder)

Description copied from interface: NodeStore

Rebases the changes between the base and head states of the given builder on top of the current root state. The base state of the given builder becomes the latest root state of the repository, and the head state will contain the rebased changes.

Specified by:

rebase in interface NodeStore

Parameters:

builder - the builder to rebase

Returns:

the node state resulting from the rebase.

reset

public NodeState reset(NodeBuilder builder)

Description copied from interface: NodeStore

Reset the passed builder by throwing away all its changes and setting its base state to the current root state.

Specified by:

reset in interface NodeStore

Parameters:

builder - the builder to reset

Returns:

the node state resulting from the reset.

createBlob

public Blob createBlob(java.io.InputStream inputStream)
                throws java.io.IOException

Description copied from interface: NodeStore

Create a Blob from the given input stream. The input stream is closed after this method returns.

Specified by:

createBlob in interface NodeStore

Parameters:

inputStream - The input stream for the Blob

Returns:

The Blob representing inputStream

Throws:

java.io.IOException - If an error occurs while reading from the stream

getBlob

public Blob getBlob(java.lang.String reference)

Description copied from interface: NodeStore

Get a blob by its reference.

Specified by:

getBlob in interface NodeStore

Parameters:

reference - reference to the blob

Returns:

blob or null if the reference does not resolve to a blob.

See Also:

Blob.getReference()

checkpoints

public java.lang.Iterable<java.lang.String> checkpoints()

Description copied from interface: NodeStore

Returns all valid checkpoints. The returned Iterable provides a snapshot of valid checkpoints at the time this method is called. That is, the Iterable will not reflect checkpoints created after this method was called.

See NodeStore.checkpoint(long, Map) for a definition of a valid checkpoint.

Specified by:

checkpoints in interface NodeStore

Returns:

valid checkpoints.

checkpoint

public java.lang.String checkpoint(long lifetime,
                                   java.util.Map<java.lang.String,java.lang.String> properties)

Description copied from interface: NodeStore

Creates a new checkpoint of the latest root of the tree. The checkpoint remains valid for at least as long as requested and allows that state of the repository to be retrieved using the returned opaque string reference.

The properties passed to this methods are associated with the checkpoint and can be retrieved through the NodeStore.checkpointInfo(String) method. Its semantics is entirely application specific.

Specified by:

checkpoint in interface NodeStore

Parameters:

lifetime - time (in milliseconds, > 0) that the checkpoint should remain available

properties - properties to associate with the checkpoint

Returns:

string reference of this checkpoint

checkpoint

public java.lang.String checkpoint(long lifetime)

Description copied from interface: NodeStore

Creates a new checkpoint of the latest root of the tree. The checkpoint remains valid for at least as long as requested and allows that state of the repository to be retrieved using the returned opaque string reference.

This method is a shortcut for NodeStore.checkpoint(long, Map) passing an empty map for its 2nd argument.

Specified by:

checkpoint in interface NodeStore

Parameters:

lifetime - time (in milliseconds, > 0) that the checkpoint should remain available

Returns:

string reference of this checkpoint

checkpointInfo

public java.util.Map<java.lang.String,java.lang.String> checkpointInfo(java.lang.String checkpoint)

Description copied from interface: NodeStore

Retrieve the properties associated with a checkpoint.

Specified by:

checkpointInfo in interface NodeStore

Parameters:

checkpoint - string reference of a checkpoint

Returns:

the properties associated with the checkpoint referenced by checkpoint or an empty map when there is no such checkpoint.

retrieve

public NodeState retrieve(java.lang.String checkpoint)

Description copied from interface: NodeStore

Retrieves the root node from a previously created repository checkpoint.

Specified by:

retrieve in interface NodeStore

Parameters:

checkpoint - string reference of a checkpoint

Returns:

the root node of the checkpoint, or null if the checkpoint is no longer available

release

public boolean release(java.lang.String checkpoint)

Description copied from interface: NodeStore

Releases the provided checkpoint. If the provided checkpoint doesn't exist this method should return true.

Specified by:

release in interface NodeStore

Parameters:

checkpoint - string reference of a checkpoint

Returns:

true if the checkpoint was successfully removed, or if it doesn't exist

addObserver

public java.io.Closeable addObserver(Observer observer)

Description copied from interface: Observable

Register a new Observer. Clients need to call Closeable.close() to stop getting notifications on the registered observer and to free up any resources associated with the registration.

Specified by:

addObserver in interface Observable

Returns:

a Closeable instance.