Package org.apache.lucene.replicator
Files replication framework
The Replicator allows replicating files between a server and client(s). Producers publish revisions and consumers update to the latest revision available. ReplicationClient is a helper utility for performing the update operation. It can be invoked either manually or periodically by starting an update thread. HttpReplicator can be used to replicate revisions by consumers that reside on a different node than the producer.The replication framework supports replicating any type of files, with built-in support for a single search index as well as an index and taxonomy pair. For a single index, the application should publish an IndexRevision and set IndexReplicationHandler on the client. For an index and taxonomy pair, the application should publish an IndexAndTaxonomyRevision and set IndexAndTaxonomyReplicationHandler on the client.
When the replication client detects that there is a newer revision available, it copies the files of the revision and then invokes the handler to complete the operation (e.g. copy the files to the index directory, fsync them, reopen an index reader etc.). By default, only files that do not exist in the handler's current revision files are copied, however this can be overridden by extending the client.
An example usage of the Replicator:
// ++++++++++++++ SERVER SIDE ++++++++++++++ // IndexWriter publishWriter; // the writer used for indexing Replicator replicator = new LocalReplicator(); replicator.publish(new IndexRevision(publishWriter)); // ++++++++++++++ CLIENT SIDE ++++++++++++++ // // either LocalReplictor, or HttpReplicator if client and server are on different nodes Replicator replicator; // callback invoked after handler finished handling the revision and e.g. can reopen the reader. Callable<Boolean> callback = null; // can also be null if no callback is needed ReplicationHandler handler = new IndexReplicationHandler(indexDir, callback); SourceDirectoryFactory factory = new PerSessionDirectoryFactory(workDir); ReplicationClient client = new ReplicationClient(replicator, handler, factory); // invoke client manually client.updateNow(); // or, periodically client.startUpdateThread(100); // check for update every 100 milliseconds
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Interface Summary Interface Description ReplicationClient.ReplicationHandler Handler for revisions obtained by the client.ReplicationClient.SourceDirectoryFactory Resolves a session and source into aDirectory
to use for copying the session files to.Replicator An interface for replicating files.Revision A revision comprises lists of files that come from different sources and need to be replicated together to e.g. -
Class Summary Class Description IndexAndTaxonomyReplicationHandler AReplicationClient.ReplicationHandler
for replication of an index and taxonomy pair.IndexAndTaxonomyRevision ARevision
of a single index and taxonomy index files which comprises the list of files from both indexes.IndexAndTaxonomyRevision.SnapshotDirectoryTaxonomyWriter ADirectoryTaxonomyWriter
which sets the underlyingIndexWriter
'sIndexDeletionPolicy
toSnapshotDeletionPolicy
.IndexInputInputStream AnInputStream
which wraps anIndexInput
.IndexReplicationHandler AReplicationClient.ReplicationHandler
for replication of an index.IndexRevision ARevision
of a single index files which comprises the list of files that are part of the currentIndexCommit
.LocalReplicator AReplicator
implementation for use by the side that publishesRevision
s, as well for clients tocheck for updates
.PerSessionDirectoryFactory AReplicationClient.SourceDirectoryFactory
which returnsFSDirectory
under a dedicated session directory.ReplicationClient A client which monitors and obtains new revisions from aReplicator
.RevisionFile Describes a file in aRevision
.SessionToken Token for a replication session, for guaranteeing that source replicated files will be kept safe until the replication completes. -
Exception Summary Exception Description SessionExpiredException Exception indicating that a revision update session was expired due to lack of activity.