org.eclipse.jgit.internal.ketch

Class KetchReplica

java.lang.Object

org.eclipse.jgit.internal.ketch.KetchReplica

Direct Known Subclasses:

LocalReplica, RemoteGitReplica

public abstract class KetchReplica
extends Object

A Ketch replica, either LocalReplica or RemoteGitReplica.

Replicas can be either a stock Git replica, or a Ketch-aware replica.

A stock Git replica has no special knowledge of Ketch and simply stores objects and references. Ketch communicates with the stock Git replica using the Git push wire protocol. The KetchLeader commits an agreed upon state by pushing all references to the Git replica, for example "refs/heads/master" is pushed during commit. Stock Git replicas use KetchReplica.CommitMethod.ALL_REFS to record the final state.

Ketch-aware replicas understand the RefTree sent during the proposal and during commit are able to update their own reference space to match the state represented by the RefTree. Ketch-aware replicas typically use a RefTreeDatabase and KetchReplica.CommitMethod.TXN_COMMITTED to record the final state.

KetchReplica instances are tightly coupled with a single KetchLeader. Some state may be accessed by the leader thread and uses the leader's own KetchLeader.lock to protect shared data.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	KetchReplica.CommitMethod How this replica wants to receive Ketch commit operations.
static class	KetchReplica.CommitSpeed Delay before committing to a replica.
static class	KetchReplica.Participation Participation of a replica in establishing consensus.
static class	KetchReplica.State Current state of a replica.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	KetchReplica(KetchLeader leader, String name, ReplicaConfig cfg) Configure a replica representation.

Method Summary

Methods

Modifier and Type	Method and Description
protected abstract void	blockingFetch(Repository repo, ReplicaFetchRequest req) Fetch objects from the remote using the calling thread.
protected String	describeForLog()
KetchReplica.CommitMethod	getCommitMethod()
KetchReplica.CommitSpeed	getCommitSpeed()
KetchLeader	getLeader()
String	getName()
KetchReplica.Participation	getParticipation()
KetchSystem	getSystem()
protected Collection<ReceiveCommand>	prepareCommit(Repository git, Map<String,Ref> current, ObjectId committed) Build a list of commands to commit KetchReplica.CommitMethod.ALL_REFS.
protected void	shutdown() Called by leader to perform graceful shutdown.
protected abstract void	startPush(ReplicaPushRequest req) Begin executing a single push.

Methods inherited from class java.lang.Object

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

Constructor Detail

KetchReplica

protected KetchReplica(KetchLeader leader,
            String name,
            ReplicaConfig cfg)

Configure a replica representation.

Parameters:

leader - instance this replica follows.

name - unique-ish name identifying this replica for debugging.

cfg - how Ketch should treat the replica.

Method Detail

getSystem

public KetchSystem getSystem()

Returns:

system configuration.

getLeader

public KetchLeader getLeader()

Returns:

leader instance this replica follows.

getName

public String getName()

Returns:

unique-ish name for debugging.

describeForLog

protected String describeForLog()

Returns:

description of this replica for error/debug logging purposes.

getParticipation

public KetchReplica.Participation getParticipation()

Returns:

how the replica participates in this Ketch system.

getCommitMethod

public KetchReplica.CommitMethod getCommitMethod()

Returns:

how Ketch will commit to the repository.

getCommitSpeed

public KetchReplica.CommitSpeed getCommitSpeed()

Returns:

when Ketch will commit to the repository.

shutdown

protected void shutdown()

Called by leader to perform graceful shutdown.

Default implementation cancels any scheduled retry. Subclasses may add additional logic before or after calling super.shutdown().

Called with KetchLeader.lock held by caller.

startPush

protected abstract void startPush(ReplicaPushRequest req)

Begin executing a single push.

This method must move processing onto another thread. Called with KetchLeader.lock held by caller.

Parameters:

req - the request to send to the replica.

blockingFetch

protected abstract void blockingFetch(Repository repo,
                 ReplicaFetchRequest req)
                               throws IOException

Fetch objects from the remote using the calling thread.

Called without KetchLeader.lock.

Parameters:

repo - local repository to fetch objects into.

req - the request to fetch from a replica.

Throws:

IOException - communication with the replica was not possible.

prepareCommit

protected Collection<ReceiveCommand> prepareCommit(Repository git,
                                       Map<String,Ref> current,
                                       ObjectId committed)
                                            throws IOException

Build a list of commands to commit KetchReplica.CommitMethod.ALL_REFS.

Parameters:

git - local leader repository to read committed state from.

current - all known references in the replica's repository. Typically this comes from a push advertisement.

committed - state being pushed to refs/txn/committed.

Returns:

commands to update during commit.

Throws:

IOException - cannot read the committed state.