com.hazelcast.cp.internal.session

Class RaftSessionService

java.lang.Object

com.hazelcast.cp.internal.session.RaftSessionService

All Implemented Interfaces:

SnapshotAwareService<com.hazelcast.cp.internal.session.RaftSessionRegistry>, RaftGroupLifecycleAwareService, SessionAccessor, TermChangeAwareService, CPSessionManagementService, ManagedService

public class RaftSessionService
extends Object
implements ManagedService, SnapshotAwareService<com.hazelcast.cp.internal.session.RaftSessionRegistry>, SessionAccessor, TermChangeAwareService, RaftGroupLifecycleAwareService, CPSessionManagementService

This service offers a set of abstractions to track liveliness of Hazelcast clients and servers that use (possibly blocking) data structures on the Raft layer, such as locks and semaphores. From the perspective of the Raft layer, there is no discrimination between Hazelcast clients and servers that use these data structures. A caller starts a session and sends periodic heartbeats to maintain its session. If there is no heartbeat for CPSubsystemConfig.getSessionTimeToLiveSeconds() seconds, its session is closed. That caller is considered to be alive as long as it is committing heartbeats.

Blocking Raft services can make use of the session abstraction to attach resources to sessions. On session termination, its attached resources will be released automatically.

Field Summary

Fields

Modifier and Type	Field and Description
static String	SERVICE_NAME

Constructor Summary

Constructors

Constructor and Description
RaftSessionService(NodeEngine nodeEngine)

Method Summary

Modifier and Type	Method and Description
void	closeInactiveSessions(CPGroupId groupId, Collection<Long> inactiveSessions)
boolean	closeSession(CPGroupId groupId, long sessionId)
SessionResponse	createNewSession(CPGroupId groupId, Address endpoint, String endpointName, CPSession.CPSessionOwnerType endpointType, long creationTime)
void	expireSessions(CPGroupId groupId, Collection<Tuple2<Long,Long>> sessionsToExpire)
ICompletableFuture<Boolean>	forceCloseSession(String groupName, long sessionId) If a Hazelcast instance that owns a CP session crashes, its CP session is not terminated immediately.
long	generateThreadId(CPGroupId groupId)
ICompletableFuture<Collection<CPSession>>	getAllSessions(String groupName) Returns a non-null collection of CP sessions that are currently active in the given CP group.
Collection<CPSession>	getSessionsLocally(CPGroupId groupId)
void	heartbeat(CPGroupId groupId, long sessionId) Performs a heartbeat for the given session id in the Raft group.
void	init(NodeEngine nodeEngine, Properties properties) Initializes this service.
boolean	isActive(CPGroupId groupId, long sessionId) Checks if there is an active session with the given id in the Raft group
void	onGroupDestroy(CPGroupId groupId) Called on the thread of the Raft group when the given Raft group is destroyed, either gracefully or forcefully.
void	onNewTermCommit(CPGroupId groupId, long commitIndex) Invokes as part of the first commit after a new leader is elected.
void	reset() Resets this service back to its initial state.
void	restoreSnapshot(CPGroupId groupId, long commitIndex, com.hazelcast.cp.internal.session.RaftSessionRegistry registry) Restores the snapshot for specified CPGroupId.
void	shutdown(boolean terminate) Shuts down this service.
com.hazelcast.cp.internal.session.RaftSessionRegistry	takeSnapshot(CPGroupId groupId, long commitIndex) Creates a snapshot for specified CPGroupId.

Methods inherited from class java.lang.Object

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

Field Detail

SERVICE_NAME

public static final String SERVICE_NAME

See Also:

Constant Field Values

Constructor Detail

RaftSessionService

public RaftSessionService(NodeEngine nodeEngine)

Method Detail

init

public void init(NodeEngine nodeEngine,
                 Properties properties)

Description copied from interface: ManagedService

Initializes this service.

Specified by:

init in interface ManagedService

Parameters:

nodeEngine - the NodeEngine that this service belongs to

properties - the Properties (can be used to pass settings to the service)

reset

public void reset()

Description copied from interface: ManagedService

Resets this service back to its initial state.

TODO: what is the purpose of reset

Specified by:

reset in interface ManagedService

shutdown

public void shutdown(boolean terminate)

Description copied from interface: ManagedService

Shuts down this service.

TODO: what is the purpose of the terminate variable

Specified by:

shutdown in interface ManagedService

Parameters:

terminate - true to shut down this service

takeSnapshot

public com.hazelcast.cp.internal.session.RaftSessionRegistry takeSnapshot(CPGroupId groupId,
                                                                          long commitIndex)

Description copied from interface: SnapshotAwareService

Creates a snapshot for specified CPGroupId. The snapshot object returned from this method will be stored among the Raft log and it can be sent to other Raft nodes anytime. Therefore, this method must not return a snapshot object that can mutate after the takeSnapshot() call.

Specified by:

takeSnapshot in interface SnapshotAwareService<com.hazelcast.cp.internal.session.RaftSessionRegistry>

Parameters:

groupId - CPGroupId which is snapshot requested for

commitIndex - commitIndex of the taken snapshot

Returns:

snapshot for specified CPGroupId.

restoreSnapshot

public void restoreSnapshot(CPGroupId groupId,
                            long commitIndex,
                            com.hazelcast.cp.internal.session.RaftSessionRegistry registry)

Description copied from interface: SnapshotAwareService

Restores the snapshot for specified CPGroupId.

Specified by:

restoreSnapshot in interface SnapshotAwareService<com.hazelcast.cp.internal.session.RaftSessionRegistry>

Parameters:

groupId - CPGroupId of the snapshot to be restored

commitIndex - commitIndex of the restored snapshot

registry - snapshot for specified CPGroupId

onNewTermCommit

public void onNewTermCommit(CPGroupId groupId,
                            long commitIndex)

Description copied from interface: TermChangeAwareService

Invokes as part of the first commit after a new leader is elected.

Specified by:

onNewTermCommit in interface TermChangeAwareService

Parameters:

groupId - id of the Raft group in which a new leader is elected

commitIndex - index of the commit in the Raft log

onGroupDestroy

public void onGroupDestroy(CPGroupId groupId)

Description copied from interface: RaftGroupLifecycleAwareService

Called on the thread of the Raft group when the given Raft group is destroyed, either gracefully or forcefully.

Specified by:

onGroupDestroy in interface RaftGroupLifecycleAwareService

getAllSessions

public ICompletableFuture<Collection<CPSession>> getAllSessions(String groupName)

Description copied from interface: CPSessionManagementService

Returns a non-null collection of CP sessions that are currently active in the given CP group.

Specified by:

getAllSessions in interface CPSessionManagementService

forceCloseSession

public ICompletableFuture<Boolean> forceCloseSession(String groupName,
                                                     long sessionId)

Description copied from interface: CPSessionManagementService

If a Hazelcast instance that owns a CP session crashes, its CP session is not terminated immediately. Instead, the session will be closed after CPSubsystemConfig.getSessionTimeToLiveSeconds() passes. If it is known for sure that the session owner is not partitioned and definitely crashed, this method can be used for closing the session and releasing its resources immediately.

Specified by:

forceCloseSession in interface CPSessionManagementService

createNewSession

public SessionResponse createNewSession(CPGroupId groupId,
                                        Address endpoint,
                                        String endpointName,
                                        CPSession.CPSessionOwnerType endpointType,
                                        long creationTime)

heartbeat

public void heartbeat(CPGroupId groupId,
                      long sessionId)

Description copied from interface: SessionAccessor

Performs a heartbeat for the given session id in the Raft group.

Specified by:

heartbeat in interface SessionAccessor

closeSession

public boolean closeSession(CPGroupId groupId,
                            long sessionId)

expireSessions

public void expireSessions(CPGroupId groupId,
                           Collection<Tuple2<Long,Long>> sessionsToExpire)

closeInactiveSessions

public void closeInactiveSessions(CPGroupId groupId,
                                  Collection<Long> inactiveSessions)

generateThreadId

public long generateThreadId(CPGroupId groupId)

getSessionsLocally

public Collection<CPSession> getSessionsLocally(CPGroupId groupId)

isActive

public boolean isActive(CPGroupId groupId,
                        long sessionId)

Description copied from interface: SessionAccessor

Checks if there is an active session with the given id in the Raft group

Specified by:

isActive in interface SessionAccessor

Returns:

true if the session is found, false otherwise