org.apache.hadoop.hbase.master.locking

Class LockProcedure

java.lang.Object

org.apache.hadoop.hbase.procedure2.Procedure<MasterProcedureEnv>

org.apache.hadoop.hbase.master.locking.LockProcedure

All Implemented Interfaces:

Comparable<Procedure<MasterProcedureEnv>>, TableProcedureInterface

@InterfaceAudience.Private
public final class LockProcedure
extends Procedure<MasterProcedureEnv>
implements TableProcedureInterface

Procedure to allow blessed clients and external admin tools to take our internal Schema locks used by the procedure framework isolating procedures doing creates/deletes etc. on table/namespace/regions. This procedure when scheduled, acquires specified locks, suspends itself and waits for:

• Call to unlock: if lock request came from the process itself, say master chore.
• Timeout : if lock request came from RPC. On timeout, evaluates if it should continue holding the lock or not based on last heartbeat timestamp.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.hbase.procedure2.Procedure

Procedure.LockState

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.master.procedure.TableProcedureInterface

TableProcedureInterface.TableOperationType

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_LOCAL_MASTER_LOCKS_TIMEOUT_MS
static int	DEFAULT_REMOTE_LOCKS_TIMEOUT_MS
static String	LOCAL_MASTER_LOCKS_TIMEOUT_MS_CONF
static String	REMOTE_LOCKS_TIMEOUT_MS_CONF

Fields inherited from class org.apache.hadoop.hbase.procedure2.Procedure

NO_PROC_ID, NO_TIMEOUT

Constructor Summary

Constructors

Constructor and Description
LockProcedure()
LockProcedure(org.apache.hadoop.conf.Configuration conf, RegionInfo[] regionInfos, LockType type, String description, CountDownLatch lockAcquireLatch) Constructor for region lock(s).
LockProcedure(org.apache.hadoop.conf.Configuration conf, String namespace, LockType type, String description, CountDownLatch lockAcquireLatch) Constructor for namespace lock.
LockProcedure(org.apache.hadoop.conf.Configuration conf, TableName tableName, LockType type, String description, CountDownLatch lockAcquireLatch) Constructor for table lock.

Method Summary

Modifier and Type	Method and Description
protected boolean	abort(MasterProcedureEnv env) The abort() call is asynchronous and each procedure must decide how to deal with it, if they want to be abortable.
protected Procedure.LockState	acquireLock(MasterProcedureEnv env) The user should override this method if they need a lock on an Entity.
protected void	beforeReplay(MasterProcedureEnv env) On recovery, re-execute from start to acquire the locks.
protected void	deserializeStateData(ProcedureStateSerializer serializer) Called on store load to allow the user to decode the previously serialized state.
protected Procedure<MasterProcedureEnv>[]	execute(MasterProcedureEnv env) The main code of the procedure.
String	getDescription()
TableName	getTableName()
TableProcedureInterface.TableOperationType	getTableOperationType() Given an operation type we can take decisions about what to do with pending operations.
LockType	getType()
boolean	holdLock(MasterProcedureEnv env) Used to keep the procedure lock even when the procedure is yielding or suspended.
boolean	isLocked()
protected void	releaseLock(MasterProcedureEnv env) The user should override this method, and release lock if necessary.
protected void	rollback(MasterProcedureEnv env) The code to undo what was done by the execute() code.
protected void	serializeStateData(ProcedureStateSerializer serializer) The user-level code of the procedure may have some state to persist (e.g.
protected boolean	setTimeoutFailure(MasterProcedureEnv env) Re run the procedure after every timeout to write new WAL entries so we don't hold back old WALs.
protected void	toStringClassDetails(StringBuilder builder) Extend the toString() information with the procedure details e.g.
void	unlock(MasterProcedureEnv env)
void	updateHeartBeat() Updates timeout deadline for the lock.

Methods inherited from class org.apache.hadoop.hbase.procedure2.Procedure

addStackIndex, afterReplay, bypass, compareTo, completionCleanup, doExecute, doRollback, elapsedTime, getChildrenLatch, getException, getLastUpdate, getNonceKey, getOwner, getParentProcId, getProcedureMetrics, getProcId, getProcIdHashCode, getProcName, getResult, getRootProcedureId, getRootProcId, getStackIndexes, getState, getSubmittedTime, getTimeout, getTimeoutTimestamp, hasChildren, hasException, hasLock, hasOwner, hasParent, hasTimeout, haveSameParent, incChildrenLatch, isBypass, isFailed, isFinished, isInitializing, isLockedWhenLoading, isRunnable, isSuccess, isWaiting, isYieldAfterExecutionStep, removeStackIndex, setAbortFailure, setChildrenLatch, setFailure, setFailure, setLastUpdate, setNonceKey, setOwner, setOwner, setParentProcId, setProcId, setResult, setRootProcId, setStackIndexes, setState, setSubmittedTime, setTimeout, shouldWaitClientAck, skipPersistence, toString, toStringClass, toStringDetails, toStringSimpleSB, toStringState, updateMetricsOnFinish, updateMetricsOnSubmit, updateTimestamp, waitInitialized, wasExecuted

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_REMOTE_LOCKS_TIMEOUT_MS

public static final int DEFAULT_REMOTE_LOCKS_TIMEOUT_MS

See Also:

Constant Field Values

REMOTE_LOCKS_TIMEOUT_MS_CONF

public static final String REMOTE_LOCKS_TIMEOUT_MS_CONF

See Also:

Constant Field Values

DEFAULT_LOCAL_MASTER_LOCKS_TIMEOUT_MS

public static final int DEFAULT_LOCAL_MASTER_LOCKS_TIMEOUT_MS

See Also:

Constant Field Values

LOCAL_MASTER_LOCKS_TIMEOUT_MS_CONF

public static final String LOCAL_MASTER_LOCKS_TIMEOUT_MS_CONF

See Also:

Constant Field Values

Constructor Detail

LockProcedure

public LockProcedure()

LockProcedure

public LockProcedure(org.apache.hadoop.conf.Configuration conf,
                     String namespace,
                     LockType type,
                     String description,
                     CountDownLatch lockAcquireLatch)
              throws IllegalArgumentException

Constructor for namespace lock.

Parameters:

lockAcquireLatch - if not null, the latch is decreased when lock is acquired.

Throws:

IllegalArgumentException

LockProcedure

public LockProcedure(org.apache.hadoop.conf.Configuration conf,
                     TableName tableName,
                     LockType type,
                     String description,
                     CountDownLatch lockAcquireLatch)
              throws IllegalArgumentException

Constructor for table lock.

Parameters:

lockAcquireLatch - if not null, the latch is decreased when lock is acquired.

Throws:

IllegalArgumentException

LockProcedure

public LockProcedure(org.apache.hadoop.conf.Configuration conf,
                     RegionInfo[] regionInfos,
                     LockType type,
                     String description,
                     CountDownLatch lockAcquireLatch)
              throws IllegalArgumentException

Constructor for region lock(s).

Parameters:

lockAcquireLatch - if not null, the latch is decreased when lock is acquired. Useful for locks acquired locally from master process.

Throws:

IllegalArgumentException - if all regions are not from same table.

Method Detail

getTableName

public TableName getTableName()

Specified by:

getTableName in interface TableProcedureInterface

Returns:

the name of the table the procedure is operating on

getTableOperationType

public TableProcedureInterface.TableOperationType getTableOperationType()

Description copied from interface: TableProcedureInterface

Given an operation type we can take decisions about what to do with pending operations. e.g. if we get a delete and we have some table operation pending (e.g. add column) we can abort those operations.

Specified by:

getTableOperationType in interface TableProcedureInterface

Returns:

the operation type that the procedure is executing.

updateHeartBeat

public void updateHeartBeat()

Updates timeout deadline for the lock.

setTimeoutFailure

protected boolean setTimeoutFailure(MasterProcedureEnv env)

Re run the procedure after every timeout to write new WAL entries so we don't hold back old WALs.

Overrides:

setTimeoutFailure in class Procedure<MasterProcedureEnv>

Returns:

false, so procedure framework doesn't mark this procedure as failure.

unlock

public void unlock(MasterProcedureEnv env)

execute

protected Procedure<MasterProcedureEnv>[] execute(MasterProcedureEnv env)
                                           throws ProcedureSuspendedException

Description copied from class: Procedure

The main code of the procedure. It must be idempotent since execute() may be called multiple times in case of machine failure in the middle of the execution.

Specified by:

execute in class Procedure<MasterProcedureEnv>

Parameters:

env - the environment passed to the ProcedureExecutor

Returns:

a set of sub-procedures to run or ourselves if there is more work to do or null if the procedure is done.

Throws:

ProcedureSuspendedException - Signal to the executor that Procedure has suspended itself and has set itself up waiting for an external event to wake it back up again.

rollback

protected void rollback(MasterProcedureEnv env)

Description copied from class: Procedure

The code to undo what was done by the execute() code. It is called when the procedure or one of the sub-procedures failed or an abort was requested. It should cleanup all the resources created by the execute() call. The implementation must be idempotent since rollback() may be called multiple time in case of machine failure in the middle of the execution.

Specified by:

rollback in class Procedure<MasterProcedureEnv>

Parameters:

env - the environment passed to the ProcedureExecutor

abort

protected boolean abort(MasterProcedureEnv env)

Description copied from class: Procedure

The abort() call is asynchronous and each procedure must decide how to deal with it, if they want to be abortable. The simplest implementation is to have an AtomicBoolean set in the abort() method and then the execute() will check if the abort flag is set or not. abort() may be called multiple times from the client, so the implementation must be idempotent.

NOTE: abort() is not like Thread.interrupt(). It is just a notification that allows the procedure implementor abort.

Specified by:

abort in class Procedure<MasterProcedureEnv>

serializeStateData

protected void serializeStateData(ProcedureStateSerializer serializer)
                           throws IOException

Description copied from class: Procedure

The user-level code of the procedure may have some state to persist (e.g. input arguments or current position in the processing state) to be able to resume on failure.

Specified by:

serializeStateData in class Procedure<MasterProcedureEnv>

Parameters:

serializer - stores the serializable state

Throws:

IOException

deserializeStateData

protected void deserializeStateData(ProcedureStateSerializer serializer)
                             throws IOException

Description copied from class: Procedure

Called on store load to allow the user to decode the previously serialized state.

Specified by:

deserializeStateData in class Procedure<MasterProcedureEnv>

Parameters:

serializer - contains the serialized state

Throws:

IOException

acquireLock

protected Procedure.LockState acquireLock(MasterProcedureEnv env)

Description copied from class: Procedure

The user should override this method if they need a lock on an Entity. A lock can be anything, and it is up to the implementor. The Procedure Framework will call this method just before it invokes Procedure.execute(Object). It calls Procedure.releaseLock(Object) after the call to execute.

If you need to hold the lock for the life of the Procedure -- i.e. you do not want any other Procedure interfering while this Procedure is running, see Procedure.holdLock(Object).

Example: in our Master we can execute request in parallel for different tables. We can create t1 and create t2 and these creates can be executed at the same time. Anything else on t1/t2 is queued waiting that specific table create to happen.

There are 3 LockState:

• LOCK_ACQUIRED should be returned when the proc has the lock and the proc is ready to execute.
• LOCK_YIELD_WAIT should be returned when the proc has not the lock and the framework should take care of readding the procedure back to the runnable set for retry
• LOCK_EVENT_WAIT should be returned when the proc has not the lock and someone will take care of readding the procedure back to the runnable set when the lock is available.

Overrides:

acquireLock in class Procedure<MasterProcedureEnv>

Returns:

the lock state as described above.

releaseLock

protected void releaseLock(MasterProcedureEnv env)

Description copied from class: Procedure

The user should override this method, and release lock if necessary.

Overrides:

releaseLock in class Procedure<MasterProcedureEnv>

beforeReplay

protected void beforeReplay(MasterProcedureEnv env)

On recovery, re-execute from start to acquire the locks. Need to explicitly set it to RUNNABLE because the procedure might have been in WAITING_TIMEOUT state when crash happened. In which case, it'll be sent back to timeout queue on recovery, which we don't want since we want to require locks.

Overrides:

beforeReplay in class Procedure<MasterProcedureEnv>

toStringClassDetails

protected void toStringClassDetails(StringBuilder builder)

Description copied from class: Procedure

Extend the toString() information with the procedure details e.g. className and parameters

Overrides:

toStringClassDetails in class Procedure<MasterProcedureEnv>

Parameters:

builder - the string builder to use to append the proc specific information

getType

public LockType getType()

getDescription

public String getDescription()

isLocked

public boolean isLocked()

holdLock

public boolean holdLock(MasterProcedureEnv env)

Description copied from class: Procedure

Used to keep the procedure lock even when the procedure is yielding or suspended.

Overrides:

holdLock in class Procedure<MasterProcedureEnv>

Returns:

true if the procedure should hold on the lock until completionCleanup()