com.bigdata.journal.IResourceLockService Maven / Gradle / Ivy
/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
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This program is distributed in the hope that it will be useful,
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
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along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Jul 10, 2008
*/
package com.bigdata.journal;
import java.util.concurrent.TimeoutException;
import com.bigdata.relation.AbstractResource;
/**
* Interface named synchronous distributed locks without deadlock detection.
*
* @author Bryan Thompson
* @version $Id$
*
* FIXME Two features need to be teased apart. On the one hand there are full
* tx, which provide deadlock detection and could support hierarchical locking
* (with changes to the lock manager to decouple threads from lock queues, the
* imposition of a path syntax on the resource names, and perhaps the
* introduction of 2PL lock modes {S,I,X}). This lock manager could then be
* exposed, providing applications with the possibility of 2PL, but bigdata does
* not require that in and of itself (it might be of interest for others).
*
* The other feature is distributed locks without deadlock detection. This is
* the kind of lock that you get with zookeeper. When running in a single JVM
* java.util.concurrent.locks provides this kind of locking. These locks are
* good for coordinating actions such as who is the master in some computation.
*
* This second role (global synchronous locks without deadlock detection) can be
* realized by a client library. When running in a single JVM, the
* java.util.concurrent.locks package can provide the implementation. When
* running in a distributed environment, zookeeper can provide the
* implementation.
*
* FIXME The main use of this interface today is creating and destroying
* relations, relation containers, and their indices "atomically". Unisolated
* operations CAN NOT be used to create more than a single resource atomically.
* A full tx should be used instead. The place where this happens is
* {@link AbstractResource#acquireExclusiveLock()}. That is invoked only when
* creating or destroying a resource. All callers should be using a full tx
* instead when creating or destroying a resource!
*/
public interface IResourceLockService {
/**
* Acquire an exclusive lock on the named resource. The request will block
* until the lock is available.
*
* @param namespace
* The named resource.
*
* @return The lock.
*
* @throws RuntimeException
* wrapping {@link InterruptedException} or
* {@link TimeoutException}
*/
public IResourceLock acquireLock(String namespace);
/**
* Acquire an exclusive lock the named resource. The request will block
* until the lock is available or the timeout expires.
*
* @param namespace
* The named resource.
* @param timeout
* Timeout in milliseconds for the request -or-
* {@link Long#MAX_VALUE} to wait forever.
*
* @return The lock.
*
* @throws TimeoutException
* @throws InterruptedException
*/
public IResourceLock acquireLock(String namespace, long timeout)
throws InterruptedException, TimeoutException;
}