001/* 002 * Licensed to DuraSpace under one or more contributor license agreements. 003 * See the NOTICE file distributed with this work for additional information 004 * regarding copyright ownership. 005 * 006 * DuraSpace licenses this file to you under the Apache License, 007 * Version 2.0 (the "License"); you may not use this file except in 008 * compliance with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.fcrepo.http.api; 019 020import javax.jcr.Session; 021 022import org.fcrepo.kernel.api.services.NodeService; 023 024/** 025 * An interface representing a utility whose locking methods can enforce 026 * the kinds of concurrency restrictions appropriate for an otherwise 027 * concurrency-naive application that operates on hierarchical resources 028 * represented by paths (as in URIs or filesystems). 029 * 030 * @author Mike Durbin 031 */ 032public interface PathLockManager { 033 034 /** 035 * An interface representing a lock (comparable to that defined in 036 * java.util.concurrent.locks) that has been acquired. Memory management 037 * for instances of this lock is handled by LockManager instances and 038 * anyone else receiving one of these such locks from a LockManager 039 * should not retain a reference to the used lock after releasing it. 040 */ 041 public interface AcquiredLock { 042 043 /** 044 * Releases the lock, after which it's useless. 045 */ 046 public void release(); 047 } 048 049 /** 050 * Locks the necessary resources affected in order to safely view a resource 051 * at the given path. A successful return from this method should guarantee 052 * that until release() is invoked on the returned Lock that no changes are made 053 * to the resource that would affect its display. 054 * 055 * @param path the path to a resource to be viewed 056 * @return an acquired Lock on the relevant resources 057 */ 058 public AcquiredLock lockForRead(String path); 059 060 /** 061 * Locks the necessary resources affected in order to safely write to a resource 062 * at the given path. A successful return from this method should guarantee 063 * that until release() is invoked on the returned Lock that no other callers 064 * may be granted locks necessary to add, modify or delete the resource at the 065 * provided path. 066 * 067 * @param path the path to a resource to be created (may involve implicitly created 068 * resources at parent paths) 069 * @param session the current session 070 * @param nodeService the repository NodeService implementation 071 * @return an acquired Lock on the relevant resources 072 */ 073 public AcquiredLock lockForWrite(String path, Session session, NodeService nodeService); 074 075 /** 076 * Locks the necessary resources affected in order to safely delete a resource 077 * at the given path. A successful return from this method should guarantee 078 * that until release() is invoked on the returned Lock that no other callers 079 * may be granted locks necessary to add, modify or delete the resource at the 080 * provided path or any child path (because deletes cascade). 081 * 082 * @param path the path to a resource to be deleted (may imply the deletion of 083 * all descendant resources) 084 * @return an acquired Lock on the relevant resources 085 */ 086 public AcquiredLock lockForDelete(String path); 087 088}