1 /*
2 * This file is part of *** M y C o R e ***
3 * See http://www.mycore.de/ for details.
4 *
5 * MyCoRe is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, either version 3 of the License, or
8 * (at your option) any later version.
9 *
10 * MyCoRe is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with MyCoRe. If not, see <http://www.gnu.org/licenses/>.
17 */
18
19 package org.mycore.datamodel.ifs2;
20
21 import java.io.IOException;
22 import java.nio.file.Files;
23 import java.nio.file.Path;
24 import java.util.Iterator;
25
26 import org.mycore.common.MCRException;
27
28 import com.google.common.cache.CacheBuilder;
29 import com.google.common.cache.CacheLoader;
30 import com.google.common.cache.LoadingCache;
31
32 /**
33 * Stores file collections containing files and directories.
34 *
35 * For each store, properties must be defined, for example
36 *
37 * MCR.IFS2.Store.ID.Class=org.mycore.datamodel.ifs2.MCRFileStore
38 * MCR.IFS2.Store.ID.BaseDir=/foo/bar MCR.IFS2.Store.ID.SlotLayout=4-2-2
39 *
40 * @author Frank Lützenkirchen
41 */
42 public class MCRFileStore extends MCRStore {
43
44 private final MCRFileStore thisInstance;
45
46 //MCR-1868: prevents parallel threads to read and write mcrmeta.xml concurrently on instantiation
47 LoadingCache<Integer, MCRFileCollection> collectionLoadingCache = CacheBuilder.newBuilder()
48 .weakValues()
49 .build(new CacheLoader<Integer, MCRFileCollection>() {
50 @Override
51 public MCRFileCollection load(Integer key) throws Exception {
52 return new MCRFileCollection(thisInstance, key);
53 }
54 });
55
56 public MCRFileStore() {
57 super();
58 thisInstance = this;
59 }
60
61 /**
62 * Creates and stores a new, empty file collection using the next free ID in
63 * the store.
64 *
65 * @return a newly created file collection
66 */
67 public MCRFileCollection create() throws IOException {
68 int id = getNextFreeID();
69 return create(id);
70 }
71
72 /**
73 * Creates and stores a new, empty file collection with the given ID
74 *
75 * @param id
76 * the ID of the file collection
77 * @return a newly created file collection
78 * @throws IOException
79 * when a file collection with the given ID already exists
80 */
81 public MCRFileCollection create(int id) throws IOException {
82 Path path = getSlot(id);
83 if (Files.exists(path)) {
84 String msg = "FileCollection with ID " + id + " already exists";
85 throw new MCRException(msg);
86 }
87 return collectionLoadingCache.getUnchecked(id);
88 }
89
90 @Override
91 public void delete(int id) throws IOException {
92 Path path = getSlot(id);
93 if (Files.exists(path)) {
94 super.delete(path);
95 }
96 collectionLoadingCache.invalidate(id);
97 }
98
99 /**
100 * Returns the file collection stored under the given ID, or null when no
101 * collection is stored for the given ID.
102 *
103 * @param id
104 * the file collection's ID
105 * @return the file collection with the given ID, or null
106 */
107 public MCRFileCollection retrieve(int id) throws IOException {
108 Path path = getSlot(id);
109 if (!Files.exists(path)) {
110 return null;
111 } else {
112 return collectionLoadingCache.getUnchecked(id);
113 }
114 }
115
116 /**
117 * Repairs metadata of all file collections stored here
118 *
119 */
120 public void repairAllMetadata() throws IOException {
121 for (Iterator<Integer> e = listIDs(MCRStore.ASCENDING); e.hasNext();) {
122 retrieve(e.next()).repairMetadata();
123 }
124 }
125 }