1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18 package org.apache.river.outrigger.proxy;
19
20 import java.rmi.RemoteException;
21
22 import net.jini.core.entry.Entry;
23 import net.jini.core.entry.UnusableEntryException;
24 import net.jini.core.lease.Lease;
25 import net.jini.id.Uuid;
26 import net.jini.space.MatchSet;
27
28 /**
29 * Outrigger's implementation of <code>MatchSet</code>.
30 * Outrigger's implementation of the <code>JavaSpace05.contents</code>
31 * method returns objects of this type. Created with an initial set of
32 * entries from the match set and supports pre-fetching whenever it
33 * needs additional entries. <code>RemoteException</code>s encountered
34 * when making a remote call to fetch the next batch of entries from
35 * the space generally do not invalidate the proxy or the match set.
36 * <p>
37 * Note, there is no way to serialize or otherwise copy instances of
38 * this class so the default equals implementation should suffice.
39 */
40 class MatchSetProxy implements MatchSet {
41 /** The remote server this proxy works with. */
42 final private OutriggerServer space;
43
44 /** ID of the associated query (and lease) */
45 final private Uuid uuid;
46
47 /** Lease assocated with this query */
48 final private Lease lease;
49
50 /** Last batch fetched from server */
51 private volatile EntryRep[] reps;
52
53 /** Last rep returned */
54 private volatile EntryRep lastRepReturned;
55
56 /** Current index into reps */
57 private volatile int i;
58
59 /** True if reps[i] could not be unpacked */
60 private volatile boolean unpackFailure = true;
61
62 MatchSetProxy(MatchSetData inital, SpaceProxy2 parent, OutriggerServer space) {
63 uuid = inital.uuid;
64 this.space = space;
65 if (uuid != null)
66 lease = parent.newLease(uuid, inital.intialLeaseDuration);
67 else
68 lease = null;
69 reps = inital.reps;
70
71 i=0;
72 }
73
74 public Lease getLease() {
75 return lease;
76 }
77
78 public Entry next() throws RemoteException, UnusableEntryException {
79 if (i >= reps.length) {
80 // Fetch another batch
81 i = 0;
82 reps = space.nextBatch(uuid, lastRepReturned.id());
83 }
84
85 if (reps[i] == null)
86 return null;
87
88 unpackFailure = true;
89 lastRepReturned = reps[i++];
90 final Entry rslt = lastRepReturned.entry();
91 unpackFailure = false;
92 return rslt;
93 }
94
95 public Entry getSnapshot() {
96 if (unpackFailure)
97 throw new IllegalStateException(
98 "getSnapshot - need successful next call first");
99
100 return new SnapshotRep(lastRepReturned);
101 }
102
103 public String toString() {
104 return getClass().getName() + " for " + uuid +
105 " (through " + space + ")";
106 }
107 }