1 /*
 2  * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.  Oracle designates this
 8  * particular file as subject to the "Classpath" exception as provided
 9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 
26 package hat.ifacemapper;
27 
28 import hat.ifacemapper.accessor.AccessorInfo;
29 //import jdk.internal.ValueBased;
30 
31 
32 import java.lang.foreign.GroupLayout;
33 import java.lang.invoke.MethodHandle;
34 import java.lang.invoke.MethodHandles;
35 import java.util.HashMap;
36 import java.util.Map;
37 import java.util.function.Consumer;
38 
39 /**
40  * This class maintains a cache of seen sub-mappers, so they do not have to be created more
41  * than once. Creating a sub-mapper is a relatively expensive operation.
42  */
43 //@ValueBased
44 final class MapperCache {
45 
46     private final MethodHandles.Lookup lookup;
47     private final Map<CacheKey, SegmentMapper<?>> subMappers;
48 
49     private MapperCache(MethodHandles.Lookup lookup) {
50         this.lookup = lookup;
51         this.subMappers = new HashMap<>();
52     }
53 
54     MethodHandle interfaceGetMethodHandleFor(AccessorInfo accessorInfo,
55                                              Consumer<? super SegmentInterfaceMapper.AffectedMemory> adder) {
56         SegmentInterfaceMapper<?> innerMapper = (SegmentInterfaceMapper<?>) cachedInterfaceMapper(accessorInfo);
57         innerMapper.affectedMemories().stream()
58                 .map(am -> am.translate(accessorInfo.offset()))
59                 .forEach(adder);
60         return innerMapper.getHandle();
61     }
62 
63     private SegmentMapper<?> cachedInterfaceMapper(AccessorInfo accessorInfo) {
64         return subMappers.computeIfAbsent(CacheKey.of(accessorInfo), k ->
65                 SegmentMapper.of(lookup, k.type(), k.layout()));
66     }
67 
68     record CacheKey(Class<?> type,
69                     GroupLayout layout) {
70 
71         static CacheKey of(AccessorInfo accessorInfo) {
72             return of(accessorInfo.type(), accessorInfo.targetLayout().withoutName());
73         }
74 
75         static CacheKey of(Class<?> type, GroupLayout layout) {
76             return new CacheKey(type, layout.withoutName());
77         }
78 
79     }
80 
81     static MapperCache of(MethodHandles.Lookup lookup) {
82         return new MapperCache(lookup);
83     }
84 
85 }