1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
// Copyright 2018 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.lib.skyframe.serialization;
import com.google.common.base.Preconditions;
import com.google.common.reflect.ClassPath;
import com.google.common.reflect.ClassPath.ClassInfo;
import com.google.devtools.build.lib.skyframe.serialization.autocodec.RegisteredSingletonDoNotUse;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashSet;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.stream.Stream;
/**
* Scans the classpath to find {@link ObjectCodec} and {@link CodecRegisterer} instances.
*
* <p>To avoid loading classes unnecessarily, the scanner filters by class name before loading.
* {@link ObjectCodec} implementation class names should end in "Codec" while {@link
* CodecRegisterer} implementation class names should end in "CodecRegisterer".
*
* <p>See {@link CodecRegisterer} for more details.
*/
public class CodecScanner {
private static final Logger log = Logger.getLogger(CodecScanner.class.getName());
/**
* Initializes an {@link ObjectCodecRegistry} builder by scanning a given package prefix.
*
* @param packagePrefix processes only classes in packages having this prefix
* @see CodecRegisterer
*/
@SuppressWarnings("unchecked")
static ObjectCodecRegistry.Builder initializeCodecRegistry(String packagePrefix)
throws IOException, ReflectiveOperationException {
log.info("Building ObjectCodecRegistry");
ArrayList<Class<? extends ObjectCodec<?>>> codecs = new ArrayList<>();
ArrayList<Class<? extends CodecRegisterer<?>>> registerers = new ArrayList<>();
ObjectCodecRegistry.Builder builder = ObjectCodecRegistry.newBuilder();
getClassInfos(packagePrefix)
.forEach(
classInfo -> {
if (classInfo.getName().endsWith("Codec")) {
processLikelyCodec(classInfo.load(), codecs);
} else if (classInfo.getName().endsWith("CodecRegisterer")) {
processLikelyRegisterer(classInfo.load(), registerers);
} else if (classInfo
.getName()
.endsWith(CodecScanningConstants.REGISTERED_SINGLETON_SUFFIX)) {
processLikelyConstant(classInfo.load(), builder);
} else {
builder.addClassName(classInfo.getName().intern());
}
});
HashSet<Class<? extends ObjectCodec<?>>> alreadyRegistered =
runRegisterers(builder, registerers);
applyDefaultRegistration(builder, alreadyRegistered, codecs);
return builder;
}
@SuppressWarnings("unchecked")
private static void processLikelyCodec(
Class<?> type, ArrayList<Class<? extends ObjectCodec<?>>> codecs) {
if (!ObjectCodec.class.equals(type)
&& ObjectCodec.class.isAssignableFrom(type)
&& !Modifier.isAbstract(type.getModifiers())) {
codecs.add((Class<? extends ObjectCodec<?>>) type);
}
}
@SuppressWarnings("unchecked")
private static void processLikelyRegisterer(
Class<?> type, ArrayList<Class<? extends CodecRegisterer<?>>> registerers) {
if (!CodecRegisterer.class.equals(type) && CodecRegisterer.class.isAssignableFrom(type)) {
registerers.add((Class<? extends CodecRegisterer<?>>) type);
}
}
private static void processLikelyConstant(Class<?> type, ObjectCodecRegistry.Builder builder) {
if (!RegisteredSingletonDoNotUse.class.isAssignableFrom(type)) {
return;
}
Field field;
try {
field = type.getDeclaredField(CodecScanningConstants.REGISTERED_SINGLETON_INSTANCE_VAR_NAME);
} catch (NoSuchFieldException e) {
throw new IllegalStateException(
type
+ " inherits from "
+ RegisteredSingletonDoNotUse.class
+ " but does not have a field "
+ CodecScanningConstants.REGISTERED_SINGLETON_INSTANCE_VAR_NAME,
e);
}
try {
builder.addReferenceConstant(
Preconditions.checkNotNull(field.get(null), "%s %s", field, type));
} catch (IllegalAccessException e) {
throw new IllegalStateException("Could not access field " + field + " for " + type, e);
}
}
@SuppressWarnings("unchecked")
private static HashSet<Class<? extends ObjectCodec<?>>> runRegisterers(
ObjectCodecRegistry.Builder builder,
ArrayList<Class<? extends CodecRegisterer<?>>> registerers)
throws ReflectiveOperationException {
HashSet<Class<? extends ObjectCodec<?>>> registered = new HashSet<>();
for (Class<? extends CodecRegisterer<?>> registererType : registerers) {
Class<? extends ObjectCodec<?>> objectCodecType = getObjectCodecType(registererType);
registered.add(objectCodecType);
Constructor<CodecRegisterer<?>> constructor =
(Constructor<CodecRegisterer<?>>) registererType.getDeclaredConstructor();
constructor.setAccessible(true);
CodecRegisterer<?> registerer = constructor.newInstance();
for (ObjectCodec<?> codec : registerer.getCodecsToRegister()) {
builder.add(codec);
}
}
return registered;
}
@SuppressWarnings({"rawtypes", "unchecked"})
private static void applyDefaultRegistration(
ObjectCodecRegistry.Builder builder,
HashSet<Class<? extends ObjectCodec<?>>> alreadyRegistered,
ArrayList<Class<? extends ObjectCodec<?>>> codecs)
throws ReflectiveOperationException {
for (Class<? extends ObjectCodec<?>> codecType : codecs) {
if (alreadyRegistered.contains(codecType)) {
continue;
}
try {
Constructor constructor = codecType.getDeclaredConstructor();
constructor.setAccessible(true);
builder.add((ObjectCodec<?>) constructor.newInstance());
} catch (NoSuchMethodException e) {
log.log(
Level.FINE,
"Skipping registration of " + codecType + " because it had no default constructor.");
}
}
}
@SuppressWarnings("unchecked")
private static Class<? extends ObjectCodec<?>> getObjectCodecType(
Class<? extends CodecRegisterer<?>> registererType) {
Type typeArg =
((ParameterizedType)
registererType.getGenericInterfaces()[getCodecRegistererIndex(registererType)])
.getActualTypeArguments()[0];
// This occurs when the generic parameter of CodecRegisterer is not reified, for example:
// class MyCodecRegisterer<T> implements CodecRegisterer<T>
Preconditions.checkArgument(
typeArg instanceof Class,
"Illegal CodecRegisterer definition: %s"
+ "\nCodecRegisterer generic parameter must be reified.",
registererType);
return (Class<? extends ObjectCodec<?>>) typeArg;
}
private static int getCodecRegistererIndex(Class<? extends CodecRegisterer<?>> registererType) {
Class<?>[] interfaces = registererType.getInterfaces();
for (int i = 0; i < interfaces.length; ++i) {
if (CodecRegisterer.class.equals(interfaces[i])) {
return i;
}
}
// The following line is reached when there are multiple layers of inheritance involving
// CodecRegisterer, which is prohibited.
throw new IllegalStateException(registererType + " doesn't directly implement CodecRegisterer");
}
/** Return the {@link ClassInfo} objects matching {@code packagePrefix} sorted by name. */
private static Stream<ClassInfo> getClassInfos(String packagePrefix) throws IOException {
return ClassPath.from(ClassLoader.getSystemClassLoader())
.getResources()
.stream()
.filter(r -> r instanceof ClassInfo)
.map(r -> (ClassInfo) r)
.filter(c -> c.getPackageName().startsWith(packagePrefix))
.sorted(Comparator.comparing(ClassInfo::getName));
}
}
|
