1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 Google Inc. All rights reserved. 3 // https://developers.google.com/protocol-buffers/ 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions are 7 // met: 8 // 9 // * Redistributions of source code must retain the above copyright 10 // notice, this list of conditions and the following disclaimer. 11 // * Redistributions in binary form must reproduce the above 12 // copyright notice, this list of conditions and the following disclaimer 13 // in the documentation and/or other materials provided with the 14 // distribution. 15 // * Neither the name of Google Inc. nor the names of its 16 // contributors may be used to endorse or promote products derived from 17 // this software without specific prior written permission. 18 // 19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31 package com.google.protobuf; 32 33 import java.util.Collections; 34 import java.util.HashMap; 35 import java.util.Map; 36 37 /** 38 * Equivalent to {@link ExtensionRegistry} but supports only "lite" types. 39 * 40 * <p>If all of your types are lite types, then you only need to use {@code ExtensionRegistryLite}. 41 * Similarly, if all your types are regular types, then you only need {@link ExtensionRegistry}. 42 * Typically it does not make sense to mix the two, since if you have any regular types in your 43 * program, you then require the full runtime and lose all the benefits of the lite runtime, so you 44 * might as well make all your types be regular types. However, in some cases (e.g. when depending 45 * on multiple third-party libraries where one uses lite types and one uses regular), you may find 46 * yourself wanting to mix the two. In this case things get more complicated. 47 * 48 * <p>There are three factors to consider: Whether the type being extended is lite, whether the 49 * embedded type (in the case of a message-typed extension) is lite, and whether the extension 50 * itself is lite. Since all three are declared in different files, they could all be different. 51 * Here are all the combinations and which type of registry to use: 52 * 53 * <pre> 54 * Extended type Inner type Extension Use registry 55 * ======================================================================= 56 * lite lite lite ExtensionRegistryLite 57 * lite regular lite ExtensionRegistry 58 * regular regular regular ExtensionRegistry 59 * all other combinations not supported 60 * </pre> 61 * 62 * <p>Note that just as regular types are not allowed to contain lite-type fields, they are also not 63 * allowed to contain lite-type extensions. This is because regular types must be fully accessible 64 * via reflection, which in turn means that all the inner messages must also support reflection. On 65 * the other hand, since regular types implement the entire lite interface, there is no problem with 66 * embedding regular types inside lite types. 67 * 68 * @author kenton@google.com Kenton Varda 69 */ 70 public class ExtensionRegistryLite { 71 72 // Set true to enable lazy parsing feature for MessageSet. 73 // 74 // TODO(xiangl): Now we use a global flag to control whether enable lazy 75 // parsing feature for MessageSet, which may be too crude for some 76 // applications. Need to support this feature on smaller granularity. 77 private static volatile boolean eagerlyParseMessageSets = false; 78 79 // short circuit the ExtensionRegistryFactory via assumevalues trickery 80 @SuppressWarnings("JavaOptionalSuggestions") 81 private static boolean doFullRuntimeInheritanceCheck = true; 82 83 // Visible for testing. 84 static final String EXTENSION_CLASS_NAME = "com.google.protobuf.Extension"; 85 86 private static class ExtensionClassHolder { 87 /* @Nullable */ 88 static final Class<?> INSTANCE = resolveExtensionClass(); 89 90 /* @Nullable */ resolveExtensionClass()91 static Class<?> resolveExtensionClass() { 92 try { 93 return Class.forName(EXTENSION_CLASS_NAME); 94 } catch (ClassNotFoundException e) { 95 // See comment in ExtensionRegistryFactory on the potential expense of this. 96 return null; 97 } 98 } 99 } 100 isEagerlyParseMessageSets()101 public static boolean isEagerlyParseMessageSets() { 102 return eagerlyParseMessageSets; 103 } 104 setEagerlyParseMessageSets(boolean isEagerlyParse)105 public static void setEagerlyParseMessageSets(boolean isEagerlyParse) { 106 eagerlyParseMessageSets = isEagerlyParse; 107 } 108 109 /** 110 * Construct a new, empty instance. 111 * 112 * <p>This may be an {@code ExtensionRegistry} if the full (non-Lite) proto libraries are 113 * available. 114 */ newInstance()115 public static ExtensionRegistryLite newInstance() { 116 return doFullRuntimeInheritanceCheck 117 ? ExtensionRegistryFactory.create() 118 : new ExtensionRegistryLite(); 119 } 120 121 private static volatile ExtensionRegistryLite emptyRegistry; 122 123 /** 124 * Get the unmodifiable singleton empty instance of either ExtensionRegistryLite or {@code 125 * ExtensionRegistry} (if the full (non-Lite) proto libraries are available). 126 */ getEmptyRegistry()127 public static ExtensionRegistryLite getEmptyRegistry() { 128 ExtensionRegistryLite result = emptyRegistry; 129 if (result == null) { 130 synchronized (ExtensionRegistryLite.class) { 131 result = emptyRegistry; 132 if (result == null) { 133 result = 134 emptyRegistry = 135 doFullRuntimeInheritanceCheck 136 ? ExtensionRegistryFactory.createEmpty() 137 : EMPTY_REGISTRY_LITE; 138 } 139 } 140 } 141 return result; 142 } 143 144 145 /** Returns an unmodifiable view of the registry. */ getUnmodifiable()146 public ExtensionRegistryLite getUnmodifiable() { 147 return new ExtensionRegistryLite(this); 148 } 149 150 /** 151 * Find an extension by containing type and field number. 152 * 153 * @return Information about the extension if found, or {@code null} otherwise. 154 */ 155 @SuppressWarnings("unchecked") 156 public <ContainingType extends MessageLite> findLiteExtensionByNumber( final ContainingType containingTypeDefaultInstance, final int fieldNumber)157 GeneratedMessageLite.GeneratedExtension<ContainingType, ?> findLiteExtensionByNumber( 158 final ContainingType containingTypeDefaultInstance, final int fieldNumber) { 159 return (GeneratedMessageLite.GeneratedExtension<ContainingType, ?>) 160 extensionsByNumber.get(new ObjectIntPair(containingTypeDefaultInstance, fieldNumber)); 161 } 162 163 /** Add an extension from a lite generated file to the registry. */ add(final GeneratedMessageLite.GeneratedExtension<?, ?> extension)164 public final void add(final GeneratedMessageLite.GeneratedExtension<?, ?> extension) { 165 extensionsByNumber.put( 166 new ObjectIntPair(extension.getContainingTypeDefaultInstance(), extension.getNumber()), 167 extension); 168 } 169 170 /** 171 * Add an extension from a lite generated file to the registry only if it is a non-lite extension 172 * i.e. {@link GeneratedMessageLite.GeneratedExtension}. 173 */ add(ExtensionLite<?, ?> extension)174 public final void add(ExtensionLite<?, ?> extension) { 175 if (GeneratedMessageLite.GeneratedExtension.class.isAssignableFrom(extension.getClass())) { 176 add((GeneratedMessageLite.GeneratedExtension<?, ?>) extension); 177 } 178 if (doFullRuntimeInheritanceCheck && ExtensionRegistryFactory.isFullRegistry(this)) { 179 try { 180 this.getClass().getMethod("add", ExtensionClassHolder.INSTANCE).invoke(this, extension); 181 } catch (Exception e) { 182 throw new IllegalArgumentException( 183 String.format("Could not invoke ExtensionRegistry#add for %s", extension), e); 184 } 185 } 186 } 187 188 // ================================================================= 189 // Private stuff. 190 191 // Constructors are package-private so that ExtensionRegistry can subclass 192 // this. 193 ExtensionRegistryLite()194 ExtensionRegistryLite() { 195 this.extensionsByNumber = 196 new HashMap<ObjectIntPair, GeneratedMessageLite.GeneratedExtension<?, ?>>(); 197 } 198 199 static final ExtensionRegistryLite EMPTY_REGISTRY_LITE = new ExtensionRegistryLite(true); 200 ExtensionRegistryLite(ExtensionRegistryLite other)201 ExtensionRegistryLite(ExtensionRegistryLite other) { 202 if (other == EMPTY_REGISTRY_LITE) { 203 this.extensionsByNumber = Collections.emptyMap(); 204 } else { 205 this.extensionsByNumber = Collections.unmodifiableMap(other.extensionsByNumber); 206 } 207 } 208 209 private final Map<ObjectIntPair, GeneratedMessageLite.GeneratedExtension<?, ?>> 210 extensionsByNumber; 211 ExtensionRegistryLite(boolean empty)212 ExtensionRegistryLite(boolean empty) { 213 this.extensionsByNumber = Collections.emptyMap(); 214 } 215 216 /** A (Object, int) pair, used as a map key. */ 217 private static final class ObjectIntPair { 218 private final Object object; 219 private final int number; 220 ObjectIntPair(final Object object, final int number)221 ObjectIntPair(final Object object, final int number) { 222 this.object = object; 223 this.number = number; 224 } 225 226 @Override hashCode()227 public int hashCode() { 228 return System.identityHashCode(object) * ((1 << 16) - 1) + number; 229 } 230 231 @Override equals(final Object obj)232 public boolean equals(final Object obj) { 233 if (!(obj instanceof ObjectIntPair)) { 234 return false; 235 } 236 final ObjectIntPair other = (ObjectIntPair) obj; 237 return object == other.object && number == other.number; 238 } 239 } 240 } 241