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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 #import "GPBRootObject_PackagePrivate.h" | |
32 | |
33 #import <objc/runtime.h> | |
34 #import <libkern/OSAtomic.h> | |
35 | |
36 #import <CoreFoundation/CoreFoundation.h> | |
37 | |
38 #import "GPBDescriptor.h" | |
39 #import "GPBExtensionRegistry.h" | |
40 #import "GPBUtilities_PackagePrivate.h" | |
41 | |
42 @interface GPBExtensionDescriptor (GPBRootObject) | |
43 // Get singletonName as a c string. | |
44 - (const char *)singletonNameC; | |
45 @end | |
46 | |
47 @implementation GPBRootObject | |
48 | |
49 // Taken from http://www.burtleburtle.net/bob/hash/doobs.html | |
50 // Public Domain | |
51 static uint32_t jenkins_one_at_a_time_hash(const char *key) { | |
52 uint32_t hash = 0; | |
53 for (uint32_t i = 0; key[i] != '\0'; ++i) { | |
54 hash += key[i]; | |
55 hash += (hash << 10); | |
56 hash ^= (hash >> 6); | |
57 } | |
58 hash += (hash << 3); | |
59 hash ^= (hash >> 11); | |
60 hash += (hash << 15); | |
61 return hash; | |
62 } | |
63 | |
64 // Key methods for our custom CFDictionary. | |
65 // Note that the dictionary lasts for the lifetime of our app, so no need | |
66 // to worry about deallocation. All of the items are added to it at | |
67 // startup, and so the keys don't need to be retained/released. | |
68 // Keys are NULL terminated char *. | |
69 static const void *GPBRootExtensionKeyRetain(CFAllocatorRef allocator, | |
70 const void *value) { | |
71 #pragma unused(allocator) | |
72 return value; | |
73 } | |
74 | |
75 static void GPBRootExtensionKeyRelease(CFAllocatorRef allocator, | |
76 const void *value) { | |
77 #pragma unused(allocator) | |
78 #pragma unused(value) | |
79 } | |
80 | |
81 static CFStringRef GPBRootExtensionCopyKeyDescription(const void *value) { | |
82 const char *key = (const char *)value; | |
83 return CFStringCreateWithCString(kCFAllocatorDefault, key, | |
84 kCFStringEncodingUTF8); | |
85 } | |
86 | |
87 static Boolean GPBRootExtensionKeyEqual(const void *value1, | |
88 const void *value2) { | |
89 const char *key1 = (const char *)value1; | |
90 const char *key2 = (const char *)value2; | |
91 return strcmp(key1, key2) == 0; | |
92 } | |
93 | |
94 static CFHashCode GPBRootExtensionKeyHash(const void *value) { | |
95 const char *key = (const char *)value; | |
96 return jenkins_one_at_a_time_hash(key); | |
97 } | |
98 | |
99 static OSSpinLock gExtensionSingletonDictionaryLock_ = OS_SPINLOCK_INIT; | |
100 static CFMutableDictionaryRef gExtensionSingletonDictionary = NULL; | |
101 static GPBExtensionRegistry *gDefaultExtensionRegistry = NULL; | |
102 | |
103 + (void)initialize { | |
104 // Ensure the global is started up. | |
105 if (!gExtensionSingletonDictionary) { | |
106 CFDictionaryKeyCallBacks keyCallBacks = { | |
107 // See description above for reason for using custom dictionary. | |
108 0, | |
109 GPBRootExtensionKeyRetain, | |
110 GPBRootExtensionKeyRelease, | |
111 GPBRootExtensionCopyKeyDescription, | |
112 GPBRootExtensionKeyEqual, | |
113 GPBRootExtensionKeyHash, | |
114 }; | |
115 gExtensionSingletonDictionary = | |
116 CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &keyCallBacks, | |
117 &kCFTypeDictionaryValueCallBacks); | |
118 gDefaultExtensionRegistry = [[GPBExtensionRegistry alloc] init]; | |
119 } | |
120 | |
121 if ([self superclass] == [GPBRootObject class]) { | |
122 // This is here to start up all the per file "Root" subclasses. | |
123 // This must be done in initialize to enforce thread safety of start up of | |
124 // the protocol buffer library. | |
125 [self extensionRegistry]; | |
126 } | |
127 } | |
128 | |
129 + (GPBExtensionRegistry *)extensionRegistry { | |
130 // Is overridden in all the subclasses that provide extensions to provide the | |
131 // per class one. | |
132 return gDefaultExtensionRegistry; | |
133 } | |
134 | |
135 + (void)globallyRegisterExtension:(GPBExtensionDescriptor *)field { | |
136 const char *key = [field singletonNameC]; | |
137 OSSpinLockLock(&gExtensionSingletonDictionaryLock_); | |
138 CFDictionarySetValue(gExtensionSingletonDictionary, key, field); | |
139 OSSpinLockUnlock(&gExtensionSingletonDictionaryLock_); | |
140 } | |
141 | |
142 static id ExtensionForName(id self, SEL _cmd) { | |
143 // Really fast way of doing "classname_selName". | |
144 // This came up as a hotspot (creation of NSString *) when accessing a | |
145 // lot of extensions. | |
146 const char *selName = sel_getName(_cmd); | |
147 if (selName[0] == '_') { | |
148 return nil; // Apple internal selector. | |
149 } | |
150 size_t selNameLen = 0; | |
151 while (1) { | |
152 char c = selName[selNameLen]; | |
153 if (c == '\0') { // String end. | |
154 break; | |
155 } | |
156 if (c == ':') { | |
157 return nil; // Selector took an arg, not one of the runtime methods. | |
158 } | |
159 ++selNameLen; | |
160 } | |
161 | |
162 const char *className = class_getName(self); | |
163 size_t classNameLen = strlen(className); | |
164 char key[classNameLen + selNameLen + 2]; | |
165 memcpy(key, className, classNameLen); | |
166 key[classNameLen] = '_'; | |
167 memcpy(&key[classNameLen + 1], selName, selNameLen); | |
168 key[classNameLen + 1 + selNameLen] = '\0'; | |
169 OSSpinLockLock(&gExtensionSingletonDictionaryLock_); | |
170 id extension = (id)CFDictionaryGetValue(gExtensionSingletonDictionary, key); | |
171 if (extension) { | |
172 // The method is getting wired in to the class, so no need to keep it in | |
173 // the dictionary. | |
174 CFDictionaryRemoveValue(gExtensionSingletonDictionary, key); | |
175 } | |
176 OSSpinLockUnlock(&gExtensionSingletonDictionaryLock_); | |
177 return extension; | |
178 } | |
179 | |
180 BOOL GPBResolveExtensionClassMethod(Class self, SEL sel) { | |
181 // Another option would be to register the extensions with the class at | |
182 // globallyRegisterExtension: | |
183 // Timing the two solutions, this solution turned out to be much faster | |
184 // and reduced startup time, and runtime memory. | |
185 // The advantage to globallyRegisterExtension is that it would reduce the | |
186 // size of the protos somewhat because the singletonNameC wouldn't need | |
187 // to include the class name. For a class with a lot of extensions it | |
188 // can add up. You could also significantly reduce the code complexity of this | |
189 // file. | |
190 id extension = ExtensionForName(self, sel); | |
191 if (extension != nil) { | |
192 const char *encoding = | |
193 GPBMessageEncodingForSelector(@selector(getClassValue), NO); | |
194 Class metaClass = objc_getMetaClass(class_getName(self)); | |
195 IMP imp = imp_implementationWithBlock(^(id obj) { | |
196 #pragma unused(obj) | |
197 return extension; | |
198 }); | |
199 if (class_addMethod(metaClass, sel, imp, encoding)) { | |
200 return YES; | |
201 } | |
202 } | |
203 return NO; | |
204 } | |
205 | |
206 | |
207 + (BOOL)resolveClassMethod:(SEL)sel { | |
208 if (GPBResolveExtensionClassMethod(self, sel)) { | |
209 return YES; | |
210 } | |
211 return [super resolveClassMethod:sel]; | |
212 } | |
213 | |
214 @end | |
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