1 // Copyright © 2021-present 650 Industries, Inc. (aka Expo)
2 
3 #include "JavaReferencesCache.h"
4 
5 namespace expo {
6 std::shared_ptr<JavaReferencesCache> JavaReferencesCache::instance() {
7   static std::shared_ptr<JavaReferencesCache> singleton{new JavaReferencesCache};
8   return singleton;
9 }
10 
11 void JavaReferencesCache::loadJClasses(JNIEnv *env) {
12   loadJClass(env, "java/lang/Double", {
13     {"<init>", "(D)V"}
14   });
15 
16   loadJClass(env, "java/lang/Boolean", {
17     {"<init>", "(Z)V"}
18   });
19 
20   loadJClass(env, "java/lang/Integer", {
21     {"<init>", "(I)V"}
22   });
23 
24   loadJClass(env, "java/lang/Float", {
25     {"<init>", "(F)V"}
26   });
27 
28   loadJClass(env, "com/facebook/react/bridge/PromiseImpl", {
29     {"<init>", "(Lcom/facebook/react/bridge/Callback;Lcom/facebook/react/bridge/Callback;)V"}
30   });
31 
32   loadJClass(env, "java/lang/Object", {});
33 }
34 
35 void JavaReferencesCache::loadJClass(
36   JNIEnv *env,
37   const std::string &name,
38   const std::vector<std::pair<std::string, std::string>> &methodsNames
39 ) {
40   // Note this clazz variable points to a leaked global reference.
41   // This is appropriate for classes that are never unloaded which is any class in an Android app.
42   auto clazz = (jclass) env->NewGlobalRef(env->FindClass(name.c_str()));
43 
44   MethodHashMap methods;
45   methods.reserve(methodsNames.size());
46 
47   for (auto &method: methodsNames) {
48     methods.insert(
49       {method, env->GetMethodID(clazz, method.first.c_str(), method.second.c_str())}
50     );
51   }
52 
53   jClassRegistry.insert(
54     {name, CachedJClass(clazz, std::move(methods))}
55   );
56 }
57 
58 JavaReferencesCache::CachedJClass &JavaReferencesCache::getJClass(
59   const std::string &className
60 ) {
61   return jClassRegistry.at(className);
62 }
63 
64 jmethodID JavaReferencesCache::CachedJClass::getMethod(
65   const std::string &name,
66   const std::string &signature
67 ) {
68   return methods.at({name, signature});
69 }
70 
71 JavaReferencesCache::CachedJClass::CachedJClass(
72   jclass clazz,
73   MethodHashMap methods
74 ) : clazz(clazz), methods(std::move(methods)) {}
75 } // namespace expo
76