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   loadJClass(env, "java/lang/String", {});
34   loadJClass(env, "expo/modules/kotlin/jni/JavaScriptObject", {});
35   loadJClass(env, "expo/modules/kotlin/jni/JavaScriptValue", {});
36   loadJClass(env, "expo/modules/kotlin/jni/JavaScriptTypedArray", {});
37   loadJClass(env, "com/facebook/react/bridge/ReadableNativeArray", {});
38   loadJClass(env, "com/facebook/react/bridge/ReadableNativeMap", {});
39 }
40 
41 void JavaReferencesCache::loadJClass(
42   JNIEnv *env,
43   const std::string &name,
44   const std::vector<std::pair<std::string, std::string>> &methodsNames
45 ) {
46   // Note this clazz variable points to a leaked global reference.
47   // This is appropriate for classes that are never unloaded which is any class in an Android app.
48   auto clazz = (jclass) env->NewGlobalRef(env->FindClass(name.c_str()));
49 
50   MethodHashMap methods;
51   methods.reserve(methodsNames.size());
52 
53   for (auto &method: methodsNames) {
54     methods.insert(
55       {method, env->GetMethodID(clazz, method.first.c_str(), method.second.c_str())}
56     );
57   }
58 
59   jClassRegistry.insert(
60     {name, CachedJClass(clazz, std::move(methods))}
61   );
62 }
63 
64 JavaReferencesCache::CachedJClass &JavaReferencesCache::getJClass(
65   const std::string &className
66 ) {
67   return jClassRegistry.at(className);
68 }
69 
70 JavaReferencesCache::CachedJClass &JavaReferencesCache::getOrLoadJClass(
71   JNIEnv *env,
72   const std::string &className
73 ) {
74   auto result = jClassRegistry.find(className);
75   if (result == jClassRegistry.end()) {
76     loadJClass(env, className, {});
77     return jClassRegistry.at(className);
78   }
79 
80   return result->second;
81 }
82 
83 jmethodID JavaReferencesCache::CachedJClass::getMethod(
84   const std::string &name,
85   const std::string &signature
86 ) {
87   return methods.at({name, signature});
88 }
89 
90 JavaReferencesCache::CachedJClass::CachedJClass(
91   jclass clazz,
92   MethodHashMap methods
93 ) : clazz(clazz), methods(std::move(methods)) {}
94 } // namespace expo
95