1 /*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef LIBTEXTCLASSIFIER_UTILS_JAVA_JNI_BASE_H_
18 #define LIBTEXTCLASSIFIER_UTILS_JAVA_JNI_BASE_H_
19
20 #include <jni.h>
21
22 #include <memory>
23 #include <string>
24
25 #include "utils/base/statusor.h"
26
27 // When we use a macro as an argument for a macro, an additional level of
28 // indirection is needed, if the macro argument is used with # or ##.
29 #define TC3_ADD_QUOTES_HELPER(TOKEN) #TOKEN
30 #define TC3_ADD_QUOTES(TOKEN) TC3_ADD_QUOTES_HELPER(TOKEN)
31
32 #ifndef TC3_PACKAGE_NAME
33 #define TC3_PACKAGE_NAME com_google_android_textclassifier
34 #endif
35
36 #ifndef TC3_PACKAGE_PATH
37 #define TC3_PACKAGE_PATH \
38 "com/google/android/textclassifier/"
39 #endif
40
41 #define TC3_JNI_METHOD_NAME_INTERNAL(package_name, class_name, method_name) \
42 Java_##package_name##_##class_name##_##method_name
43
44 #define TC3_JNI_METHOD_PRIMITIVE(return_type, package_name, class_name, \
45 method_name) \
46 JNIEXPORT return_type JNICALL TC3_JNI_METHOD_NAME_INTERNAL( \
47 package_name, class_name, method_name)
48
49 // The indirection is needed to correctly expand the TC3_PACKAGE_NAME macro.
50 // See the explanation near TC3_ADD_QUOTES macro.
51 #define TC3_JNI_METHOD2(return_type, package_name, class_name, method_name) \
52 TC3_JNI_METHOD_PRIMITIVE(return_type, package_name, class_name, method_name)
53
54 #define TC3_JNI_METHOD(return_type, class_name, method_name) \
55 TC3_JNI_METHOD2(return_type, TC3_PACKAGE_NAME, class_name, method_name)
56
57 #define TC3_JNI_METHOD_NAME2(package_name, class_name, method_name) \
58 TC3_JNI_METHOD_NAME_INTERNAL(package_name, class_name, method_name)
59
60 #define TC3_JNI_METHOD_NAME(class_name, method_name) \
61 TC3_JNI_METHOD_NAME2(TC3_PACKAGE_NAME, class_name, method_name)
62
63 namespace libtextclassifier3 {
64
65 // Returns true if the requested capacity is available.
66 bool EnsureLocalCapacity(JNIEnv* env, int capacity);
67
68 // Returns true if there was an exception. Also it clears the exception.
69 bool JniExceptionCheckAndClear(JNIEnv* env,
70 bool print_exception_on_error = true);
71
72 // A deleter to be used with std::unique_ptr to delete JNI global references.
73 class GlobalRefDeleter {
74 public:
GlobalRefDeleter(JavaVM * jvm)75 explicit GlobalRefDeleter(JavaVM* jvm) : jvm_(jvm) {}
76
77 GlobalRefDeleter(const GlobalRefDeleter& orig) = default;
78
79 // Copy assignment to allow move semantics in ScopedGlobalRef.
80 GlobalRefDeleter& operator=(const GlobalRefDeleter& rhs) {
81 TC3_CHECK_EQ(jvm_, rhs.jvm_);
82 return *this;
83 }
84
85 // The delete operator.
operator()86 void operator()(jobject object) const {
87 JNIEnv* env;
88 if (object != nullptr && jvm_ != nullptr &&
89 JNI_OK ==
90 jvm_->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_4)) {
91 env->DeleteGlobalRef(object);
92 }
93 }
94
95 private:
96 // The jvm_ stashed to use for deletion.
97 JavaVM* const jvm_;
98 };
99
100 // A deleter to be used with std::unique_ptr to delete JNI local references.
101 class LocalRefDeleter {
102 public:
LocalRefDeleter(JNIEnv * env)103 explicit LocalRefDeleter(JNIEnv* env)
104 : env_(env) {} // NOLINT(runtime/explicit)
105
106 LocalRefDeleter(const LocalRefDeleter& orig) = default;
107
108 // Copy assignment to allow move semantics in ScopedLocalRef.
109 LocalRefDeleter& operator=(const LocalRefDeleter& rhs) {
110 env_ = rhs.env_;
111 return *this;
112 }
113
114 // The delete operator.
operator()115 void operator()(jobject object) const {
116 if (env_) {
117 env_->DeleteLocalRef(object);
118 }
119 }
120
121 private:
122 // The env_ stashed to use for deletion. Thread-local, don't share!
123 JNIEnv* env_;
124 };
125
126 // A smart pointer that deletes a reference when it goes out of scope.
127 //
128 // Note that this class is not thread-safe since it caches JNIEnv in
129 // the deleter. Do not use the same jobject across different threads.
130 template <typename T, typename Env, typename Deleter>
131 class ScopedRef {
132 public:
ScopedRef()133 ScopedRef() : ptr_(nullptr, Deleter(nullptr)) {}
ScopedRef(T value,Env * env)134 ScopedRef(T value, Env* env) : ptr_(value, Deleter(env)) {}
135
get()136 T get() const { return ptr_.get(); }
137
release()138 T release() { return ptr_.release(); }
139
140 bool operator!() const { return !ptr_; }
141
142 bool operator==(void* value) const { return ptr_.get() == value; }
143
144 explicit operator bool() const { return ptr_ != nullptr; }
145
reset(T value,Env * env)146 void reset(T value, Env* env) {
147 ptr_.reset(value);
148 ptr_.get_deleter() = Deleter(env);
149 }
150
151 private:
152 std::unique_ptr<typename std::remove_pointer<T>::type, Deleter> ptr_;
153 };
154
155 template <typename T, typename U, typename Env, typename Deleter>
156 inline bool operator==(const ScopedRef<T, Env, Deleter>& x,
157 const ScopedRef<U, Env, Deleter>& y) {
158 return x.get() == y.get();
159 }
160
161 template <typename T, typename Env, typename Deleter>
162 inline bool operator==(const ScopedRef<T, Env, Deleter>& x, std::nullptr_t) {
163 return x.get() == nullptr;
164 }
165
166 template <typename T, typename Env, typename Deleter>
167 inline bool operator==(std::nullptr_t, const ScopedRef<T, Env, Deleter>& x) {
168 return nullptr == x.get();
169 }
170
171 template <typename T, typename U, typename Env, typename Deleter>
172 inline bool operator!=(const ScopedRef<T, Env, Deleter>& x,
173 const ScopedRef<U, Env, Deleter>& y) {
174 return x.get() != y.get();
175 }
176
177 template <typename T, typename Env, typename Deleter>
178 inline bool operator!=(const ScopedRef<T, Env, Deleter>& x, std::nullptr_t) {
179 return x.get() != nullptr;
180 }
181
182 template <typename T, typename Env, typename Deleter>
183 inline bool operator!=(std::nullptr_t, const ScopedRef<T, Env, Deleter>& x) {
184 return nullptr != x.get();
185 }
186
187 template <typename T, typename U, typename Env, typename Deleter>
188 inline bool operator<(const ScopedRef<T, Env, Deleter>& x,
189 const ScopedRef<U, Env, Deleter>& y) {
190 return x.get() < y.get();
191 }
192
193 template <typename T, typename U, typename Env, typename Deleter>
194 inline bool operator>(const ScopedRef<T, Env, Deleter>& x,
195 const ScopedRef<U, Env, Deleter>& y) {
196 return x.get() > y.get();
197 }
198
199 // A smart pointer that deletes a JNI global reference when it goes out
200 // of scope. Usage is:
201 // ScopedGlobalRef<jobject> scoped_global(env->JniFunction(), jvm);
202 template <typename T>
203 using ScopedGlobalRef = ScopedRef<T, JavaVM, GlobalRefDeleter>;
204
205 // Ditto, but usage is:
206 // ScopedLocalRef<jobject> scoped_local(env->JniFunction(), env);
207 template <typename T>
208 using ScopedLocalRef = ScopedRef<T, JNIEnv, LocalRefDeleter>;
209
210 // A helper to create global references.
211 template <typename T>
MakeGlobalRef(T object,JNIEnv * env,JavaVM * jvm)212 ScopedGlobalRef<T> MakeGlobalRef(T object, JNIEnv* env, JavaVM* jvm) {
213 const jobject global_object = env->NewGlobalRef(object);
214 return ScopedGlobalRef<T>(reinterpret_cast<T>(global_object), jvm);
215 }
216
217 } // namespace libtextclassifier3
218
219 #endif // LIBTEXTCLASSIFIER_UTILS_JAVA_JNI_BASE_H_
220