examples/unityplugin/class_reference_holder.cc

/*
 *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */
#include "examples/unityplugin/class_reference_holder.h"

#include <utility>

#include "sdk/android/src/jni/jni_helpers.h"

namespace unity_plugin {

// ClassReferenceHolder holds global reference to Java classes in app/webrtc.
class ClassReferenceHolder {
 public:
  explicit ClassReferenceHolder(JNIEnv* jni);
  ~ClassReferenceHolder();

  void FreeReferences(JNIEnv* jni);
  jclass GetClass(const std::string& name);

  void LoadClass(JNIEnv* jni, const std::string& name);

 private:
  std::map<std::string, jclass> classes_;
};

// Allocated in LoadGlobalClassReferenceHolder(),
// freed in FreeGlobalClassReferenceHolder().
static ClassReferenceHolder* g_class_reference_holder = nullptr;

void LoadGlobalClassReferenceHolder() {
  RTC_CHECK(g_class_reference_holder == nullptr);
  g_class_reference_holder = new ClassReferenceHolder(webrtc::jni::GetEnv());
}

void FreeGlobalClassReferenceHolder() {
  g_class_reference_holder->FreeReferences(
      webrtc::jni::AttachCurrentThreadIfNeeded());
  delete g_class_reference_holder;
  g_class_reference_holder = nullptr;
}

ClassReferenceHolder::ClassReferenceHolder(JNIEnv* jni) {
  LoadClass(jni, "org/webrtc/UnityUtility");
}

ClassReferenceHolder::~ClassReferenceHolder() {
  RTC_CHECK(classes_.empty()) << "Must call FreeReferences() before dtor!";
}

void ClassReferenceHolder::FreeReferences(JNIEnv* jni) {
  for (std::map<std::string, jclass>::const_iterator it = classes_.begin();
       it != classes_.end(); ++it) {
    jni->DeleteGlobalRef(it->second);
  }
  classes_.clear();
}

jclass ClassReferenceHolder::GetClass(const std::string& name) {
  std::map<std::string, jclass>::iterator it = classes_.find(name);
  RTC_CHECK(it != classes_.end()) << "Unexpected GetClass() call for: " << name;
  return it->second;
}

void ClassReferenceHolder::LoadClass(JNIEnv* jni, const std::string& name) {
  jclass localRef = jni->FindClass(name.c_str());
  CHECK_EXCEPTION(jni) << "error during FindClass: " << name;
  RTC_CHECK(localRef) << name;
  jclass globalRef = reinterpret_cast<jclass>(jni->NewGlobalRef(localRef));
  CHECK_EXCEPTION(jni) << "error during NewGlobalRef: " << name;
  RTC_CHECK(globalRef) << name;
  bool inserted = classes_.insert(std::make_pair(name, globalRef)).second;
  RTC_CHECK(inserted) << "Duplicate class name: " << name;
}

// Returns a global reference guaranteed to be valid for the lifetime of the
// process.
jclass FindClass(JNIEnv* jni, const char* name) {
  return g_class_reference_holder->GetClass(name);
}

}  // namespace unity_plugin