android: jni: Add IDCache to cache Java methods.

src/android/app/src/main/java/org/citra/citra_android/NativeLibrary.java

@@ -32,8 +32,6 @@ public final class NativeLibrary {
         } catch (UnsatisfiedLinkError ex) {
             Log.error("[NativeLibrary] " + ex.toString());
         }
-
-        CacheClassesAndMethods();
     }
 
     private NativeLibrary() {
@@ -268,13 +266,6 @@ public final class NativeLibrary {
      **/
     public static native double[] GetPerfStats();
 
-    /**
-     * The methods C++ uses to find references to Java classes and methods
-     * are really expensive. Rather than calling them every time we want to
-     * run them, do it once when we load the native library.
-     */
-    private static native void CacheClassesAndMethods();
-
     /**
      * Notifies the core emulation that the orientation has changed.
      */

src/android/app/src/main/jni/CMakeLists.txt

@@ -10,6 +10,8 @@ add_library(main SHARED
     emu_window/emu_window.h
     game_info.cpp
     game_info.h
+    id_cache.cpp
+    id_cache.h
     native.cpp
     native.h
 )

src/android/app/src/main/jni/id_cache.cpp

@@ -0,0 +1,93 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/common_paths.h"
+#include "common/logging/backend.h"
+#include "common/logging/filter.h"
+#include "common/logging/log.h"
+#include "core/settings.h"
+#include "jni/id_cache.h"
+
+#include <jni.h>
+
+static constexpr jint JNI_VERSION = JNI_VERSION_1_6;
+
+static JavaVM* s_java_vm;
+
+static jclass s_native_library_class;
+static jmethodID s_display_alert_msg;
+
+namespace IDCache {
+
+JNIEnv* GetEnvForThread() {
+    thread_local static struct OwnedEnv {
+        OwnedEnv() {
+            status = s_java_vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6);
+            if (status == JNI_EDETACHED)
+                s_java_vm->AttachCurrentThread(&env, nullptr);
+        }
+
+        ~OwnedEnv() {
+            if (status == JNI_EDETACHED)
+                s_java_vm->DetachCurrentThread();
+        }
+
+        int status;
+        JNIEnv* env = nullptr;
+    } owned;
+    return owned.env;
+}
+
+jclass GetNativeLibraryClass() {
+    return s_native_library_class;
+}
+
+jmethodID GetDisplayAlertMsg() {
+    return s_display_alert_msg;
+}
+
+} // namespace IDCache
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+jint JNI_OnLoad(JavaVM* vm, void* reserved) {
+    s_java_vm = vm;
+
+    JNIEnv* env;
+    if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION) != JNI_OK)
+        return JNI_ERR;
+
+    // Initialize Logger
+    Log::Filter log_filter;
+    log_filter.ParseFilterString(Settings::values.log_filter);
+    Log::SetGlobalFilter(log_filter);
+    Log::AddBackend(std::make_unique<Log::ColorConsoleBackend>());
+    FileUtil::CreateFullPath(FileUtil::GetUserPath(FileUtil::UserPath::LogDir));
+    Log::AddBackend(std::make_unique<Log::FileBackend>(
+        FileUtil::GetUserPath(FileUtil::UserPath::LogDir) + LOG_FILE));
+    LOG_INFO(Frontend, "Logging backend initialised");
+
+    // Initialize Java methods
+    const jclass native_library_class = env->FindClass("org/citra/citra_android/NativeLibrary");
+    s_native_library_class = reinterpret_cast<jclass>(env->NewGlobalRef(native_library_class));
+    s_display_alert_msg = env->GetStaticMethodID(s_native_library_class, "displayAlertMsg",
+                                                 "(Ljava/lang/String;Ljava/lang/String;Z)Z");
+
+    return JNI_VERSION;
+}
+
+void JNI_OnUnload(JavaVM* vm, void* reserved) {
+    JNIEnv* env;
+    if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION) != JNI_OK) {
+        return;
+    }
+
+    env->DeleteGlobalRef(s_native_library_class);
+}
+
+#ifdef __cplusplus
+}
+#endif

src/android/app/src/main/jni/id_cache.h

@@ -0,0 +1,15 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <jni.h>
+
+namespace IDCache {
+
+JNIEnv* GetEnvForThread();
+jclass GetNativeLibraryClass();
+jmethodID GetDisplayAlertMsg();
+
+} // namespace IDCache

src/android/app/src/main/jni/native.cpp

@@ -12,10 +12,7 @@
 #include <android/native_window_jni.h>
 #include <jni.h>
 
-#include "common/common_paths.h"
 #include "common/file_util.h"
-#include "common/logging/backend.h"
-#include "common/logging/filter.h"
 #include "common/logging/log.h"
 #include "common/scm_rev.h"
 #include "common/scope_exit.h"
@@ -32,13 +29,12 @@
 #include "jni/config.h"
 #include "jni/emu_window/emu_window.h"
 #include "jni/game_info.h"
+#include "jni/id_cache.h"
 #include "jni/native.h"
 #include "network/network.h"
 #include "video_core/renderer_base.h"
 #include "video_core/video_core.h"
 
-JavaVM* g_java_vm;
-
 namespace {
 
 ANativeWindow* s_surf;
@@ -56,27 +52,6 @@ std::condition_variable running_cv;
 
 } // Anonymous namespace
 
-/**
- * Cache the JavaVM so that we can call into it later.
- */
-jint JNI_OnLoad(JavaVM* vm, void* reserved) {
-    g_java_vm = vm;
-
-    // Initialise Logger
-    Log::Filter log_filter;
-    log_filter.ParseFilterString(Settings::values.log_filter);
-    Log::SetGlobalFilter(log_filter);
-
-    Log::AddBackend(std::make_unique<Log::ColorConsoleBackend>());
-    FileUtil::CreateFullPath(FileUtil::GetUserPath(FileUtil::UserPath::LogDir));
-    Log::AddBackend(std::make_unique<Log::FileBackend>(
-        FileUtil::GetUserPath(FileUtil::UserPath::LogDir) + LOG_FILE));
-
-    LOG_INFO(Frontend, "Logging backend initialised");
-
-    return JNI_VERSION_1_6;
-}
-
 static int RunCitra(const std::string& filepath) {
     LOG_INFO(Frontend, "Citra is Starting");
 
@@ -181,19 +156,6 @@ void Java_org_citra_citra_1android_NativeLibrary_SurfaceChanged(JNIEnv* env, job
 
 void Java_org_citra_citra_1android_NativeLibrary_SurfaceDestroyed(JNIEnv* env, jobject obj) {}
 
-void Java_org_citra_citra_1android_NativeLibrary_CacheClassesAndMethods(JNIEnv* env, jobject obj) {
-    // This class reference is only valid for the lifetime of this method.
-    jclass localClass = env->FindClass("org/citra/citra_android/NativeLibrary");
-
-    // This reference, however, is valid until we delete it.
-    s_jni_class = reinterpret_cast<jclass>(env->NewGlobalRef(localClass));
-
-    // Method signature taken from javap -s
-    // Source/Android/app/build/intermediates/classes/arm/debug/org/dolphinemu/dolphinemu/NativeLibrary.class
-    s_jni_method_alert = env->GetStaticMethodID(s_jni_class, "displayAlertMsg",
-                                                "(Ljava/lang/String;Ljava/lang/String;Z)Z");
-}
-
 void Java_org_citra_citra_1android_NativeLibrary_NotifyOrientationChange(
     JNIEnv* env, jobject obj, jint layout_option, jboolean is_portrait_mode) {
     Settings::values.layout_option = static_cast<Settings::LayoutOption>(layout_option);

src/android/app/src/main/jni/native.h

@@ -136,9 +136,6 @@ JNIEXPORT void JNICALL Java_org_citra_citra_1android_NativeLibrary_SetProfiling(
 JNIEXPORT void JNICALL Java_org_citra_citra_1android_NativeLibrary_WriteProfileResults(JNIEnv* env,
                                                                                        jobject obj);
 
-JNIEXPORT void JNICALL
-Java_org_citra_citra_1android_NativeLibrary_CacheClassesAndMethods(JNIEnv* env, jobject obj);
-
 JNIEXPORT void JNICALL Java_org_citra_citra_1android_NativeLibrary_NotifyOrientationChange(
     JNIEnv* env, jobject obj, jint layout_option, jboolean is_portrait_mode);