Android: change the way JNIEnv is retrieved
- Currently, it tries to Attach the JVM first and update the thread local storage, which are two operations.
Now, it simply gives back the JNI Env stored for the thread.
- Android_JNI_SetupThreadi() should only be used for external.
For internal SDL thread, it's already called in RunThread() (SDL_systhread.c),
and other thread are Java threads which don't need to be attached. i
(even if it doesn't hurt to do it, since it's a no-op).
- JNI_OnLoad is filled with pthread_create, GetEnv, AttachCurrentThread...
It's called for all shared libraries which may don't want this setup,
and loading libraries can be also modified to be done from a static context,
or with relinker. So it's not really clear how, who and what it sets up.
=> Reduce this function to the minimal
diff --git a/src/core/android/SDL_android.c b/src/core/android/SDL_android.c
index 40199fe..38bb3df 100644
--- a/src/core/android/SDL_android.c
+++ b/src/core/android/SDL_android.c
@@ -294,7 +294,7 @@
static SDL_bool bHasEnvironmentVariables = SDL_FALSE;
-static void Android_JNI_SetEnv(JNIEnv *env);
+static int Android_JNI_SetEnv(JNIEnv *env);
/*******************************************************************************
Functions called by JNI
@@ -321,21 +321,7 @@
/* Library init */
JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved)
{
- JNIEnv *env;
mJavaVM = vm;
- LOGI("JNI_OnLoad called");
- if ((*mJavaVM)->GetEnv(mJavaVM, (void **) &env, JNI_VERSION_1_4) != JNI_OK) {
- LOGE("Failed to get the environment using GetEnv()");
- return -1;
- }
- /*
- * Create mThreadKey so we can keep track of the JNIEnv assigned to each thread
- * Refer to http://developer.android.com/guide/practices/design/jni.html for the rationale behind this
- */
- Android_JNI_CreateKey_once();
-
- Android_JNI_SetupThread();
-
return JNI_VERSION_1_4;
}
@@ -354,6 +340,19 @@
{
__android_log_print(ANDROID_LOG_VERBOSE, "SDL", "nativeSetupJNI()");
+ /*
+ * Create mThreadKey so we can keep track of the JNIEnv assigned to each thread
+ * Refer to http://developer.android.com/guide/practices/design/jni.html for the rationale behind this
+ */
+ Android_JNI_CreateKey_once();
+
+ /* Save JNIEnv of SDLActivity */
+ Android_JNI_SetEnv(env);
+
+ if (mJavaVM == NULL) {
+ __android_log_print(ANDROID_LOG_ERROR, "SDL", "failed to found a JavaVM");
+ }
+
/* Use a mutex to prevent concurrency issues between Java Activity and Native thread code, when using 'Android_Window'.
* (Eg. Java sending Touch events, while native code is destroying the main SDL_Window. )
*/
@@ -365,8 +364,6 @@
__android_log_print(ANDROID_LOG_ERROR, "SDL", "failed to create Android_ActivityMutex mutex");
}
- Android_JNI_SetupThread();
-
mActivityClass = (jclass)((*env)->NewGlobalRef(env, cls));
midGetNativeSurface = (*env)->GetStaticMethodID(env, mActivityClass,
@@ -444,8 +441,6 @@
{
__android_log_print(ANDROID_LOG_VERBOSE, "SDL", "AUDIO nativeSetupJNI()");
- Android_JNI_SetupThread();
-
mAudioManagerClass = (jclass)((*env)->NewGlobalRef(env, cls));
midAudioOpen = (*env)->GetStaticMethodID(env, mAudioManagerClass,
@@ -484,8 +479,6 @@
{
__android_log_print(ANDROID_LOG_VERBOSE, "SDL", "CONTROLLER nativeSetupJNI()");
- Android_JNI_SetupThread();
-
mControllerManagerClass = (jclass)((*env)->NewGlobalRef(env, cls));
midPollInputDevices = (*env)->GetStaticMethodID(env, mControllerManagerClass,
@@ -516,6 +509,9 @@
__android_log_print(ANDROID_LOG_VERBOSE, "SDL", "nativeRunMain()");
+ /* Save JNIEnv of SDLThread */
+ Android_JNI_SetEnv(env);
+
library_file = (*env)->GetStringUTFChars(env, library, NULL);
library_handle = dlopen(library_file, RTLD_GLOBAL);
if (library_handle) {
@@ -1155,11 +1151,12 @@
}
}
-static void Android_JNI_SetEnv(JNIEnv *env) {
+static int Android_JNI_SetEnv(JNIEnv *env) {
int status = pthread_setspecific(mThreadKey, env);
if (status < 0) {
__android_log_print(ANDROID_LOG_ERROR, "SDL", "Failed pthread_setspecific() in Android_JNI_SetEnv() (err=%d)", status);
}
+ return status;
}
JNIEnv* Android_JNI_GetEnv(void)
@@ -1176,13 +1173,6 @@
* Note: You can call this function any number of times for the same thread, there's no harm in it
*/
- JNIEnv *env;
- int status = (*mJavaVM)->AttachCurrentThread(mJavaVM, &env, NULL);
- if (status < 0) {
- LOGE("failed to attach current thread");
- return 0;
- }
-
/* From http://developer.android.com/guide/practices/jni.html
* Threads attached through JNI must call DetachCurrentThread before they exit. If coding this directly is awkward,
* in Android 2.0 (Eclair) and higher you can use pthread_key_create to define a destructor function that will be
@@ -1192,14 +1182,43 @@
* Note: You can call this function any number of times for the same thread, there's no harm in it
* (except for some lost CPU cycles)
*/
- Android_JNI_SetEnv(env);
+
+
+
+ /* Get JNIEnv from the Thread local storage */
+ JNIEnv *env = pthread_getspecific(mThreadKey);
+ if (env == NULL) {
+ __android_log_print(ANDROID_LOG_ERROR, "SDL", "JNIEnv is NULL. Call Android_JNI_SetupThread() first.");
+ }
return env;
}
int Android_JNI_SetupThread(void)
{
- Android_JNI_GetEnv();
+ JNIEnv *env;
+ int status;
+
+ /* There should be a JVM */
+ if (mJavaVM == NULL) {
+ __android_log_print(ANDROID_LOG_ERROR, "SDL", "Failed, there is no JavaVM");
+ return 0;
+ }
+
+ /* Attach the current thread to the JVM and get a JNIEnv.
+ * It will be detached by pthread_create destructor 'Android_JNI_ThreadDestroyed'
+ */
+ status = (*mJavaVM)->AttachCurrentThread(mJavaVM, &env, NULL);
+ if (status < 0) {
+ __android_log_print(ANDROID_LOG_ERROR, "SDL", "Failed to attach current thread (err=%d)", status);
+ return 0;
+ }
+
+ /* Save JNIEnv into the Thread local storage */
+ if (Android_JNI_SetEnv(env) < 0) {
+ return 0;
+ }
+
return 1;
}
