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Handle all Android lifecycle events on the main thread
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This restructuring also allows us to wait efficiently in SDL_WaitEvent() on Android
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@slouken
slouken committed Jul 24, 2024
1 parent a7c0192 commit c601120
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Showing 8 changed files with 343 additions and 154 deletions.
183 changes: 121 additions & 62 deletions src/core/android/SDL_android.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -404,8 +404,10 @@ static jobject javaAssetManagerRef = 0;
static SDL_AtomicInt bAllowRecreateActivity;

static SDL_Mutex *Android_ActivityMutex = NULL;
SDL_Semaphore *Android_PauseSem = NULL;
SDL_Semaphore *Android_ResumeSem = NULL;
static SDL_Mutex *Android_LifecycleMutex = NULL;
static SDL_Semaphore *Android_LifecycleEventSem = NULL;
static SDL_AndroidLifecycleEvent Android_LifecycleEvents[SDL_NUM_ANDROID_LIFECYCLE_EVENTS];
static int Android_NumLifecycleEvents;

/*******************************************************************************
Functions called by JNI
Expand Down Expand Up @@ -614,14 +616,14 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeSetupJNI)(JNIEnv *env, jclass cl
__android_log_print(ANDROID_LOG_ERROR, "SDL", "failed to create Android_ActivityMutex mutex");
}

Android_PauseSem = SDL_CreateSemaphore(0);
if (!Android_PauseSem) {
__android_log_print(ANDROID_LOG_ERROR, "SDL", "failed to create Android_PauseSem semaphore");
Android_LifecycleMutex = SDL_CreateMutex();
if (!Android_LifecycleMutex) {
__android_log_print(ANDROID_LOG_ERROR, "SDL", "failed to create Android_LifecycleMutex mutex");
}

Android_ResumeSem = SDL_CreateSemaphore(0);
if (!Android_ResumeSem) {
__android_log_print(ANDROID_LOG_ERROR, "SDL", "failed to create Android_ResumeSem semaphore");
Android_LifecycleEventSem = SDL_CreateSemaphore(0);
if (!Android_LifecycleEventSem) {
__android_log_print(ANDROID_LOG_ERROR, "SDL", "failed to create Android_LifecycleEventSem semaphore");
}

mActivityClass = (jclass)((*env)->NewGlobalRef(env, cls));
Expand Down Expand Up @@ -895,46 +897,120 @@ JNIEXPORT int JNICALL SDL_JAVA_INTERFACE(nativeRunMain)(JNIEnv *env, jclass cls,
return status;
}

/* Drop file */
JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(onNativeDropFile)(
JNIEnv *env, jclass jcls,
jstring filename)
static int FindLifecycleEvent(SDL_AndroidLifecycleEvent event)
{
const char *path = (*env)->GetStringUTFChars(env, filename, NULL);
SDL_SendDropFile(NULL, NULL, path);
(*env)->ReleaseStringUTFChars(env, filename, path);
SDL_SendDropComplete(NULL);
for (int index = 0; index < Android_NumLifecycleEvents; ++index) {
if (Android_LifecycleEvents[index] == event) {
return index;
}
}
return -1;
}

/* Lock / Unlock Mutex */
void Android_LockActivityMutex(void)
static void RemoveLifecycleEvent(int index)
{
SDL_LockMutex(Android_ActivityMutex);
if (index < Android_NumLifecycleEvents - 1) {
SDL_memcpy(&Android_LifecycleEvents[index], &Android_LifecycleEvents[index+1], (Android_NumLifecycleEvents - index - 1) * sizeof(Android_LifecycleEvents[index]));
}
--Android_NumLifecycleEvents;
}

void Android_UnlockActivityMutex(void)
void Android_SendLifecycleEvent(SDL_AndroidLifecycleEvent event)
{
SDL_UnlockMutex(Android_ActivityMutex);
SDL_LockMutex(Android_LifecycleMutex);
{
int index;
SDL_bool add_event = SDL_TRUE;

switch (event) {
case SDL_ANDROID_LIFECYCLE_WAKE:
// We don't need more than one wake queued
index = FindLifecycleEvent(SDL_ANDROID_LIFECYCLE_WAKE);
if (index >= 0) {
add_event = SDL_FALSE;
}
break;
case SDL_ANDROID_LIFECYCLE_PAUSE:
// If we have a resume queued, just stay in the paused state
index = FindLifecycleEvent(SDL_ANDROID_LIFECYCLE_RESUME);
if (index >= 0) {
RemoveLifecycleEvent(index);
add_event = SDL_FALSE;
}
break;
case SDL_ANDROID_LIFECYCLE_RESUME:
// If we have a pause queued, just stay in the resumed state
index = FindLifecycleEvent(SDL_ANDROID_LIFECYCLE_PAUSE);
if (index >= 0) {
RemoveLifecycleEvent(index);
add_event = SDL_FALSE;
}
break;
case SDL_ANDROID_LIFECYCLE_LOWMEMORY:
// We don't need more than one low memory event queued
index = FindLifecycleEvent(SDL_ANDROID_LIFECYCLE_LOWMEMORY);
if (index >= 0) {
add_event = SDL_FALSE;
}
break;
case SDL_ANDROID_LIFECYCLE_DESTROY:
// Remove all other events, we're done!
while (Android_NumLifecycleEvents > 0) {
RemoveLifecycleEvent(0);
}
break;
default:
SDL_assert(!"Sending unexpected lifecycle event");
add_event = SDL_FALSE;
break;
}

if (add_event) {
SDL_assert(Android_NumLifecycleEvents < SDL_arraysize(Android_LifecycleEvents));
Android_LifecycleEvents[Android_NumLifecycleEvents++] = event;
SDL_SignalSemaphore(Android_LifecycleEventSem);
}
}
SDL_UnlockMutex(Android_LifecycleMutex);
}

/* Lock the Mutex when the Activity is in its 'Running' state */
void Android_LockActivityMutexOnceRunning(void)
SDL_bool Android_WaitLifecycleEvent(SDL_AndroidLifecycleEvent *event, Sint64 timeoutNS)
{
int pauseSignaled = 0;
int resumeSignaled = 0;
SDL_bool got_event = SDL_FALSE;

retry:
while (!got_event && SDL_WaitSemaphoreTimeoutNS(Android_LifecycleEventSem, timeoutNS) == 0) {
SDL_LockMutex(Android_LifecycleMutex);
{
if (Android_NumLifecycleEvents > 0) {
*event = Android_LifecycleEvents[0];
RemoveLifecycleEvent(0);
got_event = SDL_TRUE;
}
}
SDL_UnlockMutex(Android_LifecycleMutex);
}
return got_event;
}

void Android_LockActivityMutex(void)
{
SDL_LockMutex(Android_ActivityMutex);
}

pauseSignaled = SDL_GetSemaphoreValue(Android_PauseSem);
resumeSignaled = SDL_GetSemaphoreValue(Android_ResumeSem);
void Android_UnlockActivityMutex(void)
{
SDL_UnlockMutex(Android_ActivityMutex);
}

if (pauseSignaled > resumeSignaled) {
SDL_UnlockMutex(Android_ActivityMutex);
SDL_Delay(50);
goto retry;
}
/* Drop file */
JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(onNativeDropFile)(
JNIEnv *env, jclass jcls,
jstring filename)
{
const char *path = (*env)->GetStringUTFChars(env, filename, NULL);
SDL_SendDropFile(NULL, NULL, path);
(*env)->ReleaseStringUTFChars(env, filename, path);
SDL_SendDropComplete(NULL);
}

/* Set screen resolution */
Expand Down Expand Up @@ -1335,7 +1411,7 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(onNativeClipboardChanged)(
JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeLowMemory)(
JNIEnv *env, jclass cls)
{
SDL_SendAppEvent(SDL_EVENT_LOW_MEMORY);
Android_SendLifecycleEvent(SDL_ANDROID_LIFECYCLE_LOWMEMORY);
}

/* Locale
Expand All @@ -1357,20 +1433,7 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(onNativeDarkModeChanged)(
JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeSendQuit)(
JNIEnv *env, jclass cls)
{
/* Discard previous events. The user should have handled state storage
* in SDL_EVENT_WILL_ENTER_BACKGROUND. After nativeSendQuit() is called, no
* events other than SDL_EVENT_QUIT and SDL_EVENT_TERMINATING should fire */
SDL_FlushEvents(SDL_EVENT_FIRST, SDL_EVENT_LAST);
/* Inject a SDL_EVENT_QUIT event */
SDL_SendQuit();
SDL_SendAppEvent(SDL_EVENT_TERMINATING);
/* Robustness: clear any pending Pause */
while (SDL_TryWaitSemaphore(Android_PauseSem) == 0) {
/* empty */
}
/* Resume the event loop so that the app can catch SDL_EVENT_QUIT which
* should now be the top event in the event queue. */
SDL_SignalSemaphore(Android_ResumeSem);
Android_SendLifecycleEvent(SDL_ANDROID_LIFECYCLE_DESTROY);
}

/* Activity ends */
Expand All @@ -1384,16 +1447,18 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeQuit)(
Android_ActivityMutex = NULL;
}

if (Android_PauseSem) {
SDL_DestroySemaphore(Android_PauseSem);
Android_PauseSem = NULL;
if (Android_LifecycleMutex) {
SDL_DestroyMutex(Android_LifecycleMutex);
Android_LifecycleMutex = NULL;
}

if (Android_ResumeSem) {
SDL_DestroySemaphore(Android_ResumeSem);
Android_ResumeSem = NULL;
if (Android_LifecycleEventSem) {
SDL_DestroySemaphore(Android_LifecycleEventSem);
Android_LifecycleEventSem = NULL;
}

Android_NumLifecycleEvents = 0;

Internal_Android_Destroy_AssetManager();

str = SDL_GetError();
Expand All @@ -1410,9 +1475,7 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativePause)(
{
__android_log_print(ANDROID_LOG_VERBOSE, "SDL", "nativePause()");

/* Signal the pause semaphore so the event loop knows to pause and (optionally) block itself.
* Sometimes 2 pauses can be queued (eg pause/resume/pause), so it's always increased. */
SDL_SignalSemaphore(Android_PauseSem);
Android_SendLifecycleEvent(SDL_ANDROID_LIFECYCLE_PAUSE);
}

/* Resume */
Expand All @@ -1421,11 +1484,7 @@ JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeResume)(
{
__android_log_print(ANDROID_LOG_VERBOSE, "SDL", "nativeResume()");

/* Signal the resume semaphore so the event loop knows to resume and restore the GL Context
* We can't restore the GL Context here because it needs to be done on the SDL main thread
* and this function will be called from the Java thread instead.
*/
SDL_SignalSemaphore(Android_ResumeSem);
Android_SendLifecycleEvent(SDL_ANDROID_LIFECYCLE_RESUME);
}

JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeFocusChanged)(
Expand Down
33 changes: 22 additions & 11 deletions src/core/android/SDL_android.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,9 @@
*/
#include "SDL_internal.h"

#ifndef SDL_android_h
#define SDL_android_h

/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
/* *INDENT-OFF* */
Expand All @@ -35,6 +38,23 @@ extern "C" {
// this appears to be broken right now (on Android, not SDL, I think...?).
#define ALLOW_MULTIPLE_ANDROID_AUDIO_DEVICES 0

/* Life cycle */
typedef enum
{
SDL_ANDROID_LIFECYCLE_WAKE,
SDL_ANDROID_LIFECYCLE_PAUSE,
SDL_ANDROID_LIFECYCLE_RESUME,
SDL_ANDROID_LIFECYCLE_LOWMEMORY,
SDL_ANDROID_LIFECYCLE_DESTROY,
SDL_NUM_ANDROID_LIFECYCLE_EVENTS
} SDL_AndroidLifecycleEvent;

void Android_SendLifecycleEvent(SDL_AndroidLifecycleEvent event);
SDL_bool Android_WaitLifecycleEvent(SDL_AndroidLifecycleEvent *event, Sint64 timeoutNS);

void Android_LockActivityMutex(void);
void Android_UnlockActivityMutex(void);

/* Interface from the SDL library into the Android Java activity */
extern void Android_JNI_SetActivityTitle(const char *title);
extern void Android_JNI_SetWindowStyle(SDL_bool fullscreen);
Expand Down Expand Up @@ -111,9 +131,6 @@ int Android_JNI_GetLocale(char *buf, size_t buflen);
/* Generic messages */
int Android_JNI_SendMessage(int command, int param);

/* Init */
JNIEXPORT void JNICALL SDL_Android_Init(JNIEnv *mEnv, jclass cls);

/* MessageBox */
int Android_JNI_ShowMessageBox(const SDL_MessageBoxData *messageboxdata, int *buttonID);

Expand All @@ -139,22 +156,16 @@ SDL_bool SDL_IsAndroidTV(void);
SDL_bool SDL_IsChromebook(void);
SDL_bool SDL_IsDeXMode(void);

void Android_LockActivityMutex(void);
void Android_UnlockActivityMutex(void);
void Android_LockActivityMutexOnceRunning(void);

/* File Dialogs */
SDL_bool Android_JNI_OpenFileDialog(SDL_DialogFileCallback callback, void* userdata,
const SDL_DialogFileFilter *filters, int nfilters, SDL_bool forwrite,
SDL_bool multiple);

/* Semaphores for event state processing */
extern SDL_Semaphore *Android_PauseSem;
extern SDL_Semaphore *Android_ResumeSem;

/* Ends C function definitions when using C++ */
#ifdef __cplusplus
/* *INDENT-OFF* */
}
/* *INDENT-ON* */
#endif

#endif // SDL_android_h
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