From 22a2decf64e6a162e374aeb634fbcb21550c43a0 Mon Sep 17 00:00:00 2001
From: Sylvain Becker <sylvain.becker@gmail.com>
Date: Fri, 28 Jun 2019 16:38:42 +0200
Subject: [PATCH] Android: concurrency issues, make sure Activity is in running
 State when calling functions like SDL_CreateWindow, SDL_CreateRenderer,
 Android_GLES_CreateContext

Bugs 4694, 4681, 4142
---
 src/core/android/SDL_android.c        | 20 ++++++++++++++++++++
 src/core/android/SDL_android.h        |  1 +
 src/render/SDL_render.c               | 14 ++++++++++++++
 src/video/android/SDL_androidgl.c     | 10 +++++++++-
 src/video/android/SDL_androidwindow.c |  2 +-
 5 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/src/core/android/SDL_android.c b/src/core/android/SDL_android.c
index b0a2be397..918df7bcf 100644
--- a/src/core/android/SDL_android.c
+++ b/src/core/android/SDL_android.c
@@ -24,6 +24,7 @@
 #include "SDL_hints.h"
 #include "SDL_log.h"
 #include "SDL_main.h"
+#include "SDL_timer.h"
 
 #ifdef __ANDROID__
 
@@ -720,6 +721,25 @@ void Android_ActivityMutex_Unlock() {
     SDL_UnlockMutex(Android_ActivityMutex);
 }
 
+/* Lock the Mutex when the Activity is in its 'Running' state */
+void Android_ActivityMutex_Lock_Running() {
+    int pauseSignaled = 0;
+    int resumeSignaled = 0;
+
+retry:
+
+    SDL_LockMutex(Android_ActivityMutex);
+
+    pauseSignaled = SDL_SemValue(Android_PauseSem);
+    resumeSignaled = SDL_SemValue(Android_ResumeSem);
+
+    if (pauseSignaled > resumeSignaled) {
+        SDL_UnlockMutex(Android_ActivityMutex);
+        SDL_Delay(50);
+        goto retry;
+    }
+}
+
 /* Set screen resolution */
 JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeSetScreenResolution)(
                                     JNIEnv *env, jclass jcls,
diff --git a/src/core/android/SDL_android.h b/src/core/android/SDL_android.h
index b345b05ce..480d57ca0 100644
--- a/src/core/android/SDL_android.h
+++ b/src/core/android/SDL_android.h
@@ -133,6 +133,7 @@ SDL_bool SDL_IsDeXMode(void);
 
 void Android_ActivityMutex_Lock(void);
 void Android_ActivityMutex_Unlock(void);
+void Android_ActivityMutex_Lock_Running(void);
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus
diff --git a/src/render/SDL_render.c b/src/render/SDL_render.c
index abdca68df..5b0c1bf30 100644
--- a/src/render/SDL_render.c
+++ b/src/render/SDL_render.c
@@ -29,6 +29,9 @@
 #include "SDL_sysrender.h"
 #include "software/SDL_render_sw_c.h"
 
+#if defined(__ANDROID__)
+#  include "../core/android/SDL_android.h"
+#endif
 
 #define SDL_WINDOWRENDERDATA    "_SDL_WindowRenderData"
 
@@ -837,6 +840,10 @@ SDL_CreateRenderer(SDL_Window * window, int index, Uint32 flags)
     SDL_bool batching = SDL_TRUE;
     const char *hint;
 
+#if defined(__ANDROID__)
+    Android_ActivityMutex_Lock_Running();
+#endif
+
     if (!window) {
         SDL_SetError("Invalid window");
         goto error;
@@ -951,9 +958,16 @@ SDL_CreateRenderer(SDL_Window * window, int index, Uint32 flags)
     SDL_LogInfo(SDL_LOG_CATEGORY_RENDER,
                 "Created renderer: %s", renderer->info.name);
 
+#if defined(__ANDROID__)
+    Android_ActivityMutex_Unlock();
+#endif
     return renderer;
 
 error:
+
+#if defined(__ANDROID__)
+    Android_ActivityMutex_Unlock();
+#endif
     return NULL;
 
 #else
diff --git a/src/video/android/SDL_androidgl.c b/src/video/android/SDL_androidgl.c
index d71cd9b33..4dd982b97 100644
--- a/src/video/android/SDL_androidgl.c
+++ b/src/video/android/SDL_androidgl.c
@@ -49,7 +49,15 @@ Android_GLES_MakeCurrent(_THIS, SDL_Window * window, SDL_GLContext context)
 SDL_GLContext
 Android_GLES_CreateContext(_THIS, SDL_Window * window)
 {
-    return SDL_EGL_CreateContext(_this, ((SDL_WindowData *) window->driverdata)->egl_surface);
+    SDL_GLContext ret;
+
+    Android_ActivityMutex_Lock_Running();
+
+    ret = SDL_EGL_CreateContext(_this, ((SDL_WindowData *) window->driverdata)->egl_surface);
+
+    SDL_UnlockMutex(Android_ActivityMutex);
+
+    return ret;
 }
 
 int
diff --git a/src/video/android/SDL_androidwindow.c b/src/video/android/SDL_androidwindow.c
index 96a94e178..64eff5203 100644
--- a/src/video/android/SDL_androidwindow.c
+++ b/src/video/android/SDL_androidwindow.c
@@ -42,7 +42,7 @@ Android_CreateWindow(_THIS, SDL_Window * window)
     SDL_WindowData *data;
     int retval = 0;
 
-    SDL_LockMutex(Android_ActivityMutex);
+    Android_ActivityMutex_Lock_Running();
 
     if (Android_Window) {
         retval = SDL_SetError("Android only supports one window");