lavc/ffjni: replace ff_jni_{attach,detach} with ff_jni_get_env

If a JNI environment is not already attached to the thread where the
MediaCodec calls are made the current implementation will attach /
detach an environment for each MediaCodec call wasting some CPU time.

ff_jni_get_env replaces ff_jni_{attach,detach} by permanently attaching
an environment (if it is not already the case) to the current thread.
The environment will be automatically detached at the thread destruction
using a pthread_key callback.

Saves around 5% of CPU time (out of 20%) while decoding a stream with
MediaCodec.

1 files changed, 2 insertions, 12 deletions

diff --git a/libavcodec/mediacodec_surface.c b/libavcodec/mediacodec_surface.c
index 903ebe4d8b..aada1ecebe 100644
--- a/libavcodec/mediacodec_surface.c
+++ b/libavcodec/mediacodec_surface.c
@@ -27,40 +27,30 @@
 
 void *ff_mediacodec_surface_ref(void *surface, void *log_ctx)
 {
-    int attached = 0;
     JNIEnv *env = NULL;
 
     void *reference = NULL;
 
-    env = ff_jni_attach_env(&attached, log_ctx);
+    env = ff_jni_get_env(log_ctx);
     if (!env) {
         return NULL;
     }
 
     reference = (*env)->NewGlobalRef(env, surface);
 
-    if (attached) {
-        ff_jni_detach_env(log_ctx);
-    }
-
     return reference;
 }
 
 int ff_mediacodec_surface_unref(void *surface, void *log_ctx)
 {
-    int attached = 0;
     JNIEnv *env = NULL;
 
-    env = ff_jni_attach_env(&attached, log_ctx);
+    env = ff_jni_get_env(log_ctx);
     if (!env) {
         return AVERROR_EXTERNAL;
     }
 
     (*env)->DeleteGlobalRef(env, surface);
 
-    if (attached) {
-        ff_jni_detach_env(log_ctx);
-    }
-
     return 0;
 }