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.c b/libavcodec/mediacodec.c
index 5b79798a87..cd8766f3b1 100644
--- a/libavcodec/mediacodec.c
+++ b/libavcodec/mediacodec.c
@@ -43,9 +43,8 @@ int av_mediacodec_default_init(AVCodecContext *avctx, AVMediaCodecContext *ctx,
 {
     int ret = 0;
     JNIEnv *env = NULL;
-    int attached = 0;
 
-    env = ff_jni_attach_env(&attached, avctx);
+    env = ff_jni_get_env(avctx);
     if (!env) {
         return AVERROR_EXTERNAL;
     }
@@ -58,17 +57,12 @@ int av_mediacodec_default_init(AVCodecContext *avctx, AVMediaCodecContext *ctx,
         ret = AVERROR_EXTERNAL;
     }
 
-    if (attached) {
-        ff_jni_detach_env(avctx);
-    }
-
     return ret;
 }
 
 void av_mediacodec_default_free(AVCodecContext *avctx)
 {
     JNIEnv *env = NULL;
-    int attached = 0;
 
     AVMediaCodecContext *ctx = avctx->hwaccel_context;
 
@@ -76,7 +70,7 @@ void av_mediacodec_default_free(AVCodecContext *avctx)
         return;
     }
 
-    env = ff_jni_attach_env(&attached, avctx);
+    env = ff_jni_get_env(avctx);
     if (!env) {
         return;
     }
@@ -86,10 +80,6 @@ void av_mediacodec_default_free(AVCodecContext *avctx)
         ctx->surface = NULL;
     }
 
-    if (attached) {
-        ff_jni_detach_env(avctx);
-    }
-
     av_freep(&avctx->hwaccel_context);
 }