encode: add locking

Since the AO will run in a thread, and there's lots of shared state with
encoding, we have to add locking.

One case this doesn't handle correctly are the encode_lavc_available()
calls in ao_lavc.c and vo_lavc.c. They don't do much (and usually only
to protect against doing --ao=lavc with normal playback), and changing
it would be a bit messy. So just leave them.

1 files changed, 36 insertions, 4 deletions

diff --git a/common/encode_lavc.c b/common/encode_lavc.c
index 5f9e2a0390..5d9853673b 100644
--- a/common/encode_lavc.c
+++ b/common/encode_lavc.c
@@ -103,6 +103,15 @@ static bool value_has_flag(const char *value, const char *flag)
         return val; \
     }
 
+#define CHECK_FAIL_UNLOCK(ctx, val) \
+    if (ctx && (ctx->failed || ctx->finished)) { \
+        MP_ERR(ctx, \
+               "Called a function on a %s encoding context. Bailing out.\n", \
+               ctx->failed ? "failed" : "finished"); \
+        pthread_mutex_unlock(&ctx->lock); \
+        return val; \
+    }
+
 int encode_lavc_available(struct encode_lavc_context *ctx)
 {
     CHECK_FAIL(ctx, 0);
@@ -134,6 +143,7 @@ struct encode_lavc_context *encode_lavc_init(struct encode_output_conf *options,
         mp_msg_force_stderr(global, true);
 
     ctx = talloc_zero(NULL, struct encode_lavc_context);
+    pthread_mutex_init(&ctx->lock, NULL);
     ctx->log = mp_log_new(ctx, global->log, "encode-lavc");
     ctx->global = global;
     encode_lavc_discontinuity(ctx);
@@ -309,6 +319,7 @@ void encode_lavc_free(struct encode_lavc_context *ctx)
         encode_lavc_fail(ctx,
                          "called encode_lavc_free without encode_lavc_finish\n");
 
+    pthread_mutex_destroy(&ctx->lock);
     talloc_free(ctx);
 }
 
@@ -383,14 +394,18 @@ void encode_lavc_finish(struct encode_lavc_context *ctx)
 
 void encode_lavc_set_video_fps(struct encode_lavc_context *ctx, float fps)
 {
+    pthread_mutex_lock(&ctx->lock);
     ctx->vo_fps = fps;
+    pthread_mutex_unlock(&ctx->lock);
 }
 
 void encode_lavc_set_audio_pts(struct encode_lavc_context *ctx, double pts)
 {
     if (ctx) {
+        pthread_mutex_lock(&ctx->lock);
         ctx->last_audio_in_pts = pts;
         ctx->samples_since_last_pts = 0;
+        pthread_mutex_unlock(&ctx->lock);
     }
 }
 
@@ -780,11 +795,15 @@ void encode_lavc_discontinuity(struct encode_lavc_context *ctx)
     if (!ctx)
         return;
 
-    CHECK_FAIL(ctx, );
+    pthread_mutex_lock(&ctx->lock);
+
+    CHECK_FAIL_UNLOCK(ctx, );
 
     ctx->audio_pts_offset = MP_NOPTS_VALUE;
     ctx->last_video_in_pts = MP_NOPTS_VALUE;
     ctx->discontinuity_pts_offset = MP_NOPTS_VALUE;
+
+    pthread_mutex_unlock(&ctx->lock);
 }
 
 static void encode_lavc_printoptions(struct mp_log *log, void *obj,
@@ -1013,7 +1032,9 @@ int encode_lavc_getstatus(struct encode_lavc_context *ctx,
     if (!ctx)
         return -1;
 
-    CHECK_FAIL(ctx, -1);
+    pthread_mutex_lock(&ctx->lock);
+
+    CHECK_FAIL_UNLOCK(ctx, -1);
 
     minutes = (now - ctx->t0) / 60.0 * (1 - f) / f;
     megabytes = ctx->avc->pb ? (avio_size(ctx->avc->pb) / 1048576.0 / f) : 0;
@@ -1029,12 +1050,16 @@ int encode_lavc_getstatus(struct encode_lavc_context *ctx,
         snprintf(buf, bufsize, "{%.1fmin %.1fMB}",
                  minutes, megabytes);
     buf[bufsize - 1] = 0;
+
+    pthread_mutex_unlock(&ctx->lock);
     return 0;
 }
 
 void encode_lavc_expect_stream(struct encode_lavc_context *ctx, int mt)
 {
-    CHECK_FAIL(ctx, );
+    pthread_mutex_lock(&ctx->lock);
+
+    CHECK_FAIL_UNLOCK(ctx, );
 
     switch (mt) {
     case AVMEDIA_TYPE_VIDEO:
@@ -1044,11 +1069,18 @@ void encode_lavc_expect_stream(struct encode_lavc_context *ctx, int mt)
         ctx->expect_audio = true;
         break;
     }
+
+    pthread_mutex_unlock(&ctx->lock);
 }
 
 bool encode_lavc_didfail(struct encode_lavc_context *ctx)
 {
-    return ctx && ctx->failed;
+    if (!ctx)
+        return false;
+    pthread_mutex_lock(&ctx->lock);
+    bool fail = ctx && ctx->failed;
+    pthread_mutex_unlock(&ctx->lock);
+    return fail;
 }
 
 void encode_lavc_fail(struct encode_lavc_context *ctx, const char *format, ...)