uvstream: don't increase underrun counter if buffer still in uvstream

The underrun counter is supposed to show when there is a shortage of buffers due
to them being not put back soon enough in the incoming queue. If some of them
are still in use by the stream thread, it is not an underrun condition.

src/arvuvstream.c

@@ -86,6 +86,7 @@ typedef struct {
 	/* Statistics */
 	ArvStreamStatistics statistics;
 
+        gint n_buffer_in_use;
 } ArvUvStreamThreadData;
 
 typedef struct {
@@ -129,6 +130,8 @@ typedef struct {
         gboolean is_aborting;
 
 	ArvStreamStatistics *statistics;
+
+        gint *n_buffer_in_use;
 } ArvUvStreamBufferContext;
 
 G_DEFINE_TYPE_WITH_CODE (ArvUvStream, arv_uv_stream, ARV_TYPE_STREAM, G_ADD_PRIVATE (ArvUvStream))
@@ -299,6 +302,7 @@ void LIBUSB_CALL arv_uv_stream_trailer_cb (struct libusb_transfer *transfer)
                         ctx->callback (ctx->callback_data,
                                        ARV_STREAM_CALLBACK_TYPE_BUFFER_DONE,
                                        ctx->buffer);
+                g_atomic_int_dec_and_test(ctx->n_buffer_in_use);
                 ctx->buffer = NULL;
         }
 
@@ -321,6 +325,7 @@ arv_uv_stream_buffer_context_new (ArvBuffer *buffer, ArvUvStreamThreadData *thre
         ctx->callback_data = thread_data->callback_data;
 	ctx->transfer_completed_mtx = &thread_data->stream_mtx;
 	ctx->transfer_completed_event = &thread_data->stream_event;
+        ctx->n_buffer_in_use = &thread_data->n_buffer_in_use;
 
 	ctx->leader_buffer = g_malloc (thread_data->leader_size);
 	ctx->leader_transfer = libusb_alloc_transfer (0);
@@ -387,6 +392,7 @@ arv_uv_stream_buffer_context_free (gpointer data)
                         ctx->callback (ctx->callback_data,
                                        ARV_STREAM_CALLBACK_TYPE_BUFFER_DONE,
                                        ctx->buffer);
+                g_atomic_int_dec_and_test(ctx->n_buffer_in_use);
                 ctx->buffer = NULL;
         }
 
@@ -509,11 +515,14 @@ arv_uv_stream_thread_async (void *data)
                                                               ARV_UV_STREAM_POP_INPUT_BUFFER_TIMEOUT_MS * 1000);
 
 		if( buffer == NULL ) {
-			thread_data->statistics.n_underruns += 1;
+                        if (thread_data->n_buffer_in_use == 0)
+                                thread_data->statistics.n_underruns += 1;
                         /* NOTE: n_ignored_bytes is not accumulated because it doesn't submit next USB transfer if
                          * buffer is shortage. It means back pressure might be hanlded by USB slave side. */
 			continue;
-		}
+		} else {
+                        g_atomic_int_inc(&thread_data->n_buffer_in_use);
+                }
 
 		ctx = g_hash_table_lookup( ctx_lookup, buffer );
 		if (!ctx) {
@@ -612,10 +621,12 @@ arv_uv_stream_thread_sync (void *data)
 									       ARV_STREAM_CALLBACK_TYPE_BUFFER_DONE,
 									       buffer);
 						thread_data->statistics.n_failures++;
+                                                g_atomic_int_dec_and_test(&thread_data->n_buffer_in_use);
 						buffer = NULL;
 					}
 					buffer = arv_stream_pop_input_buffer (thread_data->stream);
 					if (buffer != NULL) {
+                                                g_atomic_int_inc(&thread_data->n_buffer_in_use);
 						buffer->priv->system_timestamp_ns = g_get_real_time () * 1000LL;
 						buffer->priv->status = ARV_BUFFER_STATUS_FILLING;
                                                 buffer->priv->received_size = 0;
@@ -671,6 +682,7 @@ arv_uv_stream_thread_sync (void *data)
                                                                                       buffer);
                                                        thread_data->statistics.n_failures++;
                                                        thread_data->statistics.n_ignored_bytes += transferred;
+                                                        g_atomic_int_dec_and_test(&thread_data->n_buffer_in_use);
                                                        buffer = NULL;
                                                 } else {
                                                         buffer->priv->status = ARV_BUFFER_STATUS_SUCCESS;
@@ -683,6 +695,7 @@ arv_uv_stream_thread_sync (void *data)
                                                                                        buffer);
                                                         thread_data->statistics.n_completed_buffers++;
                                                         thread_data->statistics.n_transferred_bytes += transferred;
+                                                        g_atomic_int_dec_and_test(&thread_data->n_buffer_in_use);
                                                         buffer = NULL;
                                                 }
                                         }
@@ -718,6 +731,7 @@ arv_uv_stream_thread_sync (void *data)
 			thread_data->callback (thread_data->callback_data,
 					       ARV_STREAM_CALLBACK_TYPE_BUFFER_DONE,
 					       buffer);
+                g_atomic_int_dec_and_test(&thread_data->n_buffer_in_use);
 	}
 
 	if (thread_data->callback != NULL)
@@ -840,6 +854,7 @@ arv_uv_stream_start_thread (ArvStream *stream)
         thread_data->payload_count = si_payload_count;
         thread_data->transfer1_size = si_transfer1_size;
 	thread_data->trailer_size = si_trailer_size;
+        thread_data->n_buffer_in_use = 0;
 	thread_data->cancel = FALSE;
 
         switch (priv->usb_mode) {
@@ -887,7 +902,6 @@ arv_uv_stream_stop_thread (ArvStream *stream)
 	si_control = 0x0;
 	arv_device_write_memory (ARV_DEVICE (thread_data->uv_device),
 				 priv->sirm_address + ARV_SIRM_CONTROL, sizeof (si_control), &si_control, NULL);
-
 }
 
 /**