[PATCH 3/5] winegstreamer: Use a GstAtomicQueue for wg_transform output queue.

[Rémi Bernon]

Some GStreamer video plugins such as vaapi do not expect their buffers
to be appended to each other, and it breaks some of their assertions.

We will also later need to queue caps change events, and the atomic
queue will let us queue GstSample instead to hold the caps too. It also
removes the need of a mutex or locking operations.

Signed-off-by: Rémi Bernon <rbernon at codeweavers.com>
---
 dlls/winegstreamer/wg_transform.c | 67 +++++++++++++++----------------
 1 file changed, 33 insertions(+), 34 deletions(-)

diff --git a/dlls/winegstreamer/wg_transform.c b/dlls/winegstreamer/wg_transform.c
index 200dd946e02..0327b92ce8e 100644
--- a/dlls/winegstreamer/wg_transform.c
+++ b/dlls/winegstreamer/wg_transform.c
@@ -50,9 +50,8 @@ struct wg_transform
     GstSegment segment;
     GstBufferList *input;
     guint input_max_length;
-
-    pthread_mutex_t mutex;
-    GstBuffer *output;
+    GstAtomicQueue *output_queue;
+    GstBuffer *output_buffer;
 };
 
 static GstFlowReturn transform_sink_chain_cb(GstPad *pad, GstObject *parent, GstBuffer *buffer)
@@ -61,12 +60,7 @@ static GstFlowReturn transform_sink_chain_cb(GstPad *pad, GstObject *parent, Gst
 
     GST_LOG("transform %p, buffer %p.", transform, buffer);
 
-    pthread_mutex_lock(&transform->mutex);
-    if (transform->output)
-        transform->output = gst_buffer_append(transform->output, buffer);
-    else
-        transform->output = buffer;
-    pthread_mutex_unlock(&transform->mutex);
+    gst_atomic_queue_push(transform->output_queue, buffer);
 
     return GST_FLOW_OK;
 }
@@ -74,19 +68,24 @@ static GstFlowReturn transform_sink_chain_cb(GstPad *pad, GstObject *parent, Gst
 NTSTATUS wg_transform_destroy(void *args)
 {
     struct wg_transform *transform = args;
+    GstBuffer *buffer;
 
     if (transform->input)
         gst_buffer_list_unref(transform->input);
-    if (transform->output)
-        gst_buffer_unref(transform->output);
 
     gst_element_set_state(transform->container, GST_STATE_NULL);
+
+    if (transform->output_buffer)
+        gst_buffer_unref(transform->output_buffer);
+    while ((buffer = gst_atomic_queue_pop(transform->output_queue)))
+        gst_buffer_unref(buffer);
+
     g_object_unref(transform->their_sink);
     g_object_unref(transform->their_src);
     g_object_unref(transform->container);
     g_object_unref(transform->my_sink);
     g_object_unref(transform->my_src);
-    pthread_mutex_destroy(&transform->mutex);
+    gst_atomic_queue_unref(transform->output_queue);
     free(transform);
 
     return STATUS_SUCCESS;
@@ -182,6 +181,8 @@ NTSTATUS wg_transform_create(void *args)
         goto out;
     if (!(transform->input = gst_buffer_list_new()))
         goto out;
+    if (!(transform->output_queue = gst_atomic_queue_new(8)))
+        goto out;
     transform->input_max_length = 1;
 
     if (!(src_caps = wg_format_to_caps(&input_format)))
@@ -308,8 +309,6 @@ NTSTATUS wg_transform_create(void *args)
     gst_caps_unref(sink_caps);
     gst_caps_unref(src_caps);
 
-    pthread_mutex_init(&transform->mutex, NULL);
-
     GST_INFO("Created winegstreamer transform %p.", transform);
     params->transform = transform;
     return STATUS_SUCCESS;
@@ -327,6 +326,8 @@ out:
         gst_object_unref(transform->my_src);
     if (src_caps)
         gst_caps_unref(src_caps);
+    if (transform->output_queue)
+        gst_atomic_queue_unref(transform->output_queue);
     if (transform->input)
         gst_buffer_list_unref(transform->input);
     if (transform->container)
@@ -368,10 +369,8 @@ NTSTATUS wg_transform_push_data(void *args)
     return STATUS_SUCCESS;
 }
 
-static NTSTATUS read_transform_output_data(struct wg_transform *transform,
-        struct wg_sample *sample)
+static NTSTATUS read_transform_output_data(GstBuffer *buffer, struct wg_sample *sample)
 {
-    GstBuffer *buffer = transform->output;
     GstMapInfo info;
 
     if (!gst_buffer_map(buffer, &info, GST_MAP_READ))
@@ -392,12 +391,6 @@ static NTSTATUS read_transform_output_data(struct wg_transform *transform,
     gst_buffer_unmap(buffer, &info);
     gst_buffer_resize(buffer, sample->size, -1);
 
-    if (info.size <= sample->size)
-    {
-        gst_buffer_unref(transform->output);
-        transform->output = NULL;
-    }
-
     GST_INFO("Copied %u bytes, sample %p, flags %#x", sample->size, sample, sample->flags);
     return STATUS_SUCCESS;
 }
@@ -424,20 +417,26 @@ NTSTATUS wg_transform_read_data(void *args)
         return STATUS_UNSUCCESSFUL;
     }
 
-    sample->size = 0;
-    pthread_mutex_lock(&transform->mutex);
-    if (transform->output)
-    {
-        params->result = S_OK;
-        status = read_transform_output_data(transform, sample);
-    }
-    else
+    if (!transform->output_buffer && !(transform->output_buffer = gst_atomic_queue_pop(transform->output_queue)))
     {
+        sample->size = 0;
         params->result = MF_E_TRANSFORM_NEED_MORE_INPUT;
-        status = STATUS_SUCCESS;
         GST_INFO("Cannot read %u bytes, no output available", sample->max_size);
+        return STATUS_SUCCESS;
     }
-    pthread_mutex_unlock(&transform->mutex);
 
-    return status;
+    if ((status = read_transform_output_data(transform->output_buffer, sample)))
+    {
+        sample->size = 0;
+        return status;
+    }
+
+    if (!(sample->flags & WG_SAMPLE_FLAG_INCOMPLETE))
+    {
+        gst_buffer_unref(transform->output_buffer);
+        transform->output_buffer = NULL;
+    }
+
+    params->result = S_OK;
+    return STATUS_SUCCESS;
 }
-- 
2.35.1