[PATCH 3/4] winegstreamer: Manage our own thread for read requests.
Zebediah Figura
z.figura12 at gmail.com
Tue Jan 26 17:45:31 CST 2021
Synchronization around flushing (on both sides) is tricky here, and the
solution used by this patch means that a "kernel" thread can be blocked on a
"user" thread. However, since it's not a real kernel thread and can't bring
down the rest of the "kernel", I don't think this is a concern.
Signed-off-by: Zebediah Figura <z.figura12 at gmail.com>
---
dlls/winegstreamer/gstdemux.c | 116 +++++++++++++++++++++++++++++++---
1 file changed, 106 insertions(+), 10 deletions(-)
diff --git a/dlls/winegstreamer/gstdemux.c b/dlls/winegstreamer/gstdemux.c
index b2d102b528e..fc861735cd7 100644
--- a/dlls/winegstreamer/gstdemux.c
+++ b/dlls/winegstreamer/gstdemux.c
@@ -63,7 +63,7 @@ struct parser
/* FIXME: It would be nice to avoid duplicating these with strmbase.
* However, synchronization is tricky; we need access to be protected by a
* separate lock. */
- bool streaming, flushing;
+ bool streaming, flushing, sink_connected;
GstElement *container;
GstPad *my_src, *their_sink;
@@ -76,6 +76,17 @@ struct parser
HANDLE push_thread;
+ HANDLE read_thread;
+ pthread_cond_t read_cond, read_done_cond;
+ struct
+ {
+ GstBuffer *buffer;
+ uint64_t offset;
+ uint32_t size;
+ bool done;
+ GstFlowReturn ret;
+ } read_request;
+
BOOL (*init_gst)(struct parser *filter);
HRESULT (*source_query_accept)(struct parser_source *pin, const AM_MEDIA_TYPE *mt);
HRESULT (*source_get_media_type)(struct parser_source *pin, unsigned int index, AM_MEDIA_TYPE *mt);
@@ -684,6 +695,12 @@ static GstFlowReturn queue_stream_event(struct parser_source *pin, const struct
{
struct parser *filter = impl_from_strmbase_filter(pin->pin.pin.filter);
+ /* Unlike request_buffer_src() [q.v.], we need to watch for GStreamer
+ * flushes here. The difference is that we can be blocked by the streaming
+ * thread not running (or itself flushing on the DirectShow side).
+ * request_buffer_src() can only be blocked by the upstream source, and that
+ * is solved by flushing the upstream source. */
+
pthread_mutex_lock(&filter->mutex);
while (!pin->flushing && pin->event.type != PARSER_EVENT_NONE)
pthread_cond_wait(&pin->event_empty_cond, &filter->mutex);
@@ -1095,14 +1112,51 @@ static DWORD CALLBACK stream_thread(void *arg)
return 0;
}
-static GstFlowReturn request_buffer_src(GstPad *pad, GstObject *parent, guint64 ofs, guint len, GstBuffer **buffer)
+static GstFlowReturn request_buffer_src(GstPad *pad, GstObject *parent, guint64 offset, guint size, GstBuffer **buffer)
{
- struct parser *This = gst_pad_get_element_private(pad);
+ struct parser *filter = gst_pad_get_element_private(pad);
GstBuffer *new_buffer = NULL;
+ GstFlowReturn ret;
+
+ GST_LOG("pad %p, offset %" G_GINT64_MODIFIER "u, length %u, buffer %p.", pad, offset, size, *buffer);
+
+ if (!*buffer)
+ *buffer = new_buffer = gst_buffer_new_and_alloc(size);
+
+ pthread_mutex_lock(&filter->mutex);
+
+ assert(!filter->read_request.buffer);
+ filter->read_request.buffer = *buffer;
+ filter->read_request.offset = offset;
+ filter->read_request.size = size;
+ filter->read_request.done = false;
+ pthread_cond_signal(&filter->read_cond);
+
+ /* Note that we don't unblock this wait on GST_EVENT_FLUSH_START. We expect
+ * the upstream pin to flush if necessary. We should never be blocked on
+ * read_thread() not running. */
+
+ while (!filter->read_request.done)
+ pthread_cond_wait(&filter->read_done_cond, &filter->mutex);
+
+ ret = filter->read_request.ret;
+
+ pthread_mutex_unlock(&filter->mutex);
+
+ GST_LOG("Request returned %s.", gst_flow_get_name(ret));
+
+ if (ret != GST_FLOW_OK && new_buffer)
+ gst_buffer_unref(new_buffer);
+
+ return ret;
+}
+
+static GstFlowReturn read_buffer(struct parser *This, guint64 ofs, guint len, GstBuffer *buffer)
+{
HRESULT hr;
GstMapInfo info;
- TRACE("pad %p, offset %s, length %u, buffer %p.\n", pad, wine_dbgstr_longlong(ofs), len, *buffer);
+ TRACE("filter %p, offset %s, length %u, buffer %p.\n", This, wine_dbgstr_longlong(ofs), len, buffer);
if (ofs == GST_BUFFER_OFFSET_NONE)
ofs = This->nextpullofs;
@@ -1114,22 +1168,47 @@ static GstFlowReturn request_buffer_src(GstPad *pad, GstObject *parent, guint64
len = This->filesize - ofs;
This->nextpullofs = ofs + len;
- if (!*buffer)
- *buffer = new_buffer = gst_buffer_new_and_alloc(len);
- gst_buffer_map(*buffer, &info, GST_MAP_WRITE);
+ gst_buffer_map(buffer, &info, GST_MAP_WRITE);
hr = IAsyncReader_SyncRead(This->reader, ofs, len, info.data);
- gst_buffer_unmap(*buffer, &info);
+ gst_buffer_unmap(buffer, &info);
if (FAILED(hr))
{
ERR("Failed to read data, hr %#x.\n", hr);
- if (new_buffer)
- gst_buffer_unref(new_buffer);
return GST_FLOW_ERROR;
}
return GST_FLOW_OK;
}
+static DWORD CALLBACK read_thread(void *arg)
+{
+ struct parser *filter = arg;
+
+ TRACE("Starting read thread for filter %p.\n", filter);
+
+ pthread_mutex_lock(&filter->mutex);
+
+ for (;;)
+ {
+ while (filter->sink_connected && !filter->read_request.buffer)
+ pthread_cond_wait(&filter->read_cond, &filter->mutex);
+
+ if (!filter->sink_connected)
+ break;
+
+ filter->read_request.done = true;
+ filter->read_request.ret = read_buffer(filter, filter->read_request.offset,
+ filter->read_request.size, filter->read_request.buffer);
+ filter->read_request.buffer = NULL;
+ pthread_cond_signal(&filter->read_done_cond);
+ }
+
+ pthread_mutex_unlock(&filter->mutex);
+
+ TRACE("Streaming stopped; exiting.\n");
+ return 0;
+}
+
static void removed_decoded_pad(GstElement *bin, GstPad *pad, gpointer user)
{
struct parser *filter = user;
@@ -1506,6 +1585,10 @@ static HRESULT GST_Connect(struct parser *This, IPin *pConnectPin)
IAsyncReader_Length(This->reader, &This->filesize, &avail);
+ This->sink_connected = true;
+
+ This->read_thread = CreateThread(NULL, 0, read_thread, This, 0, NULL);
+
if (!This->bus) {
This->bus = gst_bus_new();
gst_bus_set_sync_handler(This->bus, watch_bus, This, NULL);
@@ -1599,6 +1682,8 @@ static void parser_destroy(struct strmbase_filter *iface)
gst_object_unref(filter->bus);
}
+ pthread_cond_destroy(&filter->read_cond);
+ pthread_cond_destroy(&filter->read_done_cond);
pthread_cond_destroy(&filter->init_cond);
pthread_mutex_destroy(&filter->mutex);
@@ -1895,6 +1980,8 @@ static void parser_init_common(struct parser *object)
{
pthread_mutex_init(&object->mutex, NULL);
pthread_cond_init(&object->init_cond, NULL);
+ pthread_cond_init(&object->read_cond, NULL);
+ pthread_cond_init(&object->read_done_cond, NULL);
object->flushing = true;
}
@@ -2411,6 +2498,15 @@ static HRESULT GST_RemoveOutputPins(struct parser *This)
gst_object_unref(This->their_sink);
This->my_src = This->their_sink = NULL;
+ /* read_thread() needs to stay alive to service any read requests GStreamer
+ * sends, so we can only shut it down after GStreamer stops. */
+ pthread_mutex_lock(&This->mutex);
+ This->sink_connected = false;
+ pthread_mutex_unlock(&This->mutex);
+ pthread_cond_signal(&This->read_cond);
+ WaitForSingleObject(This->read_thread, INFINITE);
+ CloseHandle(This->read_thread);
+
for (i = 0; i < This->source_count; ++i)
free_source_pin(This->sources[i]);
--
2.30.0
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