Extend examples to showcase the use of the FdMemoryAllocator

examples/Cargo.toml

@@ -23,19 +23,23 @@ ges = { package = "gstreamer-editing-services", path = "../gstreamer-editing-ser
 gst-sdp = { package = "gstreamer-sdp", path = "../gstreamer-sdp", optional = true }
 gst-rtsp = { package = "gstreamer-rtsp", path = "../gstreamer-rtsp", optional = true }
 gst-rtsp-server = { package = "gstreamer-rtsp-server", path = "../gstreamer-rtsp-server", optional = true }
+gst-allocators = { package = "gstreamer-allocators", path = "../gstreamer-allocators", optional = true }
 gtk = { git = "https://github.com/gtk-rs/gtk3-rs", optional = true }
 gdk = { git = "https://github.com/gtk-rs/gtk3-rs", optional = true }
-gio = { git = "https://github.com/gtk-rs/gtk-rs-core" , optional = true }
+gio = { git = "https://github.com/gtk-rs/gtk-rs-core", optional = true }
 anyhow = "1.0"
 derive_more = "0.99.5"
 futures = "0.3"
 byte-slice-cast = "1"
-cairo-rs = { git = "https://github.com/gtk-rs/gtk-rs-core" , features=["use_glib"], optional = true }
+cairo-rs = { git = "https://github.com/gtk-rs/gtk-rs-core", features=["use_glib"], optional = true }
-pango = { git = "https://github.com/gtk-rs/gtk-rs-core" , optional = true }
+pango = { git = "https://github.com/gtk-rs/gtk-rs-core", optional = true }
-pangocairo = { git = "https://github.com/gtk-rs/gtk-rs-core" , optional = true }
+pangocairo = { git = "https://github.com/gtk-rs/gtk-rs-core", optional = true }
 glutin = { version = "0.28", optional = true }
 once_cell = "1.0"
-image = { version="0.24", optional = true }
+image = { version = "0.24", optional = true }
+memmap2 = { version = "0.5", optional = true }
+memfd = { version = "0.4", optional = true }
+uds = { version = "0.2", optional = true }
 
 [target.'cfg(target_os = "macos")'.dependencies]
 cocoa = "0.24"
@@ -56,6 +60,7 @@ v1_14 = ["gst/v1_14"]
 pango-cairo = ["pango", "pangocairo", "cairo-rs"]
 overlay-composition = ["pango", "pangocairo", "cairo-rs"]
 gl = ["gst-gl", "gl_generator", "glutin"]
+allocators = ["gst-allocators", "memmap2", "memfd", "uds"]
 
 [[bin]]
 name = "appsink"
@@ -178,3 +183,7 @@ name = "video_converter"
 [[bin]]
 name = "thumbnail"
 required-features = ["image"]
+
+[[bin]]
+name = "fd_allocator"
+required-features = ["allocators"]

examples/src/bin/fd_allocator.rs

@@ -0,0 +1,518 @@
+// This example demonstrates the use of the FdMemory allocator.
+// It operates the following two pipelines:
+
+// sender:   {videotestsrc} - {appsink}
+// receiver: {appsrc} - {FdMemoryVideoFilter} - {videoconvert} - {queue} - {autovideosink}
+
+// The sender creates shared memory files from the appsink which are sent
+// to the receiver using a unix domain socket.
+// The receiver creates buffers in the appsrc using the FdMemoryAllocator from
+// the received file descriptors.
+
+// Additional to demonstrating how the FdMemoryAllocator can be used to share
+// file descriptors the example implements a custom VideoFilter demonstrating
+// how the file descriptor of FdMemory can be accessed in a pipeline.
+// Note that instead of manual mapping the file descriptor it is also possible
+// to use map_writable, which will also map the file descriptor.
+use futures::StreamExt;
+use gst::{element_error, prelude::*};
+
+use anyhow::Error;
+use derive_more::{Display, Error};
+
+use memmap2::MmapMut;
+use uds::UnixStreamExt;
+
+use std::{
+    os::unix::{net::UnixStream, prelude::AsRawFd},
+    sync::{Arc, Mutex},
+};
+
+#[path = "../examples-common.rs"]
+mod examples_common;
+
+#[derive(Debug, Display, Error)]
+#[display(fmt = "Missing element {}", _0)]
+struct MissingElement(#[error(not(source))] &'static str);
+
+#[derive(Debug, Display, Error)]
+#[display(fmt = "Received error from {}: {} (debug: {:?})", src, error, debug)]
+struct ErrorMessage {
+    src: String,
+    error: String,
+    debug: Option<String>,
+    source: glib::Error,
+}
+
+fn create_receiver_pipeline(
+    video_info: &gst_video::VideoInfo,
+    receiver: UnixStream,
+) -> Result<gst::Pipeline, Error> {
+    let caps = video_info.to_caps()?;
+
+    let pipeline = gst::Pipeline::new(None);
+    let src = gst::ElementFactory::make("appsrc", None).map_err(|_| MissingElement("appsrc"))?;
+    let filter = video_filter::FdMemoryFadeInVideoFilter::new()?.upcast::<gst::Element>();
+    let convert = gst::ElementFactory::make("videoconvert", None)
+        .map_err(|_| MissingElement("videoconvert"))?;
+    let queue = gst::ElementFactory::make("queue", None).map_err(|_| MissingElement("queue"))?;
+    let sink = gst::ElementFactory::make("autovideosink", None)
+        .map_err(|_| MissingElement("autovideosink"))?;
+
+    src.downcast_ref::<gst_app::AppSrc>()
+        .ok_or_else(|| anyhow::anyhow!("is not a appsrc"))?
+        .set_caps(Some(&caps));
+
+    pipeline.add_many(&[&src, &filter, &convert, &queue, &sink])?;
+    gst::Element::link_many(&[&src, &filter, &convert, &queue, &sink])?;
+
+    let appsrc = src
+        .downcast::<gst_app::AppSrc>()
+        .map_err(|_| anyhow::anyhow!("is not a appsrc"))?;
+
+    appsrc.set_do_timestamp(true);
+    appsrc.set_is_live(true);
+
+    let fd_allocator = gst_allocators::FdAllocator::new();
+    let video_info = video_info.clone();
+    let mut fd_buf = [-1; 253];
+
+    appsrc.set_callbacks(
+        gst_app::AppSrcCallbacks::builder()
+            .need_data(move |appsrc, _| {
+                // Read the next fds from the socket, if 0
+                // is returned the sender has closed the stream
+                // which is handled as EOS here.
+                let fds = match receiver.recv_fds(&mut [0u8; 1], &mut fd_buf) {
+                    Ok((_, 0)) => {
+                        let _ = appsrc.end_of_stream();
+                        return;
+                    }
+                    Ok((_, fds)) => fds,
+                    Err(err) => {
+                        gst::error_msg!(
+                            gst::StreamError::Failed,
+                            ("failed to receive fds: {}", err)
+                        );
+                        return;
+                    }
+                };
+
+                for fd in &fd_buf[0..fds] {
+                    // Allocate a new FdMemory for the received file descriptor.
+                    // It is important that the size matches the size of the
+                    // actual backing storage. In this example we just use the
+                    // same video info in both sides, sending and receiving.
+                    // Pass FdMemoryFlags::NONE to make the FdMemory take
+                    // ownership of the passed file descriptor. The file descriptor
+                    // will be closed when the memory is released.
+                    let memory = unsafe {
+                        fd_allocator.alloc(
+                            *fd,
+                            video_info.size(),
+                            gst_allocators::FdMemoryFlags::NONE,
+                        )
+                    };
+                    let mut buffer = gst::Buffer::new();
+                    let buffer_mut = buffer.make_mut();
+                    buffer_mut.append_memory(memory);
+                    let _ = appsrc.push_buffer(buffer);
+                }
+            })
+            .build(),
+    );
+
+    Ok(pipeline)
+}
+
+fn create_sender_pipeline(
+    video_info: &gst_video::VideoInfo,
+    sender: UnixStream,
+) -> Result<gst::Pipeline, Error> {
+    let sender = Arc::new(Mutex::new(sender));
+    let caps = video_info.to_caps()?;
+
+    let pipeline = gst::Pipeline::new(None);
+    let src = gst::ElementFactory::make("videotestsrc", None)
+        .map_err(|_| MissingElement("videotestsrc"))?;
+    let sink = gst::ElementFactory::make("appsink", None).map_err(|_| MissingElement("appsink"))?;
+
+    src.set_property("num-buffers", 250i32);
+
+    sink.downcast_ref::<gst_app::AppSink>()
+        .ok_or_else(|| anyhow::anyhow!("is not a appsink"))?
+        .set_caps(Some(&caps));
+
+    pipeline.add_many(&[&src, &sink])?;
+    gst::Element::link_many(&[&src, &sink])?;
+
+    let appsink = sink
+        .downcast::<gst_app::AppSink>()
+        .map_err(|_| anyhow::anyhow!("is not a appsink"))?;
+
+    appsink.set_callbacks(
+        gst_app::AppSinkCallbacks::builder()
+            // Add a handler to the "eos" signal
+            .eos({
+                let sender = sender.clone();
+                move |_| {
+                    // Close the sender part of the UnixSocket pair, this will automatically
+                    // create a eos in the receiving part.
+                    let _ = sender.lock().unwrap().shutdown(std::net::Shutdown::Write);
+                }
+            })
+            // Add a handler to the "new-sample" signal.
+            .new_sample(move |appsink| {
+                // Pull the sample in question out of the appsink's buffer.
+                let sample = appsink.pull_sample().map_err(|_| gst::FlowError::Eos)?;
+                let buffer = sample.buffer().ok_or_else(|| {
+                    element_error!(
+                        appsink,
+                        gst::ResourceError::Failed,
+                        ("Failed to get buffer from appsink")
+                    );
+
+                    gst::FlowError::Error
+                })?;
+
+                if buffer.n_memory() != 1 {
+                    element_error!(
+                        appsink,
+                        gst::ResourceError::Failed,
+                        ("Expected buffer with single memory")
+                    );
+
+                    return Err(gst::FlowError::Error);
+                }
+
+                let mem = buffer.peek_memory(0);
+
+                // We can use downcast_memory_ref to check if the provided
+                // memory is allocated by FdMemoryAllocator or a subtype of it.
+                // Note: This is not used in the example, we will always copy
+                // the memory to a new shared memory file.
+                if let Some(fd_memory) = mem.downcast_memory_ref::<gst_allocators::FdMemory>() {
+                    // As we already got a fd we can just directly send it over the socket.
+                    // NOTE: Synchronization is left out of this example, in a real world
+                    // application access to the memory should be synchronized.
+                    // For example wayland provides a release callback to signal that
+                    // the memory is no longer in use.
+                    sender
+                        .lock()
+                        .unwrap()
+                        .send_fds(&[0u8; 1], &[fd_memory.fd()])
+                        .map_err(|_| {
+                            element_error!(
+                                appsink,
+                                gst::ResourceError::Failed,
+                                ("Failed to send fd over unix stream")
+                            );
+
+                            gst::FlowError::Error
+                        })?;
+                } else {
+                    // At this point, buffer is only a reference to an existing memory region somewhere.
+                    // When we want to access its content, we have to map it while requesting the required
+                    // mode of access (read, read/write).
+                    // This type of abstraction is necessary, because the buffer in question might not be
+                    // on the machine's main memory itself, but rather in the GPU's memory.
+                    // So mapping the buffer makes the underlying memory region accessible to us.
+                    // See: https://gstreamer.freedesktop.org/documentation/plugin-development/advanced/allocation.html
+                    let map = buffer.map_readable().map_err(|_| {
+                        element_error!(
+                            appsink,
+                            gst::ResourceError::Failed,
+                            ("Failed to map buffer readable")
+                        );
+
+                        gst::FlowError::Error
+                    })?;
+
+                    // Note: To simplify this example we always create a new shared memory file instead
+                    // of using a pool of buffers. When using a pool we need to make sure access to the
+                    // file is synchronized.
+                    let opts = memfd::MemfdOptions::default().allow_sealing(true);
+                    let mfd = opts.create("gst-examples").map_err(|err| {
+                        element_error!(
+                            appsink,
+                            gst::ResourceError::Failed,
+                            ("Failed to allocated fd: {}", err)
+                        );
+
+                        gst::FlowError::Error
+                    })?;
+
+                    mfd.as_file().set_len(map.size() as u64).map_err(|err| {
+                        element_error!(
+                            appsink,
+                            gst::ResourceError::Failed,
+                            ("Failed to resize fd memory: {}", err)
+                        );
+
+                        gst::FlowError::Error
+                    })?;
+
+                    let mut seals = memfd::SealsHashSet::new();
+                    seals.insert(memfd::FileSeal::SealShrink);
+                    seals.insert(memfd::FileSeal::SealGrow);
+                    mfd.add_seals(&seals).map_err(|err| {
+                        element_error!(
+                            appsink,
+                            gst::ResourceError::Failed,
+                            ("Failed to add fd seals: {}", err)
+                        );
+
+                        gst::FlowError::Error
+                    })?;
+
+                    mfd.add_seal(memfd::FileSeal::SealSeal).map_err(|err| {
+                        element_error!(
+                            appsink,
+                            gst::ResourceError::Failed,
+                            ("Failed to add fd seals: {}", err)
+                        );
+
+                        gst::FlowError::Error
+                    })?;
+
+                    unsafe {
+                        let mut mmap = MmapMut::map_mut(mfd.as_file()).map_err(|_| {
+                            element_error!(
+                                appsink,
+                                gst::ResourceError::Failed,
+                                ("Failed to mmap fd")
+                            );
+
+                            gst::FlowError::Error
+                        })?;
+
+                        mmap.copy_from_slice(map.as_slice());
+                    };
+
+                    sender
+                        .lock()
+                        .unwrap()
+                        .send_fds(&[0u8; 1], &[mfd.as_raw_fd()])
+                        .map_err(|_| {
+                            element_error!(
+                                appsink,
+                                gst::ResourceError::Failed,
+                                ("Failed to send fd over unix stream")
+                            );
+
+                            gst::FlowError::Error
+                        })?;
+                };
+
+                Ok(gst::FlowSuccess::Ok)
+            })
+            .build(),
+    );
+
+    Ok(pipeline)
+}
+
+async fn message_loop(bus: gst::Bus) {
+    let mut messages = bus.stream();
+
+    while let Some(msg) = messages.next().await {
+        use gst::MessageView;
+
+        // Determine whether we want to quit: on EOS or error message
+        // we quit, otherwise simply continue.
+        match msg.view() {
+            MessageView::Eos(..) => break,
+            MessageView::Error(err) => {
+                println!(
+                    "Error from {:?}: {} ({:?})",
+                    err.src().map(|s| s.path_string()),
+                    err.error(),
+                    err.debug()
+                );
+                break;
+            }
+            _ => (),
+        };
+    }
+}
+
+fn example_main() -> Result<(), Error> {
+    gst::init()?;
+
+    let video_info = gst_video::VideoInfo::builder(gst_video::VideoFormat::Bgra, 1920, 1080)
+        .fps(gst::Fraction::new(30, 1))
+        .build()?;
+
+    let (sender, receiver) = std::os::unix::net::UnixStream::pair()?;
+    let sender_pipeline = create_sender_pipeline(&video_info, sender)?;
+    let receiver_pipeline = create_receiver_pipeline(&video_info, receiver)?;
+
+    let receiver_bus = receiver_pipeline.bus().expect("pipeline without bus");
+    receiver_pipeline.set_state(gst::State::Playing)?;
+
+    let sender_bus = sender_pipeline.bus().expect("pipeline without bus");
+    sender_pipeline.set_state(gst::State::Playing)?;
+
+    futures::executor::block_on(futures::future::join(
+        message_loop(sender_bus),
+        message_loop(receiver_bus),
+    ));
+
+    sender_pipeline.set_state(gst::State::Null)?;
+    receiver_pipeline.set_state(gst::State::Null)?;
+
+    Ok(())
+}
+
+fn main() {
+    // tutorials_common::run is only required to set up the application environment on macOS
+    // (but not necessary in normal Cocoa applications where this is set up automatically)
+    match examples_common::run(example_main) {
+        Ok(r) => r,
+        Err(e) => eprintln!("Error! {}", e),
+    }
+}
+
+// The purpose of this custom video filter is to demonstrate how
+// the file descriptor of a FdMemory can be accessed.
+mod video_filter {
+    use anyhow::Error;
+
+    glib::wrapper! {
+        pub struct FdMemoryFadeInVideoFilter(ObjectSubclass<imp::FdMemoryFadeInVideoFilter>) @extends gst_video::VideoFilter, gst_base::BaseTransform, gst::Element, gst::Object;
+    }
+
+    impl FdMemoryFadeInVideoFilter {
+        pub fn new() -> Result<Self, Error> {
+            Ok(glib::Object::builder().build()?)
+        }
+    }
+    mod imp {
+        use std::{cmp, mem::ManuallyDrop, os::unix::prelude::FromRawFd};
+
+        use anyhow::Error;
+        use glib::subclass::{object::ObjectImpl, types::ObjectSubclass};
+        use gst::{
+            subclass::prelude::{ElementImpl, GstObjectImpl},
+            PadDirection, PadPresence, PadTemplate,
+        };
+        use gst_app::gst_base::subclass::BaseTransformMode;
+        use gst_video::{
+            subclass::prelude::{BaseTransformImpl, VideoFilterImpl},
+            VideoFrameRef,
+        };
+        use memmap2::MmapMut;
+        use once_cell::sync::Lazy;
+
+        static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
+            gst::DebugCategory::new(
+                "fdmemoryfilter",
+                gst::DebugColorFlags::empty(),
+                Some("Example FdMemory filter"),
+            )
+        });
+
+        #[derive(Debug, Default)]
+        pub struct FdMemoryFadeInVideoFilter;
+
+        impl FdMemoryFadeInVideoFilter {
+            fn transform_fd_mem_ip(
+                &self,
+                frame: &mut VideoFrameRef<&mut gst::BufferRef>,
+            ) -> Result<(), Error> {
+                let buffer = frame.buffer();
+                if buffer.n_memory() != 1 {
+                    return Err(anyhow::anyhow!(
+                        "only buffers with single memory are supported"
+                    ));
+                }
+                let mem = buffer.peek_memory(0);
+                if !mem.is_memory_type::<gst_allocators::FdMemory>() {
+                    return Err(anyhow::anyhow!("only fd memory is supported"));
+                }
+
+                let timestamp = buffer.pts().unwrap();
+                let factor = (timestamp.nseconds() as f64
+                    / (5 * gst::ClockTime::SECOND).nseconds() as f64)
+                    .min(1.0f64);
+
+                // If the fade-in has finished return early
+                if factor >= 1.0f64 {
+                    return Ok(());
+                }
+
+                let fd = mem
+                    .downcast_memory_ref::<gst_allocators::FdMemory>()
+                    .unwrap()
+                    .fd();
+
+                unsafe {
+                    // We wrap the Memmfd in ManuallyDrop here because from_raw_fd takes ownership of
+                    // the file descriptor which would close it on drop
+                    //
+                    // see: https://github.com/lucab/memfd-rs/issues/29
+                    let mfd = ManuallyDrop::new(memfd::Memfd::from_raw_fd(fd));
+                    let mut mmap = MmapMut::map_mut(mfd.as_file())?;
+
+                    for pixel in mmap.chunks_exact_mut(4) {
+                        pixel[0] = cmp::max(0, cmp::min(255, (pixel[0] as f64 * factor) as u8));
+                        pixel[1] = cmp::max(0, cmp::min(255, (pixel[1] as f64 * factor) as u8));
+                        pixel[2] = cmp::max(0, cmp::min(255, (pixel[2] as f64 * factor) as u8));
+                    }
+                }
+
+                Ok(())
+            }
+        }
+
+        impl ElementImpl for FdMemoryFadeInVideoFilter {
+            fn pad_templates() -> &'static [PadTemplate] {
+                static PAD_TEMPLATES: Lazy<Vec<PadTemplate>> = Lazy::new(|| {
+                    let caps = gst::Caps::builder("video/x-raw")
+                        .field("format", "BGRA")
+                        .build();
+                    vec![
+                        PadTemplate::new("sink", PadDirection::Sink, PadPresence::Always, &caps)
+                            .unwrap(),
+                        PadTemplate::new("src", PadDirection::Src, PadPresence::Always, &caps)
+                            .unwrap(),
+                    ]
+                });
+
+                PAD_TEMPLATES.as_ref()
+            }
+        }
+
+        impl BaseTransformImpl for FdMemoryFadeInVideoFilter {
+            const MODE: BaseTransformMode = BaseTransformMode::AlwaysInPlace;
+            const PASSTHROUGH_ON_SAME_CAPS: bool = false;
+            const TRANSFORM_IP_ON_PASSTHROUGH: bool = true;
+        }
+
+        impl VideoFilterImpl for FdMemoryFadeInVideoFilter {
+            fn transform_frame_ip(
+                &self,
+                element: &Self::Type,
+                frame: &mut VideoFrameRef<&mut gst::BufferRef>,
+            ) -> Result<gst::FlowSuccess, gst::FlowError> {
+                self.transform_fd_mem_ip(frame).map_err(|err| {
+                    gst::error!(CAT, obj: element, "Failed to transform frame`: {}", err);
+                    gst::FlowError::Error
+                })?;
+
+                Ok(gst::FlowSuccess::Ok)
+            }
+        }
+
+        impl ObjectImpl for FdMemoryFadeInVideoFilter {}
+
+        impl GstObjectImpl for FdMemoryFadeInVideoFilter {}
+
+        #[glib::object_subclass]
+        impl ObjectSubclass for FdMemoryFadeInVideoFilter {
+            const NAME: &'static str = "FdMemoryVideoFilter";
+            type Type = super::FdMemoryFadeInVideoFilter;
+            type ParentType = gst_video::VideoFilter;
+        }
+    }
+}