Implement a generic Element implementation infrastructure

And implement the Demuxer base class on top of that, with no unsafe code
left whatsoever

gst-plugin-flv/src/flvdemux.rs

@@ -490,7 +490,7 @@ pub struct FlvDemux {
 }
 
 impl FlvDemux {
-    pub fn new(_demuxer: &RsDemuxerWrapper) -> FlvDemux {
+    pub fn new(_demuxer: &RsDemuxer) -> FlvDemux {
         FlvDemux {
             cat: gst::DebugCategory::new(
                 "rsflvdemux",
@@ -503,13 +503,13 @@ impl FlvDemux {
         }
     }
 
-    pub fn new_boxed(demuxer: &RsDemuxerWrapper) -> Box<Demuxer> {
+    pub fn new_boxed(demuxer: &RsDemuxer) -> Box<DemuxerImpl> {
         Box::new(Self::new(demuxer))
     }
 
     fn handle_script_tag(
         &mut self,
-        demuxer: &RsDemuxerWrapper,
+        demuxer: &RsDemuxer,
         tag_header: &flavors::TagHeader,
     ) -> Result<HandleBufferResult, FlowError> {
         if self.adapter.get_available() < (15 + tag_header.data_size) as usize {
@@ -577,7 +577,7 @@ impl FlvDemux {
 
     fn update_audio_stream(
         &mut self,
-        demuxer: &RsDemuxerWrapper,
+        demuxer: &RsDemuxer,
         data_header: &flavors::AudioDataHeader,
     ) -> Result<HandleBufferResult, FlowError> {
         gst_trace!(
@@ -631,7 +631,7 @@ impl FlvDemux {
 
     fn handle_audio_tag(
         &mut self,
-        demuxer: &RsDemuxerWrapper,
+        demuxer: &RsDemuxer,
         tag_header: &flavors::TagHeader,
         data_header: &flavors::AudioDataHeader,
     ) -> Result<HandleBufferResult, FlowError> {
@@ -754,7 +754,7 @@ impl FlvDemux {
 
     fn update_video_stream(
         &mut self,
-        demuxer: &RsDemuxerWrapper,
+        demuxer: &RsDemuxer,
         data_header: &flavors::VideoDataHeader,
     ) -> Result<HandleBufferResult, FlowError> {
         gst_trace!(
@@ -809,7 +809,7 @@ impl FlvDemux {
 
     fn handle_video_tag(
         &mut self,
-        demuxer: &RsDemuxerWrapper,
+        demuxer: &RsDemuxer,
         tag_header: &flavors::TagHeader,
         data_header: &flavors::VideoDataHeader,
     ) -> Result<HandleBufferResult, FlowError> {
@@ -954,10 +954,7 @@ impl FlvDemux {
         Ok(HandleBufferResult::BufferForStream(VIDEO_STREAM_ID, buffer))
     }
 
-    fn update_state(
-        &mut self,
-        demuxer: &RsDemuxerWrapper,
-    ) -> Result<HandleBufferResult, FlowError> {
+    fn update_state(&mut self, demuxer: &RsDemuxer) -> Result<HandleBufferResult, FlowError> {
         match self.state {
             State::Stopped => unreachable!(),
             State::NeedHeader => {
@@ -1100,10 +1097,10 @@ impl FlvDemux {
     }
 }
 
-impl Demuxer for FlvDemux {
+impl DemuxerImpl for FlvDemux {
     fn start(
         &mut self,
-        demuxer: &RsDemuxerWrapper,
+        demuxer: &RsDemuxer,
         _upstream_size: Option<u64>,
         _random_access: bool,
     ) -> Result<(), ErrorMessage> {
@@ -1112,7 +1109,7 @@ impl Demuxer for FlvDemux {
         Ok(())
     }
 
-    fn stop(&mut self, demuxer: &RsDemuxerWrapper) -> Result<(), ErrorMessage> {
+    fn stop(&mut self, demuxer: &RsDemuxer) -> Result<(), ErrorMessage> {
         self.state = State::Stopped;
         self.adapter.clear();
         self.streaming_state = None;
@@ -1122,7 +1119,7 @@ impl Demuxer for FlvDemux {
 
     fn seek(
         &mut self,
-        demuxer: &RsDemuxerWrapper,
+        demuxer: &RsDemuxer,
         start: u64,
         stop: Option<u64>,
     ) -> Result<SeekResult, ErrorMessage> {
@@ -1131,7 +1128,7 @@ impl Demuxer for FlvDemux {
 
     fn handle_buffer(
         &mut self,
-        demuxer: &RsDemuxerWrapper,
+        demuxer: &RsDemuxer,
         buffer: Option<gst::Buffer>,
     ) -> Result<HandleBufferResult, FlowError> {
         if let Some(buffer) = buffer {
@@ -1141,16 +1138,16 @@ impl Demuxer for FlvDemux {
         self.update_state(demuxer)
     }
 
-    fn end_of_stream(&mut self, demuxer: &RsDemuxerWrapper) -> Result<(), ErrorMessage> {
+    fn end_of_stream(&mut self, demuxer: &RsDemuxer) -> Result<(), ErrorMessage> {
         // nothing to do here, all data we have left is incomplete
         Ok(())
     }
 
-    fn is_seekable(&self, demuxer: &RsDemuxerWrapper) -> bool {
+    fn is_seekable(&self, demuxer: &RsDemuxer) -> bool {
         false
     }
 
-    fn get_position(&self, demuxer: &RsDemuxerWrapper) -> Option<u64> {
+    fn get_position(&self, demuxer: &RsDemuxer) -> Option<u64> {
         if let Some(StreamingState { last_position, .. }) = self.streaming_state {
             return last_position;
         }
@@ -1158,7 +1155,7 @@ impl Demuxer for FlvDemux {
         None
     }
 
-    fn get_duration(&self, demuxer: &RsDemuxerWrapper) -> Option<u64> {
+    fn get_duration(&self, demuxer: &RsDemuxer) -> Option<u64> {
         if let Some(StreamingState {
             metadata: Some(Metadata { duration, .. }),
             ..

gst-plugin/Cargo.toml

@@ -10,6 +10,7 @@ libc = "0.2"
 url = "1.1"
 lazy_static = "0.2"
 byteorder = "1.0"
+mopa = "0.2"
 glib-sys = { git = "https://github.com/gtk-rs/sys" }
 gobject-sys = { git = "https://github.com/gtk-rs/sys" }
 gstreamer-sys = { git = "https://github.com/sdroege/gstreamer-sys", features = ["v1_10"] }

gst-plugin/src/element.rs

@@ -0,0 +1,305 @@
+// Copyright (C) 2017 Sebastian Dröge <sebastian@centricular.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::ffi::CString;
+use std::ptr;
+use std::mem;
+use std::sync::atomic::AtomicBool;
+use mopa;
+
+use glib_ffi;
+use gobject_ffi;
+use gst_ffi;
+
+use glib;
+use glib::translate::*;
+use gst;
+use gst::prelude::*;
+
+pub trait ElementImpl: mopa::Any + Send + Sync + 'static {
+    fn change_state(
+        &self,
+        element: &RsElement,
+        transition: gst::StateChange,
+    ) -> gst::StateChangeReturn {
+        element.parent_change_state(transition)
+    }
+}
+
+mopafy!(ElementImpl);
+
+pub unsafe trait Element: IsA<gst::Element> {
+    fn parent_change_state(&self, transition: gst::StateChange) -> gst::StateChangeReturn {
+        unsafe {
+            // Our class
+            let klass = *(self.to_glib_none().0 as *const glib_ffi::gpointer);
+            // The parent class, RsElement or any other first-level Rust implementation
+            let parent_klass = gobject_ffi::g_type_class_peek_parent(klass);
+            // The actual parent class as defined in C
+            let parent_klass = &*(gobject_ffi::g_type_class_peek_parent(parent_klass) as
+                *const gst_ffi::GstElementClass);
+            parent_klass
+                .change_state
+                .map(|f| {
+                    from_glib(f(self.to_glib_none().0, transition.to_glib()))
+                })
+                .unwrap_or(gst::StateChangeReturn::Success)
+        }
+    }
+}
+
+pub unsafe trait ElementClass {
+    fn add_pad_template(&mut self, pad_template: gst::PadTemplate) {
+        unsafe {
+            gst_ffi::gst_element_class_add_pad_template(
+                self as *const Self as *mut gst_ffi::GstElementClass,
+                pad_template.to_glib_full(),
+            );
+        }
+    }
+
+    fn set_metadata(
+        &mut self,
+        long_name: &str,
+        classification: &str,
+        description: &str,
+        author: &str,
+    ) {
+        unsafe {
+            gst_ffi::gst_element_class_set_metadata(
+                self as *const Self as *mut gst_ffi::GstElementClass,
+                long_name.to_glib_none().0,
+                classification.to_glib_none().0,
+                description.to_glib_none().0,
+                author.to_glib_none().0,
+            );
+        }
+    }
+}
+
+glib_wrapper! {
+    pub struct RsElement(Object<ffi::RsElement>): [gst::Element => gst_ffi::GstElement,
+                                                   gst::Object => gst_ffi::GstObject];
+
+    match fn {
+        get_type => || ffi::rs_element_get_type(),
+    }
+}
+
+impl RsElement {
+    pub fn get_impl(&self) -> &ElementImpl {
+        unsafe {
+            let stash = self.to_glib_none();
+            let ptr: *const ffi::RsElement = stash.0;
+            (*ptr).get_impl()
+        }
+    }
+}
+
+unsafe impl<T: IsA<gst::Element>> Element for T {}
+unsafe impl ElementClass for RsElementClass {}
+
+struct ElementData {
+    class_init: Box<Fn(&mut RsElementClass) + Send + 'static>,
+    init: Box<Fn(&RsElement) -> Box<ElementImpl> + Send + Sync + 'static>,
+}
+
+pub mod ffi {
+    use super::*;
+    use super::RsElement as RsElementWrapper;
+
+    #[repr(C)]
+    pub struct RsElement {
+        parent: gst_ffi::GstElement,
+        imp: *const Box<ElementImpl>,
+        panicked: AtomicBool,
+    }
+
+    impl RsElement {
+        pub fn get_impl(&self) -> &ElementImpl {
+            unsafe {
+                assert!(!self.imp.is_null());
+                &*(*self.imp)
+            }
+        }
+    }
+
+    #[repr(C)]
+    pub struct RsElementClass {
+        parent_class: gst_ffi::GstElementClass,
+        element_data: *const ElementData,
+    }
+
+    pub unsafe fn rs_element_get_type() -> glib_ffi::GType {
+        use std::sync::{Once, ONCE_INIT};
+
+        static mut TYPE: glib_ffi::GType = gobject_ffi::G_TYPE_INVALID;
+        static ONCE: Once = ONCE_INIT;
+
+        ONCE.call_once(|| {
+            let type_info = gobject_ffi::GTypeInfo {
+                class_size: mem::size_of::<RsElementClass>() as u16,
+                base_init: None,
+                base_finalize: None,
+                class_init: Some(element_class_init),
+                class_finalize: None,
+                class_data: ptr::null_mut(),
+                instance_size: mem::size_of::<RsElement>() as u16,
+                n_preallocs: 0,
+                instance_init: None,
+                value_table: ptr::null(),
+            };
+
+            let type_name = {
+                let mut idx = 0;
+
+                loop {
+                    let type_name = CString::new(format!("RsElement-{}", idx)).unwrap();
+                    if gobject_ffi::g_type_from_name(type_name.as_ptr()) ==
+                        gobject_ffi::G_TYPE_INVALID
+                    {
+                        break type_name;
+                    }
+                    idx += 1;
+                }
+            };
+
+            TYPE = gobject_ffi::g_type_register_static(
+                gst_ffi::gst_element_get_type(),
+                type_name.as_ptr(),
+                &type_info,
+                gobject_ffi::GTypeFlags::empty(),
+            );
+        });
+
+        TYPE
+    }
+
+    unsafe extern "C" fn element_finalize(obj: *mut gobject_ffi::GObject) {
+        callback_guard!();
+        let element = &mut *(obj as *mut RsElement);
+
+        drop(Box::from_raw(element.imp as *mut Box<ElementImpl>));
+        element.imp = ptr::null_mut();
+
+        let klass = *(obj as *const glib_ffi::gpointer);
+        let parent_klass = gobject_ffi::g_type_class_peek_parent(klass);
+        let parent_klass = &*(gobject_ffi::g_type_class_peek_parent(parent_klass) as
+            *const gobject_ffi::GObjectClass);
+        parent_klass.finalize.map(|f| f(obj));
+    }
+
+    unsafe extern "C" fn element_sub_class_init(
+        klass: glib_ffi::gpointer,
+        klass_data: glib_ffi::gpointer,
+    ) {
+        callback_guard!();
+        let element_data = &*(klass_data as *const ElementData);
+
+        {
+            let klass = &mut *(klass as *mut RsElementClass);
+
+            klass.element_data = element_data;
+
+            (element_data.class_init)(klass);
+        }
+    }
+
+    unsafe extern "C" fn element_class_init(
+        klass: glib_ffi::gpointer,
+        _klass_data: glib_ffi::gpointer,
+    ) {
+        callback_guard!();
+        {
+            let gobject_klass = &mut *(klass as *mut gobject_ffi::GObjectClass);
+
+            gobject_klass.finalize = Some(element_finalize);
+        }
+
+        {
+            let element_klass = &mut *(klass as *mut gst_ffi::GstElementClass);
+
+            element_klass.change_state = Some(element_change_state);
+        }
+    }
+
+    unsafe extern "C" fn element_change_state(
+        ptr: *mut gst_ffi::GstElement,
+        transition: gst_ffi::GstStateChange,
+    ) -> gst_ffi::GstStateChangeReturn {
+        callback_guard!();
+        let element = &*(ptr as *mut RsElement);
+        let wrap: RsElementWrapper = from_glib_borrow(ptr as *mut RsElement);
+        let imp = &*element.imp;
+
+        panic_to_error2!(&wrap, &element.panicked, gst::StateChangeReturn::Failure, {
+            imp.change_state(&wrap, from_glib(transition))
+        }).to_glib()
+    }
+
+    unsafe extern "C" fn element_sub_init(
+        instance: *mut gobject_ffi::GTypeInstance,
+        klass: glib_ffi::gpointer,
+    ) {
+        callback_guard!();
+        let element = &mut *(instance as *mut RsElement);
+        let wrap: RsElementWrapper = from_glib_borrow(instance as *mut RsElement);
+        let klass = &*(klass as *const RsElementClass);
+        let element_data = &*klass.element_data;
+
+        let imp = (element_data.init)(&wrap);
+        element.imp = Box::into_raw(Box::new(imp));
+    }
+
+    pub fn element_register<F, G>(
+        plugin: &gst::Plugin,
+        name: &str,
+        rank: u32,
+        class_init: F,
+        init: G,
+    ) where
+        F: Fn(&mut RsElementClass) + Send + 'static,
+        G: Fn(&RsElementWrapper) -> Box<ElementImpl> + Send + Sync + 'static,
+    {
+        unsafe {
+            let parent_type = rs_element_get_type();
+            let type_name = format!("RsElement-{}", name);
+
+            let element_data = ElementData {
+                class_init: Box::new(class_init),
+                init: Box::new(init),
+            };
+            let element_data = Box::into_raw(Box::new(element_data)) as glib_ffi::gpointer;
+
+            let type_info = gobject_ffi::GTypeInfo {
+                class_size: mem::size_of::<RsElementClass>() as u16,
+                base_init: None,
+                base_finalize: None,
+                class_init: Some(element_sub_class_init),
+                class_finalize: None,
+                class_data: element_data,
+                instance_size: mem::size_of::<RsElement>() as u16,
+                n_preallocs: 0,
+                instance_init: Some(element_sub_init),
+                value_table: ptr::null(),
+            };
+
+            let type_ = gobject_ffi::g_type_register_static(
+                parent_type,
+                type_name.to_glib_none().0,
+                &type_info,
+                gobject_ffi::GTypeFlags::empty(),
+            );
+
+            gst::Element::register(plugin, &name, rank, from_glib(type_));
+        }
+    }
+}
+
+pub use self::ffi::RsElementClass;
+pub use self::ffi::element_register;

gst-plugin/src/error.rs

@@ -243,3 +243,34 @@ macro_rules! panic_to_error(
         }
     }};
 );
+
+#[macro_export]
+macro_rules! panic_to_error2(
+    ($element:expr, $panicked:expr, $ret:expr, $code:block) => {{
+        use std::panic::{self, AssertUnwindSafe};
+        use std::sync::atomic::Ordering;
+        use $crate::error::ErrorMessage;
+
+        if $panicked.load(Ordering::Relaxed) {
+            error_msg!(gst::LibraryError::Failed, ["Panicked"]).post($element);
+            $ret
+        } else {
+            let result = panic::catch_unwind(AssertUnwindSafe(|| $code));
+
+            match result {
+                Ok(result) => result,
+                Err(err) => {
+                    $panicked.store(true, Ordering::Relaxed);
+                    if let Some(cause) = err.downcast_ref::<&str>() {
+                        error_msg!(gst::LibraryError::Failed, ["Panicked: {}", cause]).post($element);
+                    } else if let Some(cause) = err.downcast_ref::<String>() {
+                        error_msg!(gst::LibraryError::Failed, ["Panicked: {}", cause]).post($element);
+                    } else {
+                        error_msg!(gst::LibraryError::Failed, ["Panicked"]).post($element);
+                    }
+                    $ret
+                }
+            }
+        }
+    }};
+);

gst-plugin/src/lib.rs

@@ -12,6 +12,8 @@ extern crate gstreamer_base_sys as gst_base_ffi;
 #[macro_use]
 extern crate lazy_static;
 extern crate libc;
+#[macro_use]
+extern crate mopa;
 extern crate url;
 pub extern crate glib_sys as glib_ffi;
 pub extern crate gobject_sys as gobject_ffi;
@@ -23,6 +25,12 @@ pub extern crate glib;
 #[macro_use]
 pub extern crate gstreamer as gst;
 
+macro_rules! callback_guard {
+    () => (
+        let _guard = ::glib::CallbackGuard::new();
+    )
+}
+
 #[macro_use]
 pub mod utils;
 #[macro_use]
@@ -34,3 +42,5 @@ pub mod source;
 pub mod sink;
 pub mod demuxer;
 pub mod bytes;
+
+pub mod element;

gst-plugin/src/sink.rs

@@ -40,7 +40,7 @@ pub struct SinkWrapper {
     panicked: AtomicBool,
 }
 
-pub trait Sink {
+pub trait Sink: Send + 'static {
     fn uri_validator(&self) -> Box<UriValidator>;
 
     fn start(&mut self, sink: &RsSinkWrapper, uri: Url) -> Result<(), ErrorMessage>;

gst-plugin/src/source.rs

@@ -40,7 +40,7 @@ pub struct SourceWrapper {
     panicked: AtomicBool,
 }
 
-pub trait Source {
+pub trait Source: Send + 'static {
     fn uri_validator(&self) -> Box<UriValidator>;
 
     fn is_seekable(&self, src: &RsSrcWrapper) -> bool;