support for subclassing buffer pool

gstreamer/src/buffer_pool.rs

@@ -4,51 +4,106 @@ use crate::AllocationParams;
 use crate::Allocator;
 use crate::BufferPool;
 use crate::Structure;
+use crate::StructureRef;
 
 use glib::prelude::*;
 use glib::translate::*;
 
 use std::mem;
 use std::ops;
+use std::ops::Deref;
+use std::ops::DerefMut;
 use std::ptr;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[repr(transparent)]
 pub struct BufferPoolConfig(Structure);
 
-impl ops::Deref for BufferPoolConfig {
+impl Deref for BufferPoolConfig {
+    type Target = BufferPoolConfigRef;
+
+    fn deref(&self) -> &BufferPoolConfigRef {
+        unsafe { &*(self.0.as_ptr() as *const StructureRef as *const BufferPoolConfigRef) }
+    }
+}
+
+impl DerefMut for BufferPoolConfig {
+    fn deref_mut(&mut self) -> &mut BufferPoolConfigRef {
+        unsafe { &mut *(self.0.as_ptr() as *mut StructureRef as *mut BufferPoolConfigRef) }
+    }
+}
+
+impl AsRef<BufferPoolConfigRef> for BufferPoolConfig {
+    fn as_ref(&self) -> &BufferPoolConfigRef {
+        self.deref()
+    }
+}
+
+impl AsMut<BufferPoolConfigRef> for BufferPoolConfig {
+    fn as_mut(&mut self) -> &mut BufferPoolConfigRef {
+        self.deref_mut()
+    }
+}
+
+#[derive(Debug)]
+#[repr(transparent)]
+pub struct BufferPoolConfigRef(StructureRef);
+
+impl BufferPoolConfigRef {
+    pub unsafe fn from_glib_borrow<'a>(ptr: *const ffi::GstStructure) -> &'a BufferPoolConfigRef {
+        assert!(!ptr.is_null());
+
+        &*(ptr as *mut StructureRef as *mut BufferPoolConfigRef)
+    }
+
+    pub unsafe fn from_glib_borrow_mut<'a>(
+        ptr: *mut ffi::GstStructure,
+    ) -> &'a mut BufferPoolConfigRef {
+        assert!(!ptr.is_null());
+
+        &mut *(ptr as *mut StructureRef as *mut BufferPoolConfigRef)
+    }
+
+    pub unsafe fn as_ptr(&self) -> *const ffi::GstStructure {
+        self as *const Self as *const ffi::GstStructure
+    }
+
+    pub unsafe fn as_mut_ptr(&self) -> *mut ffi::GstStructure {
+        self as *const Self as *mut ffi::GstStructure
+    }
+}
+
+impl ops::Deref for BufferPoolConfigRef {
     type Target = crate::StructureRef;
 
     fn deref(&self) -> &crate::StructureRef {
-        self.0.deref()
+        &self.0
     }
 }
 
-impl ops::DerefMut for BufferPoolConfig {
+impl ops::DerefMut for BufferPoolConfigRef {
     fn deref_mut(&mut self) -> &mut crate::StructureRef {
-        self.0.deref_mut()
+        &mut self.0
     }
 }
 
-impl AsRef<crate::StructureRef> for BufferPoolConfig {
+impl AsRef<crate::StructureRef> for BufferPoolConfigRef {
     fn as_ref(&self) -> &crate::StructureRef {
-        self.0.as_ref()
+        &self.0
     }
 }
 
-impl AsMut<crate::StructureRef> for BufferPoolConfig {
+impl AsMut<crate::StructureRef> for BufferPoolConfigRef {
     fn as_mut(&mut self) -> &mut crate::StructureRef {
-        self.0.as_mut()
+        &mut self.0
     }
 }
 
-impl BufferPoolConfig {
+impl BufferPoolConfigRef {
     #[doc(alias = "gst_buffer_pool_config_add_option")]
     pub fn add_option(&mut self, option: &str) {
         unsafe {
-            ffi::gst_buffer_pool_config_add_option(
+            ffi::gst_buffer_pool_config_add_option(self.0.as_mut_ptr(), option.to_glib_none().0);
-                self.0.to_glib_none_mut().0,
-                option.to_glib_none().0,
-            );
         }
     }
 
@@ -56,7 +111,7 @@ impl BufferPoolConfig {
     pub fn has_option(&self, option: &str) -> bool {
         unsafe {
             from_glib(ffi::gst_buffer_pool_config_has_option(
-                self.0.to_glib_none().0,
+                self.0.as_mut_ptr(),
                 option.to_glib_none().0,
             ))
         }
@@ -66,12 +121,12 @@ impl BufferPoolConfig {
     #[doc(alias = "gst_buffer_pool_config_n_options")]
     pub fn options(&self) -> Vec<String> {
         unsafe {
-            let n = ffi::gst_buffer_pool_config_n_options(self.0.to_glib_none().0) as usize;
+            let n = ffi::gst_buffer_pool_config_n_options(self.0.as_mut_ptr()) as usize;
             let mut options = Vec::with_capacity(n);
 
             for i in 0..n {
                 options.push(from_glib_none(ffi::gst_buffer_pool_config_get_option(
-                    self.0.to_glib_none().0,
+                    self.0.as_mut_ptr(),
                     i as u32,
                 )));
             }
@@ -90,7 +145,7 @@ impl BufferPoolConfig {
     ) {
         unsafe {
             ffi::gst_buffer_pool_config_set_params(
-                self.0.to_glib_none_mut().0,
+                self.0.as_mut_ptr(),
                 caps.to_glib_none().0,
                 size,
                 min_buffers,
@@ -109,7 +164,7 @@ impl BufferPoolConfig {
             let mut max_buffers = mem::MaybeUninit::uninit();
 
             let ret: bool = from_glib(ffi::gst_buffer_pool_config_get_params(
-                self.0.to_glib_none().0,
+                self.0.as_mut_ptr(),
                 &mut caps,
                 size.as_mut_ptr(),
                 min_buffers.as_mut_ptr(),
@@ -139,7 +194,7 @@ impl BufferPoolConfig {
         unsafe {
             glib::result_from_gboolean!(
                 ffi::gst_buffer_pool_config_validate_params(
-                    self.0.to_glib_none().0,
+                    self.0.as_mut_ptr(),
                     caps.to_glib_none().0,
                     size,
                     min_buffers,
@@ -157,7 +212,7 @@ impl BufferPoolConfig {
             let mut allocator = ptr::null_mut();
             let mut params = mem::MaybeUninit::zeroed();
             let ret = from_glib(ffi::gst_buffer_pool_config_get_allocator(
-                self.0.to_glib_none().0,
+                self.0.as_mut_ptr(),
                 &mut allocator,
                 params.as_mut_ptr(),
             ));
@@ -174,7 +229,7 @@ impl BufferPoolConfig {
         assert!(allocator.is_some() || params.is_some());
         unsafe {
             ffi::gst_buffer_pool_config_set_allocator(
-                self.0.to_glib_none().0,
+                self.0.as_mut_ptr(),
                 allocator.to_glib_none().0,
                 match params {
                     Some(val) => val.as_ptr(),
@@ -271,6 +326,13 @@ impl<'a> ToGlibPtrMut<'a, *mut ffi::GstBufferPoolAcquireParams> for BufferPoolAc
     }
 }
 
+#[doc(hidden)]
+impl FromGlibPtrNone<*mut ffi::GstBufferPoolAcquireParams> for BufferPoolAcquireParams {
+    unsafe fn from_glib_none(ptr: *mut ffi::GstBufferPoolAcquireParams) -> Self {
+        Self(*ptr)
+    }
+}
+
 impl BufferPool {
     #[doc(alias = "gst_buffer_pool_new")]
     pub fn new() -> BufferPool {

gstreamer/src/subclass/buffer_pool.rs

@@ -0,0 +1,642 @@
+// Take a look at the license at the top of the repository in the LICENSE file.
+
+use super::prelude::*;
+use glib::{
+    subclass::{prelude::*, InitializingObject},
+    translate::*,
+    Cast, StaticType,
+};
+use libc::c_char;
+
+use crate::{BufferPool, BufferPoolAcquireParams, BufferPoolConfigRef};
+
+pub trait BufferPoolImpl: BufferPoolImplExt + GstObjectImpl + Send + Sync {
+    fn acquire_buffer(
+        &self,
+        buffer_pool: &Self::Type,
+        params: Option<&BufferPoolAcquireParams>,
+    ) -> Result<crate::Buffer, crate::FlowError> {
+        self.parent_acquire_buffer(buffer_pool, params)
+    }
+
+    fn alloc_buffer(
+        &self,
+        buffer_pool: &Self::Type,
+        params: Option<&BufferPoolAcquireParams>,
+    ) -> Result<crate::Buffer, crate::FlowError> {
+        self.parent_alloc_buffer(buffer_pool, params)
+    }
+
+    fn flush_start(&self, buffer_pool: &Self::Type) {
+        self.parent_flush_start(buffer_pool)
+    }
+
+    fn flush_stop(&self, buffer_pool: &Self::Type) {
+        self.parent_flush_stop(buffer_pool)
+    }
+
+    fn free_buffer(&self, buffer_pool: &Self::Type, buffer: crate::Buffer) {
+        self.parent_free_buffer(buffer_pool, buffer)
+    }
+
+    fn release_buffer(&self, buffer_pool: &Self::Type, buffer: crate::Buffer) {
+        self.parent_release_buffer(buffer_pool, buffer)
+    }
+
+    fn reset_buffer(&self, buffer_pool: &Self::Type, buffer: &mut crate::BufferRef) {
+        self.parent_reset_buffer(buffer_pool, buffer)
+    }
+
+    fn start(&self, buffer_pool: &Self::Type) -> bool {
+        self.parent_start(buffer_pool)
+    }
+
+    fn stop(&self, buffer_pool: &Self::Type) -> bool {
+        self.parent_stop(buffer_pool)
+    }
+
+    fn options() -> &'static [&'static str] {
+        &[]
+    }
+
+    fn set_config(&self, buffer_pool: &Self::Type, config: &mut BufferPoolConfigRef) -> bool {
+        self.parent_set_config(buffer_pool, config)
+    }
+}
+
+pub trait BufferPoolImplExt: ObjectSubclass {
+    fn parent_acquire_buffer(
+        &self,
+        buffer_pool: &Self::Type,
+        params: Option<&BufferPoolAcquireParams>,
+    ) -> Result<crate::Buffer, crate::FlowError>;
+
+    fn parent_alloc_buffer(
+        &self,
+        buffer_pool: &Self::Type,
+        params: Option<&BufferPoolAcquireParams>,
+    ) -> Result<crate::Buffer, crate::FlowError>;
+
+    fn parent_free_buffer(&self, buffer_pool: &Self::Type, buffer: crate::Buffer);
+
+    fn parent_release_buffer(&self, buffer_pool: &Self::Type, buffer: crate::Buffer);
+
+    fn parent_reset_buffer(&self, buffer_pool: &Self::Type, buffer: &mut crate::BufferRef);
+
+    fn parent_start(&self, buffer_pool: &Self::Type) -> bool;
+
+    fn parent_stop(&self, buffer_pool: &Self::Type) -> bool;
+
+    fn parent_set_config(&self, buffer_pool: &Self::Type, config: &mut BufferPoolConfigRef)
+        -> bool;
+
+    fn parent_flush_start(&self, _buffer_pool: &Self::Type);
+
+    fn parent_flush_stop(&self, _buffer_pool: &Self::Type);
+}
+
+impl<T: BufferPoolImpl> BufferPoolImplExt for T {
+    fn parent_acquire_buffer(
+        &self,
+        buffer_pool: &Self::Type,
+        params: Option<&BufferPoolAcquireParams>,
+    ) -> Result<crate::Buffer, crate::FlowError> {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).acquire_buffer {
+                let params_ptr = mut_override(params.to_glib_none().0);
+                let mut buffer = std::ptr::null_mut();
+
+                let result = f(
+                    buffer_pool
+                        .unsafe_cast_ref::<crate::BufferPool>()
+                        .to_glib_none()
+                        .0,
+                    &mut buffer,
+                    params_ptr,
+                );
+
+                crate::FlowSuccess::try_from_glib(result).map(|_| from_glib_full(buffer))
+            } else {
+                Err(crate::FlowError::NotSupported)
+            }
+        }
+    }
+
+    fn parent_alloc_buffer(
+        &self,
+        buffer_pool: &Self::Type,
+        params: Option<&BufferPoolAcquireParams>,
+    ) -> Result<crate::Buffer, crate::FlowError> {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).alloc_buffer {
+                let params_ptr = mut_override(params.to_glib_none().0);
+                let mut buffer = std::ptr::null_mut();
+
+                let result = f(
+                    buffer_pool
+                        .unsafe_cast_ref::<crate::BufferPool>()
+                        .to_glib_none()
+                        .0,
+                    &mut buffer,
+                    params_ptr,
+                );
+
+                crate::FlowSuccess::try_from_glib(result).map(|_| from_glib_full(buffer))
+            } else {
+                Err(crate::FlowError::NotSupported)
+            }
+        }
+    }
+
+    fn parent_free_buffer(&self, buffer_pool: &Self::Type, buffer: crate::Buffer) {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).free_buffer {
+                f(
+                    buffer_pool
+                        .unsafe_cast_ref::<crate::BufferPool>()
+                        .to_glib_none()
+                        .0,
+                    buffer.into_ptr(),
+                )
+            }
+        }
+    }
+
+    fn parent_release_buffer(&self, buffer_pool: &Self::Type, buffer: crate::Buffer) {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).release_buffer {
+                f(
+                    buffer_pool
+                        .unsafe_cast_ref::<crate::BufferPool>()
+                        .to_glib_none()
+                        .0,
+                    buffer.into_ptr(),
+                )
+            }
+        }
+    }
+
+    fn parent_reset_buffer(&self, buffer_pool: &Self::Type, buffer: &mut crate::BufferRef) {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).reset_buffer {
+                f(
+                    buffer_pool
+                        .unsafe_cast_ref::<crate::BufferPool>()
+                        .to_glib_none()
+                        .0,
+                    buffer.as_mut_ptr(),
+                )
+            }
+        }
+    }
+
+    fn parent_start(&self, buffer_pool: &Self::Type) -> bool {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).start {
+                let result = f(buffer_pool
+                    .unsafe_cast_ref::<crate::BufferPool>()
+                    .to_glib_none()
+                    .0);
+
+                from_glib(result)
+            } else {
+                true
+            }
+        }
+    }
+
+    fn parent_stop(&self, buffer_pool: &Self::Type) -> bool {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).stop {
+                let result = f(buffer_pool
+                    .unsafe_cast_ref::<crate::BufferPool>()
+                    .to_glib_none()
+                    .0);
+
+                from_glib(result)
+            } else {
+                true
+            }
+        }
+    }
+
+    fn parent_set_config(
+        &self,
+        buffer_pool: &Self::Type,
+        config: &mut BufferPoolConfigRef,
+    ) -> bool {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).set_config {
+                let result = f(
+                    buffer_pool
+                        .unsafe_cast_ref::<crate::BufferPool>()
+                        .to_glib_none()
+                        .0,
+                    (*config).as_mut_ptr(),
+                );
+
+                from_glib(result)
+            } else {
+                false
+            }
+        }
+    }
+
+    fn parent_flush_start(&self, buffer_pool: &Self::Type) {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).flush_start {
+                f(buffer_pool
+                    .unsafe_cast_ref::<crate::BufferPool>()
+                    .to_glib_none()
+                    .0)
+            }
+        }
+    }
+
+    fn parent_flush_stop(&self, buffer_pool: &Self::Type) {
+        unsafe {
+            let data = Self::type_data();
+            let parent_class = data.as_ref().parent_class() as *mut ffi::GstBufferPoolClass;
+            if let Some(f) = (*parent_class).flush_stop {
+                f(buffer_pool
+                    .unsafe_cast_ref::<crate::BufferPool>()
+                    .to_glib_none()
+                    .0)
+            }
+        }
+    }
+}
+
+// Send+Sync wrapper around a NULL-terminated C string array
+struct CStrV(*mut *const libc::c_char);
+unsafe impl Send for CStrV {}
+unsafe impl Sync for CStrV {}
+
+impl Drop for CStrV {
+    fn drop(&mut self) {
+        unsafe { glib::ffi::g_strfreev(self.0 as *mut _) };
+    }
+}
+
+unsafe impl<T: BufferPoolImpl> IsSubclassable<T> for BufferPool {
+    fn class_init(klass: &mut glib::Class<Self>) {
+        Self::parent_class_init::<T>(klass);
+        let klass = klass.as_mut();
+        klass.acquire_buffer = Some(buffer_pool_acquire_buffer::<T>);
+        klass.alloc_buffer = Some(buffer_pool_alloc_buffer::<T>);
+        klass.release_buffer = Some(buffer_pool_release_buffer::<T>);
+        klass.reset_buffer = Some(buffer_pool_reset_buffer::<T>);
+        klass.start = Some(buffer_pool_start::<T>);
+        klass.stop = Some(buffer_pool_stop::<T>);
+        klass.get_options = Some(buffer_pool_get_options::<T>);
+        klass.set_config = Some(buffer_pool_set_config::<T>);
+        klass.flush_start = Some(buffer_pool_flush_start::<T>);
+        klass.flush_stop = Some(buffer_pool_flush_stop::<T>);
+        klass.free_buffer = Some(buffer_pool_free_buffer::<T>);
+    }
+
+    fn instance_init(instance: &mut InitializingObject<T>) {
+        Self::parent_instance_init(instance);
+
+        // Store the pool options in the instance data
+        // for later retrieval in buffer_pool_get_options
+        let options = T::options();
+        let options = options.to_glib_full();
+        instance.set_instance_data(T::type_(), CStrV(options));
+    }
+}
+
+unsafe extern "C" fn buffer_pool_acquire_buffer<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+    buffer: *mut *mut ffi::GstBuffer,
+    params: *mut ffi::GstBufferPoolAcquireParams,
+) -> ffi::GstFlowReturn {
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    let params: Option<BufferPoolAcquireParams> = from_glib_none(params);
+
+    match imp.acquire_buffer(wrap.unsafe_cast_ref(), params.as_ref()) {
+        Ok(b) => {
+            *buffer = b.into_ptr();
+            ffi::GST_FLOW_OK
+        }
+        Err(err) => err.into_glib(),
+    }
+}
+
+unsafe extern "C" fn buffer_pool_alloc_buffer<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+    buffer: *mut *mut ffi::GstBuffer,
+    params: *mut ffi::GstBufferPoolAcquireParams,
+) -> ffi::GstFlowReturn {
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    let params: Option<BufferPoolAcquireParams> = from_glib_none(params);
+
+    match imp.alloc_buffer(wrap.unsafe_cast_ref(), params.as_ref()) {
+        Ok(b) => {
+            *buffer = b.into_ptr();
+            ffi::GST_FLOW_OK
+        }
+        Err(err) => err.into_glib(),
+    }
+}
+
+unsafe extern "C" fn buffer_pool_flush_start<T: BufferPoolImpl>(ptr: *mut ffi::GstBufferPool) {
+    // the GstBufferPool implementation calls this
+    // in finalize where the ref_count will already
+    // be zero and we are actually destroyed
+    // see: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1645
+    if (*(ptr as *const glib::gobject_ffi::GObject)).ref_count == 0 {
+        // flush_start is a no-op in GstBufferPool
+        return;
+    }
+
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    imp.flush_start(wrap.unsafe_cast_ref());
+}
+
+unsafe extern "C" fn buffer_pool_flush_stop<T: BufferPoolImpl>(ptr: *mut ffi::GstBufferPool) {
+    // the GstBufferPool implementation calls this
+    // in finalize where the ref_count will already
+    // be zero and we are actually destroyed
+    // see: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1645
+    if (*(ptr as *const glib::gobject_ffi::GObject)).ref_count == 0 {
+        // flush_stop is a no-op in GstBufferPool
+        return;
+    }
+
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    imp.flush_stop(wrap.unsafe_cast_ref());
+}
+
+unsafe extern "C" fn buffer_pool_free_buffer<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+    buffer: *mut ffi::GstBuffer,
+) {
+    // the GstBufferPool implementation calls this
+    // in finalize where the ref_count will already
+    // be zero and we are actually destroyed
+    // see: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1645
+    if (*(ptr as *const glib::gobject_ffi::GObject)).ref_count == 0 {
+        // As a workaround we call free_buffer directly on the
+        // GstBufferPool to prevent leaking the buffer
+        // This will NOT call free_buffer on a subclass.
+        let pool_class =
+            glib::Class::<crate::BufferPool>::from_type(crate::BufferPool::static_type()).unwrap();
+        let pool_class = pool_class.as_ref();
+        if let Some(f) = pool_class.free_buffer {
+            f(ptr, buffer)
+        }
+        return;
+    }
+
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    imp.free_buffer(wrap.unsafe_cast_ref(), from_glib_full(buffer));
+}
+
+unsafe extern "C" fn buffer_pool_release_buffer<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+    buffer: *mut ffi::GstBuffer,
+) {
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    imp.release_buffer(wrap.unsafe_cast_ref(), from_glib_full(buffer));
+}
+
+unsafe extern "C" fn buffer_pool_reset_buffer<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+    buffer: *mut ffi::GstBuffer,
+) {
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    imp.reset_buffer(
+        wrap.unsafe_cast_ref(),
+        crate::BufferRef::from_mut_ptr(buffer),
+    );
+}
+
+unsafe extern "C" fn buffer_pool_start<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+) -> glib::ffi::gboolean {
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    imp.start(wrap.unsafe_cast_ref()).into_glib()
+}
+
+unsafe extern "C" fn buffer_pool_stop<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+) -> glib::ffi::gboolean {
+    // the GstBufferPool implementation calls this
+    // in finalize where the ref_count will already
+    // be zero and we are actually destroyed
+    // see: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1645
+    if (*(ptr as *const glib::gobject_ffi::GObject)).ref_count == 0 {
+        // As a workaround we call stop directly on the GstBufferPool
+        // This is needed because the default implementation clears
+        // the pool in stop.
+        let pool_class =
+            glib::Class::<crate::BufferPool>::from_type(crate::BufferPool::static_type()).unwrap();
+        let pool_class = pool_class.as_ref();
+        let result = if let Some(f) = pool_class.stop {
+            f(ptr)
+        } else {
+            true.into_glib()
+        };
+
+        return result;
+    }
+
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    imp.stop(wrap.unsafe_cast_ref()).into_glib()
+}
+
+unsafe extern "C" fn buffer_pool_get_options<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+) -> *mut *const c_char {
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    T::instance_data::<CStrV>(imp, T::type_())
+        .unwrap_or(&CStrV(std::ptr::null_mut()))
+        .0
+}
+
+unsafe extern "C" fn buffer_pool_set_config<T: BufferPoolImpl>(
+    ptr: *mut ffi::GstBufferPool,
+    config: *mut ffi::GstStructure,
+) -> glib::ffi::gboolean {
+    let instance = &*(ptr as *mut T::Instance);
+    let imp = instance.imp();
+    let wrap: Borrowed<BufferPool> = from_glib_borrow(ptr);
+    imp.set_config(
+        wrap.unsafe_cast_ref(),
+        BufferPoolConfigRef::from_glib_borrow_mut(config),
+    )
+    .into_glib()
+}
+
+#[cfg(test)]
+mod tests {
+    use std::sync::{
+        atomic::{AtomicBool, Ordering},
+        Arc,
+    };
+
+    use super::*;
+    use crate::prelude::*;
+
+    pub mod imp {
+        use super::*;
+
+        #[derive(Default)]
+        pub struct TestBufferPool;
+
+        impl ObjectImpl for TestBufferPool {}
+        impl GstObjectImpl for TestBufferPool {}
+        impl BufferPoolImpl for TestBufferPool {
+            fn options() -> &'static [&'static str] {
+                &["TEST_OPTION"]
+            }
+
+            fn set_config(
+                &self,
+                buffer_pool: &Self::Type,
+                config: &mut BufferPoolConfigRef,
+            ) -> bool {
+                let (caps, size, min_buffers, max_buffers) = config.params().unwrap();
+                config.set_params(caps.as_ref(), size * 2, min_buffers, max_buffers);
+                self.parent_set_config(buffer_pool, config)
+            }
+        }
+
+        #[glib::object_subclass]
+        impl ObjectSubclass for TestBufferPool {
+            const NAME: &'static str = "TestBufferPool";
+            type Type = super::TestBufferPool;
+            type ParentType = BufferPool;
+            type Interfaces = ();
+        }
+    }
+
+    glib::wrapper! {
+        pub struct TestBufferPool(ObjectSubclass<imp::TestBufferPool>) @extends BufferPool, crate::Object;
+    }
+
+    impl Default for TestBufferPool {
+        fn default() -> Self {
+            glib::Object::new(&[]).unwrap()
+        }
+    }
+
+    #[test]
+    fn test_pool_options() {
+        crate::init().unwrap();
+        let pool = TestBufferPool::default();
+        assert_eq!(pool.options(), vec!["TEST_OPTION"]);
+    }
+
+    #[test]
+    fn test_pool_acquire() {
+        crate::init().unwrap();
+        let pool = TestBufferPool::default();
+        let mut config = pool.config();
+        config.set_params(None, 1024, 1, 1);
+        pool.set_config(config).expect("failed to set pool config");
+        pool.set_active(true).expect("failed to activate pool");
+        let buffer = pool
+            .acquire_buffer(None)
+            .expect("failed to acquire buffer from pool");
+        assert_eq!(buffer.size(), 2048);
+    }
+
+    #[test]
+    fn test_pool_free_on_finalize() {
+        crate::init().unwrap();
+        let pool = TestBufferPool::default();
+        let mut config = pool.config();
+        config.set_params(None, 1024, 1, 1);
+        pool.set_config(config).expect("failed to set pool config");
+        pool.set_active(true).expect("failed to activate pool");
+        let mut buffer = pool
+            .acquire_buffer(None)
+            .expect("failed to acquire buffer from pool");
+        let finalized = Arc::new(AtomicBool::new(false));
+        unsafe {
+            ffi::gst_mini_object_weak_ref(
+                buffer.make_mut().upcast_mut().as_mut_ptr(),
+                Some(buffer_finalized),
+                Arc::into_raw(finalized.clone()) as *mut _,
+            )
+        };
+        // return the buffer to the pool
+        std::mem::drop(buffer);
+        // drop should finalize the buffer pool which frees all allocated buffers
+        std::mem::drop(pool);
+        assert!(finalized.load(Ordering::SeqCst));
+    }
+
+    #[test]
+    fn test_pool_free_on_deactivate() {
+        crate::init().unwrap();
+        let pool = TestBufferPool::default();
+        let mut config = pool.config();
+        config.set_params(None, 1024, 1, 1);
+        pool.set_config(config).expect("failed to set pool config");
+        pool.set_active(true).expect("failed to activate pool");
+        let mut buffer = pool
+            .acquire_buffer(None)
+            .expect("failed to acquire buffer from pool");
+        let finalized = Arc::new(AtomicBool::new(false));
+        unsafe {
+            ffi::gst_mini_object_weak_ref(
+                buffer.make_mut().upcast_mut().as_mut_ptr(),
+                Some(buffer_finalized),
+                Arc::into_raw(finalized.clone()) as *mut _,
+            )
+        };
+        // return the buffer to the pool
+        std::mem::drop(buffer);
+        // de-activating a poll should free all buffers
+        pool.set_active(false).expect("failed to de-activate pool");
+        assert!(finalized.load(Ordering::SeqCst));
+    }
+
+    unsafe extern "C" fn buffer_finalized(
+        data: *mut libc::c_void,
+        _mini_object: *mut ffi::GstMiniObject,
+    ) {
+        let finalized = &*(data as *const AtomicBool);
+        finalized.store(true, Ordering::SeqCst);
+    }
+}

gstreamer/src/subclass/mod.rs

@@ -16,6 +16,7 @@ mod plugin;
 mod plugin;
 
 mod bin;
+mod buffer_pool;
 mod child_proxy;
 mod element;
 mod ghost_pad;
@@ -46,6 +47,7 @@ pub mod prelude {
     pub use glib::subclass::prelude::*;
 
     pub use super::bin::{BinImpl, BinImplExt};
+    pub use super::buffer_pool::{BufferPoolImpl, BufferPoolImplExt};
     pub use super::child_proxy::{ChildProxyImpl, ChildProxyImplExt};
     pub use super::clock::{ClockImpl, ClockImplExt};
     pub use super::device::{DeviceImpl, DeviceImplExt};