rutabaga_gfx/src/rutabaga_utils.rs

// Copyright 2020 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//! rutabaga_utils: Utility enums, structs, and implementations needed by the rest of the crate.

use std::ffi::NulError;
use std::io::Error as IoError;
use std::num::TryFromIntError;
use std::os::raw::c_void;
use std::path::PathBuf;
use std::str::Utf8Error;

use data_model::VolatileMemoryError;
#[cfg(unix)]
use nix::Error as NixError;
use remain::sorted;
use serde::Deserialize;
use serde::Serialize;
use thiserror::Error;
#[cfg(feature = "vulkano")]
use vulkano::device::DeviceCreationError;
#[cfg(feature = "vulkano")]
use vulkano::image::ImageCreationError;
#[cfg(feature = "vulkano")]
use vulkano::instance::InstanceCreationError;
#[cfg(feature = "vulkano")]
use vulkano::memory::DeviceMemoryError;
#[cfg(feature = "vulkano")]
use vulkano::memory::MemoryMapError;
#[cfg(feature = "vulkano")]
use vulkano::LoadingError;
#[cfg(feature = "vulkano")]
use vulkano::VulkanError;

use crate::rutabaga_os::SafeDescriptor;

/// Represents a buffer.  `base` contains the address of a buffer, while `len` contains the length
/// of the buffer.
#[repr(C)]
#[derive(Copy, Clone)]
pub struct RutabagaIovec {
    pub base: *mut c_void,
    pub len: usize,
}

unsafe impl Send for RutabagaIovec {}
unsafe impl Sync for RutabagaIovec {}

/// 3D resource creation parameters.  Also used to create 2D resource.  Constants based on Mesa's
/// (internal) Gallium interface.  Not in the virtio-gpu spec, but should be since dumb resources
/// can't work with gfxstream/virglrenderer without this.
pub const RUTABAGA_PIPE_TEXTURE_2D: u32 = 2;
pub const RUTABAGA_PIPE_BIND_RENDER_TARGET: u32 = 2;
#[repr(C)]
#[derive(Copy, Clone, Debug)]
pub struct ResourceCreate3D {
    pub target: u32,
    pub format: u32,
    pub bind: u32,
    pub width: u32,
    pub height: u32,
    pub depth: u32,
    pub array_size: u32,
    pub last_level: u32,
    pub nr_samples: u32,
    pub flags: u32,
}

/// Blob resource creation parameters.
pub const RUTABAGA_BLOB_MEM_GUEST: u32 = 0x0001;
pub const RUTABAGA_BLOB_MEM_HOST3D: u32 = 0x0002;
pub const RUTABAGA_BLOB_MEM_HOST3D_GUEST: u32 = 0x0003;

pub const RUTABAGA_BLOB_FLAG_USE_MAPPABLE: u32 = 0x0001;
pub const RUTABAGA_BLOB_FLAG_USE_SHAREABLE: u32 = 0x0002;
pub const RUTABAGA_BLOB_FLAG_USE_CROSS_DEVICE: u32 = 0x0004;
#[repr(C)]
#[derive(Copy, Clone, Debug)]
pub struct ResourceCreateBlob {
    pub blob_mem: u32,
    pub blob_flags: u32,
    pub blob_id: u64,
    pub size: u64,
}

#[repr(C)]
#[derive(Copy, Clone, Debug)]
pub struct RutabagaMapping {
    pub ptr: u64,
    pub size: u64,
}

/// Metadata associated with a swapchain, video or camera image.
#[derive(Default, Copy, Clone, Debug)]
pub struct Resource3DInfo {
    pub width: u32,
    pub height: u32,
    pub drm_fourcc: u32,
    pub strides: [u32; 4],
    pub offsets: [u32; 4],
    pub modifier: u64,
}

/// A unique identifier for a device.
#[derive(
    Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash, Deserialize, Serialize,
)]
pub struct DeviceId {
    pub device_uuid: [u8; 16],
    pub driver_uuid: [u8; 16],
}

/// Memory index and physical device id of the associated VkDeviceMemory.
#[derive(Copy, Clone, Default)]
pub struct VulkanInfo {
    pub memory_idx: u32,
    pub device_id: DeviceId,
}

/// Rutabaga context init capset id mask.
pub const RUTABAGA_CONTEXT_INIT_CAPSET_ID_MASK: u32 = 0x00ff;

/// Rutabaga flags for creating fences.
pub const RUTABAGA_FLAG_FENCE: u32 = 1 << 0;
pub const RUTABAGA_FLAG_INFO_RING_IDX: u32 = 1 << 1;

/// Convenience struct for Rutabaga fences
#[repr(C)]
#[derive(Copy, Clone)]
pub struct RutabagaFence {
    pub flags: u32,
    pub fence_id: u64,
    pub ctx_id: u32,
    pub ring_idx: u8,
}

/// Mapped memory caching flags (see virtio_gpu spec)
pub const RUTABAGA_MAP_CACHE_CACHED: u32 = 0x01;
pub const RUTABAGA_MAP_CACHE_UNCACHED: u32 = 0x02;
pub const RUTABAGA_MAP_CACHE_WC: u32 = 0x03;

/// Rutabaga capsets.
pub const RUTABAGA_CAPSET_VIRGL: u32 = 1;
pub const RUTABAGA_CAPSET_VIRGL2: u32 = 2;
pub const RUTABAGA_CAPSET_GFXSTREAM: u32 = 3;
pub const RUTABAGA_CAPSET_VENUS: u32 = 4;
pub const RUTABAGA_CAPSET_CROSS_DOMAIN: u32 = 5;
pub const RUTABAGA_CAPSET_DRM: u32 = 6;

/// An error generated while using this crate.
#[sorted]
#[derive(Error, Debug)]
pub enum RutabagaError {
    /// Indicates `Rutabaga` was already initialized since only one Rutabaga instance per process
    /// is allowed.
    #[error("attempted to use a rutabaga asset already in use")]
    AlreadyInUse,
    /// Checked Arithmetic error
    #[error("arithmetic failed: {}({}) {op} {}({})", .field1.0, .field1.1, .field2.0, .field2.1)]
    CheckedArithmetic {
        field1: (&'static str, usize),
        field2: (&'static str, usize),
        op: &'static str,
    },
    /// Checked Range error
    #[error("range check failed: {}({}) vs {}({})", .field1.0, .field1.1, .field2.0, .field2.1)]
    CheckedRange {
        field1: (&'static str, usize),
        field2: (&'static str, usize),
    },
    /// An internal Rutabaga component error was returned.
    #[error("rutabaga component failed with error {0}")]
    ComponentError(i32),
    /// Invalid 2D info
    #[error("invalid 2D info")]
    Invalid2DInfo,
    /// Invalid Capset
    #[error("invalid capset")]
    InvalidCapset,
    /// A command buffer with insufficient space was submitted.
    #[error("invalid command buffer submitted")]
    InvalidCommandBuffer,
    /// A command size was submitted that was invalid.
    #[error("command buffer submitted with invalid size: {0}")]
    InvalidCommandSize(usize),
    /// Invalid RutabagaComponent
    #[error("invalid rutabaga component")]
    InvalidComponent,
    /// Invalid Context ID
    #[error("invalid context id")]
    InvalidContextId,
    /// Invalid cross domain channel
    #[error("invalid cross domain channel")]
    InvalidCrossDomainChannel,
    /// Invalid cross domain item ID
    #[error("invalid cross domain item id")]
    InvalidCrossDomainItemId,
    /// Invalid cross domain item type
    #[error("invalid cross domain item type")]
    InvalidCrossDomainItemType,
    /// Invalid cross domain state
    #[error("invalid cross domain state")]
    InvalidCrossDomainState,
    /// Invalid gralloc backend.
    #[error("invalid gralloc backend")]
    InvalidGrallocBackend,
    /// Invalid gralloc dimensions.
    #[error("invalid gralloc dimensions")]
    InvalidGrallocDimensions,
    /// Invalid gralloc DRM format.
    #[error("invalid gralloc DRM format")]
    InvalidGrallocDrmFormat,
    /// Invalid GPU type.
    #[error("invalid GPU type for gralloc")]
    InvalidGrallocGpuType,
    /// Invalid number of YUV planes.
    #[error("invalid number of YUV planes")]
    InvalidGrallocNumberOfPlanes,
    /// The indicated region of guest memory is invalid.
    #[error("an iovec is outside of guest memory's range")]
    InvalidIovec,
    /// Invalid Resource ID.
    #[error("invalid resource id")]
    InvalidResourceId,
    /// Indicates an error in the RutabagaBuilder.
    #[error("invalid rutabaga build parameters: {0}")]
    InvalidRutabagaBuild(&'static str),
    /// An error with the RutabagaHandle
    #[error("invalid rutabaga handle")]
    InvalidRutabagaHandle,
    /// Invalid Vulkan info
    #[error("invalid vulkan info")]
    InvalidVulkanInfo,
    /// An input/output error occured.
    #[error("an input/output error occur: {0}")]
    IoError(IoError),
    /// The mapping failed.
    #[error("The mapping failed with library error: {0}")]
    MappingFailed(i32),
    /// Nix crate error.
    #[cfg(unix)]
    #[error("The errno is {0}")]
    NixError(NixError),
    #[error("Nul Error occured {0}")]
    NulError(NulError),
    /// Violation of the Rutabaga spec occured.
    #[error("violation of the rutabaga spec: {0}")]
    SpecViolation(&'static str),
    /// An attempted integer conversion failed.
    #[error("int conversion failed: {0}")]
    TryFromIntError(TryFromIntError),
    /// The command is unsupported.
    #[error("the requested function is not implemented")]
    Unsupported,
    /// Utf8 error.
    #[error("an utf8 error occured: {0}")]
    Utf8Error(Utf8Error),
    /// Device creation error
    #[cfg(feature = "vulkano")]
    #[error("vulkano device creation failure {0}")]
    VkDeviceCreationError(DeviceCreationError),
    /// Device memory error
    #[cfg(feature = "vulkano")]
    #[error("vulkano device memory failure {0}")]
    VkDeviceMemoryError(DeviceMemoryError),
    /// General Vulkan error
    #[cfg(feature = "vulkano")]
    #[error("vulkano failure {0}")]
    VkError(VulkanError),
    /// Image creation error
    #[cfg(feature = "vulkano")]
    #[error("vulkano image creation failure {0}")]
    VkImageCreationError(ImageCreationError),
    /// Instance creation error
    #[cfg(feature = "vulkano")]
    #[error("vulkano instance creation failure {0}")]
    VkInstanceCreationError(InstanceCreationError),
    /// Loading error
    #[cfg(feature = "vulkano")]
    #[error("vulkano loading failure {0}")]
    VkLoadingError(LoadingError),
    /// Memory map error
    #[cfg(feature = "vulkano")]
    #[error("vulkano memory map failure {0}")]
    VkMemoryMapError(MemoryMapError),
    /// Volatile memory error
    #[error("noticed a volatile memory error {0}")]
    VolatileMemoryError(VolatileMemoryError),
}

#[cfg(unix)]
impl From<NixError> for RutabagaError {
    fn from(e: NixError) -> RutabagaError {
        RutabagaError::NixError(e)
    }
}

impl From<NulError> for RutabagaError {
    fn from(e: NulError) -> RutabagaError {
        RutabagaError::NulError(e)
    }
}

impl From<IoError> for RutabagaError {
    fn from(e: IoError) -> RutabagaError {
        RutabagaError::IoError(e)
    }
}

impl From<TryFromIntError> for RutabagaError {
    fn from(e: TryFromIntError) -> RutabagaError {
        RutabagaError::TryFromIntError(e)
    }
}

impl From<Utf8Error> for RutabagaError {
    fn from(e: Utf8Error) -> RutabagaError {
        RutabagaError::Utf8Error(e)
    }
}

impl From<VolatileMemoryError> for RutabagaError {
    fn from(e: VolatileMemoryError) -> RutabagaError {
        RutabagaError::VolatileMemoryError(e)
    }
}

/// The result of an operation in this crate.
pub type RutabagaResult<T> = std::result::Result<T, RutabagaError>;

/// Flags for virglrenderer.  Copied from virglrenderer bindings.
const VIRGLRENDERER_USE_EGL: u32 = 1 << 0;
const VIRGLRENDERER_THREAD_SYNC: u32 = 1 << 1;
const VIRGLRENDERER_USE_GLX: u32 = 1 << 2;
const VIRGLRENDERER_USE_SURFACELESS: u32 = 1 << 3;
const VIRGLRENDERER_USE_GLES: u32 = 1 << 4;
const VIRGLRENDERER_USE_EXTERNAL_BLOB: u32 = 1 << 5;
const VIRGLRENDERER_VENUS: u32 = 1 << 6;
const VIRGLRENDERER_NO_VIRGL: u32 = 1 << 7;
const VIRGLRENDERER_USE_ASYNC_FENCE_CB: u32 = 1 << 8;
const VIRGLRENDERER_RENDER_SERVER: u32 = 1 << 9;
const VIRGLRENDERER_DRM: u32 = 1 << 10;

/// virglrenderer flag struct.
#[derive(Copy, Clone)]
pub struct VirglRendererFlags(u32);

impl Default for VirglRendererFlags {
    fn default() -> VirglRendererFlags {
        VirglRendererFlags::new()
            .use_virgl(true)
            .use_venus(false)
            .use_egl(true)
            .use_surfaceless(true)
            .use_gles(true)
            .use_render_server(false)
    }
}

impl From<VirglRendererFlags> for u32 {
    fn from(flags: VirglRendererFlags) -> u32 {
        flags.0
    }
}

impl From<VirglRendererFlags> for i32 {
    fn from(flags: VirglRendererFlags) -> i32 {
        flags.0 as i32
    }
}

impl VirglRendererFlags {
    /// Create new virglrenderer flags.
    pub fn new() -> VirglRendererFlags {
        VirglRendererFlags(0)
    }

    fn set_flag(self, bitmask: u32, set: bool) -> VirglRendererFlags {
        if set {
            VirglRendererFlags(self.0 | bitmask)
        } else {
            VirglRendererFlags(self.0 & (!bitmask))
        }
    }

    /// Enable virgl support
    pub fn use_virgl(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_NO_VIRGL, !v)
    }

    /// Enable venus support
    pub fn use_venus(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_VENUS, v)
    }

    /// Enable drm native context support
    pub fn use_drm(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_DRM, v)
    }

    /// Use EGL for context creation.
    pub fn use_egl(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_USE_EGL, v)
    }

    /// Use a dedicated thread for fence synchronization.
    pub fn use_thread_sync(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_THREAD_SYNC, v)
    }

    /// Use GLX for context creation.
    pub fn use_glx(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_USE_GLX, v)
    }

    /// No surfaces required when creating context.
    pub fn use_surfaceless(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_USE_SURFACELESS, v)
    }

    /// Use GLES drivers.
    pub fn use_gles(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_USE_GLES, v)
    }

    /// Use external memory when creating blob resources.
    pub fn use_external_blob(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_USE_EXTERNAL_BLOB, v)
    }

    /// Retire fence directly from sync thread.
    pub fn use_async_fence_cb(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_USE_ASYNC_FENCE_CB, v)
    }

    pub fn use_render_server(self, v: bool) -> VirglRendererFlags {
        self.set_flag(VIRGLRENDERER_RENDER_SERVER, v)
    }
}

/// Flags for the gfxstream renderer.
const GFXSTREAM_RENDERER_FLAGS_USE_EGL: u32 = 1 << 0;
#[allow(dead_code)]
const GFXSTREAM_RENDERER_FLAGS_THREAD_SYNC: u32 = 1 << 1;
const GFXSTREAM_RENDERER_FLAGS_USE_GLX: u32 = 1 << 2;
const GFXSTREAM_RENDERER_FLAGS_USE_SURFACELESS: u32 = 1 << 3;
const GFXSTREAM_RENDERER_FLAGS_USE_GLES: u32 = 1 << 4;
const GFXSTREAM_RENDERER_FLAGS_NO_VK_BIT: u32 = 1 << 5;
const GFXSTREAM_RENDERER_FLAGS_ENABLE_GLES31_BIT: u32 = 1 << 9;
const GFXSTREAM_RENDERER_FLAGS_USE_EXTERNAL_BLOB: u32 = 1 << 10;
const GFXSTREAM_RENDERER_FLAGS_USE_SYSTEM_BLOB: u32 = 1 << 11;
const GFXSTREAM_RENDERER_FLAGS_GUEST_USES_ANGLE: u32 = 1 << 21;
const GFXSTREAM_RENDERER_FLAGS_VULKAN_NATIVE_SWAPCHAIN_BIT: u32 = 1 << 22;
const GFXSTREAM_RENDERER_FLAGS_ASYNC_FENCE_CB: u32 = 1 << 23;

/// gfxstream flag struct.
#[derive(Copy, Clone, Default)]
pub struct GfxstreamFlags(u32);

#[derive(Clone, Debug, Serialize, Deserialize)]
#[serde(rename_all = "kebab-case")]
pub enum RutabagaWsi {
    #[serde(alias = "vk")]
    Vulkan,
}

impl GfxstreamFlags {
    /// Create new gfxstream flags.
    pub fn new() -> GfxstreamFlags {
        GfxstreamFlags(0)
    }

    fn set_flag(self, bitmask: u32, set: bool) -> GfxstreamFlags {
        if set {
            GfxstreamFlags(self.0 | bitmask)
        } else {
            GfxstreamFlags(self.0 & (!bitmask))
        }
    }

    /// Use EGL for context creation.
    pub fn use_egl(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_USE_EGL, v)
    }

    /// Use GLX for context creation.
    pub fn use_glx(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_USE_GLX, v)
    }

    /// No surfaces required when creating context.
    pub fn use_surfaceless(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_USE_SURFACELESS, v)
    }

    /// Use GLES drivers.
    pub fn use_gles(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_USE_GLES, v)
    }

    /// Support using Vulkan.
    pub fn use_vulkan(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_NO_VK_BIT, !v)
    }

    /// Use ANGLE as the guest GLES driver.
    pub fn use_guest_angle(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_GUEST_USES_ANGLE, v)
    }

    /// Use async fence completion callback.
    pub fn use_async_fence_cb(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_ASYNC_FENCE_CB, v)
    }

    /// Enable GLES 3.1 support.
    pub fn support_gles31(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_ENABLE_GLES31_BIT, v)
    }

    /// Use the Vulkan swapchain to draw on the host window.
    pub fn set_wsi(self, v: Option<&RutabagaWsi>) -> GfxstreamFlags {
        let use_vulkan_swapchain = matches!(v, Some(RutabagaWsi::Vulkan));
        self.set_flag(
            GFXSTREAM_RENDERER_FLAGS_VULKAN_NATIVE_SWAPCHAIN_BIT,
            use_vulkan_swapchain,
        )
    }

    /// Use external blob when creating resources.
    pub fn use_external_blob(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_USE_EXTERNAL_BLOB, v)
    }

    /// Use system blob when creating resources.
    pub fn use_system_blob(self, v: bool) -> GfxstreamFlags {
        self.set_flag(GFXSTREAM_RENDERER_FLAGS_USE_SYSTEM_BLOB, v)
    }
}

impl From<GfxstreamFlags> for u32 {
    fn from(flags: GfxstreamFlags) -> u32 {
        flags.0
    }
}

impl From<GfxstreamFlags> for i32 {
    fn from(flags: GfxstreamFlags) -> i32 {
        flags.0 as i32
    }
}

impl From<GfxstreamFlags> for u64 {
    fn from(flags: GfxstreamFlags) -> u64 {
        flags.0 as u64
    }
}

/// Transfers {to, from} 1D buffers, 2D textures, 3D textures, and cubemaps.
#[repr(C)]
#[derive(Copy, Clone, Debug)]
pub struct Transfer3D {
    pub x: u32,
    pub y: u32,
    pub z: u32,
    pub w: u32,
    pub h: u32,
    pub d: u32,
    pub level: u32,
    pub stride: u32,
    pub layer_stride: u32,
    pub offset: u64,
}

impl Transfer3D {
    /// Constructs a 2 dimensional XY box in 3 dimensional space with unit depth and zero
    /// displacement on the Z axis.
    pub fn new_2d(x: u32, y: u32, w: u32, h: u32) -> Transfer3D {
        Transfer3D {
            x,
            y,
            z: 0,
            w,
            h,
            d: 1,
            level: 0,
            stride: 0,
            layer_stride: 0,
            offset: 0,
        }
    }

    /// Returns true if this box represents a volume of zero.
    pub fn is_empty(&self) -> bool {
        self.w == 0 || self.h == 0 || self.d == 0
    }
}

/// Rutabaga channel types
pub const RUTABAGA_CHANNEL_TYPE_WAYLAND: u32 = 0x0001;
pub const RUTABAGA_CHANNEL_TYPE_CAMERA: u32 = 0x0002;

/// Information needed to open an OS-specific RutabagaConnection (TBD).  Only Linux hosts are
/// considered at the moment.
#[derive(Clone)]
pub struct RutabagaChannel {
    pub base_channel: PathBuf,
    pub channel_type: u32,
}

/// Enumeration of possible rutabaga components.
#[repr(u8)]
#[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord)]
pub enum RutabagaComponentType {
    Rutabaga2D,
    VirglRenderer,
    Gfxstream,
    CrossDomain,
}

/// Rutabaga handle types (memory and sync in same namespace)
pub const RUTABAGA_MEM_HANDLE_TYPE_OPAQUE_FD: u32 = 0x0001;
pub const RUTABAGA_MEM_HANDLE_TYPE_DMABUF: u32 = 0x0002;
pub const RUTABAGA_MEM_HANDLE_TYPE_OPAQUE_WIN32: u32 = 0x0003;
pub const RUTABAGA_MEM_HANDLE_TYPE_SHM: u32 = 0x0004;
pub const RUTABAGA_FENCE_HANDLE_TYPE_OPAQUE_FD: u32 = 0x0010;
pub const RUTABAGA_FENCE_HANDLE_TYPE_SYNC_FD: u32 = 0x0011;
pub const RUTABAGA_FENCE_HANDLE_TYPE_OPAQUE_WIN32: u32 = 0x0012;

/// Handle to OS-specific memory or synchronization objects.
pub struct RutabagaHandle {
    pub os_handle: SafeDescriptor,
    pub handle_type: u32,
}

impl RutabagaHandle {
    /// Clones an existing rutabaga handle, by using OS specific mechanisms.
    pub fn try_clone(&self) -> RutabagaResult<RutabagaHandle> {
        let clone = self
            .os_handle
            .try_clone()
            .map_err(|_| RutabagaError::InvalidRutabagaHandle)?;
        Ok(RutabagaHandle {
            os_handle: clone,
            handle_type: self.handle_type,
        })
    }
}

/// Trait for fence completion handlers
pub trait RutabagaFenceCallback: Send {
    fn call(&self, data: RutabagaFence);
    fn clone_box(&self) -> RutabagaFenceHandler;
}

/// Wrapper type to allow cloning while respecting object-safety
pub type RutabagaFenceHandler = Box<dyn RutabagaFenceCallback>;

impl Clone for RutabagaFenceHandler {
    fn clone(&self) -> Self {
        self.clone_box()
    }
}

/// Fence handler implementation that wraps a closure
#[derive(Clone)]
pub struct RutabagaFenceClosure<T> {
    closure: T,
}

impl<T> RutabagaFenceClosure<T>
where
    T: Fn(RutabagaFence) + Clone + Send + 'static,
{
    pub fn new(closure: T) -> RutabagaFenceHandler {
        Box::new(RutabagaFenceClosure { closure })
    }
}

impl<T> RutabagaFenceCallback for RutabagaFenceClosure<T>
where
    T: Fn(RutabagaFence) + Clone + Send + 'static,
{
    fn call(&self, data: RutabagaFence) {
        (self.closure)(data)
    }

    fn clone_box(&self) -> RutabagaFenceHandler {
        Box::new(self.clone())
    }
}