Expose VringPollEvent to replace mio::Interest

Signed-off-by: Wenyu Huang <huangwenyuu@outlook.com>

Author: uran0sH

vhost-user-backend/src/event_loop.rs

@@ -17,6 +17,7 @@ use vmm_sys_util::eventfd::EventFd;
 
 use super::backend::VhostUserBackend;
 use super::vring::VringT;
+use bitflags::bitflags;
 
 /// Errors related to vring epoll event handling.
 #[derive(Debug)]
@@ -57,6 +58,44 @@ impl std::error::Error for VringPollError {}
 /// Result of vring epoll operations.
 pub type VringEpollResult<T> = std::result::Result<T, VringPollError>;
 
+bitflags! {
+    #[derive(Debug, PartialEq, PartialOrd)]
+    pub struct VringPollEvent: u32 {
+        const READABLE = 1u32;
+        const WRITABLE = 2u32;
+    }
+}
+
+impl From<Interest> for VringPollEvent {
+    fn from(value: Interest) -> Self {
+        let mut event = VringPollEvent::empty();
+        if value.is_readable() {
+            event |= VringPollEvent::READABLE;
+        }
+        if value.is_writable() {
+            event |= VringPollEvent::WRITABLE;
+        }
+        return event;
+    }
+}
+
+impl From<VringPollEvent> for Interest {
+    fn from(value: VringPollEvent) -> Self {
+        let mut interest = None;
+        if value == VringPollEvent::READABLE {
+            interest = interest
+                .map(|interest| Interest::READABLE | interest)
+                .or(Some(Interest::READABLE));
+        }
+        if value == VringPollEvent::WRITABLE {
+            interest = interest
+                .map(|interest| Interest::WRITABLE | interest)
+                .or(Some(Interest::WRITABLE));
+        }
+        return interest.expect("Interest is invalid");
+    }
+}
+
 // According https://github.com/tokio-rs/mio/blob/cd972977e7a8234e62c7ba8bd4d4ec1da208e576/src/interest.rs#L27
 // the function is implemented to convert Event into Interest
 fn convert_event_to_interest(value: &Event) -> Option<Interest> {
@@ -175,7 +214,7 @@ where
     ///
     /// When this event is later triggered, the backend implementation of `handle_event` will be
     /// called.
-    pub fn register_listener(&self, fd: RawFd, ev_type: Interest, data: u64) -> Result<()> {
+    pub fn register_listener(&self, fd: RawFd, ev_type: VringPollEvent, data: u64) -> Result<()> {
         // `data` range [0...num_queues] is reserved for queues and exit event.
         if data <= self.backend.num_queues() as u64 {
             Err(io::Error::from_raw_os_error(libc::EINVAL))
@@ -188,7 +227,7 @@ where
     ///
     /// If the event is triggered after this function has been called, the event will be silently
     /// dropped.
-    pub fn unregister_listener(&self, fd: RawFd, ev_type: Interest, data: u64) -> Result<()> {
+    pub fn unregister_listener(&self, fd: RawFd, ev_type: VringPollEvent, data: u64) -> Result<()> {
         // `data` range [0...num_queues] is reserved for queues and exit event.
         if data <= self.backend.num_queues() as u64 {
             Err(io::Error::from_raw_os_error(libc::EINVAL))
@@ -197,19 +236,29 @@ where
         }
     }
 
-    pub(crate) fn register_event(&self, fd: RawFd, ev_type: Interest, data: u64) -> Result<()> {
+    pub(crate) fn register_event(
+        &self,
+        fd: RawFd,
+        ev_type: VringPollEvent,
+        data: u64,
+    ) -> Result<()> {
         let mut fd_set = self.fd_set.lock().unwrap();
         if fd_set.contains(&fd) {
             return Err(io::Error::from_raw_os_error(libc::EEXIST));
         }
         self.registry
-            .register(&mut SourceFd(&fd), Token(data as usize), ev_type)
+            .register(&mut SourceFd(&fd), Token(data as usize), ev_type.into())
             .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
         fd_set.insert(fd);
         Ok(())
     }
 
-    pub(crate) fn unregister_event(&self, fd: RawFd, _ev_type: Interest, _data: u64) -> Result<()> {
+    pub(crate) fn unregister_event(
+        &self,
+        fd: RawFd,
+        _ev_type: VringPollEvent,
+        _data: u64,
+    ) -> Result<()> {
         let mut fd_set = self.fd_set.lock().unwrap();
         if !fd_set.contains(&fd) {
             return Err(io::Error::from_raw_os_error(libc::ENOENT));
@@ -306,27 +355,27 @@ mod tests {
 
         let eventfd = EventFd::new(0).unwrap();
         handler
-            .register_listener(eventfd.as_raw_fd(), Interest::READABLE, 3)
+            .register_listener(eventfd.as_raw_fd(), VringPollEvent::READABLE, 3)
             .unwrap();
         // Register an already registered fd.
         handler
-            .register_listener(eventfd.as_raw_fd(), Interest::READABLE, 3)
+            .register_listener(eventfd.as_raw_fd(), VringPollEvent::READABLE, 3)
             .unwrap_err();
         // Register an invalid data.
         handler
-            .register_listener(eventfd.as_raw_fd(), Interest::READABLE, 1)
+            .register_listener(eventfd.as_raw_fd(), VringPollEvent::READABLE, 1)
             .unwrap_err();
 
         handler
-            .unregister_listener(eventfd.as_raw_fd(), Interest::READABLE, 3)
+            .unregister_listener(eventfd.as_raw_fd(), VringPollEvent::READABLE, 3)
             .unwrap();
         // unregister an already unregistered fd.
         handler
-            .unregister_listener(eventfd.as_raw_fd(), Interest::READABLE, 3)
+            .unregister_listener(eventfd.as_raw_fd(), VringPollEvent::READABLE, 3)
             .unwrap_err();
         // unregister an invalid data.
         handler
-            .unregister_listener(eventfd.as_raw_fd(), Interest::READABLE, 1)
+            .unregister_listener(eventfd.as_raw_fd(), VringPollEvent::READABLE, 1)
             .unwrap_err();
         // Check we retrieve the correct file descriptor
         assert_eq!(

vhost-user-backend/src/handler.rs

@@ -14,7 +14,7 @@ use std::sync::Arc;
 use std::thread;
 
 use crate::bitmap::{BitmapReplace, MemRegionBitmap, MmapLogReg};
-use mio::Interest;
+use crate::event_loop::VringPollEvent;
 #[cfg(feature = "postcopy")]
 use userfaultfd::{Uffd, UffdBuilder};
 use vhost::vhost_user::message::{
@@ -212,7 +212,11 @@ where
                 if shifted_queues_mask & 1u64 == 1u64 {
                     let evt_idx = queues_mask.count_ones() - shifted_queues_mask.count_ones();
                     self.handlers[thread_index]
-                        .register_event(fd.as_raw_fd(), Interest::READABLE, u64::from(evt_idx))
+                        .register_event(
+                            fd.as_raw_fd(),
+                            VringPollEvent::READABLE,
+                            u64::from(evt_idx),
+                        )
                         .map_err(VhostUserError::ReqHandlerError)?;
                     break;
                 }
@@ -436,7 +440,11 @@ where
                 if shifted_queues_mask & 1u64 == 1u64 {
                     let evt_idx = queues_mask.count_ones() - shifted_queues_mask.count_ones();
                     self.handlers[thread_index]
-                        .unregister_event(fd.as_raw_fd(), Interest::READABLE, u64::from(evt_idx))
+                        .unregister_event(
+                            fd.as_raw_fd(),
+                            VringPollEvent::READABLE,
+                            u64::from(evt_idx),
+                        )
                         .map_err(VhostUserError::ReqHandlerError)?;
                     break;
                 }

vhost-user-backend/src/lib.rs

@@ -23,7 +23,7 @@ mod backend;
 pub use self::backend::{VhostUserBackend, VhostUserBackendMut};
 
 mod event_loop;
-pub use self::event_loop::VringEpollHandler;
+pub use self::event_loop::{VringEpollHandler, VringPollEvent};
 
 mod handler;
 pub use self::handler::VhostUserHandlerError;