Reuse the wait_events method in pipes

kernel/aster-nix/src/fs/utils/channel.rs

@@ -10,7 +10,7 @@ use super::StatusFlags;
 use crate::{
     events::{IoEvents, Observer},
     prelude::*,
-    process::signal::{Pollee, Poller},
+    process::signal::{Pollable, Pollee, Poller},
 };
 
 /// A unidirectional communication channel, intended to implement IPC, e.g., pipe,
@@ -137,29 +137,18 @@ impl<T> Producer<T> {
     impl_common_methods_for_channel!();
 }
 
+impl<T> Pollable for Producer<T> {
+    fn poll(&self, mask: IoEvents, poller: Option<&Poller>) -> IoEvents {
+        self.poll(mask, poller)
+    }
+}
+
 impl<T: Copy> Producer<T> {
     pub fn write(&self, buf: &[T]) -> Result<usize> {
-        let is_nonblocking = self.is_nonblocking();
-
-        // Fast path
-        let res = self.try_write(buf);
-        if should_io_return(&res, is_nonblocking) {
-            return res;
-        }
-
-        // Slow path
-        let mask = IoEvents::OUT;
-        let poller = Poller::new();
-        loop {
-            let res = self.try_write(buf);
-            if should_io_return(&res, is_nonblocking) {
-                return res;
-            }
-            let events = self.poll(mask, Some(&poller));
-            if events.is_empty() {
-                // FIXME: should channel deal with timeout?
-                poller.wait()?;
-            }
+        if self.is_nonblocking() {
+            self.try_write(buf)
+        } else {
+            self.wait_events(IoEvents::OUT, || self.try_write(buf))
         }
     }
 
@@ -190,31 +179,25 @@ impl<T> Producer<T> {
     /// On failure, this method returns `Err` containing
     /// the item fails to push.
     pub fn push(&self, item: T) -> core::result::Result<(), (Error, T)> {
-        let is_nonblocking = self.is_nonblocking();
-
-        // Fast path
-        let mut res = self.try_push(item);
-        if should_io_return(&res, is_nonblocking) {
-            return res;
+        if self.is_nonblocking() {
+            return self.try_push(item);
         }
 
-        // Slow path
-        let mask = IoEvents::OUT;
-        let poller = Poller::new();
-        loop {
-            let (_, item) = res.unwrap_err();
+        let mut stored_item = Some(item);
 
-            res = self.try_push(item);
-            if should_io_return(&res, is_nonblocking) {
-                return res;
-            }
-            let events = self.poll(mask, Some(&poller));
-            if events.is_empty() {
-                // FIXME: should channel deal with timeout?
-                if let Err(err) = poller.wait() {
-                    return Err((err, res.unwrap_err().1));
+        let result = self.wait_events(IoEvents::OUT, || {
+            match self.try_push(stored_item.take().unwrap()) {
+                Ok(()) => Ok(()),
+                Err((err, item)) => {
+                    stored_item = Some(item);
+                    Err(err)
                 }
             }
+        });
+
+        match result {
+            Ok(()) => Ok(()),
+            Err(err) => Err((err, stored_item.unwrap())),
         }
     }
 
@@ -277,29 +260,18 @@ impl<T> Consumer<T> {
     impl_common_methods_for_channel!();
 }
 
+impl<T> Pollable for Consumer<T> {
+    fn poll(&self, mask: IoEvents, poller: Option<&Poller>) -> IoEvents {
+        self.poll(mask, poller)
+    }
+}
+
 impl<T: Copy> Consumer<T> {
     pub fn read(&self, buf: &mut [T]) -> Result<usize> {
-        let is_nonblocking = self.is_nonblocking();
-
-        // Fast path
-        let res = self.try_read(buf);
-        if should_io_return(&res, is_nonblocking) {
-            return res;
-        }
-
-        // Slow path
-        let mask = IoEvents::IN;
-        let poller = Poller::new();
-        loop {
-            let res = self.try_read(buf);
-            if should_io_return(&res, is_nonblocking) {
-                return res;
-            }
-            let events = self.poll(mask, Some(&poller));
-            if events.is_empty() {
-                // FIXME: should channel have timeout?
-                poller.wait()?;
-            }
+        if self.is_nonblocking() {
+            self.try_read(buf)
+        } else {
+            self.wait_events(IoEvents::IN, || self.try_read(buf))
         }
     }
 
@@ -330,27 +302,10 @@ impl<T: Copy> Consumer<T> {
 impl<T> Consumer<T> {
     /// Pops an item from the consumer
     pub fn pop(&self) -> Result<T> {
-        let is_nonblocking = self.is_nonblocking();
-
-        // Fast path
-        let res = self.try_pop();
-        if should_io_return(&res, is_nonblocking) {
-            return res;
-        }
-
-        // Slow path
-        let mask = IoEvents::IN;
-        let poller = Poller::new();
-        loop {
-            let res = self.try_pop();
-            if should_io_return(&res, is_nonblocking) {
-                return res;
-            }
-            let events = self.poll(mask, Some(&poller));
-            if events.is_empty() {
-                // FIXME: should channel have timeout?
-                poller.wait()?;
-            }
+        if self.is_nonblocking() {
+            self.try_pop()
+        } else {
+            self.wait_events(IoEvents::IN, || self.try_pop())
         }
     }
 
@@ -510,26 +465,6 @@ fn check_status_flags(flags: StatusFlags) -> Result<()> {
     Ok(())
 }
 
-fn should_io_return<T, E: AsRef<Error>>(
-    res: &core::result::Result<T, E>,
-    is_nonblocking: bool,
-) -> bool {
-    if is_nonblocking {
-        return true;
-    }
-    match res {
-        Ok(_) => true,
-        Err(e) if e.as_ref().error() == Errno::EAGAIN => false,
-        Err(_) => true,
-    }
-}
-
-impl<T> AsRef<Error> for (Error, T) {
-    fn as_ref(&self) -> &Error {
-        &self.0
-    }
-}
-
 #[cfg(ktest)]
 mod test {
     use alloc::sync::Arc;