cros_async: convert to ThisError and sort

BUG=b:197143586
TEST=cargo check

Cq-Depend: chromium:3105313
Change-Id: Ic9757b7e1947970910245fe954e47e4a2b7aa28e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3105074
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>

Cargo.lock

@@ -196,6 +196,7 @@ dependencies = [
  "once_cell",
  "paste",
  "pin-utils",
+ "remain",
  "slab",
  "sync",
  "sys_util",

cros_async/Cargo.toml

@@ -14,6 +14,7 @@ libc = "*"
 once_cell = "1.7.2"
 paste = "1.0"
 pin-utils = "0.1.0-alpha.4"
+remain = "0.2"
 slab = "0.4"
 sync = { path = "../sync" } # provided by ebuild
 sys_util = { path = "../sys_util" } # provided by ebuild

cros_async/src/fd_executor.rs

@@ -22,6 +22,7 @@ use std::task::{Context, Poll, Waker};
 use async_task::Task;
 use futures::task::noop_waker;
 use pin_utils::pin_mut;
+use remain::sorted;
 use slab::Slab;
 use sync::Mutex;
 use sys_util::{add_fd_flags, warn, EpollContext, EpollEvents, EventFd, WatchingEvents};
@@ -30,6 +31,7 @@ use thiserror::Error as ThisError;
 use crate::waker::{new_waker, WakerToken, WeakWake};
 use crate::{queue::RunnableQueue, BlockingPool};
 
+#[sorted]
 #[derive(Debug, ThisError)]
 pub enum Error {
     /// Failed to clone the EventFd for waking the executor.
@@ -38,15 +40,15 @@ pub enum Error {
     /// Failed to create the EventFd for waking the executor.
     #[error("Failed to create the EventFd for waking the executor: {0}")]
     CreateEventFd(sys_util::Error),
+    /// Creating a context to wait on FDs failed.
+    #[error("An error creating the fd waiting context: {0}")]
+    CreatingContext(sys_util::Error),
     /// Failed to copy the FD for the polling context.
     #[error("Failed to copy the FD for the polling context: {0}")]
     DuplicatingFd(sys_util::Error),
     /// The Executor is gone.
     #[error("The FDExecutor is gone")]
     ExecutorGone,
-    /// Creating a context to wait on FDs failed.
-    #[error("An error creating the fd waiting context: {0}")]
-    CreatingContext(sys_util::Error),
     /// PollContext failure.
     #[error("PollContext failure: {0}")]
     PollContextError(sys_util::Error),

cros_async/src/io_ext.rs

@@ -22,11 +22,13 @@ use std::os::unix::io::{AsRawFd, RawFd};
 use std::sync::Arc;
 
 use async_trait::async_trait;
+use remain::sorted;
 use sys_util::net::UnixSeqpacket;
 use thiserror::Error as ThisError;
 
 use crate::{BackingMemory, MemRegion};
 
+#[sorted]
 #[derive(ThisError, Debug)]
 pub enum Error {
     /// An error with a polled(FD) source.

cros_async/src/lib.rs

@@ -96,22 +96,24 @@ use std::marker::PhantomData;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
+use remain::sorted;
 use thiserror::Error as ThisError;
 
+#[sorted]
 #[derive(ThisError, Debug)]
 pub enum Error {
     /// Error from the FD executor.
     #[error("Failure in the FD executor: {0}")]
     FdExecutor(fd_executor::Error),
-    /// Error from the uring executor.
-    #[error("Failure in the uring executor: {0}")]
-    URingExecutor(uring_executor::Error),
-    /// Error from TimerFd.
-    #[error("Failure in TimerFd: {0}")]
-    TimerFd(sys_util::Error),
     /// Error from TimerFd.
     #[error("Failure in TimerAsync: {0}")]
     TimerAsync(AsyncError),
+    /// Error from TimerFd.
+    #[error("Failure in TimerFd: {0}")]
+    TimerFd(sys_util::Error),
+    /// Error from the uring executor.
+    #[error("Failure in the uring executor: {0}")]
+    URingExecutor(uring_executor::Error),
 }
 pub type Result<T> = std::result::Result<T, Error>;
 

cros_async/src/mem.rs

@@ -2,32 +2,19 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-use std::fmt::{self, Display};
-
 use data_model::VolatileSlice;
+use remain::sorted;
+use thiserror::Error as ThisError;
 
-#[derive(Debug)]
+#[sorted]
+#[derive(ThisError, Debug)]
 pub enum Error {
     /// Invalid offset or length given for an iovec in backing memory.
+    #[error("Invalid offset/len for getting a slice from {0} with len {1}.")]
     InvalidOffset(u64, usize),
 }
 pub type Result<T> = std::result::Result<T, Error>;
 
-impl Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use self::Error::*;
-
-        match self {
-            InvalidOffset(base, len) => write!(
-                f,
-                "Invalid offset/len for getting a slice from {} with len {}.",
-                base, len
-            ),
-        }
-    }
-}
-impl std::error::Error for Error {}
-
 /// Used to index subslices of backing memory. Like an iovec, but relative to the start of the
 /// memory region instead of an absolute pointer.
 /// The backing memory referenced by the region can be an array, an mmapped file, or guest memory.

cros_async/src/poll_source.rs

@@ -12,6 +12,7 @@ use std::sync::Arc;
 
 use async_trait::async_trait;
 use data_model::VolatileSlice;
+use remain::sorted;
 use thiserror::Error as ThisError;
 
 use crate::fd_executor::{self, FdExecutor, RegisteredSource};
@@ -19,6 +20,7 @@ use crate::mem::{BackingMemory, MemRegion};
 use crate::{AsyncError, AsyncResult};
 use crate::{IoSourceExt, ReadAsync, WriteAsync};
 
+#[sorted]
 #[derive(ThisError, Debug)]
 pub enum Error {
     /// An error occurred attempting to register a waker with the executor.

cros_async/src/uring_executor.rs

@@ -70,6 +70,7 @@ use futures::task::noop_waker;
 use io_uring::URingContext;
 use once_cell::sync::Lazy;
 use pin_utils::pin_mut;
+use remain::sorted;
 use slab::Slab;
 use sync::Mutex;
 use sys_util::{warn, WatchingEvents};
@@ -82,8 +83,12 @@ use crate::{
     BlockingPool,
 };
 
+#[sorted]
 #[derive(Debug, ThisError)]
 pub enum Error {
+    /// Creating a context to wait on FDs failed.
+    #[error("Error creating the fd waiting context: {0}")]
+    CreatingContext(io_uring::Error),
     /// Failed to copy the FD for the polling context.
     #[error("Failed to copy the FD for the polling context: {0}")]
     DuplicatingFd(sys_util::Error),
@@ -99,9 +104,6 @@ pub enum Error {
     /// Error doing the IO.
     #[error("Error during IO: {0}")]
     Io(io::Error),
-    /// Creating a context to wait on FDs failed.
-    #[error("Error creating the fd waiting context: {0}")]
-    CreatingContext(io_uring::Error),
     /// Failed to remove the waker remove the polling context.
     #[error("Error removing from the URing context: {0}")]
     RemovingWaker(io_uring::Error),