fix: make tracing dependency optional

Author: fogti

Cargo.toml

@@ -23,11 +23,15 @@ unexpected_cfgs = { level = "warn", check-cfg = ['cfg(polling_test_poll_backend)
 [features]
 # Enable calling of `tracing` functions from `Drop` handlers.
 # Enabling this can lead to unexpected double panics during panic unwindings.
-tracing_in_drop = []
+tracing_in_drop = ["tracing"]
 
 [dependencies]
 cfg-if = "1"
-tracing = { version = "0.1.37", default-features = false }
+
+[dependencies.tracing]
+version = "0.1.37"
+default-features = false
+optional = true
 
 [target.'cfg(any(unix, target_os = "fuchsia", target_os = "vxworks"))'.dependencies.rustix]
 version = "1.0.5"

src/epoll.rs

@@ -77,6 +77,7 @@ impl Poller {
             )?;
         }
 
+        #[cfg(feature = "tracing")]
         tracing::trace!(
             epoll_fd = ?poller.epoll_fd.as_raw_fd(),
             notifier = ?poller.notifier,
@@ -102,12 +103,14 @@ impl Poller {
     /// The `fd` must be a valid file descriptor. The usual condition of remaining registered in
     /// the `Poller` doesn't apply to `epoll`.
     pub unsafe fn add(&self, fd: RawFd, ev: Event, mode: PollMode) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "add",
             epoll_fd = ?self.epoll_fd.as_raw_fd(),
             ?fd,
             ?ev,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         epoll::add(
@@ -122,12 +125,14 @@ impl Poller {
 
     /// Modifies an existing file descriptor.
     pub fn modify(&self, fd: BorrowedFd<'_>, ev: Event, mode: PollMode) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "modify",
             epoll_fd = ?self.epoll_fd.as_raw_fd(),
             ?fd,
             ?ev,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         epoll::modify(
@@ -146,24 +151,29 @@ impl Poller {
     }
 
     /// Deletes a file descriptor.
+    #[cfg_attr(not(feature = "tracing"), inline(always))]
     pub fn delete(&self, fd: BorrowedFd<'_>) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "delete",
             epoll_fd = ?self.epoll_fd.as_raw_fd(),
             ?fd,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
         self.delete_intern(fd)
     }
 
     /// Waits for I/O events with an optional timeout.
     #[allow(clippy::needless_update)]
     pub fn wait(&self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "wait",
             epoll_fd = ?self.epoll_fd.as_raw_fd(),
             ?timeout,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         #[cfg(not(target_os = "redox"))]
@@ -211,6 +221,7 @@ impl Poller {
             spare_capacity(&mut events.list),
             timeout.as_ref(),
         )?;
+        #[cfg(feature = "tracing")]
         tracing::trace!(
             epoll_fd = ?self.epoll_fd.as_raw_fd(),
             res = ?events.list.len(),
@@ -229,11 +240,13 @@ impl Poller {
 
     /// Sends a notification to wake up the current or next `wait()` call.
     pub fn notify(&self) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "notify",
             epoll_fd = ?self.epoll_fd.as_raw_fd(),
             notifier = ?self.notifier,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         self.notifier.notify();
@@ -438,14 +451,16 @@ impl Notifier {
                 // Try to create an eventfd.
                 match eventfd(0, EventfdFlags::CLOEXEC | EventfdFlags::NONBLOCK) {
                     Ok(fd) => {
+                        #[cfg(feature = "tracing")]
                         tracing::trace!("created eventfd for notifier");
                         return Ok(Notifier::EventFd(fd));
                     }
 
-                    Err(err) => {
+                    Err(_err) => {
+                        #[cfg(feature = "tracing")]
                         tracing::warn!(
                             "eventfd() failed with error ({}), falling back to pipe",
-                            err
+                            _err
                         );
                     }
                 }

src/iocp/afd.rs

@@ -197,6 +197,7 @@ macro_rules! define_ntdll_import {
                         let addr = match addr {
                             Some(addr) => addr,
                             None => {
+                                #[cfg(feature = "tracing")]
                                 tracing::error!("Failed to load ntdll function {}", NAME);
                                 return Err(io::Error::last_os_error());
                             },
@@ -298,6 +299,7 @@ impl NtdllImports {
                 let ntdll = GetModuleHandleW(NTDLL_NAME.as_ptr() as *const _);
 
                 if ntdll.is_null() {
+                    #[cfg(feature = "tracing")]
                     tracing::error!("Failed to load ntdll.dll");
                     return Err(io::Error::last_os_error());
                 }

src/iocp/mod.rs

@@ -136,6 +136,7 @@ impl Poller {
         })?;
 
         let port = IoCompletionPort::new(0)?;
+        #[cfg(feature = "tracing")]
         tracing::trace!(handle = ?port, "new");
 
         Ok(Poller {
@@ -175,12 +176,14 @@ impl Poller {
         interest: Event,
         mode: PollMode,
     ) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "add",
             handle = ?self.port,
             sock = ?socket,
             ev = ?interest,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         // We don't support edge-triggered events.
@@ -238,12 +241,14 @@ impl Poller {
         interest: Event,
         mode: PollMode,
     ) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "modify",
             handle = ?self.port,
             sock = ?socket,
             ev = ?interest,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         // We don't support edge-triggered events.
@@ -275,11 +280,13 @@ impl Poller {
 
     /// Delete a source from the poller.
     pub(super) fn delete(&self, socket: BorrowedSocket<'_>) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "remove",
             handle = ?self.port,
             sock = ?socket,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         // Remove the source from our associative map.
@@ -307,6 +314,7 @@ impl Poller {
         interest: Event,
         mode: PollMode,
     ) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         tracing::trace!(
             "add_waitable: handle={:?}, waitable={:p}, ev={:?}",
             self.port,
@@ -363,6 +371,7 @@ impl Poller {
         interest: Event,
         mode: PollMode,
     ) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         tracing::trace!(
             "modify_waitable: handle={:?}, waitable={:p}, ev={:?}",
             self.port,
@@ -398,6 +407,7 @@ impl Poller {
 
     /// Delete a waitable from the poller.
     pub(super) fn remove_waitable(&self, waitable: RawHandle) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         tracing::trace!("remove: handle={:?}, waitable={:p}", self.port, waitable);
 
         // Get a reference to the source.
@@ -420,11 +430,13 @@ impl Poller {
 
     /// Wait for events.
     pub(super) fn wait(&self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "wait",
             handle = ?self.port,
             ?timeout,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         // Make sure we have a consistent timeout.
@@ -451,10 +463,11 @@ impl Poller {
             let timeout = deadline.map(|t| t.saturating_duration_since(Instant::now()));
 
             // Wait for I/O events.
-            let len = self.port.wait(&mut events.completions, timeout)?;
+            let _len = self.port.wait(&mut events.completions, timeout)?;
+            #[cfg(feature = "tracing")]
             tracing::trace!(
                 handle = ?self.port,
-                res = ?len,
+                res = ?_len,
                 "new events");
 
             // We are no longer polling.
@@ -484,6 +497,7 @@ impl Poller {
                 break;
             }
 
+            #[cfg(feature = "tracing")]
             tracing::trace!("wait: no events found, re-entering polling loop");
         }
 
@@ -860,8 +874,9 @@ impl PacketUnwrapped {
 
                         // Push this packet.
                         drop(handle);
-                        if let Err(e) = iocp.post(0, 0, packet) {
-                            tracing::error!("failed to post completion packet: {}", e);
+                        if let Err(_e) = iocp.post(0, 0, packet) {
+                            #[cfg(feature = "tracing")]
+                            tracing::error!("failed to post completion packet: {}", _e);
                         }
                     },
                     None,

src/kqueue.rs

@@ -63,6 +63,7 @@ impl Poller {
         // Register the notification pipe.
         poller.notify.register(&poller)?;
 
+        #[cfg(feature = "tracing")]
         tracing::trace!(
             kqueue_fd = ?poller.kqueue_fd.as_raw_fd(),
             "new"
@@ -94,6 +95,7 @@ impl Poller {
 
     /// Modifies an existing file descriptor.
     pub fn modify(&self, fd: BorrowedFd<'_>, ev: Event, mode: PollMode) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = if !self.notify.has_fd(fd) {
             let span = tracing::trace_span!(
                 "add",
@@ -105,6 +107,7 @@ impl Poller {
         } else {
             None
         };
+        #[cfg(feature = "tracing")]
         let _enter = span.as_ref().map(|s| s.enter());
 
         self.has_source(SourceId::Fd(fd.as_raw_fd()))?;
@@ -233,11 +236,13 @@ impl Poller {
 
     /// Waits for I/O events with an optional timeout.
     pub fn wait(&self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "wait",
             kqueue_fd = ?self.kqueue_fd.as_raw_fd(),
             ?timeout,
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         // Timeout for kevent. In case of overflow, use no timeout.
@@ -248,7 +253,7 @@ impl Poller {
 
         // Wait for I/O events.
         let changelist = [];
-        let res = unsafe {
+        let _res = unsafe {
             kqueue::kevent_timespec(
                 &self.kqueue_fd,
                 &changelist,
@@ -257,9 +262,10 @@ impl Poller {
             )?
         };
 
+        #[cfg(feature = "tracing")]
         tracing::trace!(
             kqueue_fd = ?self.kqueue_fd.as_raw_fd(),
-            ?res,
+            res = ?_res,
             "new events",
         );
 
@@ -271,10 +277,12 @@ impl Poller {
 
     /// Sends a notification to wake up the current or next `wait()` call.
     pub fn notify(&self) -> io::Result<()> {
+        #[cfg(feature = "tracing")]
         let span = tracing::trace_span!(
             "notify",
             kqueue_fd = ?self.kqueue_fd.as_raw_fd(),
         );
+        #[cfg(feature = "tracing")]
         let _enter = span.enter();
 
         self.notify.notify(self).ok();
@@ -423,6 +431,7 @@ mod notify {
     use super::Poller;
     use rustix::event::kqueue;
     use std::io;
+    #[cfg(feature = "tracing")]
     use std::os::unix::io::BorrowedFd;
 
     /// A notification pipe.
@@ -488,6 +497,7 @@ mod notify {
         }
 
         /// Whether this raw file descriptor is associated with this pipe.
+        #[cfg(feature = "tracing")]
         pub(super) fn has_fd(&self, _fd: BorrowedFd<'_>) -> bool {
             false
         }
@@ -503,8 +513,10 @@ mod notify {
     use super::Poller;
     use crate::{Event, PollMode, NOTIFY_KEY};
     use std::io::{self, prelude::*};
+    #[cfg(feature = "tracing")]
+    use std::os::unix::io::BorrowedFd;
     use std::os::unix::{
-        io::{AsFd, AsRawFd, BorrowedFd},
+        io::{AsFd, AsRawFd},
         net::UnixStream,
     };
 
@@ -574,6 +586,7 @@ mod notify {
         }
 
         /// Whether this raw file descriptor is associated with this pipe.
+        #[cfg(feature = "tracing")]
         pub(super) fn has_fd(&self, fd: BorrowedFd<'_>) -> bool {
             self.read_stream.as_raw_fd() == fd.as_raw_fd()
         }