circmgr: re-export clock skew estimates.

crates/tor-circmgr/src/lib.rs

@@ -77,6 +77,7 @@ mod usage;
 pub use err::Error;
 pub use isolation::IsolationToken;
 use tor_guardmgr::fallback::FallbackList;
+pub use tor_guardmgr::{ClockSkewEvents, SkewEstimate};
 pub use usage::{TargetPort, TargetPorts};
 
 pub use config::{
@@ -722,6 +723,17 @@ impl<R: Runtime> CircMgr<R> {
             external_activity,
         );
     }
+
+    /// Return a stream of events about our estimated clock skew; these events
+    /// are `None` when we don't have enough information to make an estimate,
+    /// and `Some(`[`SkewEstiamte`]`)` otherwise.
+    ///
+    /// Note that this stream can be lossy: if the estimate changes more than
+    /// one before you read from the stream, you might only get the most recent
+    /// update.
+    pub fn skew_events(&self) -> ClockSkewEvents {
+        self.mgr.peek_builder().guardmgr().skew_events()
+    }
 }
 
 impl<R: Runtime> Drop for CircMgr<R> {

crates/tor-guardmgr/src/events.rs

@@ -12,6 +12,8 @@ use tor_basic_utils::skip_fmt;
 ///
 /// Note that this stream can be lossy: if multiple events trigger before you
 /// read from it, you will only get the most recent estimate.
+//
+// SEMVER NOTE: this type is re-exported from tor-circmgr.
 #[derive(Clone, Educe)]
 #[educe(Debug)]
 pub struct ClockSkewEvents {

crates/tor-guardmgr/src/skew.rs

@@ -29,6 +29,8 @@ impl SkewObservation {
 }
 
 /// An estimate of how skewed our clock is, plus a summary of why we think so.
+//
+// SEMVER NOTE: this type is re-exported from tor-circmgr.
 #[derive(Clone, Debug)]
 pub struct SkewEstimate {
     /// Our best guess for the magnitude of the skew.