feat: don't undeclare objects on drop

examples/examples/z_liveliness.rs

@@ -31,8 +31,6 @@ async fn main() {
     println!("Press CTRL-C to undeclare LivelinessToken and quit...");
     std::thread::park();
 
-    // LivelinessTokens are automatically closed when dropped
-    // Use the code below to manually undeclare it if needed
     token.undeclare().await.unwrap();
 }
 

examples/examples/z_sub_thr.rs

@@ -87,9 +87,7 @@ fn main() {
             }
         })
         .wait()
-        .unwrap()
-        // Make the subscriber run in background, until the session is closed.
-        .background();
+        .unwrap();
 
     println!("Press CTRL-C to quit...");
     std::thread::park();

zenoh/src/api/builders/publisher.rs

@@ -307,7 +307,6 @@ impl<'a, 'b> PublisherBuilder<'a, 'b> {
             destination: self.destination,
             #[cfg(feature = "unstable")]
             matching_listeners: Default::default(),
-            undeclare_on_drop: true,
         })
     }
 }
@@ -362,7 +361,6 @@ impl<'a, 'b> Wait for PublisherBuilder<'a, 'b> {
                 destination: self.destination,
                 #[cfg(feature = "unstable")]
                 matching_listeners: Default::default(),
-                undeclare_on_drop: true,
             })
     }
 }

zenoh/src/api/key_expr.rs

@@ -549,8 +549,9 @@ impl<'a> KeyExpr<'a> {
     }
 }
 
-impl<'a> UndeclarableSealed<&'a Session, KeyExprUndeclaration<'a>> for KeyExpr<'a> {
-    fn undeclare_inner(self, session: &'a Session) -> KeyExprUndeclaration<'a> {
+impl<'a> UndeclarableSealed<&'a Session> for KeyExpr<'a> {
+    type Res = KeyExprUndeclaration<'a>;
+    fn undeclare_inner(self, session: &'a Session) -> Self::Res {
         KeyExprUndeclaration {
             session,
             expr: self,

zenoh/src/api/liveliness.rs

@@ -31,6 +31,7 @@ use super::{
     subscriber::{Subscriber, SubscriberInner},
     Id,
 };
+use crate::api::session::WeakSessionRef;
 
 /// A structure with functions to declare a
 /// [`LivelinessToken`](LivelinessToken), query
@@ -254,9 +255,8 @@ impl Wait for LivelinessTokenBuilder<'_, '_> {
         session
             .declare_liveliness_inner(&key_expr)
             .map(|tok_state| LivelinessToken {
-                session,
+                session: session.into(),
                 state: tok_state,
-                undeclare_on_drop: true,
             })
     }
 }
@@ -283,13 +283,11 @@ pub(crate) struct LivelinessTokenState {
 ///
 /// A declared liveliness token will be seen as alive by any other Zenoh
 /// application in the system that monitors it while the liveliness token
-/// is not undeclared or dropped, while the Zenoh application that declared
+/// is not undeclared, while the Zenoh application that declared
 /// it is alive (didn't stop or crashed) and while the Zenoh application
 /// that declared the token has Zenoh connectivity with the Zenoh application
 /// that monitors it.
 ///
-/// `LivelinessTokens` are automatically undeclared when dropped.
-///
 /// # Examples
 /// ```no_run
 /// # #[tokio::main]
@@ -307,9 +305,8 @@ pub(crate) struct LivelinessTokenState {
 #[zenoh_macros::unstable]
 #[derive(Debug)]
 pub struct LivelinessToken<'a> {
-    pub(crate) session: SessionRef<'a>,
+    pub(crate) session: WeakSessionRef<'a>,
     pub(crate) state: Arc<LivelinessTokenState>,
-    undeclare_on_drop: bool,
 }
 
 /// A [`Resolvable`] returned when undeclaring a [`LivelinessToken`](LivelinessToken).
@@ -343,10 +340,11 @@ impl Resolvable for LivelinessTokenUndeclaration<'_> {
 
 #[zenoh_macros::unstable]
 impl Wait for LivelinessTokenUndeclaration<'_> {
-    fn wait(mut self) -> <Self as Resolvable>::To {
-        // set the flag first to avoid double panic if this function panic
-        self.token.undeclare_on_drop = false;
-        self.token.session.undeclare_liveliness(self.token.state.id)
+    fn wait(self) -> <Self as Resolvable>::To {
+        let Some(session) = self.token.session.upgrade() else {
+            return Ok(());
+        };
+        session.undeclare_liveliness(self.token.state.id)
     }
 }
 
@@ -362,11 +360,7 @@ impl<'a> IntoFuture for LivelinessTokenUndeclaration<'a> {
 
 #[zenoh_macros::unstable]
 impl<'a> LivelinessToken<'a> {
-    /// Undeclare a [`LivelinessToken`].
-    ///
-    /// LivelinessTokens are automatically closed when dropped,
-    /// but you may want to use this function to handle errors or
-    /// undeclare the LivelinessToken asynchronously.
+    /// Undeclare the [`LivelinessToken`].
     ///
     /// # Examples
     /// ```
@@ -388,31 +382,14 @@ impl<'a> LivelinessToken<'a> {
     pub fn undeclare(self) -> impl Resolve<ZResult<()>> + 'a {
         UndeclarableSealed::undeclare_inner(self, ())
     }
-
-    /// Keep this liveliness token in background, until the session is closed.
-    #[inline]
-    #[zenoh_macros::unstable]
-    pub fn background(mut self) {
-        // It's not necessary to undeclare this resource when session close, as other sessions
-        // will clean all resources related to the closed one.
-        // So we can just never undeclare it.
-        self.undeclare_on_drop = false;
-    }
 }
 
 #[zenoh_macros::unstable]
-impl<'a> UndeclarableSealed<(), LivelinessTokenUndeclaration<'a>> for LivelinessToken<'a> {
-    fn undeclare_inner(self, _: ()) -> LivelinessTokenUndeclaration<'a> {
-        LivelinessTokenUndeclaration { token: self }
-    }
-}
+impl<'a> UndeclarableSealed<()> for LivelinessToken<'a> {
+    type Res = LivelinessTokenUndeclaration<'a>;
 
-#[zenoh_macros::unstable]
-impl Drop for LivelinessToken<'_> {
-    fn drop(&mut self) {
-        if self.undeclare_on_drop {
-            let _ = self.session.undeclare_liveliness(self.state.id);
-        }
+    fn undeclare_inner(self, _: ()) -> Self::Res {
+        LivelinessTokenUndeclaration { token: self }
     }
 }
 
@@ -579,10 +556,11 @@ where
             .declare_liveliness_subscriber_inner(&key_expr, Locality::default(), callback)
             .map(|sub_state| Subscriber {
                 subscriber: SubscriberInner {
-                    session,
+                    #[cfg(feature = "unstable")]
+                    session_id: session.zid(),
+                    session: session.into(),
                     state: sub_state,
                     kind: SubscriberKind::LivelinessSubscriber,
-                    undeclare_on_drop: true,
                 },
                 handler,
             })

zenoh/src/api/publisher.rs

@@ -78,7 +78,7 @@ impl fmt::Debug for PublisherState {
 #[derive(Clone)]
 pub enum PublisherRef<'a> {
     Borrow(&'a Publisher<'a>),
-    Shared(std::sync::Arc<Publisher<'static>>),
+    Shared(Arc<Publisher<'static>>),
 }
 
 #[zenoh_macros::unstable]
@@ -105,8 +105,6 @@ impl std::fmt::Debug for PublisherRef<'_> {
 
 /// A publisher that allows to send data through a stream.
 ///
-/// Publishers are automatically undeclared when dropped.
-///
 /// # Examples
 /// ```
 /// # #[tokio::main]
@@ -146,7 +144,6 @@ pub struct Publisher<'a> {
     pub(crate) destination: Locality,
     #[cfg(feature = "unstable")]
     pub(crate) matching_listeners: Arc<Mutex<HashSet<Id>>>,
-    pub(crate) undeclare_on_drop: bool,
 }
 
 impl<'a> Publisher<'a> {
@@ -347,7 +344,7 @@ impl<'a> Publisher<'a> {
         }
     }
 
-    /// Undeclares the [`Publisher`], informing the network that it needn't optimize publications for its key expression anymore.
+    /// Undeclare the [`Publisher`], informing the network that it needn't optimize publications for its key expression anymore.
     ///
     /// # Examples
     /// ```
@@ -462,8 +459,10 @@ impl PublisherDeclarations for std::sync::Arc<Publisher<'static>> {
     }
 }
 
-impl<'a> UndeclarableSealed<(), PublisherUndeclaration<'a>> for Publisher<'a> {
-    fn undeclare_inner(self, _: ()) -> PublisherUndeclaration<'a> {
+impl<'a> UndeclarableSealed<()> for Publisher<'a> {
+    type Res = PublisherUndeclaration<'a>;
+
+    fn undeclare_inner(self, _: ()) -> Self::Res {
         PublisherUndeclaration { publisher: self }
     }
 }
@@ -491,9 +490,7 @@ impl Resolvable for PublisherUndeclaration<'_> {
 }
 
 impl Wait for PublisherUndeclaration<'_> {
-    fn wait(mut self) -> <Self as Resolvable>::To {
-        // set the flag first to avoid double panic if this function panic
-        self.publisher.undeclare_on_drop = false;
+    fn wait(self) -> <Self as Resolvable>::To {
         #[cfg(feature = "unstable")]
         self.publisher.undeclare_matching_listeners()?;
         self.publisher
@@ -513,11 +510,8 @@ impl IntoFuture for PublisherUndeclaration<'_> {
 
 impl Drop for Publisher<'_> {
     fn drop(&mut self) {
-        if self.undeclare_on_drop {
-            #[cfg(feature = "unstable")]
-            let _ = self.undeclare_matching_listeners();
-            let _ = self.session.undeclare_publisher_inner(self.id);
-        }
+        #[cfg(feature = "unstable")]
+        let _ = self.undeclare_matching_listeners();
     }
 }
 
@@ -922,7 +916,6 @@ where
             listener: MatchingListenerInner {
                 publisher: self.publisher,
                 state,
-                undeclare_on_drop: true,
             },
             receiver,
         })
@@ -947,7 +940,7 @@ where
 #[zenoh_macros::unstable]
 pub(crate) struct MatchingListenerState {
     pub(crate) id: Id,
-    pub(crate) current: std::sync::Mutex<bool>,
+    pub(crate) current: Mutex<bool>,
     pub(crate) key_expr: KeyExpr<'static>,
     pub(crate) destination: Locality,
     pub(crate) callback: Callback<'static, MatchingStatus>,
@@ -966,8 +959,7 @@ impl std::fmt::Debug for MatchingListenerState {
 #[zenoh_macros::unstable]
 pub(crate) struct MatchingListenerInner<'a> {
     pub(crate) publisher: PublisherRef<'a>,
-    pub(crate) state: std::sync::Arc<MatchingListenerState>,
-    undeclare_on_drop: bool,
+    pub(crate) state: Arc<MatchingListenerState>,
 }
 
 #[zenoh_macros::unstable]
@@ -979,15 +971,20 @@ impl<'a> MatchingListenerInner<'a> {
 }
 
 #[zenoh_macros::unstable]
-impl<'a> UndeclarableSealed<(), MatchingListenerUndeclaration<'a>> for MatchingListenerInner<'a> {
-    fn undeclare_inner(self, _: ()) -> MatchingListenerUndeclaration<'a> {
+impl<'a> UndeclarableSealed<()> for MatchingListenerInner<'a> {
+    type Res = MatchingListenerUndeclaration<'a>;
+
+    fn undeclare_inner(self, _: ()) -> Self::Res {
         MatchingListenerUndeclaration { subscriber: self }
     }
 }
 
 /// A listener that sends notifications when the [`MatchingStatus`] of a
 /// publisher changes.
 ///
+/// Matching litsteners run in background until the publisher is undeclared.
+/// They can be manually undeclared, but will not be undeclared on drop.
+///
 /// # Examples
 /// ```no_run
 /// # #[tokio::main]
@@ -1014,10 +1011,7 @@ pub struct MatchingListener<'a, Receiver> {
 
 #[zenoh_macros::unstable]
 impl<'a, Receiver> MatchingListener<'a, Receiver> {
-    /// Close a [`MatchingListener`].
-    ///
-    /// MatchingListeners are automatically closed when dropped, but you may want to use this function to handle errors or
-    /// close the MatchingListener asynchronously.
+    /// Undeclare the [`MatchingListener`].
     ///
     /// # Examples
     /// ```
@@ -1035,19 +1029,13 @@ impl<'a, Receiver> MatchingListener<'a, Receiver> {
     pub fn undeclare(self) -> MatchingListenerUndeclaration<'a> {
         self.listener.undeclare()
     }
-
-    /// Make the matching listener run in background, until the publisher is undeclared.
-    #[inline]
-    #[zenoh_macros::unstable]
-    pub fn background(mut self) {
-        // The matching listener will be undeclared as part of publisher undeclaration.
-        self.listener.undeclare_on_drop = false;
-    }
 }
 
 #[zenoh_macros::unstable]
-impl<'a, T> UndeclarableSealed<(), MatchingListenerUndeclaration<'a>> for MatchingListener<'a, T> {
-    fn undeclare_inner(self, _: ()) -> MatchingListenerUndeclaration<'a> {
+impl<'a, T> UndeclarableSealed<()> for MatchingListener<'a, T> {
+    type Res = MatchingListenerUndeclaration<'a>;
+
+    fn undeclare_inner(self, _: ()) -> Self::Res {
         UndeclarableSealed::undeclare_inner(self.listener, ())
     }
 }
@@ -1079,9 +1067,7 @@ impl Resolvable for MatchingListenerUndeclaration<'_> {
 
 #[zenoh_macros::unstable]
 impl Wait for MatchingListenerUndeclaration<'_> {
-    fn wait(mut self) -> <Self as Resolvable>::To {
-        // set the flag first to avoid double panic if this function panic
-        self.subscriber.undeclare_on_drop = false;
+    fn wait(self) -> <Self as Resolvable>::To {
         zlock!(self.subscriber.publisher.matching_listeners).remove(&self.subscriber.state.id);
         self.subscriber
             .publisher
@@ -1100,19 +1086,6 @@ impl IntoFuture for MatchingListenerUndeclaration<'_> {
     }
 }
 
-#[zenoh_macros::unstable]
-impl Drop for MatchingListenerInner<'_> {
-    fn drop(&mut self) {
-        if self.undeclare_on_drop {
-            zlock!(self.publisher.matching_listeners).remove(&self.state.id);
-            let _ = self
-                .publisher
-                .session
-                .undeclare_matches_listener_inner(self.state.id);
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use zenoh_config::Config;