From c763e2a0fd903b1579bf08d68f0c930bd3ed9e64 Mon Sep 17 00:00:00 2001
From: Denis Biryukov <denis.biryukov@zettascale.tech>
Date: Tue, 29 Oct 2024 15:02:48 +0100
Subject: [PATCH 1/2] add empty gravestone values for Sample, Reply, Query and
 Hello

---
 commons/zenoh-config/src/wrappers.rs | 11 +++++++++++
 zenoh/src/api/query.rs               |  9 +++++++++
 zenoh/src/api/queryable.rs           | 11 +++++++++++
 zenoh/src/api/sample.rs              | 16 ++++++++++++++++
 4 files changed, 47 insertions(+)

diff --git a/commons/zenoh-config/src/wrappers.rs b/commons/zenoh-config/src/wrappers.rs
index 31afe358e7..44ccfa7a52 100644
--- a/commons/zenoh-config/src/wrappers.rs
+++ b/commons/zenoh-config/src/wrappers.rs
@@ -119,6 +119,17 @@ impl Hello {
     pub fn whatami(&self) -> WhatAmI {
         self.0.whatami
     }
+
+    /// Constructs an empty Hello message.
+    #[zenoh_macros::internal]
+    pub fn empty() -> Self {
+        Hello(HelloProto {
+            version: zenoh_protocol::VERSION,
+            whatami: WhatAmI::default(),
+            zid: ZenohIdProto::default(),
+            locators: Vec::default(),
+        })
+    }
 }
 
 impl From<HelloProto> for Hello {
diff --git a/zenoh/src/api/query.rs b/zenoh/src/api/query.rs
index 4633f6d437..f3f0c1abcd 100644
--- a/zenoh/src/api/query.rs
+++ b/zenoh/src/api/query.rs
@@ -140,6 +140,15 @@ impl Reply {
     pub fn replier_id(&self) -> Option<ZenohId> {
         self.replier_id.map(Into::into)
     }
+
+    /// Constructs an uninitialized empty Reply.
+    #[zenoh_macros::internal]
+    pub unsafe fn empty() -> Self {
+        Reply {
+            result: Ok(Sample::empty()),
+            replier_id: None,
+        }
+    }
 }
 
 impl From<Reply> for Result<Sample, ReplyError> {
diff --git a/zenoh/src/api/queryable.rs b/zenoh/src/api/queryable.rs
index ad8ab59f85..91bc4af2de 100644
--- a/zenoh/src/api/queryable.rs
+++ b/zenoh/src/api/queryable.rs
@@ -200,6 +200,17 @@ impl Query {
     fn _accepts_any_replies(&self) -> ZResult<bool> {
         Ok(self.parameters().reply_key_expr_any())
     }
+
+    /// Constructs an empty Query without payload, nor attachment referencing the same inner query.
+    #[zenoh_macros::internal]
+    pub unsafe fn empty(&self) -> Self {
+        Query {
+            inner: self.inner.clone(),
+            eid: 0,
+            value: None,
+            attachment: None,
+        }
+    }
 }
 
 impl fmt::Debug for Query {
diff --git a/zenoh/src/api/sample.rs b/zenoh/src/api/sample.rs
index b3c5e0ede5..376cad51ef 100644
--- a/zenoh/src/api/sample.rs
+++ b/zenoh/src/api/sample.rs
@@ -409,6 +409,22 @@ impl Sample {
     pub fn attachment_mut(&mut self) -> Option<&mut ZBytes> {
         self.attachment.as_mut()
     }
+
+    /// Constructs an uninitialized empty Sample.
+    #[zenoh_macros::internal]
+    pub unsafe fn empty() -> Self {
+        Sample {
+            key_expr: KeyExpr::from_str_unchecked(""),
+            payload: ZBytes::new(),
+            kind: SampleKind::Put,
+            encoding: Encoding::default(),
+            timestamp: None,
+            qos: QoS::default(),
+            reliability: Reliability::default(),
+            source_info: SourceInfo::empty(),
+            attachment: None,
+        }
+    }
 }
 
 impl From<Sample> for Value {

From 9dea4c149d555d9b7b6184931d2036cce0b377f8 Mon Sep 17 00:00:00 2001
From: Denis Biryukov <denis.biryukov@zettascale.tech>
Date: Wed, 30 Oct 2024 10:31:59 +0100
Subject: [PATCH 2/2] add empty gravestone value for ReplyErr

---
 zenoh/src/api/query.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/zenoh/src/api/query.rs b/zenoh/src/api/query.rs
index f3f0c1abcd..8379ac8097 100644
--- a/zenoh/src/api/query.rs
+++ b/zenoh/src/api/query.rs
@@ -84,6 +84,15 @@ impl ReplyError {
     pub fn encoding(&self) -> &Encoding {
         &self.encoding
     }
+
+    /// Constructs an uninitialized empty ReplyError.
+    #[zenoh_macros::internal]
+    pub fn empty() -> Self {
+        ReplyError {
+            payload: ZBytes::new(),
+            encoding: Encoding::default(),
+        }
+    }
 }
 
 impl Display for ReplyError {