Ensures the affinity function is the same as in Quickwit 0.8

Closes #5576

quickwit/quickwit-common/src/lib.rs

@@ -48,6 +48,10 @@ pub mod tower;
 pub mod type_map;
 pub mod uri;
 
+mod socket_addr_legacy_hash;
+
+pub use socket_addr_legacy_hash::SocketAddrLegacyHash;
+
 use std::env;
 use std::fmt::{Debug, Display};
 use std::future::Future;

quickwit/quickwit-common/src/rendezvous_hasher.rs

@@ -19,7 +19,6 @@
 
 use std::cmp::Reverse;
 use std::hash::{Hash, Hasher};
-
 use siphasher::sip::SipHasher;
 
 /// Computes the affinity of a node for a given `key`.
@@ -42,6 +41,8 @@ pub fn sort_by_rendez_vous_hash<T: Hash, U: Hash>(nodes: &mut [T], key: U) {
 mod tests {
     use std::net::SocketAddr;
 
+    use crate::SocketAddrLegacyHash;
+
     use super::*;
 
     fn test_socket_addr(last_byte: u8) -> SocketAddr {
@@ -55,17 +56,22 @@ mod tests {
         let socket3 = test_socket_addr(3);
         let socket4 = test_socket_addr(4);
 
-        let mut socket_set1 = vec![socket4, socket3, socket1, socket2];
+        let legacy_socket1 = SocketAddrLegacyHash(&socket1);
+        let legacy_socket2 = SocketAddrLegacyHash(&socket2);
+        let legacy_socket3 = SocketAddrLegacyHash(&socket3);
+        let legacy_socket4 = SocketAddrLegacyHash(&socket4);
+
+        let mut socket_set1 = vec![legacy_socket4, legacy_socket3, legacy_socket1, legacy_socket2];
         sort_by_rendez_vous_hash(&mut socket_set1, "key");
 
-        let mut socket_set2 = vec![socket1, socket2, socket4];
+        let mut socket_set2 = vec![legacy_socket1, legacy_socket2, legacy_socket4];
         sort_by_rendez_vous_hash(&mut socket_set2, "key");
 
-        let mut socket_set3 = vec![socket1, socket4];
+        let mut socket_set3 = vec![legacy_socket1, legacy_socket4];
         sort_by_rendez_vous_hash(&mut socket_set3, "key");
 
-        assert_eq!(socket_set1, &[socket1, socket3, socket2, socket4]);
-        assert_eq!(socket_set2, &[socket1, socket2, socket4]);
-        assert_eq!(socket_set3, &[socket1, socket4]);
+        assert_eq!(socket_set1, &[legacy_socket1, legacy_socket2, legacy_socket3, legacy_socket4]);
+        assert_eq!(socket_set2, &[legacy_socket1, legacy_socket2, legacy_socket4]);
+        assert_eq!(socket_set3, &[legacy_socket1, legacy_socket4]);
     }
 }

quickwit/quickwit-common/src/socket_addr_legacy_hash.rs

@@ -0,0 +1,99 @@
+// Copyright (C) 2024 Quickwit, Inc.
+//
+// Quickwit is offered under the AGPL v3.0 and as commercial software.
+// For commercial licensing, contact us at [email protected].
+//
+// AGPL:
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+use std::hash::Hasher;
+use std::net::SocketAddr;
+
+/// Computes the hash of socket addr, the way it was done before Rust 1.81
+///
+/// In https://github.com/rust-lang/rust/commit/ba620344301aaa3b2733575a0696cdfd877edbdf
+/// rustc change the implementation of Hash for IpAddr v4 and v6.
+///
+/// The idea was to not hash an array of bytes but instead interpret it as a register
+/// and hash this.
+///
+/// This was done for performance reason, but this change the result of the hash function
+/// used to compute affinity in quickwit. As a result, the switch would invalidate all
+/// existing cache.
+///
+/// In order to avoid this, we introduce the following function that reproduces the old
+/// behavior.
+#[repr(transparent)]
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+pub struct SocketAddrLegacyHash<'a>(pub &'a SocketAddr);
+
+impl<'a> std::hash::Hash for SocketAddrLegacyHash<'a> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        std::mem::discriminant(self.0).hash(state);
+        match self.0 {
+                SocketAddr::V4(socket_addr_v4) => {
+                    socket_addr_v4.ip().octets().hash(state);
+                    socket_addr_v4.port().hash(state);
+                }
+                SocketAddr::V6(socket_addr_v6) => {
+                    socket_addr_v6.ip().octets().hash(state);
+                    socket_addr_v6.port().hash(state);
+                    socket_addr_v6.flowinfo().hash(state);
+                    socket_addr_v6.scope_id().hash(state);
+                },
+        }
+    }
+}
+
+
+
+#[cfg(test)]
+mod tests {
+    use std::net::SocketAddrV6;
+    use super::*;
+
+    fn sample_socket_addr_v4() -> SocketAddr {
+        "17.12.15.3:1834".parse().unwrap()
+    }
+
+    fn sample_socket_addr_v6() -> SocketAddr {
+        let mut socket_addr_v6: SocketAddrV6 = "[fe80::240:63ff:fede:3c19]:8080".parse().unwrap();
+        socket_addr_v6.set_scope_id(4047u32);
+        socket_addr_v6.set_flowinfo(303u32);
+        socket_addr_v6.into()
+    }
+
+    fn compute_hash(hashable: impl std::hash::Hash) -> u64 {
+        // I wish I could have used the sip hasher but we don't have the deps here and I did
+        // not want to move that code to quickwit-common.
+        //
+        // If test break because rust changed its default hasher, we can just update the tests in this
+        // file with the new values.
+        let mut hasher = siphasher::sip::SipHasher::default();
+        hashable.hash(&mut hasher);
+        hasher.finish()
+    }
+
+    #[test]
+    fn test_legacy_hash_socket_addr_v4() {
+        let h = compute_hash(SocketAddrLegacyHash(&sample_socket_addr_v4()));
+        assert_eq!(h, 8725442259486497862);
+    }
+
+    #[test]
+    fn test_legacy_hash_socket_addr_v6() {
+        let h = compute_hash(SocketAddrLegacyHash(&sample_socket_addr_v6()));
+        assert_eq!(h, 14277248675058176752);
+    }
+}

quickwit/quickwit-search/src/search_job_placer.rs

@@ -30,6 +30,7 @@ use quickwit_common::rendezvous_hasher::{node_affinity, sort_by_rendez_vous_hash
 use quickwit_proto::search::{ReportSplit, ReportSplitsRequest};
 use tracing::{info, warn};
 
+use quickwit_common::SocketAddrLegacyHash;
 use crate::{SearchJob, SearchServiceClient, SearcherPool, SEARCH_METRICS};
 
 /// Job.
@@ -64,6 +65,7 @@ pub struct SearchJobPlacer {
     searcher_pool: SearcherPool,
 }
 
+
 #[async_trait]
 impl EventSubscriber<ReportSplitsRequest> for SearchJobPlacer {
     async fn handle_event(&mut self, evt: ReportSplitsRequest) {
@@ -77,7 +79,7 @@ impl EventSubscriber<ReportSplitsRequest> for SearchJobPlacer {
         for report_split in evt.report_splits {
             let node_addr = nodes
                 .keys()
-                .max_by_key(|node_addr| node_affinity(*node_addr, &report_split.split_id))
+                .max_by_key(|node_addr| node_affinity(SocketAddrLegacyHash(*node_addr), &report_split.split_id))
                 // This actually never happens thanks to the if-condition at the
                 // top of this function.
                 .expect("`nodes` should not be empty");
@@ -115,7 +117,7 @@ struct SocketAddrAndClient {
 
 impl Hash for SocketAddrAndClient {
     fn hash<H: Hasher>(&self, hasher: &mut H) {
-        self.socket_addr.hash(hasher);
+        SocketAddrLegacyHash(&self.socket_addr).hash(hasher);
     }
 }
 
@@ -174,7 +176,7 @@ impl SearchJobPlacer {
                 all_nodes.len()
             );
         }
-        let mut candidate_nodes: Vec<_> = all_nodes
+        let mut candidate_nodes: Vec<CandidateNode> = all_nodes
             .into_iter()
             .map(|(grpc_addr, client)| CandidateNode {
                 grpc_addr,
@@ -259,7 +261,7 @@ struct CandidateNode {
 
 impl Hash for CandidateNode {
     fn hash<H: Hasher>(&self, state: &mut H) {
-        self.grpc_addr.hash(state);
+        SocketAddrLegacyHash(&self.grpc_addr).hash(state);
     }
 }