From 881f67de89ec2bf2bdf47c0c2dd641847f14c40b Mon Sep 17 00:00:00 2001
From: Benny Halevy <bhalevy@scylladb.com>
Date: Mon, 23 Feb 2026 19:49:05 +0200
Subject: [PATCH] db: snapshot-ctl: add cancel_expiration

Cancel outstanding snapshot expiration when a snapshot is
backed up and when clear_snapshot is called from the api.

Fixes SCYLLADB-787
Fixes SCYLLADB-789

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
---
 db/snapshot-ctl.cc | 28 ++++++++++++++++++++++++++++
 db/snapshot-ctl.hh |  6 ++++++
 2 files changed, 34 insertions(+)

diff --git a/db/snapshot-ctl.cc b/db/snapshot-ctl.cc
index f5907f730a..c0bbbdde85 100644
--- a/db/snapshot-ctl.cc
+++ b/db/snapshot-ctl.cc
@@ -12,6 +12,8 @@
 
 #include <algorithm>
 #include <stdexcept>
+#include <unordered_set>
+
 #include <seastar/core/coroutine.hh>
 #include <seastar/core/on_internal_error.hh>
 #include <seastar/coroutine/maybe_yield.hh>
@@ -201,6 +203,9 @@ future<> snapshot_ctl::do_take_column_family_snapshot(sstring ks_name, std::vect
 
 future<> snapshot_ctl::clear_snapshot(sstring tag, std::vector<sstring> keyspace_names, sstring cf_name) {
     snap_log.debug("clear_snapshot: tag={} keyspaces={} table={}", tag, fmt::join(keyspace_names, ","), cf_name);
+    co_await container().invoke_on(0, [&] (auto& sc) {
+        return sc.cancel_expiration(tag, keyspace_names, cf_name);
+    });
     co_return co_await run_snapshot_modify_operation([this, tag = std::move(tag), keyspace_names = std::move(keyspace_names), cf_name = std::move(cf_name)] (this auto) -> future<> {
         // clear_snapshot enumerates keyspace_names and uses cf_name as a
         // filter in each. When cf_name needs resolution (e.g. logical index
@@ -276,6 +281,7 @@ future<tasks::task_id> snapshot_ctl::start_backup(sstring endpoint, sstring buck
     if (!storage_options.is_local_type()) {
         throw std::invalid_argument("not able to backup a non-local table");
     }
+    cancel_expiration(snapshot_name, {keyspace}, table);
     auto& local_storage_options = std::get<data_dictionary::storage_options::local>(storage_options.value);
     //
     // The keyspace data directories and their snapshots are arranged as follows:
@@ -366,4 +372,26 @@ void snapshot_ctl::schedule_expiration(gc_clock::time_point when, sstring ks_nam
     }
 }
 
+void snapshot_ctl::cancel_expiration(sstring tag, std::vector<sstring> ks_names, sstring table_name) {
+    if (this_shard_id() != 0) {
+        on_internal_error(snap_log, "cancel_expiration must be called on shard 0");
+    }
+    snap_log.debug("Cancel expiration of snapshots with tag='{}' in keyspaces={} table={}", tag, fmt::join(ks_names, ","), table_name);
+    std::unordered_set<sstring> keyspaces;
+    std::ranges::move(ks_names, std::inserter(keyspaces, keyspaces.end()));
+    _expiration_queue.erase(std::remove_if(_expiration_queue.begin(), _expiration_queue.end(), [&] (const expiration_info& info) {
+        if (!tag.empty() && info.tag != tag) {
+            return false;
+        }
+        if (!keyspaces.empty() && !keyspaces.contains(info.ks_name)) {
+            return false;
+        }
+        if (!table_name.empty() && info.table_name != table_name) {
+            return false;
+        }
+        return true;
+    }), _expiration_queue.end());
+    std::ranges::make_heap(_expiration_queue, std::greater{}, &expiration_info::expires_at);
+}
+
 } // namespace db
diff --git a/db/snapshot-ctl.hh b/db/snapshot-ctl.hh
index b0030bfc06..95e9c5b8d3 100644
--- a/db/snapshot-ctl.hh
+++ b/db/snapshot-ctl.hh
@@ -126,6 +126,12 @@ public:
 
     // Must be called on shard 0
     void schedule_expiration(gc_clock::time_point when, sstring ks_name, sstring table_name, sstring tag);
+
+    // For canceling expiration, ks_name or table_name can be empty
+    // And then all snapshots with the given tag (or all, if `tag` is empty) are erased from the expiration queue
+    // within the given scope.
+    // Must be called on shard 0
+    void cancel_expiration(sstring tag, std::vector<sstring> ks_names = {}, sstring table_name = "");
 private:
     config _config;
     sharded<replica::database>& _db;