fix: Fix test_network_disconnect_during_migration test (#4224)

There are actually a few failures fixed in this PR, only one of which is a test bug:

* `db_slice_->Traverse()` can yield, causing `fiber_cancelled_`'s value to change
* When a migration is cancelled, it may never finish `WaitForInflightToComplete()` because it has `in_flight_bytes_` that will never reach destination due to the cancellation
* `IterateMap()` with numeric key/values overrode the key's buffer with the value's buffer

Fixes #4207

src/server/cluster/outgoing_slot_migration.cc

@@ -37,7 +37,7 @@ class OutgoingMigration::SliceSlotMigration : private ProtocolClient {
   }
 
   ~SliceSlotMigration() {
-    streamer_.Cancel();
+    Cancel();
     cntx_.JoinErrorHandler();
   }
 
@@ -81,6 +81,7 @@ class OutgoingMigration::SliceSlotMigration : private ProtocolClient {
   }
 
   void Cancel() {
+    cntx_.Cancel();
     streamer_.Cancel();
   }
 

src/server/container_utils.cc

@@ -274,13 +274,13 @@ bool IterateMap(const PrimeValue& pv, const IterateKVFunc& func) {
   bool finished = true;
 
   if (pv.Encoding() == kEncodingListPack) {
-    uint8_t intbuf[LP_INTBUF_SIZE];
+    uint8_t k_intbuf[LP_INTBUF_SIZE], v_intbuf[LP_INTBUF_SIZE];
     uint8_t* lp = (uint8_t*)pv.RObjPtr();
     uint8_t* fptr = lpFirst(lp);
     while (fptr) {
-      string_view key = LpGetView(fptr, intbuf);
+      string_view key = LpGetView(fptr, k_intbuf);
       fptr = lpNext(lp, fptr);
-      string_view val = LpGetView(fptr, intbuf);
+      string_view val = LpGetView(fptr, v_intbuf);
       fptr = lpNext(lp, fptr);
       if (!func(ContainerEntry{key.data(), key.size()}, ContainerEntry{val.data(), val.size()})) {
         finished = false;

src/server/journal/streamer.cc

@@ -41,7 +41,9 @@ JournalStreamer::JournalStreamer(journal::Journal* journal, Context* cntx)
 }
 
 JournalStreamer::~JournalStreamer() {
+  if (!cntx_->IsCancelled()) {
     DCHECK_EQ(in_flight_bytes_, 0u);
+  }
   VLOG(1) << "~JournalStreamer";
 }
 
@@ -79,7 +81,9 @@ void JournalStreamer::Cancel() {
   VLOG(1) << "JournalStreamer::Cancel";
   waker_.notifyAll();
   journal_->UnregisterOnChange(journal_cb_id_);
+  if (!cntx_->IsCancelled()) {
     WaitForInflightToComplete();
+  }
 }
 
 size_t JournalStreamer::GetTotalBufferCapacities() const {
@@ -215,8 +219,15 @@ void RestoreStreamer::Run() {
       return;
 
     cursor = db_slice_->Traverse(pt, cursor, [&](PrimeTable::bucket_iterator it) {
+      if (fiber_cancelled_)  // Could be cancelled any time as Traverse may preempt
+        return;
+
       db_slice_->FlushChangeToEarlierCallbacks(0 /*db_id always 0 for cluster*/,
                                                DbSlice::Iterator::FromPrime(it), snapshot_version_);
+
+      if (fiber_cancelled_)  // Could have been cancelled in above call too
+        return;
+
       WriteBucket(it);
     });
 

src/server/multi_command_squasher.cc

@@ -112,6 +112,8 @@ MultiCommandSquasher::SquashResult MultiCommandSquasher::TrySquash(StoredCmd* cm
 
   cmd->Fill(&tmp_keylist_);
   auto args = absl::MakeSpan(tmp_keylist_);
+  if (args.empty())
+    return SquashResult::NOT_SQUASHED;
 
   auto keys = DetermineKeys(cmd->Cid(), args);
   if (!keys.ok())

tests/dragonfly/cluster_test.py

@@ -1290,7 +1290,7 @@ async def test_migration_with_key_ttl(df_factory):
 
 
 @dfly_args({"proactor_threads": 4, "cluster_mode": "yes"})
-async def test_network_disconnect_during_migration(df_factory, df_seeder_factory):
+async def test_network_disconnect_during_migration(df_factory):
     instances = [
         df_factory.create(port=BASE_PORT + i, admin_port=BASE_PORT + i + 1000) for i in range(2)
     ]
@@ -1328,7 +1328,7 @@ async def test_network_disconnect_during_migration(df_factory, df_seeder_factory
 
     await proxy.start()
 
-    await wait_for_status(nodes[0].admin_client, nodes[1].id, "FINISHED", 20)
+    await wait_for_status(nodes[0].admin_client, nodes[1].id, "FINISHED", 60)
     nodes[0].migrations = []
     nodes[0].slots = []
     nodes[1].slots = [(0, 16383)]
@@ -1336,6 +1336,7 @@ async def test_network_disconnect_during_migration(df_factory, df_seeder_factory
     await push_config(json.dumps(generate_config(nodes)), [node.admin_client for node in nodes])
 
     assert (await StaticSeeder.capture(nodes[1].client)) == start_capture
+    await proxy.close()
 
 
 @pytest.mark.parametrize(