[8.2] reading indexUpdateScheduled under the lock guard (#815)

* reading `indexUpdateScheduled` under the lock guard (#813)

* reading indexUpdateScheduled under the lock

* dont lock twice

(cherry picked from commit 1db4e00)

* revert removing addVector test from svs tiered (#814)

revert removeing addVector test from svs tiered

(cherry picked from commit 3513261)

* remove multi

Author: meiravgri

src/VecSim/algorithms/svs/svs_tiered.h

@@ -774,14 +774,17 @@ class TieredSVSIndex : public VecSimTieredIndex<DataType, float> {
     VecSimIndexDebugInfo debugInfo() const override {
         auto info = Base::debugInfo();
 
-        SvsTieredInfo svsTieredInfo = {.trainingTriggerThreshold = this->trainingTriggerThreshold,
-                                       .updateTriggerThreshold = this->updateTriggerThreshold,
-                                       .updateJobWaitTime = this->updateJobWaitTime,
-                                       .indexUpdateScheduled =
-                                           static_cast<bool>(this->indexUpdateScheduled.test())};
+        SvsTieredInfo svsTieredInfo = {
+            .trainingTriggerThreshold = this->trainingTriggerThreshold,
+            .updateTriggerThreshold = this->updateTriggerThreshold,
+            .updateJobWaitTime = this->updateJobWaitTime,
+        };
+        {
+            std::lock_guard<std::mutex> lock(this->updateJobMutex);
+            svsTieredInfo.indexUpdateScheduled =
+                this->indexUpdateScheduled.test() == VecSimBool_TRUE;
+        }
         info.tieredInfo.specificTieredBackendInfo.svsTieredInfo = svsTieredInfo;
-        // prevent parallel updates
-        std::lock_guard<std::mutex> lock(this->updateJobMutex);
         info.tieredInfo.backgroundIndexing =
             svsTieredInfo.indexUpdateScheduled && info.tieredInfo.frontendCommonInfo.indexSize > 0
                 ? VecSimBool_TRUE

tests/unit/test_svs_tiered.cpp

@@ -539,6 +539,55 @@ TYPED_TEST(SVSTieredIndexTest, addVector) {
     ASSERT_LE(expected_mem, tiered_index->getAllocationSize());
 }
 
+TYPED_TEST(SVSTieredIndexTest, background_indexing_check) {
+    // Create TieredSVS index instance with a mock queue.
+    size_t dim = 2;
+    constexpr size_t training_th = DEFAULT_BLOCK_SIZE;
+    constexpr size_t update_th = DEFAULT_BLOCK_SIZE;
+    SVSParams params = {.type = TypeParam::get_index_type(), .dim = dim, .metric = VecSimMetric_L2};
+
+    VecSimParams svs_params = CreateParams(params);
+
+    auto mock_thread_pool = tieredIndexMock();
+
+    auto tiered_params =
+        this->CreateTieredSVSParams(svs_params, mock_thread_pool, training_th, update_th);
+    auto *tiered_index = this->CreateTieredSVSIndex(tiered_params, mock_thread_pool);
+    ASSERT_INDEX(tiered_index);
+
+    mock_thread_pool.init_threads();
+
+    for (size_t i = 0; i < training_th; i++) {
+        TEST_DATA_T vector[dim];
+        GenerateVector<TEST_DATA_T>(vector, dim, i);
+        VecSimIndex_AddVector(tiered_index, vector, i);
+    }
+
+    while (tiered_index->debugInfo().tieredInfo.backgroundIndexing != VecSimBool_FALSE) {
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    }
+
+    ASSERT_EQ(tiered_index->GetBackendIndex()->indexSize(), training_th);
+    ASSERT_EQ(tiered_index->GetFlatIndex()->indexSize(), 0);
+    ASSERT_EQ(tiered_index->indexSize(), training_th);
+
+    constexpr size_t second_batch = 2500;
+
+    for (size_t i = 0; i < second_batch; i++) {
+        TEST_DATA_T vector[dim];
+        GenerateVector<TEST_DATA_T>(vector, dim, i);
+        VecSimIndex_AddVector(tiered_index, vector, training_th + i);
+    }
+
+    while (tiered_index->debugInfo().tieredInfo.backgroundIndexing != VecSimBool_FALSE) {
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    }
+
+    ASSERT_GT(tiered_index->GetBackendIndex()->indexSize(), training_th + second_batch / update_th);
+    ASSERT_LT(tiered_index->GetFlatIndex()->indexSize(), update_th);
+    ASSERT_EQ(tiered_index->indexSize(), second_batch + training_th);
+}
+
 TYPED_TEST(SVSTieredIndexTest, insertJob) {
     // Create TieredSVS index instance with a mock queue.
     size_t dim = 4;