initizl api to change global number of threads

src/VecSim/vec_sim.cpp

@@ -27,6 +27,10 @@ extern "C" void VecSim_SetLogCallbackFunction(logCallbackFunction callback) {
 
 extern "C" void VecSim_SetWriteMode(VecSimWriteMode mode) { VecSimIndex::setWriteMode(mode); }
 
+extern "C" void VecSim_SetNumThreads(size_t new_num_threads) {
+    VecSimIndex::setNumThreads(new_num_threads);
+}
+
 static VecSimResolveCode _ResolveParams_EFRuntime(VecSimAlgo index_type, VecSimRawParam rparam,
                                                   VecSimQueryParams *qparams,
                                                   VecsimQueryType query_type) {

src/VecSim/vec_sim.h

@@ -259,6 +259,12 @@ void VecSim_SetTestLogContext(const char *test_name, const char *test_type);
  */
 void VecSim_SetWriteMode(VecSimWriteMode mode);
 
+/**
+ * num_threads: new threads
+ * TODO: is 0 allowed
+ */
+void VecSim_SetNumThreads(size_t new_num_threads);
+
 #ifdef __cplusplus
 }
 #endif

src/VecSim/vec_sim_interface.h

@@ -215,6 +215,12 @@ struct VecSimIndexInterface : public VecsimBaseObject {
     inline static void setWriteMode(VecSimWriteMode mode) {
         VecSimIndexInterface::asyncWriteMode = mode;
     }
+
+    inline static void setNumThreads(size_t new_num_threads) {
+
+        // iterate all registered thpools and update their num_threads
+        VecSimThreadPool::setNumThreads(new_num_threads);
+    }
 #ifdef BUILD_TESTS
     virtual void fitMemory() = 0;
 #endif

tests/unit/test_svs.cpp

@@ -143,6 +143,30 @@ TYPED_TEST(SVSTest, svs_vector_add_test) {
 
     VecSimIndex_Free(index);
 }
+TYPED_TEST(SVSTest, svs_miltiple_indexes) {
+
+    size_t dim = 4;
+
+    SVSParams params = {
+        .dim = dim,
+        .metric = VecSimMetric_IP,
+        /* SVS-Vamana specifics */
+        .alpha = 1.2,
+        .graph_max_degree = 64,
+        .construction_window_size = 20,
+        .max_candidate_pool_size = 1024,
+        .prune_to = 60,
+        .use_search_history = VecSimOption_ENABLE,
+    };
+
+    VecSimIndex *index = this->CreateNewIndex(params);
+    ASSERT_INDEX(index);
+    VecSimIndex *index2 = this->CreateNewIndex(params);
+    ASSERT_INDEX(index2);
+
+    VecSimIndex_Free(index);
+    VecSimIndex_Free(index2);
+}
 
 TYPED_TEST(SVSTest, svs_vector_update_test) {
     size_t dim = 4;