do not use async in tests

worker/tools/folder_to_db/src/folder_db_importer.cpp

@@ -125,7 +125,9 @@ void FolderToDbImporter::ProcessNextChunk(const FileInfos& file_list,
     p->next_chunk_size = p->chunk + (p->remainder ? 1 : 0);
     if (p->next_chunk_size == 0) return;
 
-    res->push_back(std::async(std::launch::async, &FolderToDbImporter::PerformParallelTask, this,
+    auto method =async_?std::launch::async:std::launch::deferred;
+
+    res->push_back(std::async(method, &FolderToDbImporter::PerformParallelTask, this,
                               file_list, p->begin, p->begin + p->next_chunk_size));
 
     p->begin = p->begin + p->next_chunk_size;
@@ -185,9 +187,10 @@ void FolderToDbImporter::IgnoreDuplicates(bool ignore_duplicates) {
     ignore_duplicates_ = ignore_duplicates;
 }
 
-unsigned int FolderToDbImporter::SetNParallelTasks(unsigned int ntasks) {
+unsigned int FolderToDbImporter::SetNParallelTasks(unsigned int ntasks,bool async) {
     unsigned int nthreads = std::thread::hardware_concurrency();
     n_tasks_ = std::max((unsigned int)1, std::min(ntasks, nthreads));
+    async_ = async;
     return n_tasks_;
 }
 

worker/tools/folder_to_db/src/folder_db_importer.h

@@ -43,7 +43,7 @@ class FolderToDbImporter {
     FolderToDbImportError Convert(const std::string& uri, const std::string& folder,
                                   FolderImportStatistics* statistics = nullptr) const;
 
-    unsigned int SetNParallelTasks(unsigned int ntasks);
+    unsigned int SetNParallelTasks(unsigned int ntasks,bool async = true);
     void IgnoreDuplicates(bool ignore_duplicates = true);
     std::unique_ptr<hidra2::DatabaseFactory>
     db_factory__; // modified in testings to mock system calls,otherwise do not touch
@@ -51,6 +51,7 @@ class FolderToDbImporter {
   private:
     bool ignore_duplicates_{false};
     unsigned int n_tasks_{1};
+    bool async_{true};
     mutable std::string db_uri_ ;
     mutable std::string db_collection_name;
     FolderToDbImportError ConnectToDb(const std::unique_ptr<hidra2::Database>& db) const;

worker/tools/folder_to_db/unittests/test_folder_to_db.cpp

@@ -238,7 +238,7 @@ TEST_F(FolderDBConverterTests, PassesFileListToInsertInParallel3by3) {
     EXPECT_CALL(*(mock_dbf->db[2]), Insert(CompareFileInfo(file_infos[2]), _)).
     WillOnce(testing::Return(DBError::kNoError));
 
-    converter.SetNParallelTasks(3);
+    converter.SetNParallelTasks(3,false);
     auto error = converter.Convert(uri, folder);
     ASSERT_THAT(error, Eq(FolderToDbImportError::kOK));
 }
@@ -252,7 +252,7 @@ TEST_F(FolderDBConverterTests, PassesFileListToInsertInParallel3by2) {
     EXPECT_CALL(*(mock_dbf->db[1]), Insert(CompareFileInfo(file_infos[2]), _)).
     WillOnce(testing::Return(DBError::kNoError));
 
-    converter.SetNParallelTasks(2);
+    converter.SetNParallelTasks(2,false);
     auto error = converter.Convert(uri, folder);
     ASSERT_THAT(error, Eq(FolderToDbImportError::kOK));
 }