HarmonyOS rdbstore 在 c++ 层开多线程进行事务操作具体有什么限制？

Question

如题，在 worker 里面 beginTransation 会有异常，执行失败，但用 c 层开启了子线程查询并没有出现异常，测试代码如下

// 创建数据库 config 对象
static napi_value OpenDB(napi_env env, napi_callback_info info)
{
  size_t argc = 1;
  napi_value argv[1] = {nullptr};
  napi_get_cb_info(env, info, &argc, argv, nullptr, nullptr);

  // 获取函数argv[1]，此为为rawfile相对路径
  size_t strSize;
  char strBuf[256];
  napi_get_value_string_utf8(env, argv[0], strBuf, sizeof(strBuf), &strSize);
  std::string dirName(strBuf, strSize);
  std::cout << "dir is" << dirName << std::endl;


  const char* your_dataBaseDir = dirName.c_str();
  const char* your_storeName = "RdbTest.db";
  const char* your_bundleName = "com.example.ndk";
  const char* your_moduleName = "entry";
  bool your_isEncrypt = false; // 或者true，根据你的需求
  int your_securityLevel = OH_Rdb_SecurityLevel::S1; // 根据你的需求设置
  int your_area = RDB_SECURITY_AREA_EL1; // 根据你的需求设置

  OH_Rdb_Config oh_rdb_config = {
  .selfSize = sizeof(OH_Rdb_Config),
  .dataBaseDir = your_dataBaseDir,
  .storeName = your_storeName,
  .bundleName = your_bundleName,
  .moduleName = your_moduleName,
  .isEncrypt = your_isEncrypt,
  .securityLevel = your_securityLevel,
  .area = your_area
};

  int errCode = 0;
  // 获取获取OH_Rdb_Store实例
  OH_Rdb_Store *store_ = OH_Rdb_GetOrOpen(&oh_rdb_config, &errCode);
  char createTableSql[] = "CREATE TABLE IF NOT EXISTS EMPLOYEE (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT NOT NULL, "
  "AGE INTEGER, SALARY REAL, CODES BLOB)";
  // 执行建表语句
  OH_Rdb_Execute(store_, createTableSql);

  // 创建键值对实例
  OH_VBucket *valueBucket = OH_Rdb_CreateValuesBucket();
  valueBucket->putText(valueBucket, "NAME", "Lisa");
  valueBucket->putInt64(valueBucket, "AGE", 188);
  valueBucket->putReal(valueBucket, "SALARY", 100.5);
  uint8_t arr[] = {1, 2, 3, 4, 5};
  int len = sizeof(arr) / sizeof(arr[0]);
  valueBucket->putBlob(valueBucket, "CODES", arr, len);
  // 插入数据
  int rowId = OH_Rdb_Insert(store_, "EMPLOYEE", valueBucket);
  // 开启线程开启事务查询
  std::thread mythread([=]() {
  int64_t age;
  int transactionId = OH_Rdb_BeginTransaction (store_);
  OH_Predicates *predicates = OH_Rdb_CreatePredicates("EMPLOYEE");
  const char *columnNames[] = {"NAME", "AGE"};
  int len = sizeof(columnNames) / sizeof(columnNames[0]);
  OH_Cursor *cursor = OH_Rdb_Query(store_, predicates, columnNames, len);

  int columnCount = 0;
  cursor->getColumnCount(cursor, &columnCount);

  // OH_Cursor是一个数据集合的游标，默认指向第-1个记录，有效的数据从0开始

  while (cursor->goToNextRow(cursor) == OH_Rdb_ErrCode::RDB_OK) {
    cursor->getInt64(cursor, 1, &age);
  }

  OH_Rdb_Commit (store_);

  // 释放谓词实例
  predicates->destroy(predicates);
  // 释放结果集
  cursor->destroy(cursor);
});
  mythread.detach();

  // 销毁键值对实例
  valueBucket->destroy(valueBucket);
  napi_value num;
  napi_create_double(env, rowId, &num);
  return num;
}

Answer 1

目前不能并发操作事务，开启事务和提交事务要在同一个线程中，并且此时另一个线程不能并发的再去开启事务和提交事务。