c – MySQL NDB API AccessViolationException

@H_874_1@我面临一个只在 Windows上发生的有趣问题,而在 Linux / Mono上一切正常.我已经构建了一个围绕 MySQL Cluster NDB API库的C包装器,我通过P / Invoke从C#代码调用它.到目前为止,我有三种方法： @H_673_2@> init()初始化环境并返回句柄
> read()使用句柄从数据库中读取数据
> release(),它释放资源

@H_673_2@init()在每个设置中都能正常工作.但是,read()抛出AccessviolationException,但仅在Windows上,并且只有在一个线程中调用init()而在另一个线程中调用read()时才会抛出.如果我们在一个线程中做所有事情,那就有效！任何关于可能原因的想法将不胜感激.

@H_673_2@2016年12月4日更新 – 使用简单的C测试程序注意到相同的行为,其中init()在一个线程中调用,而read()在另一个线程中调用.因此,错误与C#/ c interop无关,它可以在NDB API库中下载here(lib文件夹,MysqLclient.lib和ndbclient_static.lib).

@H_673_2@C#代码：

private const String ndbapi = "ndb";

[DllImport(ndbapi)]
public extern static intPtr init(IntPtr conn_String);

[DllImport(ndbapi)]
public extern static void read(IntPtr ndb_cluster_conn);

[DllImport(ndbapi)]
public extern static void release(IntPtr ndb_cluster_conn,IntPtr char_arr_ptr);

private static intPtr handle;

private static void InitNdb() {
    unsafe {
        fixed (byte* conn_buf = Encoding.UTF8.GetBytes("node1:1186")) {            
            handle = ndb_api_init(new IntPtr(conn_buf));
        }
    }
}
static void Main(String[] args) {
    Thread t = new Thread(InitNdb);// IF I CALL InitNDB IN THE SAME THREAD,EVERYTHING WORKS
    t.Start();
    .. //waiTing for Thread t to complete...
    IntPtr bytes_read = read(handlE);
    ...
}

@H_673_2@C代码:(基于official documentation的例子)：

#if Defined(WIN32)

#define DLLEXPORT __declspec(dllexport)
#define CALLCV __stdcall

#else

#define DLLEXPORT __attribute__((visibility("default")))
#define CALLCV __attribute__((cdecl))

#endif
..
extern "C" DLLEXPORT Ndb_cluster_connection* CALLCV init(char* connection_String) {

    ndb_init();

    // Object represenTing the cluster
    Ndb_cluster_connection* cluster_connection = new Ndb_cluster_connection(connection_String); 

    if (cluster_connection->connect(3,2,1)) {
        std::cout << "Cluster management server not ready,error:" << cluster_connection->get_la@R_450_9214@error_msg() << "\n";
        exit(-1);
    }
    if (cluster_connection->wait_until_ready(10,0) < 0) {
        std::cout << "Cluster not ready within 10 secs,error:" << cluster_connection->get_la@R_450_9214@error_msg() << std::endl;
    }

    return cluster_connection;
}
extern "C" DLLEXPORT char** CALLCV read(Ndb_cluster_connection* cluster_connection) {
    Ndb *ndb_obj = new Ndb(cluster_connection,db_name);
    if (ndb_obj->init()) {
        std::cout << "Error while initializing Ndb " << std::endl;
    }

    const NdbDictionary::Dictionary* Dict = ndb_obj->getDictionary();
    const NdbDictionary::Table *table = Dict->getTable("table_name"); <-- THIS IS THE LINE THAT THROWS ACCESS VIOLATION EXCEPTION
    ..
}