如何使用boosts io_service.post（）來執行函數並使用數組或指針作爲參數？

Question

在試圖建立一個程序，它可以傳輸與提升async_write數據塊/陣列，我大概遇到了我的線程的麻煩：

這是我想執行什麼：

write(unsigned char *pMsg, unsigned short nMsgLen){ 
     io_service_.post(boost::bind(&m_client::write_buf, this, pMsg, nMsgLen)); 
} 

write_buf(unsigned char *pMsg, unsigned short nMsgLen){ 

      boost::asio::async_write(target, 
          boost::asio::buffer(pMsg, nMsgLen), 
          boost::bind(&m_client::write_buf_compl, 
          this, 
          boost::asio::placeholders::error)); 
} 

它編譯，但pMsg沒有正確的內容，當write_buf被調用時，我認爲這是因爲它被調用不在同一個線程內。

那麼，我怎麼能調整這個構造來傳遞我的數組作爲參數？！

Answer 1

看來你很明白你的問題在哪裏。快速修復它是通過複製其內容通過該緩衝區：

void write(unsigned char *pMsg, unsigned short nMsgLen) { 
    // TODO: Take care of exception safety... 
    char *pMsgCopy = (char *)malloc(nMsgLen); 
    memcpy(pMsgCopy, pMsg, nMsgLen); 
    io_service_.post(boost::bind(&m_client::write_buf, this, 
           pMsgCopy, nMsgLen)); 
} 

void write_buf(unsigned char *pMsg, unsigned short nMsgLen) 
{ 
    // Achtung! Don't forget to free memory in complection callback. 
    boost::asio::async_write(target, 
          boost::asio::buffer(pMsg, nMsgLen), 
          boost::bind(&m_client::write_buf_compl, 
             this, 
             boost::asio::placeholders::error)); 
} 

void write_buf_compl(...) 
{ 
    free(pMsg); 
} 

如果你是瘋狂的效率，那麼你可以通過具有write()呼叫者提供一個首位動態分配的緩衝區避免副本。但是，如果你真的對性能感到瘋狂，那麼我建議不要使用Boost.ASIO。不過那是另一回事了。