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我使用boost 1.52.0 32位庫與OpenSSL 32位庫與非託管Visual C++ 2008爲新客戶端I正在寫信與現有的服務器進行通信。我的測試機器使用Windows 8.我正在使用同步讀取和寫入。該代碼內置於可從C＃訪問的DLL中，但所有的asio調用都是在使用boost :: thread_group創建的非託管線程上完成的。boost :: asio :: write似乎不工作，而boost :: asio :: read是優秀的
我發現的是，當一個同步讀取正在等待數據時，在另一個線程中發生的同步寫入看起來被阻塞，並且不會出去 - 至少通過我編碼的方式。所以我的問題是 - 同步讀取是否需要等待另一個線程中的數據才能完成同步寫入？
我已經驗證過，如果在另一個線程中沒有掛起的讀取操作，我可以成功寫入數據。我通過在讀取之前凍結讀取的線程來做到這一點。編寫線程然後寫出一條消息。然後我解凍了讀取的線程，並且它能夠成功地從服務器讀取關於發送的消息的響應。
以下方法由create_thread方法調用來處理從服務器讀取消息脫絲：
void SSLSocket::ProcessServerRequests()
{
// This method is responsible for processing requests from a server.
Byte *pByte;
int ByteCount;
size_t BytesTransferred;
boost::system::error_code Err;
Byte* pReqBuf;
string s;
stringstream ss;
//
try
{
ss << "ProcessServerRequests: Worker thread: " << Logger::NumberToString(boost::this_thread::get_id()) << " started.\n";
Log.LogString(ss.str(), LogInfo);
// Enable the handlers for the handshaking.
IOService->run();
// Wait for the handshake to be sucessfully completed.
do
{
Sleep(50);
} while (!HandShakeReady);
//
sClientIp = pSocket->lowest_layer().remote_endpoint().address().to_string();
uiClientPort = pSocket->lowest_layer().remote_endpoint().port();
ReqAlive = true;
// If the thread that handles sending msgs to all servers has not been created yet, then create that one.
// This thread is created just once to handle all outbound msgs to all servers.
WorkerThreads.create_thread(boost::bind(&SSLSocket::SendWorkerThread));
// Loop until the user quits, or an error is detected. The read method should wait until there is something to read.
do
{
pReqBuf = BufMang.GetPtr(MsgLenBytes);
boost::asio::read(*pSocket, boost::asio::buffer(pReqBuf, MsgLenBytes), boost::asio::transfer_exactly(MsgLenBytes), Err);
if (Err)
{
s = Err.message();
if ((s.find("short r")) == string::npos)
{
ss.str("");
ss << "SSLSocket::ProcessServerRequests: read(1) error = " << Err.message() << "\n. Terminating.\n\n";
Log.LogString(ss.str(), LogError);
}
Terminate();
// Notify the client that an error has been encountered and the program needs to shut down. TBD.
}
else
{
// Get the number of bytes in the message.
pByte = pReqBuf;
B2I.B.B1 = *pByte++;
B2I.B.B2 = *pByte++;
B2I.B.B3 = *pByte++;
B2I.B.B4 = *pByte;
ByteCount = B2I.IntVal;
pReqBuf = BufMang.GetPtr(ByteCount);
// Do a synchronous read which will hang until the entire message is read off the wire.
BytesTransferred = boost::asio::read(*pSocket, boost::asio::buffer(pReqBuf, ByteCount), boost::asio::transfer_exactly(ByteCount), Err);
ss.str("");
ss << "SSLSocket::ProcessServerRequests: # bytes rcvd = " << Logger::NumberToString(BytesTransferred).c_str() << " from ";
ss << sClientIp.c_str() << " : " << Logger::NumberToString(uiClientPort) << "\n";
Log.LogString(ss.str(), LogDebug2);
Log.LogBuf(pReqBuf, (int)BytesTransferred, DisplayInHex, LogDebug3);
if ((Err) || (ByteCount != BytesTransferred))
{
if (Err)
{
ss.str("");
ss << "ProcessServerRequests:read(2) error = " << Err.message() << "\n. Terminating.\n\n";
}
else
{
ss.str("");
ss << "ProcessServerRequests:read(3) error - BytesTransferred (" << Logger::NumberToString(BytesTransferred).c_str() <<
") != ByteCount (" << Logger::NumberToString(ByteCount).c_str() << "). Terminating.\n\n";
}
Log.LogString(ss.str(), LogError);
Terminate();
// Notify the client that an error has been encountered and the program needs to shut down. TBD.
break;
}
// Call the C# callback method that will handle the message.
Log.LogString("SSLSocket::ProcessServerRequests: sending msg to the C# client.\n\n", LogDebug2);
CallbackFunction(this, BytesTransferred, (void*)pReqBuf);
}
} while (ReqAlive);
Log.LogString("SSLSocket::ProcessServerRequests: worker thread done.\n", LogInfo);
}
catch (std::exception& e)
{
stringstream ss;
ss << "SSLSocket::ProcessServerRequests: threw an error - " << e.what() << ".\n";
Log.LogString(ss.str(), LogError);
}
}
以下方法由create_thread方法調用來處理將消息發送到服務器：
void SSLSocket::SendWorkerThread()
{
// This method handles sending msgs to the server. It is called upon 1st time class initialization.
//
DWORD WaitResult;
Log.LogString("SSLSocket::SendWorkerThread: Worker thread " + Logger::NumberToString(boost::this_thread::get_id()) + " started.\n", LogInfo);
// Loop until the user quits, or an error of some sort is thrown.
try
{
do
{
// If there are one or more msgs that need to be sent to a server, then send them out.
if (SendMsgQ.Count() > 0)
{
Message* pMsg = SendMsgQ.Pop();
// Byte* pBuf = pMsg->pBuf;
const Byte* pBuf = pMsg->pBuf;
SSLSocket* pSSL = pMsg->pSSL;
int BytesInMsg = pMsg->BytesInMsg;
boost::system::error_code Error;
unsigned int BytesTransferred = boost::asio::write(*pSSL->pSocket, boost::asio::buffer(pBuf, BytesInMsg), Error);
string s = "SSLSocket::SendWorkerThread: # bytes sent = ";
s += Logger::NumberToString(BytesInMsg).c_str();
s += "\n";
Log.LogString(s, LogDebug2);
Log.LogBuf(pBuf, BytesInMsg, DisplayInHex, LogDebug3);
if (Error)
{
Log.LogString("SSLSocket::SendWorkerThread: error sending message - " + Error.message() + "\n", LogError);
}
}
else
{
// Nothing to send, so go into a wait state.
WaitResult = WaitForSingleObject(hEvent, INFINITE);
if (WaitResult != 0L)
{
Log.LogString("SSLSocket::SendWorkerThread: WaitForSingleObject event error. Code = " + Logger::NumberToString(GetLastError()) + ". \n", LogError);
}
}
} while (ReqAlive);
Log.LogString("SSLSocket::SendWorkerThread: Worker thread " + Logger::NumberToString(boost::this_thread::get_id()) + " done.\n", LogInfo);
}
catch (std::exception& e)
{
stringstream ss;
ss << "SSLSocket::SendWorkerThread: threw an error - " << e.what() << ".\n";
Log.LogString(ss.str(), LogError);
}
}
因此，如果同步寫入應該能夠在另一個線程中同步讀取掛起時執行，那麼有人可以告訴我我的代碼做錯了什麼。
我剛剛發現問題的原因。在將調用從同步轉換爲異步之後，它仍然表現出同樣的問題。事實證明，這是由於一個畸形的消息。服務器根本不會對格式錯誤的消息做出響應，我剛發現這些消息。所以，我猜測同步調用可能沒問題，但現在我暫時將它保持異步。 – 2013-02-20 00:26:25