Thrift第四課 連接中斷異常處理
Thrift框架采用了異常處理機制，當客戶端異常斷開連接，服務端這個時候嘗試發送數據給客戶端，Thrift庫會拋出異常，導致進程中斷。這種情況是非常正常的，服務器端應該捕獲異常的發生，但是不應該異常退出。所以應該當前發送數據失敗，直接返回
修改代碼如下：
uint32_t TSocket::write_partial(const uint8_t* buf, uint32_t len) {
if (socket_ == -1) {
return -1;
throw TTransportException(TTransportException::NOT_OPEN, "Called write on non-open socket");
}
uint32_t sent = 0;
int flags = 0;
#ifdef MSG_NOSIGNAL
// Note the use of MSG_NOSIGNAL to suppress SIGPIPE errors, instead we
// check for the EPIPE return condition and close the socket in that case
flags |= MSG_NOSIGNAL;
#endif // ifdef MSG_NOSIGNAL
int b = send(socket_, const_cast_sockopt(buf + sent), len - sent, flags);
++g_socket_syscalls;
if (b < 0) {
if (errno == EWOULDBLOCK || errno == EAGAIN) {
return 0;
}
// Fail on a send error
int errno_copy = errno;
GlobalOutput.perror("TSocket::write_partial() send() " + getSocketInfo(), errno_copy);
if (errno_copy == EPIPE || errno_copy == ECONNRESET || errno_copy == ENOTCONN) {
//修改的第一個地方，直接返回-1，不拋出異常
close();
return -1;
//throw TTransportException(TTransportException::NOT_OPEN, "write() send()", errno_copy);
}
//修改的第二個地方，直接返回-1，不拋出異常
close();
return -1;
throw TTransportException(TTransportException::UNKNOWN, "write() send()", errno_copy);
}
// Fail on blocked send
if (b == 0) {
throw TTransportException(TTransportException::NOT_OPEN, "Socket send returned 0.");
}
return b;
}
如下是新的嘗試，嘗試在最外層進行異常的捕獲
void TSocket::write(const uint8_t* buf, uint32_t len) {
uint32_t sent = 0;
while (sent < len) {
//嘗試通過try捕獲write_partial函數拋出的異常，但是在測試結果中並沒有什麽用，異常還是中斷程序
try
{
uint32_t b = write_partial(buf + sent, len - sent);
if (b == 0) {
// This should only happen if the timeout set with SO_SNDTIMEO expired.
// Raise an exception.
throw TTransportException(TTransportException::TIMED_OUT,
"send timeout expired");
}
sent += b;
}
catch (apache::thrift::transport::TTransportException* e)
{
return;
}
}
}
分析一下服務器發送數據的函數
void TSocket::write(const uint8_t* buf, uint32_t len) {
uint32_t sent = 0;
while (sent < len) {
uint32_t b = write_partial(buf + sent, len - sent);
if (b == 0) {
// This should only happen if the timeout set with SO_SNDTIMEO expired.
// Raise an exception.
throw TTransportException(TTransportException::TIMED_OUT,
"send timeout expired");
}
sent += b;
}
}
但b==0拋出異常，代表當前發送超時。while循環是為了循環發送，因為一次不一定發送完用戶數據，畢竟MTU的限制。註意sent是一個無符號整型，當b返回-1的時候，sent==0-1意味著將達到32位整數最大值，大於len，從而直接退出循環。因為套接字已經中斷，所以發送失敗，在調用write_partial函數的時候，返回b ==-1,導致退出循環，從而避免了拋出異常，因此返回-1，是非常合理的值
Thrift第四課 連接中斷異常處理