場景
Thrift框架採用了異常處理機制,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;
}
第二種情況,在最外層進行異常捕獲
void TSocket::write(const uint8_t* buf, uint32_t len) {
uint32_t sent = 0;
while (sent < len) {
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 (const TTransportException& e)
{
return;
}
}
}
第三種情況下,在用戶調用的線程進行異常捕獲,這樣子不需要修改代碼
catch (const TTransportException& ttx)
{
//Thrift框架拋出的所有異常都會直接返回
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循環是爲了循環發送,因爲一次不一定發送完用戶數據,畢竟MTU的限制。注意sent是一個無符號整型,當b返回-1的時候,sent==0-1意味着將達到32位整數最大值,大於len,從而直接退出循環。因爲套接字已經中斷,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
問題
當用戶異常中斷連接,Thrift框架是如何捕獲到該中斷信號的,暫時不清楚。
TThreadPoolServer.cpp void run()函數中斷
if (!processor_->process(input_, output_, connectionContext)||
!input_->getTransport()->peek())
當前函數處理髮送的數據包