[llvm] [llvm][Support] Improvements to ListeningSocket functionality and documentation (PR #84710)
Jordan Rupprecht via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 10 19:30:08 PDT 2024
================
@@ -56,104 +61,231 @@ static std::error_code getLastSocketErrorCode() {
#endif
}
-ListeningSocket::ListeningSocket(int SocketFD, StringRef SocketPath)
- : FD(SocketFD), SocketPath(SocketPath) {}
+static sockaddr_un setSocketAddr(StringRef SocketPath) {
+ struct sockaddr_un Addr;
+ memset(&Addr, 0, sizeof(Addr));
+ Addr.sun_family = AF_UNIX;
+ strncpy(Addr.sun_path, SocketPath.str().c_str(), sizeof(Addr.sun_path) - 1);
+ return Addr;
+}
+
+static Expected<int> getSocketFD(StringRef SocketPath) {
+#ifdef _WIN32
+ SOCKET Socket = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (Socket == INVALID_SOCKET) {
+#else
+ int Socket = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (Socket == -1) {
+#endif // _WIN32
+ return llvm::make_error<StringError>(getLastSocketErrorCode(),
+ "Create socket failed");
+ }
+
+ struct sockaddr_un Addr = setSocketAddr(SocketPath);
+ if (::connect(Socket, (struct sockaddr *)&Addr, sizeof(Addr)) == -1)
+ return llvm::make_error<StringError>(getLastSocketErrorCode(),
+ "Connect socket failed");
+
+#ifdef _WIN32
+ return _open_osfhandle(Socket, 0);
+#else
+ return Socket;
+#endif // _WIN32
+}
+
+ListeningSocket::ListeningSocket(int SocketFD, StringRef SocketPath,
+ int PipeFD[2])
+ : FD(SocketFD), SocketPath(SocketPath), PipeFD{PipeFD[0], PipeFD[1]} {}
ListeningSocket::ListeningSocket(ListeningSocket &&LS)
- : FD(LS.FD), SocketPath(LS.SocketPath) {
+ : FD(LS.FD.load()), SocketPath(LS.SocketPath),
+ PipeFD{LS.PipeFD[0], LS.PipeFD[1]} {
+
LS.FD = -1;
+ LS.SocketPath.clear();
+ LS.PipeFD[0] = -1;
+ LS.PipeFD[1] = -1;
}
Expected<ListeningSocket> ListeningSocket::createUnix(StringRef SocketPath,
int MaxBacklog) {
+ // Handle instances where the target socket address already exists and
+ // differentiate between a preexisting file with and without a bound socket
+ //
+ // ::bind will return std::errc:address_in_use if a file at the socket address
+ // already exists (e.g., the file was not properly unlinked due to a crash)
+ // even if another socket has not yet binded to that address
+ if (llvm::sys::fs::exists(SocketPath)) {
+ Expected<int> MaybeFD = getSocketFD(SocketPath);
+ if (!MaybeFD) {
+
+ // Regardless of the error, notify the caller that a file already exists
+ // at the desired socket address and that there is no bound socket at that
+ // address. The file must be removed before ::bind can use the address
+ consumeError(MaybeFD.takeError());
+ return llvm::make_error<StringError>(
+ std::make_error_code(std::errc::file_exists),
+ "Socket address unavailable");
+ }
+ ::close(std::move(*MaybeFD));
+
+ // Notify caller that the provided socket address already has a bound socket
+ return llvm::make_error<StringError>(
+ std::make_error_code(std::errc::address_in_use),
+ "Socket address unavailable");
+ }
+
#ifdef _WIN32
WSABalancer _;
- SOCKET MaybeWinsocket = socket(AF_UNIX, SOCK_STREAM, 0);
- if (MaybeWinsocket == INVALID_SOCKET) {
+ SOCKET Socket = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (Socket == INVALID_SOCKET)
#else
- int MaybeWinsocket = socket(AF_UNIX, SOCK_STREAM, 0);
- if (MaybeWinsocket == -1) {
+ int Socket = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (Socket == -1)
#endif
return llvm::make_error<StringError>(getLastSocketErrorCode(),
"socket create failed");
- }
- struct sockaddr_un Addr;
- memset(&Addr, 0, sizeof(Addr));
- Addr.sun_family = AF_UNIX;
- strncpy(Addr.sun_path, SocketPath.str().c_str(), sizeof(Addr.sun_path) - 1);
-
- if (bind(MaybeWinsocket, (struct sockaddr *)&Addr, sizeof(Addr)) == -1) {
- std::error_code Err = getLastSocketErrorCode();
- if (Err == std::errc::address_in_use)
- ::close(MaybeWinsocket);
- return llvm::make_error<StringError>(Err, "Bind error");
+ struct sockaddr_un Addr = setSocketAddr(SocketPath);
+ if (::bind(Socket, (struct sockaddr *)&Addr, sizeof(Addr)) == -1) {
+ // Grab error code from call to ::bind before calling ::close
+ std::error_code EC = getLastSocketErrorCode();
+ ::close(Socket);
+ return llvm::make_error<StringError>(EC, "Bind error");
}
- if (listen(MaybeWinsocket, MaxBacklog) == -1) {
+
+ // Mark socket as passive so incoming connections can be accepted
+ if (::listen(Socket, MaxBacklog) == -1)
return llvm::make_error<StringError>(getLastSocketErrorCode(),
"Listen error");
- }
- int UnixSocket;
+
+ int PipeFD[2];
#ifdef _WIN32
- UnixSocket = _open_osfhandle(MaybeWinsocket, 0);
+ // Reserve 1 byte for the pipe and use default textmode
+ if (::_pipe(PipeFD, 1, 0) == -1)
#else
- UnixSocket = MaybeWinsocket;
+ if (::pipe(PipeFD) == -1)
+#endif // _WIN32
+ return llvm::make_error<StringError>(getLastSocketErrorCode(),
+ "pipe failed");
+
+#ifdef _WIN32
+ return ListeningSocket{_open_osfhandle(Socket, 0), SocketPath, PipeFD};
+#else
+ return ListeningSocket{Socket, SocketPath, PipeFD};
#endif // _WIN32
- return ListeningSocket{UnixSocket, SocketPath};
}
-Expected<std::unique_ptr<raw_socket_stream>> ListeningSocket::accept() {
- int AcceptFD;
+Expected<std::unique_ptr<raw_socket_stream>>
+ListeningSocket::accept(std::chrono::milliseconds Timeout) {
+
+ struct pollfd FDs[2];
+ FDs[0].events = POLLIN;
#ifdef _WIN32
SOCKET WinServerSock = _get_osfhandle(FD);
+ FDs[0].fd = WinServerSock;
+#else
+ FDs[0].fd = FD;
+#endif
+ FDs[1].events = POLLIN;
+ FDs[1].fd = PipeFD[0];
+
+ // Keep track of how much time has passed in case poll is interupted by a
+ // signal and needs to be recalled
+ int RemainingTime = Timeout.count();
+ std::chrono::milliseconds ElapsedTime = std::chrono::milliseconds(0);
+ int PollStatus = -1;
+
+ while (PollStatus == -1 && (Timeout.count() == -1 || ElapsedTime < Timeout)) {
+ if (Timeout.count() != -1)
+ RemainingTime -= ElapsedTime.count();
+
+ auto Start = std::chrono::steady_clock::now();
+#ifdef _WIN32
+ PollStatus = WSAPoll(FDs, 2, RemainingTime);
+ if (PollStatus == SOCKET_ERROR) {
+#else
+ PollStatus = ::poll(FDs, 2, RemainingTime);
+ if (PollStatus == -1) {
+#endif
+ // Ignore error if caused by interupting signal
+ std::error_code PollErrCode = getLastSocketErrorCode();
+ if (PollErrCode != std::errc::interrupted)
+ return llvm::make_error<StringError>(PollErrCode, "FD poll failed");
+ }
+
+ if (PollStatus == 0)
+ return llvm::make_error<StringError>(
+ std::make_error_code(std::errc::timed_out),
+ "No client requests within timeout window");
+
+ if (FDs[0].revents & POLLNVAL)
+ return llvm::make_error<StringError>(
+ std::make_error_code(std::errc::bad_file_descriptor),
+ "File descriptor closed by another thread");
+
+ if (FDs[1].revents & POLLIN)
+ return llvm::make_error<StringError>(
+ std::make_error_code(std::errc::operation_canceled),
+ "Accept canceled");
+
+ auto Stop = std::chrono::steady_clock::now();
+ ElapsedTime +=
+ std::chrono::duration_cast<std::chrono::milliseconds>(Stop - Start);
+ }
+
+ int AcceptFD;
+#ifdef _WIN32
SOCKET WinAcceptSock = ::accept(WinServerSock, NULL, NULL);
AcceptFD = _open_osfhandle(WinAcceptSock, 0);
#else
AcceptFD = ::accept(FD, NULL, NULL);
-#endif //_WIN32
+#endif
+
if (AcceptFD == -1)
return llvm::make_error<StringError>(getLastSocketErrorCode(),
- "Accept failed");
+ "Socket accept failed");
return std::make_unique<raw_socket_stream>(AcceptFD);
}
-ListeningSocket::~ListeningSocket() {
- if (FD == -1)
+void ListeningSocket::shutdown() {
+ int ObservedFD = FD.load();
+
+ if (ObservedFD == -1)
return;
- ::close(FD);
- unlink(SocketPath.c_str());
-}
-static Expected<int> GetSocketFD(StringRef SocketPath) {
-#ifdef _WIN32
- SOCKET MaybeWinsocket = socket(AF_UNIX, SOCK_STREAM, 0);
- if (MaybeWinsocket == INVALID_SOCKET) {
-#else
- int MaybeWinsocket = socket(AF_UNIX, SOCK_STREAM, 0);
- if (MaybeWinsocket == -1) {
-#endif // _WIN32
- return llvm::make_error<StringError>(getLastSocketErrorCode(),
- "Create socket failed");
- }
+ // If FD equals ObservedFD set FD to -1; If FD doesn't equal ObservedFD then
+ // another thread is responsible for shutdown so return
+ if (!FD.compare_exchange_strong(ObservedFD, -1))
+ return;
- struct sockaddr_un Addr;
- memset(&Addr, 0, sizeof(Addr));
- Addr.sun_family = AF_UNIX;
- strncpy(Addr.sun_path, SocketPath.str().c_str(), sizeof(Addr.sun_path) - 1);
+ ::close(ObservedFD);
+ ::unlink(SocketPath.c_str());
- int status = connect(MaybeWinsocket, (struct sockaddr *)&Addr, sizeof(Addr));
- if (status == -1) {
- return llvm::make_error<StringError>(getLastSocketErrorCode(),
- "Connect socket failed");
- }
-#ifdef _WIN32
- return _open_osfhandle(MaybeWinsocket, 0);
-#else
- return MaybeWinsocket;
-#endif // _WIN32
+ // Ensure ::poll returns if shutdown is called by a seperate thread
+ char Byte = 'A';
+ ::write(PipeFD[1], &Byte, 1);
----------------
rupprecht wrote:
This causes `-Wunused-result`, suppressed by 6b46166ef2612d2a58767447b3db8f0343afb552.
Is there any meaningful way to recover from an error returned by write? Or is it even relevant at all whether it fails? If no recovery is necessary, 6b46166ef2612d2a58767447b3db8f0343afb552 should be sufficient. If you'd like to propagate some error or log something in case of failure, you may want to follow up.
https://github.com/llvm/llvm-project/pull/84710
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