MainLoop.cpp revision 317778
1//===-- MainLoop.cpp --------------------------------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9 10#include "llvm/Config/llvm-config.h" 11 12#include "lldb/Host/MainLoop.h" 13#include "lldb/Utility/Error.h" 14#include <algorithm> 15#include <cassert> 16#include <cerrno> 17#include <csignal> 18#include <vector> 19#include <time.h> 20 21#if HAVE_SYS_EVENT_H 22#include <sys/event.h> 23#elif defined(LLVM_ON_WIN32) 24#include <winsock2.h> 25#else 26#include <poll.h> 27#endif 28 29#ifdef LLVM_ON_WIN32 30#define POLL WSAPoll 31#else 32#define POLL poll 33#endif 34 35#ifdef __ANDROID__ 36#define FORCE_PSELECT 37#endif 38 39#if SIGNAL_POLLING_UNSUPPORTED 40#ifdef LLVM_ON_WIN32 41typedef int sigset_t; 42typedef int siginfo_t; 43#endif 44 45int ppoll(struct pollfd *fds, size_t nfds, const struct timespec *timeout_ts, 46 const sigset_t *) { 47 int timeout = 48 (timeout_ts == nullptr) 49 ? -1 50 : (timeout_ts->tv_sec * 1000 + timeout_ts->tv_nsec / 1000000); 51 return POLL(fds, nfds, timeout); 52} 53 54#endif 55 56using namespace lldb; 57using namespace lldb_private; 58 59static sig_atomic_t g_signal_flags[NSIG]; 60 61static void SignalHandler(int signo, siginfo_t *info, void *) { 62 assert(signo < NSIG); 63 g_signal_flags[signo] = 1; 64} 65 66class MainLoop::RunImpl { 67public: 68 // TODO: Use llvm::Expected<T> 69 static std::unique_ptr<RunImpl> Create(MainLoop &loop, Error &error); 70 ~RunImpl(); 71 72 Error Poll(); 73 74 template <typename F> void ForEachReadFD(F &&f); 75 template <typename F> void ForEachSignal(F &&f); 76 77private: 78 MainLoop &loop; 79 80#if HAVE_SYS_EVENT_H 81 int queue_id; 82 std::vector<struct kevent> in_events; 83 struct kevent out_events[4]; 84 int num_events = -1; 85 86 RunImpl(MainLoop &loop, int queue_id) : loop(loop), queue_id(queue_id) { 87 in_events.reserve(loop.m_read_fds.size() + loop.m_signals.size()); 88 } 89#else 90 std::vector<int> signals; 91#ifdef FORCE_PSELECT 92 fd_set read_fd_set; 93#else 94 std::vector<struct pollfd> read_fds; 95#endif 96 97 RunImpl(MainLoop &loop) : loop(loop) { 98 signals.reserve(loop.m_signals.size()); 99 } 100 101 sigset_t get_sigmask(); 102#endif 103}; 104 105#if HAVE_SYS_EVENT_H 106MainLoop::RunImpl::~RunImpl() { 107 int r = close(queue_id); 108 assert(r == 0); 109 (void)r; 110} 111std::unique_ptr<MainLoop::RunImpl> MainLoop::RunImpl::Create(MainLoop &loop, Error &error) 112{ 113 error.Clear(); 114 int queue_id = kqueue(); 115 if(queue_id < 0) { 116 error = Error(errno, eErrorTypePOSIX); 117 return nullptr; 118 } 119 return std::unique_ptr<RunImpl>(new RunImpl(loop, queue_id)); 120} 121 122Error MainLoop::RunImpl::Poll() { 123 in_events.resize(loop.m_read_fds.size() + loop.m_signals.size()); 124 unsigned i = 0; 125 for (auto &fd : loop.m_read_fds) 126 EV_SET(&in_events[i++], fd.first, EVFILT_READ, EV_ADD, 0, 0, 0); 127 128 for (const auto &sig : loop.m_signals) 129 EV_SET(&in_events[i++], sig.first, EVFILT_SIGNAL, EV_ADD, 0, 0, 0); 130 131 num_events = kevent(queue_id, in_events.data(), in_events.size(), out_events, 132 llvm::array_lengthof(out_events), nullptr); 133 134 if (num_events < 0) 135 return Error("kevent() failed with error %d\n", num_events); 136 return Error(); 137} 138 139template <typename F> void MainLoop::RunImpl::ForEachReadFD(F &&f) { 140 assert(num_events >= 0); 141 for (int i = 0; i < num_events; ++i) { 142 f(out_events[i].ident); 143 if (loop.m_terminate_request) 144 return; 145 } 146} 147template <typename F> void MainLoop::RunImpl::ForEachSignal(F && f) {} 148#else 149MainLoop::RunImpl::~RunImpl() {} 150std::unique_ptr<MainLoop::RunImpl> MainLoop::RunImpl::Create(MainLoop &loop, Error &error) 151{ 152 error.Clear(); 153 return std::unique_ptr<RunImpl>(new RunImpl(loop)); 154} 155 156sigset_t MainLoop::RunImpl::get_sigmask() { 157#if SIGNAL_POLLING_UNSUPPORTED 158 return 0; 159#else 160 sigset_t sigmask; 161 int ret = pthread_sigmask(SIG_SETMASK, nullptr, &sigmask); 162 assert(ret == 0); 163 (void) ret; 164 165 for (const auto &sig : loop.m_signals) { 166 signals.push_back(sig.first); 167 sigdelset(&sigmask, sig.first); 168 } 169 return sigmask; 170#endif 171} 172 173#ifdef FORCE_PSELECT 174Error MainLoop::RunImpl::Poll() { 175 signals.clear(); 176 177 FD_ZERO(&read_fd_set); 178 int nfds = 0; 179 for (const auto &fd : loop.m_read_fds) { 180 FD_SET(fd.first, &read_fd_set); 181 nfds = std::max(nfds, fd.first + 1); 182 } 183 184 sigset_t sigmask = get_sigmask(); 185 if (pselect(nfds, &read_fd_set, nullptr, nullptr, nullptr, &sigmask) == -1 && 186 errno != EINTR) 187 return Error(errno, eErrorTypePOSIX); 188 189 return Error(); 190} 191 192template <typename F> void MainLoop::RunImpl::ForEachReadFD(F &&f) { 193 for (const auto &fd : loop.m_read_fds) { 194 if(!FD_ISSET(fd.first, &read_fd_set)) 195 continue; 196 197 f(fd.first); 198 if (loop.m_terminate_request) 199 return; 200 } 201} 202#else 203Error MainLoop::RunImpl::Poll() { 204 signals.clear(); 205 read_fds.clear(); 206 207 sigset_t sigmask = get_sigmask(); 208 209 for (const auto &fd : loop.m_read_fds) { 210 struct pollfd pfd; 211 pfd.fd = fd.first; 212 pfd.events = POLLIN; 213 pfd.revents = 0; 214 read_fds.push_back(pfd); 215 } 216 217 if (ppoll(read_fds.data(), read_fds.size(), nullptr, &sigmask) == -1 && 218 errno != EINTR) 219 return Error(errno, eErrorTypePOSIX); 220 221 return Error(); 222} 223 224template <typename F> void MainLoop::RunImpl::ForEachReadFD(F &&f) { 225 for (const auto &fd : read_fds) { 226 if ((fd.revents & POLLIN) == 0) 227 continue; 228 229 f(fd.fd); 230 if (loop.m_terminate_request) 231 return; 232 } 233} 234#endif 235 236template <typename F> void MainLoop::RunImpl::ForEachSignal(F &&f) { 237 for (int sig : signals) { 238 if (g_signal_flags[sig] == 0) 239 continue; // No signal 240 g_signal_flags[sig] = 0; 241 f(sig); 242 243 if (loop.m_terminate_request) 244 return; 245 } 246} 247#endif 248 249MainLoop::~MainLoop() { 250 assert(m_read_fds.size() == 0); 251 assert(m_signals.size() == 0); 252} 253 254MainLoop::ReadHandleUP 255MainLoop::RegisterReadObject(const IOObjectSP &object_sp, 256 const Callback &callback, Error &error) { 257#ifdef LLVM_ON_WIN32 258 if (object_sp->GetFdType() != IOObject:: eFDTypeSocket) { 259 error.SetErrorString("MainLoop: non-socket types unsupported on Windows"); 260 return nullptr; 261 } 262#endif 263 if (!object_sp || !object_sp->IsValid()) { 264 error.SetErrorString("IO object is not valid."); 265 return nullptr; 266 } 267 268 const bool inserted = 269 m_read_fds.insert({object_sp->GetWaitableHandle(), callback}).second; 270 if (!inserted) { 271 error.SetErrorStringWithFormat("File descriptor %d already monitored.", 272 object_sp->GetWaitableHandle()); 273 return nullptr; 274 } 275 276 return CreateReadHandle(object_sp); 277} 278 279// We shall block the signal, then install the signal handler. The signal will 280// be unblocked in 281// the Run() function to check for signal delivery. 282MainLoop::SignalHandleUP 283MainLoop::RegisterSignal(int signo, const Callback &callback, 284 Error &error) { 285#ifdef SIGNAL_POLLING_UNSUPPORTED 286 error.SetErrorString("Signal polling is not supported on this platform."); 287 return nullptr; 288#else 289 if (m_signals.find(signo) != m_signals.end()) { 290 error.SetErrorStringWithFormat("Signal %d already monitored.", signo); 291 return nullptr; 292 } 293 294 SignalInfo info; 295 info.callback = callback; 296 struct sigaction new_action; 297 new_action.sa_sigaction = &SignalHandler; 298 new_action.sa_flags = SA_SIGINFO; 299 sigemptyset(&new_action.sa_mask); 300 sigaddset(&new_action.sa_mask, signo); 301 302 sigset_t old_set; 303 if (int ret = pthread_sigmask(SIG_BLOCK, &new_action.sa_mask, &old_set)) { 304 error.SetErrorStringWithFormat("pthread_sigmask failed with error %d\n", 305 ret); 306 return nullptr; 307 } 308 309 info.was_blocked = sigismember(&old_set, signo); 310 if (sigaction(signo, &new_action, &info.old_action) == -1) { 311 error.SetErrorToErrno(); 312 if (!info.was_blocked) 313 pthread_sigmask(SIG_UNBLOCK, &new_action.sa_mask, nullptr); 314 return nullptr; 315 } 316 317 m_signals.insert({signo, info}); 318 g_signal_flags[signo] = 0; 319 320 return SignalHandleUP(new SignalHandle(*this, signo)); 321#endif 322} 323 324void MainLoop::UnregisterReadObject(IOObject::WaitableHandle handle) { 325 bool erased = m_read_fds.erase(handle); 326 UNUSED_IF_ASSERT_DISABLED(erased); 327 assert(erased); 328} 329 330void MainLoop::UnregisterSignal(int signo) { 331#if SIGNAL_POLLING_UNSUPPORTED 332 Error("Signal polling is not supported on this platform."); 333#else 334 // We undo the actions of RegisterSignal on a best-effort basis. 335 auto it = m_signals.find(signo); 336 assert(it != m_signals.end()); 337 338 sigaction(signo, &it->second.old_action, nullptr); 339 340 sigset_t set; 341 sigemptyset(&set); 342 sigaddset(&set, signo); 343 pthread_sigmask(it->second.was_blocked ? SIG_BLOCK : SIG_UNBLOCK, &set, 344 nullptr); 345 346 m_signals.erase(it); 347#endif 348} 349 350Error MainLoop::Run() { 351 m_terminate_request = false; 352 353 Error error; 354 auto impl = RunImpl::Create(*this, error); 355 if (!impl) 356 return error; 357 358 // run until termination or until we run out of things to listen to 359 while (!m_terminate_request && (!m_read_fds.empty() || !m_signals.empty())) { 360 361 error = impl->Poll(); 362 if (error.Fail()) 363 return error; 364 365 impl->ForEachSignal([&](int sig) { 366 auto it = m_signals.find(sig); 367 if (it != m_signals.end()) 368 it->second.callback(*this); // Do the work 369 }); 370 if (m_terminate_request) 371 return Error(); 372 373 impl->ForEachReadFD([&](int fd) { 374 auto it = m_read_fds.find(fd); 375 if (it != m_read_fds.end()) 376 it->second(*this); // Do the work 377 }); 378 if (m_terminate_request) 379 return Error(); 380 } 381 return Error(); 382} 383