1 //===-- MainLoop.h ----------------------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLDB_HOST_MAINLOOP_H 10 #define LLDB_HOST_MAINLOOP_H 11 12 #include "lldb/Host/Config.h" 13 #include "lldb/Host/MainLoopBase.h" 14 #include "llvm/ADT/DenseMap.h" 15 #include <csignal> 16 17 #if !HAVE_PPOLL && !HAVE_SYS_EVENT_H && !defined(__ANDROID__) 18 #define SIGNAL_POLLING_UNSUPPORTED 1 19 #endif 20 21 namespace lldb_private { 22 23 // Implementation of the MainLoopBase class. It can monitor file descriptors 24 // for readability using ppoll, kqueue, poll or WSAPoll. On Windows it only 25 // supports polling sockets, and will not work on generic file handles or 26 // pipes. On systems without kqueue or ppoll handling singnals is not 27 // supported. In addition to the common base, this class provides the ability 28 // to invoke a given handler when a signal is received. 29 // 30 // Since this class is primarily intended to be used for single-threaded 31 // processing, it does not attempt to perform any internal synchronisation and 32 // any concurrent accesses must be protected externally. However, it is 33 // perfectly legitimate to have more than one instance of this class running on 34 // separate threads, or even a single thread (with some limitations on signal 35 // monitoring). 36 // TODO: Add locking if this class is to be used in a multi-threaded context. 37 class MainLoop : public MainLoopBase { 38 private: 39 class SignalHandle; 40 41 public: 42 typedef std::unique_ptr<SignalHandle> SignalHandleUP; 43 44 MainLoop(); 45 ~MainLoop() override; 46 47 ReadHandleUP RegisterReadObject(const lldb::IOObjectSP &object_sp, 48 const Callback &callback, 49 Status &error) override; 50 51 // Listening for signals from multiple MainLoop instances is perfectly safe 52 // as long as they don't try to listen for the same signal. The callback 53 // function is invoked when the control returns to the Run() function, not 54 // when the hander is executed. This mean that you can treat the callback as 55 // a normal function and perform things which would not be safe in a signal 56 // handler. However, since the callback is not invoked synchronously, you 57 // cannot use this mechanism to handle SIGSEGV and the like. 58 SignalHandleUP RegisterSignal(int signo, const Callback &callback, 59 Status &error); 60 61 Status Run() override; 62 63 // This should only be performed from a callback. Do not attempt to terminate 64 // the processing from another thread. 65 // TODO: Add synchronization if we want to be terminated from another thread. RequestTermination()66 void RequestTermination() override { m_terminate_request = true; } 67 68 protected: 69 void UnregisterReadObject(IOObject::WaitableHandle handle) override; 70 71 void UnregisterSignal(int signo); 72 73 private: 74 void ProcessReadObject(IOObject::WaitableHandle handle); 75 void ProcessSignal(int signo); 76 77 class SignalHandle { 78 public: ~SignalHandle()79 ~SignalHandle() { m_mainloop.UnregisterSignal(m_signo); } 80 81 private: SignalHandle(MainLoop & mainloop,int signo)82 SignalHandle(MainLoop &mainloop, int signo) 83 : m_mainloop(mainloop), m_signo(signo) {} 84 85 MainLoop &m_mainloop; 86 int m_signo; 87 88 friend class MainLoop; 89 SignalHandle(const SignalHandle &) = delete; 90 const SignalHandle &operator=(const SignalHandle &) = delete; 91 }; 92 93 struct SignalInfo { 94 Callback callback; 95 #if HAVE_SIGACTION 96 struct sigaction old_action; 97 #endif 98 bool was_blocked : 1; 99 }; 100 class RunImpl; 101 102 llvm::DenseMap<IOObject::WaitableHandle, Callback> m_read_fds; 103 llvm::DenseMap<int, SignalInfo> m_signals; 104 #if HAVE_SYS_EVENT_H 105 int m_kqueue; 106 #endif 107 bool m_terminate_request : 1; 108 }; 109 110 } // namespace lldb_private 111 112 #endif // LLDB_HOST_MAINLOOP_H 113