1 //===-- MainLoop.h ----------------------------------------------*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 #ifndef lldb_Host_MainLoop_h_
10 #define lldb_Host_MainLoop_h_
12 #include "lldb/Host/Config.h"
13 #include "lldb/Host/MainLoopBase.h"
14 #include "llvm/ADT/DenseMap.h"
17 #if !HAVE_PPOLL && !HAVE_SYS_EVENT_H && !defined(__ANDROID__)
18 #define SIGNAL_POLLING_UNSUPPORTED 1
21 namespace lldb_private {
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.
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
36 // TODO: Add locking if this class is to be used in a multi-threaded context.
37 class MainLoop : public MainLoopBase {
42 typedef std::unique_ptr<SignalHandle> SignalHandleUP;
47 ReadHandleUP RegisterReadObject(const lldb::IOObjectSP &object_sp,
48 const Callback &callback,
49 Status &error) override;
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,
61 Status Run() override;
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.
66 void RequestTermination() override { m_terminate_request = true; }
69 void UnregisterReadObject(IOObject::WaitableHandle handle) override;
71 void UnregisterSignal(int signo);
74 void ProcessReadObject(IOObject::WaitableHandle handle);
75 void ProcessSignal(int signo);
79 ~SignalHandle() { m_mainloop.UnregisterSignal(m_signo); }
82 SignalHandle(MainLoop &mainloop, int signo)
83 : m_mainloop(mainloop), m_signo(signo) {}
88 friend class MainLoop;
89 DISALLOW_COPY_AND_ASSIGN(SignalHandle);
95 struct sigaction old_action;
101 llvm::DenseMap<IOObject::WaitableHandle, Callback> m_read_fds;
102 llvm::DenseMap<int, SignalInfo> m_signals;
106 bool m_terminate_request : 1;
109 } // namespace lldb_private
111 #endif // lldb_Host_MainLoop_h_