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//===-- MainLoop.h ----------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef lldb_Host_MainLoop_h_
#define lldb_Host_MainLoop_h_
#include "lldb/Host/Config.h"
#include "lldb/Host/MainLoopBase.h"
#include "llvm/ADT/DenseMap.h"
#include <csignal>
#if !HAVE_PPOLL && !HAVE_SYS_EVENT_H && !defined(__ANDROID__)
#define SIGNAL_POLLING_UNSUPPORTED 1
#endif
namespace lldb_private {
// Implementation of the MainLoopBase class. It can monitor file descriptors
// for readability using ppoll, kqueue, poll or WSAPoll. On Windows it only
// supports polling sockets, and will not work on generic file handles or
// pipes. On systems without kqueue or ppoll handling singnals is not
// supported. In addition to the common base, this class provides the ability
// to invoke a given handler when a signal is received.
//
// Since this class is primarily intended to be used for single-threaded
// processing, it does not attempt to perform any internal synchronisation and
// any concurrent accesses must be protected externally. However, it is
// perfectly legitimate to have more than one instance of this class running on
// separate threads, or even a single thread (with some limitations on signal
// monitoring).
// TODO: Add locking if this class is to be used in a multi-threaded context.
class MainLoop : public MainLoopBase {
private:
class SignalHandle;
public:
typedef std::unique_ptr<SignalHandle> SignalHandleUP;
MainLoop();
~MainLoop() override;
ReadHandleUP RegisterReadObject(const lldb::IOObjectSP &object_sp,
const Callback &callback,
Status &error) override;
// Listening for signals from multiple MainLoop instances is perfectly safe
// as long as they don't try to listen for the same signal. The callback
// function is invoked when the control returns to the Run() function, not
// when the hander is executed. This mean that you can treat the callback as
// a normal function and perform things which would not be safe in a signal
// handler. However, since the callback is not invoked synchronously, you
// cannot use this mechanism to handle SIGSEGV and the like.
SignalHandleUP RegisterSignal(int signo, const Callback &callback,
Status &error);
Status Run() override;
// This should only be performed from a callback. Do not attempt to terminate
// the processing from another thread.
// TODO: Add synchronization if we want to be terminated from another thread.
void RequestTermination() override { m_terminate_request = true; }
protected:
void UnregisterReadObject(IOObject::WaitableHandle handle) override;
void UnregisterSignal(int signo);
private:
void ProcessReadObject(IOObject::WaitableHandle handle);
void ProcessSignal(int signo);
class SignalHandle {
public:
~SignalHandle() { m_mainloop.UnregisterSignal(m_signo); }
private:
SignalHandle(MainLoop &mainloop, int signo)
: m_mainloop(mainloop), m_signo(signo) {}
MainLoop &m_mainloop;
int m_signo;
friend class MainLoop;
DISALLOW_COPY_AND_ASSIGN(SignalHandle);
};
struct SignalInfo {
Callback callback;
#if HAVE_SIGACTION
struct sigaction old_action;
#endif
bool was_blocked : 1;
};
class RunImpl;
llvm::DenseMap<IOObject::WaitableHandle, Callback> m_read_fds;
llvm::DenseMap<int, SignalInfo> m_signals;
#if HAVE_SYS_EVENT_H
int m_kqueue;
#endif
bool m_terminate_request : 1;
};
} // namespace lldb_private
#endif // lldb_Host_MainLoop_h_
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