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//===-- MainLoopPosix.h -----------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef lldb_Host_posix_MainLoopPosix_h_
#define lldb_Host_posix_MainLoopPosix_h_
#include "lldb/Host/MainLoopBase.h"
#include "llvm/ADT/DenseMap.h"
namespace lldb_private {
// Posix implementation of the MainLoopBase class. It can monitor file descriptors for
// readability using pselect. 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 MainLoopPosix: public MainLoopBase
{
private:
class SignalHandle;
public:
typedef std::unique_ptr<SignalHandle> SignalHandleUP;
~MainLoopPosix() override;
ReadHandleUP
RegisterReadObject(const lldb::IOObjectSP &object_sp, const Callback &callback, Error &error) override;
// Listening for signals from multiple MainLoopPosix 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 means 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, Error &error);
Error
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(const lldb::IOObjectSP &object_sp) override;
void
UnregisterSignal(int signo);
private:
class SignalHandle
{
public:
~SignalHandle() { m_mainloop.UnregisterSignal(m_signo); }
private:
SignalHandle(MainLoopPosix &mainloop, int signo) : m_mainloop(mainloop), m_signo(signo) { }
MainLoopPosix &m_mainloop;
int m_signo;
friend class MainLoopPosix;
DISALLOW_COPY_AND_ASSIGN(SignalHandle);
};
struct SignalInfo
{
Callback callback;
struct sigaction old_action;
bool was_blocked : 1;
};
llvm::DenseMap<IOObject::WaitableHandle, Callback> m_read_fds;
llvm::DenseMap<int, SignalInfo> m_signals;
bool m_terminate_request : 1;
};
} // namespace lldb_private
#endif // lldb_Host_posix_MainLoopPosix_h_
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