SelectHelper.h revision 360660 
1//===-- SelectHelper.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 liblldb_SelectHelper_h_
10#define liblldb_SelectHelper_h_
11
12#include "lldb/Utility/Status.h"
13#include "lldb/lldb-types.h"
14
15#include "llvm/ADT/DenseMap.h"
16#include "llvm/ADT/Optional.h"
17
18#include <chrono>
19
20class SelectHelper {
21public:
22  // Defaults to infinite wait for select unless you call SetTimeout()
23  SelectHelper();
24
25  // Call SetTimeout() before calling SelectHelper::Select() to set the timeout
26  // based on the current time + the timeout. This allows multiple calls to
27  // SelectHelper::Select() without having to worry about the absolute timeout
28  // as this class manages to set the relative timeout correctly.
29  void SetTimeout(const std::chrono::microseconds &timeout);
30
31  // Call the FDSet*() functions before calling SelectHelper::Select() to set
32  // the file descriptors that we will watch for when calling select. This will
33  // cause FD_SET() to be called prior to calling select using the "fd"
34  // provided.
35  void FDSetRead(lldb::socket_t fd);
36  void FDSetWrite(lldb::socket_t fd);
37  void FDSetError(lldb::socket_t fd);
38
39  // Call the FDIsSet*() functions after calling SelectHelper::Select() to
40  // check which file descriptors are ready for read/write/error. This will
41  // contain the result of FD_ISSET after calling select for a given file
42  // descriptor.
43  bool FDIsSetRead(lldb::socket_t fd) const;
44  bool FDIsSetWrite(lldb::socket_t fd) const;
45  bool FDIsSetError(lldb::socket_t fd) const;
46
47  // Call the system's select() to wait for descriptors using timeout provided
48  // in a call the SelectHelper::SetTimeout(), or infinite wait if no timeout
49  // was set.
50  lldb_private::Status Select();
51
52protected:
53  struct FDInfo {
54    FDInfo()
55        : read_set(false), write_set(false), error_set(false),
56          read_is_set(false), write_is_set(false), error_is_set(false) {}
57
58    void PrepareForSelect() {
59      read_is_set = false;
60      write_is_set = false;
61      error_is_set = false;
62    }
63
64    bool read_set : 1, write_set : 1, error_set : 1, read_is_set : 1,
65        write_is_set : 1, error_is_set : 1;
66  };
67  llvm::DenseMap<lldb::socket_t, FDInfo> m_fd_map;
68  llvm::Optional<std::chrono::steady_clock::time_point> m_end_time;
69};
70
71#endif // liblldb_SelectHelper_h_
72