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 LLDB_UTILITY_SELECTHELPER_H
10#define LLDB_UTILITY_SELECTHELPER_H
11
12#include "lldb/Utility/Status.h"
13#include "lldb/lldb-types.h"
14
15#include "llvm/ADT/DenseMap.h"
16
17#include <chrono>
18#include <optional>
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 std::optional<std::chrono::steady_clock::time_point> m_end_time;
69};
70
71#endif // LLDB_UTILITY_SELECTHELPER_H
72

source code of lldb/include/lldb/Utility/SelectHelper.h