1 //===-- SelectHelper.h ------------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef liblldb_SelectHelper_h_
11 #define liblldb_SelectHelper_h_
12 
13 #include "lldb/Utility/Status.h"
14 #include "lldb/lldb-types.h"
15 
16 #include "llvm/ADT/DenseMap.h"
17 #include "llvm/ADT/Optional.h"
18 
19 #include <chrono>
20 
21 class SelectHelper {
22 public:
23   // Defaults to infinite wait for select unless you call SetTimeout()
24   SelectHelper();
25 
26   // Call SetTimeout() before calling SelectHelper::Select() to set the timeout
27   // based on the current time + the timeout. This allows multiple calls to
28   // SelectHelper::Select() without having to worry about the absolute timeout
29   // as this class manages to set the relative timeout correctly.
30   void SetTimeout(const std::chrono::microseconds &timeout);
31 
32   // Call the FDSet*() functions before calling SelectHelper::Select() to set
33   // the file descriptors that we will watch for when calling select. This will
34   // cause FD_SET() to be called prior to calling select using the "fd"
35   // provided.
36   void FDSetRead(lldb::socket_t fd);
37   void FDSetWrite(lldb::socket_t fd);
38   void FDSetError(lldb::socket_t fd);
39 
40   // Call the FDIsSet*() functions after calling SelectHelper::Select() to
41   // check which file descriptors are ready for read/write/error. This will
42   // contain the result of FD_ISSET after calling select for a given file
43   // descriptor.
44   bool FDIsSetRead(lldb::socket_t fd) const;
45   bool FDIsSetWrite(lldb::socket_t fd) const;
46   bool FDIsSetError(lldb::socket_t fd) const;
47 
48   // Call the system's select() to wait for descriptors using timeout provided
49   // in a call the SelectHelper::SetTimeout(), or infinite wait if no timeout
50   // was set.
51   lldb_private::Status Select();
52 
53 protected:
54   struct FDInfo {
FDInfoFDInfo55     FDInfo()
56         : read_set(false), write_set(false), error_set(false),
57           read_is_set(false), write_is_set(false), error_is_set(false) {}
58 
PrepareForSelectFDInfo59     void PrepareForSelect() {
60       read_is_set = false;
61       write_is_set = false;
62       error_is_set = false;
63     }
64 
65     bool read_set : 1, write_set : 1, error_set : 1, read_is_set : 1,
66         write_is_set : 1, error_is_set : 1;
67   };
68   llvm::DenseMap<lldb::socket_t, FDInfo> m_fd_map;
69   llvm::Optional<std::chrono::steady_clock::time_point> m_end_time;
70 };
71 
72 #endif // liblldb_SelectHelper_h_
73