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 #include "llvm/ADT/Optional.h" 17 18 #include <chrono> 19 20 class SelectHelper { 21 public: 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 52 protected: 53 struct FDInfo { FDInfoFDInfo54 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 PrepareForSelectFDInfo58 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 // LLDB_UTILITY_SELECTHELPER_H 72