1//===-- Connection.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_Connection_h_
10#define liblldb_Connection_h_
11
12#include "lldb/lldb-defines.h"
13#include "lldb/lldb-enumerations.h"
14#include "lldb/lldb-forward.h"
15
16#include "llvm/ADT/StringRef.h"
17
18#include <ratio>
19#include <string>
20
21#include <stddef.h>
22
23namespace lldb_private {
24class Status;
25template <typename Ratio> class Timeout;
26}
27
28namespace lldb_private {
29
30/// \class Connection Connection.h "lldb/Utility/Connection.h"
31/// A communication connection class.
32///
33/// A class that implements that actual communication functions for
34/// connecting/disconnecting, reading/writing, and waiting for bytes to become
35/// available from a two way communication connection.
36///
37/// This class is designed to only do very simple communication functions.
38/// Instances can be instantiated and given to a Communication class to
39/// perform communications where clients can listen for broadcasts, and
40/// perform other higher level communications.
41class Connection {
42public:
43  /// Default constructor
44  Connection() = default;
45
46  /// Virtual destructor since this class gets subclassed and handed to a
47  /// Communication object.
48  virtual ~Connection();
49
50  /// Connect using the connect string \a url.
51  ///
52  /// \param[in] url
53  ///     A string that contains all information needed by the
54  ///     subclass to connect to another client.
55  ///
56  /// \param[out] error_ptr
57  ///     A pointer to an error object that should be given an
58  ///     appropriate error value if this method returns false. This
59  ///     value can be NULL if the error value should be ignored.
60  ///
61  /// \return
62  ///     \b True if the connect succeeded, \b false otherwise. The
63  ///     internal error object should be filled in with an
64  ///     appropriate value based on the result of this function.
65  ///
66  /// \see Status& Communication::GetError ();
67  virtual lldb::ConnectionStatus Connect(llvm::StringRef url,
68                                         Status *error_ptr) = 0;
69
70  /// Disconnect the communications connection if one is currently connected.
71  ///
72  /// \param[out] error_ptr
73  ///     A pointer to an error object that should be given an
74  ///     appropriate error value if this method returns false. This
75  ///     value can be NULL if the error value should be ignored.
76  ///
77  /// \return
78  ///     \b True if the disconnect succeeded, \b false otherwise. The
79  ///     internal error object should be filled in with an
80  ///     appropriate value based on the result of this function.
81  ///
82  /// \see Status& Communication::GetError ();
83  virtual lldb::ConnectionStatus Disconnect(Status *error_ptr) = 0;
84
85  /// Check if the connection is valid.
86  ///
87  /// \return
88  ///     \b True if this object is currently connected, \b false
89  ///     otherwise.
90  virtual bool IsConnected() const = 0;
91
92  /// The read function that attempts to read from the connection.
93  ///
94  /// \param[in] dst
95  ///     A destination buffer that must be at least \a dst_len bytes
96  ///     long.
97  ///
98  /// \param[in] dst_len
99  ///     The number of bytes to attempt to read, and also the max
100  ///     number of bytes that can be placed into \a dst.
101  ///
102  /// \param[in] timeout
103  ///     The number of microseconds to wait for the data.
104  ///
105  /// \param[out] status
106  ///     On return, indicates whether the call was successful or terminated
107  ///     due to some error condition.
108  ///
109  /// \param[out] error_ptr
110  ///     A pointer to an error object that should be given an
111  ///     appropriate error value if this method returns zero. This
112  ///     value can be NULL if the error value should be ignored.
113  ///
114  /// \return
115  ///     The number of bytes actually read.
116  ///
117  /// \see size_t Communication::Read (void *, size_t, uint32_t);
118  virtual size_t Read(void *dst, size_t dst_len,
119                      const Timeout<std::micro> &timeout,
120                      lldb::ConnectionStatus &status, Status *error_ptr) = 0;
121
122  /// The actual write function that attempts to write to the communications
123  /// protocol.
124  ///
125  /// Subclasses must override this function.
126  ///
127  /// \param[in] dst
128  ///     A desination buffer that must be at least \a dst_len bytes
129  ///     long.
130  ///
131  /// \param[in] dst_len
132  ///     The number of bytes to attempt to write, and also the
133  ///     number of bytes are currently available in \a dst.
134  ///
135  /// \param[out] error_ptr
136  ///     A pointer to an error object that should be given an
137  ///     appropriate error value if this method returns zero. This
138  ///     value can be NULL if the error value should be ignored.
139  ///
140  /// \return
141  ///     The number of bytes actually Written.
142  virtual size_t Write(const void *dst, size_t dst_len,
143                       lldb::ConnectionStatus &status, Status *error_ptr) = 0;
144
145  /// Returns a URI that describes this connection object
146  ///
147  /// Subclasses may override this function.
148  ///
149  /// \return
150  ///     Returns URI or an empty string if disconnecteds
151  virtual std::string GetURI() = 0;
152
153  /// Interrupts an ongoing Read() operation.
154  ///
155  /// If there is an ongoing read operation in another thread, this operation
156  /// return with status == eConnectionStatusInterrupted. Note that if there
157  /// data waiting to be read and an interrupt request is issued, the Read()
158  /// function will return the data immediately without processing the
159  /// interrupt request (which will remain queued for the next Read()
160  /// operation).
161  ///
162  /// \return
163  ///     Returns true is the interrupt request was successful.
164  virtual bool InterruptRead() = 0;
165
166  /// Returns the underlying IOObject used by the Connection.
167  ///
168  /// The IOObject can be used to wait for data to become available on the
169  /// connection. If the Connection does not use IOObjects (and hence does not
170  /// support waiting) this function should return a null pointer.
171  ///
172  /// \return
173  ///     The underlying IOObject used for reading.
174  virtual lldb::IOObjectSP GetReadObject() { return lldb::IOObjectSP(); };
175
176private:
177  // For Connection only
178  DISALLOW_COPY_AND_ASSIGN(Connection);
179};
180
181} // namespace lldb_private
182
183#endif // liblldb_Connection_h_
184