Bitcoin Core  26.99.0
P2P Digital Currency
signalinterrupt.cpp
Go to the documentation of this file.
1 // Copyright (c) 2022 The Bitcoin Core developers
2 // Distributed under the MIT software license, see the accompanying
3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 
5 #include <util/signalinterrupt.h>
6 
7 #ifdef WIN32
8 #include <mutex>
9 #else
10 #include <util/tokenpipe.h>
11 #endif
12 
13 #include <ios>
14 #include <optional>
15 
16 namespace util {
17 
19 {
20 #ifndef WIN32
21  std::optional<TokenPipe> pipe = TokenPipe::Make();
22  if (!pipe) throw std::ios_base::failure("Could not create TokenPipe");
23  m_pipe_r = pipe->TakeReadEnd();
24  m_pipe_w = pipe->TakeWriteEnd();
25 #endif
26 }
27 
28 SignalInterrupt::operator bool() const
29 {
30  return m_flag;
31 }
32 
34 {
35  // Cancel existing interrupt by waiting for it, this will reset condition flags and remove
36  // the token from the pipe.
37  if (*this && !wait()) return false;
38  m_flag = false;
39  return true;
40 }
41 
43 {
44 #ifdef WIN32
45  std::unique_lock<std::mutex> lk(m_mutex);
46  m_flag = true;
47  m_cv.notify_one();
48 #else
49  // This must be reentrant and safe for calling in a signal handler, so using a condition variable is not safe.
50  // Make sure that the token is only written once even if multiple threads call this concurrently or in
51  // case of a reentrant signal.
52  if (!m_flag.exchange(true)) {
53  // Write an arbitrary byte to the write end of the pipe.
54  int res = m_pipe_w.TokenWrite('x');
55  if (res != 0) {
56  return false;
57  }
58  }
59 #endif
60  return true;
61 }
62 
64 {
65 #ifdef WIN32
66  std::unique_lock<std::mutex> lk(m_mutex);
67  m_cv.wait(lk, [this] { return m_flag.load(); });
68 #else
69  int res = m_pipe_r.TokenRead();
70  if (res != 'x') {
71  return false;
72  }
73 #endif
74  return true;
75 }
76 
77 } // namespace util
int TokenWrite(uint8_t token)
Write token to endpoint.
Definition: tokenpipe.cpp:40
int TokenRead()
Read token from endpoint.
Definition: tokenpipe.cpp:58
static std::optional< TokenPipe > Make()
Create a new pipe.
Definition: tokenpipe.cpp:84
std::atomic< bool > m_flag