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75 lines
1.8 KiB
C++
75 lines
1.8 KiB
C++
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// Copyright (c) 2022 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <util/signalinterrupt.h>
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#ifdef WIN32
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#include <mutex>
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#else
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#include <util/tokenpipe.h>
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#endif
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#include <ios>
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#include <optional>
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namespace util {
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SignalInterrupt::SignalInterrupt() : m_flag{false}
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{
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#ifndef WIN32
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std::optional<TokenPipe> pipe = TokenPipe::Make();
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if (!pipe) throw std::ios_base::failure("Could not create TokenPipe");
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m_pipe_r = pipe->TakeReadEnd();
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m_pipe_w = pipe->TakeWriteEnd();
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#endif
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}
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SignalInterrupt::operator bool() const
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{
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return m_flag;
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}
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void SignalInterrupt::reset()
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{
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// Cancel existing interrupt by waiting for it, this will reset condition flags and remove
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// the token from the pipe.
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if (*this) wait();
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m_flag = false;
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}
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void SignalInterrupt::operator()()
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{
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#ifdef WIN32
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std::unique_lock<std::mutex> lk(m_mutex);
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m_flag = true;
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m_cv.notify_one();
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#else
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// This must be reentrant and safe for calling in a signal handler, so using a condition variable is not safe.
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// Make sure that the token is only written once even if multiple threads call this concurrently or in
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// case of a reentrant signal.
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if (!m_flag.exchange(true)) {
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// Write an arbitrary byte to the write end of the pipe.
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int res = m_pipe_w.TokenWrite('x');
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if (res != 0) {
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throw std::ios_base::failure("Could not write interrupt token");
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}
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}
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#endif
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}
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void SignalInterrupt::wait()
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{
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#ifdef WIN32
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std::unique_lock<std::mutex> lk(m_mutex);
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m_cv.wait(lk, [this] { return m_flag.load(); });
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#else
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int res = m_pipe_r.TokenRead();
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if (res != 'x') {
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throw std::ios_base::failure("Did not read expected interrupt token");
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}
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#endif
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}
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} // namespace util
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