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84 lines
2.3 KiB
C++
84 lines
2.3 KiB
C++
//------------------------------------------------------------------------------
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/*
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This file is part of rippled: https://github.com/ripple/rippled
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Copyright (c) 2012, 2013 Ripple Labs Inc.
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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//==============================================================================
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#ifndef RIPPLE_CORE_SEMAPHORE_H_INCLUDED
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#define RIPPLE_CORE_SEMAPHORE_H_INCLUDED
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#include <condition_variable>
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#include <mutex>
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namespace ripple {
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template <class Mutex, class CondVar>
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class basic_semaphore
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{
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private:
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Mutex m_mutex;
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CondVar m_cond;
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std::size_t m_count;
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public:
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using size_type = std::size_t;
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/** Create the semaphore, with an optional initial count.
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If unspecified, the initial count is zero.
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*/
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explicit basic_semaphore(size_type count = 0) : m_count(count)
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{
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}
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/** Increment the count and unblock one waiting thread. */
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void
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notify()
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{
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std::lock_guard lock{m_mutex};
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++m_count;
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m_cond.notify_one();
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}
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/** Block until notify is called. */
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void
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wait()
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{
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std::unique_lock lock{m_mutex};
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while (m_count == 0)
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m_cond.wait(lock);
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--m_count;
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}
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/** Perform a non-blocking wait.
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@return `true` If the wait would be satisfied.
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*/
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bool
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try_wait()
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{
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std::lock_guard lock{m_mutex};
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if (m_count == 0)
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return false;
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--m_count;
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return true;
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}
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};
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using semaphore = basic_semaphore<std::mutex, std::condition_variable>;
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} // namespace ripple
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#endif
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