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Replace the poco semaphore with C++11 mutex/lock.
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Rework the FAILURE macro's to be safer
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Remy van Elst committed May 1, 2024
1 parent d26f87b commit f3bd6f4
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2 changes: 2 additions & 0 deletions .gitignore
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Expand Up @@ -4,3 +4,5 @@ build**/
.idea/
.vs/
CMakeSettings.json
run/
img/
79 changes: 0 additions & 79 deletions src/base/Semaphore.cpp
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186 changes: 56 additions & 130 deletions src/base/Semaphore.hpp
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Expand Up @@ -28,138 +28,64 @@
* Parts of this file based upon the Poco C++ Libraries, which is Copyright (C)
* 2004-2006, Applied Informatics Software Engineering GmbH. and Contributors.
*/
#pragma once

//
// Semaphore.h
//
// $Id: Semaphore.h,v 1.1 2008/05/31 15:47:28 iamcamiel Exp $
//
// Library: Foundation
// Package: Threading
// Module: Semaphore
//
// Definition of the Semaphore class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
#include "es40_debug.hpp"
#include <chrono>
#include <mutex>
#include <condition_variable>

#ifndef Foundation_Semaphore_INCLUDED
#define Foundation_Semaphore_INCLUDED

#include "Exception.hpp"
#include "Foundation.hpp"

#if defined(POCO_OS_FAMILY_WINDOWS)
#include "Semaphore_WIN32.hpp"
#else
#include "Semaphore_POSIX.hpp"
#endif

class CSemaphore : private CSemaphoreImpl
/// A Semaphore is a synchronization object with the following
/// characteristics:
/// A semaphore has a value that is constrained to be a non-negative
/// integer and two atomic operations. The allowable operations are V
/// (here called set()) and P (here called wait()). A V (set()) operation
/// increases the value of the semaphore by one.
/// A P (wait()) operation decreases the value of the semaphore by one,
/// provided that can be done without violating the constraint that the
/// value be non-negative. A P (wait()) operation that is initiated when
/// the value of the semaphore is 0 suspends the calling thread.
/// The calling thread may continue when the value becomes positive again.
{
class CSemaphore {
public:
CSemaphore(int n);
CSemaphore(int n, int max);
/// Creates the semaphore. The current value
/// of the semaphore is given in n. The
/// maximum value of the semaphore is given
/// in max.
/// If only n is given, it must be greater than
/// zero.
/// If both n and max are given, max must be
/// greater than zero, n must be greater than
/// or equal to zero and less than or equal
/// to max.

~CSemaphore();
/// Destroys the semaphore.

void set();
/// Increments the semaphore's value by one and
/// thus signals the semaphore. Another thread
/// waiting for the semaphore will be able
/// to continue.

void wait();
/// Waits for the semaphore to become signalled.
/// To become signalled, a semaphore's value must
/// be greater than zero.
/// Decrements the semaphore's value by one.

void wait(long milliseconds);
/// Waits for the semaphore to become signalled.
/// To become signalled, a semaphore's value must
/// be greater than zero.
/// Throws a TimeoutException if the semaphore
/// does not become signalled within the specified
/// time interval.
/// Decrements the semaphore's value by one
/// if successful.

bool tryWait(long milliseconds);
/// Waits for the semaphore to become signalled.
/// To become signalled, a semaphore's value must
/// be greater than zero.
/// Returns true if the semaphore
/// became signalled within the specified
/// time interval, false otherwise.
/// Decrements the semaphore's value by one
/// if successful.
explicit CSemaphore(int n) : m_count(n), m_max(n) {}
CSemaphore(int n, int max) : m_count(n), m_max(max) {
if (n < 0 || n > max) {
FAILURE(InvalidArgument, "Invalid initial count for semaphore");
}
}

~CSemaphore() = default;
CSemaphore() = delete;
CSemaphore(const CSemaphore &) = delete;
CSemaphore &operator=(const CSemaphore &) = delete;
CSemaphore(const CSemaphore &&) = delete;
CSemaphore &operator=(const CSemaphore &&) = delete;

void set() {
std::unique_lock<std::mutex> const lock(m_mutex);
if (m_count >= m_max) {
FAILURE(System, "cannot signal semaphore: count would exceed maximum");
}
++m_count;
m_cv.notify_one();
}

void wait() {
std::unique_lock<std::mutex> lock(m_mutex);
m_cv.wait(lock, [this] { return m_count > 0; });
--m_count;
}

void wait(long milliseconds) {
std::unique_lock<std::mutex> lock(m_mutex);
if (!m_cv.wait_for(lock, std::chrono::milliseconds(milliseconds), [this] { return m_count > 0; })) {
FAILURE(Timeout, "Timeout");
}
--m_count;
}

bool tryWait(long milliseconds) {
std::unique_lock<std::mutex> lock(m_mutex);
if (m_cv.wait_for(lock, std::chrono::milliseconds(milliseconds), [this] { return m_count > 0; })) {
--m_count;
return true;
}
return false;
}

private:
CSemaphore();
CSemaphore(const CSemaphore &);
CSemaphore &operator=(const CSemaphore &);
};

//
// inlines
//
inline void CSemaphore::set() { setImpl(); }

inline void CSemaphore::wait() { waitImpl(); }

inline void CSemaphore::wait(long milliseconds) {
if (!waitImpl(milliseconds))
throw CTimeoutException();
}

inline bool CSemaphore::tryWait(long milliseconds) {
return waitImpl(milliseconds);
}

#endif // Foundation_Semaphore_INCLUDED
int m_count;
int m_max;
std::mutex m_mutex;
std::condition_variable m_cv;
};
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