c-resources/CPlusPlus20ForProgrammers-m.../examples/ch17/fig17_16/SynchronizedBuffer.h

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// Fig. 17.16: SynchronizedBuffer.h
// SynchronizedBuffer using two binary_semaphores to
// maintain synchronized access to a shared mutable int.
#pragma once
#include <fmt/format.h>
#include <iostream>
#include <semaphore>
#include <string>
using namespace std::string_literals;
class SynchronizedBuffer {
public:
// place value into m_buffer
void put(int value) {
// acquire m_produce semaphore to be able to write to m_buffer
m_produce.acquire(); // blocks if it's not the producer's turn
m_buffer = value; // write to m_buffer
m_occupied = true;
std::cout << fmt::format("{:<40}{}\t\t{}\n",
"Producer writes "s + std::to_string(value),
m_buffer, m_occupied);
m_consume.release(); // allow consumer to read
}
// return value from m_buffer
int get() {
int value; // will store the value returned by get
// acquire m_consume semaphore to be able to read from m_buffer
m_consume.acquire(); // blocks if it's not the consumer's turn
value = m_buffer; // read from m_buffer
m_occupied = false;
std::cout << fmt::format("{:<40}{}\t\t{}\n",
"Consumer reads "s + std::to_string(m_buffer),
m_buffer, m_occupied);
m_produce.release(); // allow producer to write
return value;
}
private:
std::binary_semaphore m_produce{1}; // producer can produce
std::binary_semaphore m_consume{0}; // consumer can't consume
bool m_occupied{false};
int m_buffer{-1}; // shared by producer and consumer threads
};
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