110 lines
2.4 KiB
C++
110 lines
2.4 KiB
C++
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#include <thread>
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#include <string>
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#include <iostream>
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#include <queue>
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#include <random>
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#include <chrono>
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#include <mutex>
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#include <condition_variable>
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/*
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* Compile with 'g++ -pthread a.cpp'
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*/
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using namespace std;
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std::mutex q_mutex;
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std::mutex cout_mutex;
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std::condition_variable q_cv;
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void producer1( queue<int>& q, const int id ) {
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// Make sure our cout does not cross some other thread's cout
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cout_mutex.lock();
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cout << "======================" << endl;
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cout << " Starting Producer " << id << endl;
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cout << "======================" << endl;
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cout_mutex.unlock();
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random_device d;
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mt19937 mt(d());
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int t_max = 3000;
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uniform_int_distribution<> distr(0., t_max);
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int n = 0;
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while (true) {
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n = distr(mt);
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this_thread::sleep_for(chrono::milliseconds(n));
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// Make sure our cout does not cross some other thread's cout
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cout_mutex.lock();
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cout << "Producer " << id << " : " << n << endl;
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cout_mutex.unlock();
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// Lock q so we can push a new element
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std::unique_lock<std::mutex> q_lock(q_mutex);
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q.push(n);
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// Notify one of the consumers
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q_cv.notify_one();
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}
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}
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void consumer( queue<int>& q, const int id ) {
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// Make sure our cout does not cross some other thread's cout
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cout_mutex.lock();
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cout << "======================" << endl;
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cout << " Starting Consumer " << id << endl;
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cout << "======================" << endl;
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cout_mutex.unlock();
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int b = 0;
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while ( true ) {
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{ // Scope the lock of the queue
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std::unique_lock<std::mutex> q_lock(q_mutex);
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while ( q.empty() ) {
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// Wait until we get a signal from the condition variable
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q_cv.wait(q_lock);
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}
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// Get a value and pop it off
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b = q.front();
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q.pop();
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}
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// Make sure our cout does not cross some other thread's cout
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cout_mutex.lock();
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cout << " -- Consumer " << id << " : " << b << endl;
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cout_mutex.unlock();
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// Slow down this thread to have a race between the consumers and the producers
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// This only works after we have successfully read an int
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this_thread::sleep_for(chrono::milliseconds(2000));
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}
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}
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int main() {
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queue<int> q;
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thread cons1( consumer, std::ref(q), 1 ) ;
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// make sure the consumer must have slept at least once
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this_thread::sleep_for(chrono::seconds(2));
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thread prod( producer1, std::ref(q), 1);
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this_thread::sleep_for(chrono::seconds(5));
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thread cons2( consumer, std::ref(q), 2) ;
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prod.join();
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cons1.join();
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cons2.join();
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cout << "Finishing up" << endl;
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return 0;
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}
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