POSIX threads (pthread): multiple reader one writer demo

multiple-reader-one-writer-test.cpp

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <list>

bool quitting = false;
int data = 0;

pthread_rwlock_t rwlock = PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP;

class Reader {
	int id_;
	pthread_t thread_;

public:
	explicit Reader(int id) :
		id_(id)
	{
		pthread_create(&thread_, nullptr, &Reader::_run, this);
	}

	~Reader() {
		pthread_join(thread_, nullptr);
	}

	void run() {
		while (!quitting) {
			pthread_rwlock_rdlock(&rwlock);
			printf("[%d]: %d\n", id_, data);
			pthread_rwlock_unlock(&rwlock);

			pthread_yield(); // junk
		}
	}

private:
	static void* _run(void* p) {
		Reader* reader = static_cast<Reader*>(p);
		reader->run();
		return nullptr;
	}
};

void writer() {
	pthread_yield();
	for (;;) {
		sleep(1);

		printf("rwlock: Acquiring for WRITE\n");
		pthread_rwlock_wrlock(&rwlock);
		printf("rwlock: hardcore WRITE-action @.@ BEGIN\n");
		data = data + 1;
		quitting = data == 42;
		sleep(2);
		printf("rwlock: hardcore WRITE-action @.@ DONE\n");
		pthread_rwlock_unlock(&rwlock);
	}
}

int main(int argc, const char *argv[])
{
	srand(time(nullptr));

	std::list<Reader*> readers;

	for (int i = 1, e = (argc == 2 ? atoi(argv[1]) : 4); i <= e; ++i)
		readers.push_back(new Reader(i));

	writer();

	for (auto reader: readers)
		delete reader;

	return 0;
}