File: thread.cpp

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#include <assert.h>
#include <errno.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "log.h"
#include "mutexlock.h"
#include "thread.h"

Thread::~Thread() {}

void Thread::run()
{
	pthread_mutex_init(&should_stop_mutex, NULL);
	should_stop_status = false;
	pthread_create(&worker_thread, NULL, &Thread::do_work_thunk, this);
}

void Thread::stop()
{
	{
		MutexLock lock(&should_stop_mutex);
		should_stop_status = true;
	}
	wakeup();
	if (pthread_join(worker_thread, NULL) == -1) {
		log_perror("pthread_join");
		exit(1);
	}
}

void *Thread::do_work_thunk(void *arg)
{
	Thread *thread = reinterpret_cast<Thread *>(arg);

	// Block SIGHUP; only the main thread should see that.
	// (This isn't strictly required, but it makes it easier to debug that indeed
	// SIGUSR1 was what woke us up.)
	sigset_t set;
	sigemptyset(&set);
	sigaddset(&set, SIGHUP);
	int err = pthread_sigmask(SIG_BLOCK, &set, NULL);
	if (err != 0) {
		errno = err;
		log_perror("pthread_sigmask");
		exit(1);
	}

	// Block SIGUSR1, and store the old signal mask.
	sigemptyset(&set);
	sigaddset(&set, SIGUSR1);
	err = pthread_sigmask(SIG_BLOCK, &set, &thread->sigset_without_usr1_block);
	if (err != 0) {
		errno = err;
		log_perror("pthread_sigmask");
		exit(1);
	}

	// Call the right thunk.
	thread->do_work();
	return NULL;
}

bool Thread::wait_for_activity(int fd, short events, const struct timespec *timeout_ts)
{
	pollfd pfd;
	pfd.fd = fd;
	pfd.events = events;

	for ( ;; ) {
		int nfds = ppoll(&pfd, (fd == -1) ? 0 : 1, timeout_ts, &sigset_without_usr1_block);
		if (nfds == -1 && errno == EINTR) {
			return false;
		}
		if (nfds == -1) {
			log_perror("poll");
			usleep(100000);
			continue;
		}
		assert(nfds <= 1);
		return (nfds == 1);
	}
}

void Thread::wakeup()
{
	pthread_kill(worker_thread, SIGUSR1);
}

bool Thread::should_stop()
{
	MutexLock lock(&should_stop_mutex);
	return should_stop_status;
}