Simplified distributed block storage with strong consistency, like in Ceph
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#include <sys/socket.h>
#include <sys/epoll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "osd_ops.h"
#include "ringloop.h"
struct osd_client_t
{
sockaddr_in peer_addr;
socklen_t peer_addr_size;
int peer_fd;
bool ready;
bool reading;
iovec iov;
msghdr msg;
void *cur_buf = NULL;
int cur_len = 0;
};
class osd_t
{
int wait_state = 0;
int epoll_fd = 0;
int listen_fd = 0;
ring_consumer_t consumer;
std::string bind_address;
int bind_port, listen_backlog;
ring_loop_t *ringloop;
std::unordered_map<int,osd_client_t> clients;
std::deque<int> ready_clients;
void handle_epoll_events();
public:
osd_t(ring_loop_t *ringloop);
~osd_t();
void loop();
};
osd_t::osd_t(ring_loop_t *ringloop)
{
this->ringloop = ringloop;
listen_fd = socket(AF_INET, SOCK_STREAM, 0);
if (listen_fd < 0)
{
throw std::runtime_error(std::string("socket: ") + strerror(errno));
}
int enable = 1;
setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(enable));
sockaddr_in addr;
if ((int r = inet_pton(AF_INET, bind_address.c_str(), &addr.sin_addr)) != 1)
{
close(listen_fd);
throw std::runtime_error("bind address "+bind_address+(r == 0 ? " is not valid" : ": no ipv4 support"));
}
addr.sin_family = AF_INET;
addr.sin_port = htons(bind_port);
if (bind(listen_fd, &addr, sizeof(addr)) < 0)
{
close(listen_fd);
throw std::runtime_error(std::string("bind: ") + strerror(errno));
}
if (listen(listen_fd, listen_backlog) < 0)
{
close(listen_fd);
throw std::runtime_error(std::string("listen: ") + strerror(errno));
}
fcntl(listen_fd, F_SETFL, fcntl(listen_fd, F_GETFL, 0) | O_NONBLOCK);
epoll_fd = epoll_create(1);
if (epoll_fd < 0)
{
close(listen_fd);
throw std::runtime_error(std::string("epoll_create: ") + strerror(errno));
}
struct epoll_event ev;
ev.data.fd = listen_fd;
ev.events = EPOLLIN;
if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, listen_fd, &ev) < 0)
{
throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
}
consumer.loop = [this]() { loop(); };
ringloop->register_consumer(consumer);
}
osd_t::~osd_t()
{
ringloop->unregister_consumer(consumer);
close(epoll_fd);
close(listen_fd);
}
void osd_t::loop()
{
if (wait_state == 1)
{
return;
}
struct io_uring_sqe *sqe = ringloop->get_sqe();
if (!sqe)
{
wait_state = 0;
return;
}
struct ring_data_t *data = ((ring_data_t*)sqe->user_data);
my_uring_prep_poll_add(sqe, epoll_fd, POLLIN);
data->callback = [&](ring_data_t *data)
{
if (data->res < 0)
{
throw std::runtime_error(std::string("epoll failed: ") + strerror(-data->res));
}
handle_epoll_events();
wait_state = 0;
};
wait_state = 1;
ringloop->submit();
}
#define MAX_EPOLL_EVENTS 16
int osd_t::handle_epoll_events()
{
epoll_event events[MAX_EPOLL_EVENTS];
int count = 0;
int nfds;
// FIXME: We shouldn't probably handle ALL available events, we should sometimes
// yield control to Blockstore and possibly other consumers
while ((nfds = epoll_wait(epoll_fd, events, MAX_EPOLL_EVENTS, 0)) > 0)
{
for (int i = 0; i < nfds; i++)
{
if (events[i].data.fd == listen_fd)
{
// Accept new connections
struct sockaddr_in addr;
socklen_t peer_addr_size = sizeof(addr);
int peer_fd;
while ((peer_fd = accept(listen_fd, &addr, &peer_addr_size)) >= 0)
{
fcntl(peer_fd, F_SETFL, fcntl(listen_fd, F_GETFL, 0) | O_NONBLOCK);
clients[peer_fd] = {
.peer_addr = addr,
.peer_addr_size = peer_addr_size,
.peer_fd = peer_fd,
.ready = false,
};
// Add FD to epoll
struct epoll_event ev;
ev.data.fd = peer_fd;
ev.events = EPOLLIN | EPOLLHUP;
if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, peer_fd, &ev) < 0)
{
throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
}
// Try to accept next connection
peer_addr_size = sizeof(addr);
}
if (peer_fd == -1 && errno != EAGAIN)
{
throw std::runtime_error(std::string("accept: ") + strerror(errno));
}
}
else
{
auto & cl = clients[events[i].data.fd];
if (events[i].events & EPOLLHUP)
{
// Stop client
stop_client(cl.peer_fd);
}
else if (!cl.ready)
{
// Mark client as ready (i.e. some data is available)
cl.ready = true;
if (!cl.reading)
ready_clients.push_back(cl.peer_fd);
}
}
count++;
}
}
return count;
}
void osd_t::stop_client(int peer_fd)
{
struct epoll_event ev;
ev.data.fd = peer_fd;
ev.events = EPOLLIN | EPOLLHUP;
if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, peer_fd, &ev) < 0)
{
throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
}
auto it = clients.find(peer_fd);
clients.erase(it);
if (cl.ready)
{
for (auto it = ready_clients.begin(); it != ready_clients.end(); it++)
{
if (*it == peer_fd)
{
ready_clients.erase(it);
break;
}
}
}
close(peer_fd);
}
void osd_t::read_commands()
{
for (int i = 0; i < ready_clients.size(); i++)
{
int peer_fd = ready_clients[i];
auto & cl = clients[peer_fd];
if (!cl.cur_buf)
{
// no reads in progress, this is probably a new command
cl.cur_buf = cl.command_buffer;
cl.cur_len = OSD_OP_PACKET_SIZE;
}
struct io_uring_sqe* sqe = ringloop->get_sqe();
if (!sqe)
{
ready_clients.erase(ready_clients.begin(), ready_clients().begin() + i);
return;
}
struct ring_data_t* data = ((ring_data_t*)sqe->user_data);
cl.iov.iov_base = cl.cur_buf;
cl.iov.iov_len = cl.cur_len;
cl.msg.msg_iov = &cl.iov;
cl.msg.msg_iovlen = 1;
data->callback = [this, peer_fd](ring_data_t *data) { handle_read(data, peer_fd); };
my_uring_prep_recvmsg(sqe, peer_fd, &cl.msg, 0);
ringloop->submit();
cl.reading = true;
}
ready_clients.clear();
}
void osd_t::handle_read(ring_data_t *data, int peer_fd)
{
auto cl = clients.find(peer_fd);
if (cl != clients.end())
{
if (data->res < 0 && data->res != -EAGAIN)
{
// this is a client socket, so don't panic. just disconnect it
printf("Client %d socket read error: %d (%s). Disconnecting client\n", peer_fd, -data->res, strerror(-data->res));
stop_client(peer_fd);
return;
}
cl->reading = false;
if (cl->ready)
ready_clients.push_back(peer_fd);
}
}