Use a separate thread for epoll

Simplest, but absolutely inefficient, way to test openonload epoll

Makefile

@@ -18,7 +18,7 @@ OSD_OBJS := osd.o osd_secondary.o msgr_receive.o msgr_send.o osd_peering.o osd_f
 	osd_primary.o osd_primary_subops.o etcd_state_client.o messenger.o osd_cluster.o http_client.o pg_states.o \
 	osd_rmw.o json11.o base64.o timerfd_manager.o
 osd: ./libblockstore.so osd_main.cpp osd.h osd_ops.h $(OSD_OBJS)
-	g++ $(CXXFLAGS) -o $@ osd_main.cpp $(OSD_OBJS) ./libblockstore.so -ltcmalloc_minimal -luring
+	g++ $(CXXFLAGS) -o $@ osd_main.cpp $(OSD_OBJS) ./libblockstore.so -ltcmalloc_minimal -luring -lpthread
 
 stub_osd: stub_osd.o rw_blocking.o
 	g++ $(CXXFLAGS) -o $@ stub_osd.o rw_blocking.o -ltcmalloc_minimal
@@ -87,7 +87,7 @@ dump_journal.o: dump_journal.cpp allocator.h blockstore.h blockstore_flush.h blo
 	g++ $(CXXFLAGS) -c -o $@ $<
 epoll_manager.o: epoll_manager.cpp epoll_manager.h ringloop.h timerfd_manager.h
 	g++ $(CXXFLAGS) -c -o $@ $<
-etcd_state_client.o: etcd_state_client.cpp base64.h etcd_state_client.h http_client.h json11/json11.hpp object_id.h osd_id.h osd_ops.h pg_states.h timerfd_manager.h
+etcd_state_client.o: etcd_state_client.cpp base64.h etcd_state_client.h http_client.h json11/json11.hpp object_id.h osd_id.h osd_ops.h pg_states.h ringloop.h timerfd_manager.h
 	g++ $(CXXFLAGS) -c -o $@ $<
 fio_cluster.o: fio_cluster.cpp cluster_client.h epoll_manager.h etcd_state_client.h fio/fio.h fio/optgroup.h http_client.h json11/json11.hpp messenger.h object_id.h osd_id.h osd_ops.h ringloop.h timerfd_manager.h
 	g++ $(CXXFLAGS) -c -o $@ $<
@@ -95,7 +95,7 @@ fio_engine.o: fio_engine.cpp blockstore.h fio/fio.h fio/optgroup.h json11/json11
 	g++ $(CXXFLAGS) -c -o $@ $<
 fio_sec_osd.o: fio_sec_osd.cpp fio/fio.h fio/optgroup.h object_id.h osd_id.h osd_ops.h rw_blocking.h
 	g++ $(CXXFLAGS) -c -o $@ $<
-http_client.o: http_client.cpp http_client.h json11/json11.hpp timerfd_manager.h
+http_client.o: http_client.cpp http_client.h json11/json11.hpp ringloop.h timerfd_manager.h
 	g++ $(CXXFLAGS) -c -o $@ $<
 messenger.o: messenger.cpp json11/json11.hpp messenger.h object_id.h osd_id.h osd_ops.h ringloop.h timerfd_manager.h
 	g++ $(CXXFLAGS) -c -o $@ $<
@@ -149,5 +149,5 @@ test_blockstore.o: test_blockstore.cpp blockstore.h object_id.h ringloop.h timer
 	g++ $(CXXFLAGS) -c -o $@ $<
 timerfd_interval.o: timerfd_interval.cpp ringloop.h timerfd_interval.h
 	g++ $(CXXFLAGS) -c -o $@ $<
-timerfd_manager.o: timerfd_manager.cpp timerfd_manager.h
+timerfd_manager.o: timerfd_manager.cpp ringloop.h timerfd_manager.h
 	g++ $(CXXFLAGS) -c -o $@ $<

msgr_receive.cpp

@@ -2,17 +2,10 @@
 
 void osd_messenger_t::read_requests()
 {
-    for (int i = 0; i < read_ready_clients.size(); i++)
+    while (read_ready_clients.size() > 0)
     {
-        int peer_fd = read_ready_clients[i];
+        int peer_fd = read_ready_clients[0];
         auto & cl = clients[peer_fd];
-        io_uring_sqe* sqe = ringloop->get_sqe();
-        if (!sqe)
-        {
-            read_ready_clients.erase(read_ready_clients.begin(), read_ready_clients.begin() + i);
-            return;
-        }
-        ring_data_t* data = ((ring_data_t*)sqe->user_data);
         if (!cl.read_op || cl.read_remaining < receive_buffer_size)
         {
             cl.read_iov.iov_base = cl.in_buf;
@@ -25,10 +18,14 @@ void osd_messenger_t::read_requests()
         }
         cl.read_msg.msg_iov = &cl.read_iov;
         cl.read_msg.msg_iovlen = 1;
-        data->callback = [this, peer_fd](ring_data_t *data) { handle_read(data->res, peer_fd); };
-        my_uring_prep_recvmsg(sqe, peer_fd, &cl.read_msg, 0);
+        read_ready_clients.erase(read_ready_clients.begin(), read_ready_clients.begin() + 1);
+        int result = recvmsg(peer_fd, &cl.read_msg, 0);
+        if (result < 0)
+        {
+            result = -errno;
+        }
+        handle_read(result, peer_fd);
     }
-    read_ready_clients.clear();
 }
 
 bool osd_messenger_t::handle_read(int result, int peer_fd)

msgr_send.cpp

@@ -42,12 +42,6 @@ void osd_messenger_t::outbox_push(osd_op_t *cur_op)
 bool osd_messenger_t::try_send(osd_client_t & cl)
 {
     int peer_fd = cl.peer_fd;
-    io_uring_sqe* sqe = ringloop->get_sqe();
-    if (!sqe)
-    {
-        return false;
-    }
-    ring_data_t* data = ((ring_data_t*)sqe->user_data);
     if (!cl.write_op)
     {
         // pick next command
@@ -84,23 +78,21 @@ bool osd_messenger_t::try_send(osd_client_t & cl)
     }
     cl.write_msg.msg_iov = cl.write_op->send_list.get_iovec();
     cl.write_msg.msg_iovlen = cl.write_op->send_list.get_size();
-    data->callback = [this, peer_fd](ring_data_t *data) { handle_send(data->res, peer_fd); };
-    my_uring_prep_sendmsg(sqe, peer_fd, &cl.write_msg, 0);
+    int result = sendmsg(peer_fd, &cl.write_msg, MSG_NOSIGNAL);
+    if (result < 0)
+        result = -errno;
+    handle_send(result, peer_fd);
     return true;
 }
 
 void osd_messenger_t::send_replies()
 {
-    for (int i = 0; i < write_ready_clients.size(); i++)
+    while (write_ready_clients.size() > 0)
     {
-        int peer_fd = write_ready_clients[i];
-        if (!try_send(clients[peer_fd]))
-        {
-            write_ready_clients.erase(write_ready_clients.begin(), write_ready_clients.begin() + i);
-            return;
+        auto & cl = clients[write_ready_clients[0]];
+        write_ready_clients.erase(write_ready_clients.begin(), write_ready_clients.begin() + 1);
+        try_send(cl);
     }
-    }
-    write_ready_clients.clear();
 }
 
 void osd_messenger_t::handle_send(int result, int peer_fd)

osd.cpp

@@ -1,5 +1,6 @@
 #include <sys/socket.h>
 #include <sys/epoll.h>
+#include <sys/eventfd.h>
 #include <sys/poll.h>
 #include <netinet/in.h>
 #include <netinet/tcp.h>
@@ -43,8 +44,14 @@ osd_t::osd_t(blockstore_config_t & config, blockstore_t *bs, ring_loop_t *ringlo
     {
         throw std::runtime_error(std::string("epoll_create: ") + strerror(errno));
     }
+    event_fd = eventfd(0, EFD_NONBLOCK);
+    if (event_fd < 0)
+    {
+        throw std::runtime_error(std::string("eventfd: ") + strerror(errno));
+    }
 
-    this->tfd = new timerfd_manager_t([this](int fd, std::function<void(int, int)> handler) { set_fd_handler(fd, handler); });
+    this->tfd = new timerfd_manager_t(ringloop);
+    this->tfd->set_fd_handler = [this](int fd, std::function<void(int, int)> handler) { set_fd_handler(fd, handler); };
     this->tfd->set_timer(print_stats_interval*1000, true, [this](int timer_id)
     {
         print_stats();
@@ -59,17 +66,40 @@ osd_t::osd_t(blockstore_config_t & config, blockstore_t *bs, ring_loop_t *ringlo
 
     consumer.loop = [this]() { loop(); };
     ringloop->register_consumer(&consumer);
+    epoll_thread = new std::thread([this]()
+    {
+        int nfds;
+        epoll_event events[MAX_EPOLL_EVENTS];
+        while (1)
+        {
+            nfds = epoll_wait(epoll_fd, events, MAX_EPOLL_EVENTS, -1);
+            {
+                std::lock_guard<std::mutex> guard(epoll_mutex);
+                for (int i = 0; i < nfds; i++)
+                {
+                    int fd = events[i].data.fd;
+                    int ev = events[i].events;
+                    epoll_ready[fd] |= ev;
+                }
+                uint64_t n = 1;
+                write(event_fd, &n, 8);
+            }
+        }
+    });
 }
 
 osd_t::~osd_t()
 {
+    close(epoll_fd);
+    epoll_thread->join();
+    delete epoll_thread;
     if (tfd)
     {
         delete tfd;
         tfd = NULL;
     }
     ringloop->unregister_consumer(&consumer);
-    close(epoll_fd);
+    close(event_fd);
     close(listen_fd);
 }
 
@@ -188,8 +218,13 @@ void osd_t::bind_socket()
     {
         close(listen_fd);
         close(epoll_fd);
-        throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
+        throw std::runtime_error(std::string("epoll_ctl (add listen_fd): ") + strerror(errno));
     }
+
+    epoll_handlers[listen_fd] = [this](int peer_fd, int epoll_events)
+    {
+        c_cli.accept_connections(listen_fd);
+    };
 }
 
 bool osd_t::shutdown()
@@ -204,10 +239,23 @@ bool osd_t::shutdown()
 
 void osd_t::loop()
 {
-    if (!wait_state)
+    std::map<int,int> cur_epoll;
     {
-        handle_epoll_events();
-        wait_state = 1;
+        std::lock_guard<std::mutex> guard(epoll_mutex);
+        cur_epoll.swap(epoll_ready);
+    }
+    for (auto p: cur_epoll)
+    {
+        auto cb_it = epoll_handlers.find(p.first);
+        if (cb_it != epoll_handlers.end())
+        {
+            cb_it->second(p.first, p.second);
+        }
+    }
+    if (!(wait_state & 2))
+    {
+        handle_eventfd();
+        wait_state = wait_state | 2;
     }
     handle_peers();
     c_cli.read_requests();
@@ -225,7 +273,7 @@ void osd_t::set_fd_handler(int fd, std::function<void(int, int)> handler)
         ev.events = EPOLLOUT | EPOLLIN | EPOLLRDHUP | EPOLLET;
         if (epoll_ctl(epoll_fd, exists ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev) < 0)
         {
-            throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
+            throw std::runtime_error(std::string(exists ? "epoll_ctl (mod fd): " : "epoll_ctl (add fd): ") + strerror(errno));
         }
         epoll_handlers[fd] = handler;
     }
@@ -233,49 +281,36 @@ void osd_t::set_fd_handler(int fd, std::function<void(int, int)> handler)
     {
         if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, fd, NULL) < 0 && errno != ENOENT)
         {
-            throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
+            throw std::runtime_error(std::string("epoll_ctl (remove fd): ") + strerror(errno));
         }
         epoll_handlers.erase(fd);
     }
 }
 
-void osd_t::handle_epoll_events()
+void osd_t::handle_eventfd()
 {
     io_uring_sqe *sqe = ringloop->get_sqe();
     if (!sqe)
     {
-        throw std::runtime_error("can't get SQE, will fall out of sync with EPOLLET");
+        throw std::runtime_error("can't get SQE, will fall out of sync with eventfd");
     }
     ring_data_t *data = ((ring_data_t*)sqe->user_data);
-    my_uring_prep_poll_add(sqe, epoll_fd, POLLIN);
+    my_uring_prep_poll_add(sqe, event_fd, POLLIN);
     data->callback = [this](ring_data_t *data)
     {
         if (data->res < 0)
         {
             throw std::runtime_error(std::string("epoll failed: ") + strerror(-data->res));
         }
-        handle_epoll_events();
+        handle_eventfd();
     };
     ringloop->submit();
-    int nfds;
-    epoll_event events[MAX_EPOLL_EVENTS];
-restart:
-    nfds = epoll_wait(epoll_fd, events, MAX_EPOLL_EVENTS, 0);
-    for (int i = 0; i < nfds; i++)
+    uint64_t n = 0;
+    size_t res = read(event_fd, &n, 8);
+    if (res == 8)
     {
-        if (events[i].data.fd == listen_fd)
-        {
-            c_cli.accept_connections(listen_fd);
-        }
-        else
-        {
-            auto & cb = epoll_handlers[events[i].data.fd];
-            cb(events[i].data.fd, events[i].events);
-        }
-    }
-    if (nfds == MAX_EPOLL_EVENTS)
-    {
-        goto restart;
+        // No need to do anything, the loop has already woken up
+        ringloop->wakeup();
     }
 }
 

osd.h

@@ -12,6 +12,8 @@
 
 #include <set>
 #include <deque>
+#include <mutex>
+#include <thread>
 
 #include "blockstore.h"
 #include "ringloop.h"
@@ -114,6 +116,10 @@ class osd_t
 
     int wait_state = 0;
     int epoll_fd = 0;
+    int event_fd = 0;
+    std::thread *epoll_thread = NULL;
+    std::mutex epoll_mutex;
+    std::map<int, int> epoll_ready;
     int listening_port = 0;
     int listen_fd = 0;
     ring_consumer_t consumer;
@@ -150,7 +156,7 @@ class osd_t
     // event loop, socket read/write
     void loop();
     void set_fd_handler(int fd, std::function<void(int, int)> handler);
-    void handle_epoll_events();
+    void handle_eventfd();
 
     // peer handling (primary OSD logic)
     void parse_test_peer(std::string peer);

timerfd_manager.cpp

@@ -1,29 +1,24 @@
 #include <sys/timerfd.h>
 #include <sys/poll.h>
-#include <sys/epoll.h>
 #include <unistd.h>
-#include <errno.h>
-#include <string.h>
 #include "timerfd_manager.h"
 
-timerfd_manager_t::timerfd_manager_t(std::function<void(int, std::function<void(int, int)>)> set_fd_handler)
+timerfd_manager_t::timerfd_manager_t(ring_loop_t *ringloop)
 {
-    this->set_fd_handler = set_fd_handler;
     wait_state = 0;
     timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK);
     if (timerfd < 0)
     {
         throw std::runtime_error(std::string("timerfd_create: ") + strerror(errno));
     }
-    set_fd_handler(timerfd, [this](int fd, int events)
-    {
-        handle_readable();
-    });
+    consumer.loop = [this]() { loop(); };
+    ringloop->register_consumer(&consumer);
+    this->ringloop = ringloop;
 }
 
 timerfd_manager_t::~timerfd_manager_t()
 {
-    set_fd_handler(timerfd, NULL);
+    ringloop->unregister_consumer(&consumer);
     close(timerfd);
 }
 
@@ -53,6 +48,7 @@ int timerfd_manager_t::set_timer(uint64_t millis, bool repeat, std::function<voi
     });
     inc_timer(timers[timers.size()-1]);
     set_nearest();
+    set_wait();
     return timer_id;
 }
 
@@ -73,6 +69,7 @@ void timerfd_manager_t::clear_timer(int timer_id)
                 nearest--;
             }
             set_nearest();
+            set_wait();
             break;
         }
     }
@@ -157,3 +154,36 @@ void timerfd_manager_t::trigger_nearest()
     cb(nearest_id);
     nearest = -1;
 }
+
+void timerfd_manager_t::loop()
+{
+    if (!(wait_state & 1) && timers.size())
+    {
+        set_nearest();
+    }
+    set_wait();
+}
+
+void timerfd_manager_t::set_wait()
+{
+    if ((wait_state & 3) == 1)
+    {
+        io_uring_sqe *sqe = ringloop->get_sqe();
+        if (!sqe)
+        {
+            return;
+        }
+        ring_data_t *data = ((ring_data_t*)sqe->user_data);
+        my_uring_prep_poll_add(sqe, timerfd, POLLIN);
+        data->callback = [this](ring_data_t *data)
+        {
+            if (data->res < 0)
+            {
+                throw std::runtime_error(std::string("waiting for timer failed: ") + strerror(-data->res));
+            }
+            handle_readable();
+            set_wait();
+        };
+        wait_state = 3;
+    }
+}

timerfd_manager.h

@@ -1,8 +1,7 @@
 #pragma once
 
 #include <time.h>
-#include <vector>
-#include <functional>
+#include "ringloop.h"
 
 struct timerfd_timer_t
 {
@@ -20,15 +19,20 @@ class timerfd_manager_t
     int nearest = -1;
     int id = 1;
     std::vector<timerfd_timer_t> timers;
+    ring_loop_t *ringloop;
+    ring_consumer_t consumer;
 
     void inc_timer(timerfd_timer_t & t);
     void set_nearest();
     void trigger_nearest();
     void handle_readable();
+    void set_wait();
+    void loop();
 public:
+    // FIXME shouldn't be here
     std::function<void(int, std::function<void(int, int)>)> set_fd_handler;
 
-    timerfd_manager_t(std::function<void(int, std::function<void(int, int)>)> set_fd_handler);
+    timerfd_manager_t(ring_loop_t *ringloop);
     ~timerfd_manager_t();
     int set_timer(uint64_t millis, bool repeat, std::function<void(int)> callback);
     void clear_timer(int timer_id);