| /* |
| * |
| * Copyright 2016 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| #include <grpc/support/port_platform.h> |
| #include "src/core/lib/iomgr/port.h" |
| #if GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET) |
| |
| #include <ares.h> |
| #include <sys/ioctl.h> |
| |
| #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h" |
| |
| #include <grpc/support/alloc.h> |
| #include <grpc/support/log.h> |
| #include <grpc/support/string_util.h> |
| #include <grpc/support/time.h> |
| #include <grpc/support/useful.h> |
| #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h" |
| #include "src/core/lib/iomgr/ev_posix.h" |
| #include "src/core/lib/iomgr/iomgr_internal.h" |
| #include "src/core/lib/iomgr/sockaddr_utils.h" |
| #include "src/core/lib/support/string.h" |
| |
| typedef struct fd_node { |
| /** the owner of this fd node */ |
| grpc_ares_ev_driver *ev_driver; |
| /** a closure wrapping on_readable_cb, which should be invoked when the |
| grpc_fd in this node becomes readable. */ |
| grpc_closure read_closure; |
| /** a closure wrapping on_writable_cb, which should be invoked when the |
| grpc_fd in this node becomes writable. */ |
| grpc_closure write_closure; |
| /** next fd node in the list */ |
| struct fd_node *next; |
| |
| /** mutex guarding the rest of the state */ |
| gpr_mu mu; |
| /** the grpc_fd owned by this fd node */ |
| grpc_fd *fd; |
| /** if the readable closure has been registered */ |
| bool readable_registered; |
| /** if the writable closure has been registered */ |
| bool writable_registered; |
| /** if the fd is being shut down */ |
| bool shutting_down; |
| } fd_node; |
| |
| struct grpc_ares_ev_driver { |
| /** the ares_channel owned by this event driver */ |
| ares_channel channel; |
| /** pollset set for driving the IO events of the channel */ |
| grpc_pollset_set *pollset_set; |
| /** refcount of the event driver */ |
| gpr_refcount refs; |
| |
| /** mutex guarding the rest of the state */ |
| gpr_mu mu; |
| /** a list of grpc_fd that this event driver is currently using. */ |
| fd_node *fds; |
| /** is this event driver currently working? */ |
| bool working; |
| /** is this event driver being shut down */ |
| bool shutting_down; |
| }; |
| |
| static void grpc_ares_notify_on_event_locked(grpc_exec_ctx *exec_ctx, |
| grpc_ares_ev_driver *ev_driver); |
| |
| static grpc_ares_ev_driver *grpc_ares_ev_driver_ref( |
| grpc_ares_ev_driver *ev_driver) { |
| gpr_log(GPR_DEBUG, "Ref ev_driver %" PRIuPTR, (uintptr_t)ev_driver); |
| gpr_ref(&ev_driver->refs); |
| return ev_driver; |
| } |
| |
| static void grpc_ares_ev_driver_unref(grpc_ares_ev_driver *ev_driver) { |
| gpr_log(GPR_DEBUG, "Unref ev_driver %" PRIuPTR, (uintptr_t)ev_driver); |
| if (gpr_unref(&ev_driver->refs)) { |
| gpr_log(GPR_DEBUG, "destroy ev_driver %" PRIuPTR, (uintptr_t)ev_driver); |
| GPR_ASSERT(ev_driver->fds == NULL); |
| gpr_mu_destroy(&ev_driver->mu); |
| ares_destroy(ev_driver->channel); |
| gpr_free(ev_driver); |
| } |
| } |
| |
| static void fd_node_destroy(grpc_exec_ctx *exec_ctx, fd_node *fdn) { |
| gpr_log(GPR_DEBUG, "delete fd: %d", grpc_fd_wrapped_fd(fdn->fd)); |
| GPR_ASSERT(!fdn->readable_registered); |
| GPR_ASSERT(!fdn->writable_registered); |
| gpr_mu_destroy(&fdn->mu); |
| /* c-ares library has closed the fd inside grpc_fd. This fd may be picked up |
| immediately by another thread, and should not be closed by the following |
| grpc_fd_orphan. */ |
| grpc_fd_orphan(exec_ctx, fdn->fd, NULL, NULL, true /* already_closed */, |
| "c-ares query finished"); |
| gpr_free(fdn); |
| } |
| |
| static void fd_node_shutdown(grpc_exec_ctx *exec_ctx, fd_node *fdn) { |
| gpr_mu_lock(&fdn->mu); |
| fdn->shutting_down = true; |
| if (!fdn->readable_registered && !fdn->writable_registered) { |
| gpr_mu_unlock(&fdn->mu); |
| fd_node_destroy(exec_ctx, fdn); |
| } else { |
| grpc_fd_shutdown(exec_ctx, fdn->fd, GRPC_ERROR_CREATE_FROM_STATIC_STRING( |
| "c-ares fd shutdown")); |
| gpr_mu_unlock(&fdn->mu); |
| } |
| } |
| |
| grpc_error *grpc_ares_ev_driver_create(grpc_ares_ev_driver **ev_driver, |
| grpc_pollset_set *pollset_set) { |
| *ev_driver = (grpc_ares_ev_driver *)gpr_malloc(sizeof(grpc_ares_ev_driver)); |
| int status = ares_init(&(*ev_driver)->channel); |
| gpr_log(GPR_DEBUG, "grpc_ares_ev_driver_create"); |
| if (status != ARES_SUCCESS) { |
| char *err_msg; |
| gpr_asprintf(&err_msg, "Failed to init ares channel. C-ares error: %s", |
| ares_strerror(status)); |
| grpc_error *err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(err_msg); |
| gpr_free(err_msg); |
| gpr_free(*ev_driver); |
| return err; |
| } |
| gpr_mu_init(&(*ev_driver)->mu); |
| gpr_ref_init(&(*ev_driver)->refs, 1); |
| (*ev_driver)->pollset_set = pollset_set; |
| (*ev_driver)->fds = NULL; |
| (*ev_driver)->working = false; |
| (*ev_driver)->shutting_down = false; |
| return GRPC_ERROR_NONE; |
| } |
| |
| void grpc_ares_ev_driver_destroy(grpc_ares_ev_driver *ev_driver) { |
| // It's not safe to shut down remaining fds here directly, becauses |
| // ares_host_callback does not provide an exec_ctx. We mark the event driver |
| // as being shut down. If the event driver is working, |
| // grpc_ares_notify_on_event_locked will shut down the fds; if it's not |
| // working, there are no fds to shut down. |
| gpr_mu_lock(&ev_driver->mu); |
| ev_driver->shutting_down = true; |
| gpr_mu_unlock(&ev_driver->mu); |
| grpc_ares_ev_driver_unref(ev_driver); |
| } |
| |
| void grpc_ares_ev_driver_shutdown(grpc_exec_ctx *exec_ctx, |
| grpc_ares_ev_driver *ev_driver) { |
| gpr_mu_lock(&ev_driver->mu); |
| ev_driver->shutting_down = true; |
| fd_node *fn = ev_driver->fds; |
| while (fn != NULL) { |
| grpc_fd_shutdown(exec_ctx, fn->fd, GRPC_ERROR_CREATE_FROM_STATIC_STRING( |
| "grpc_ares_ev_driver_shutdown")); |
| fn = fn->next; |
| } |
| gpr_mu_unlock(&ev_driver->mu); |
| } |
| |
| // Search fd in the fd_node list head. This is an O(n) search, the max possible |
| // value of n is ARES_GETSOCK_MAXNUM (16). n is typically 1 - 2 in our tests. |
| static fd_node *pop_fd_node(fd_node **head, int fd) { |
| fd_node dummy_head; |
| dummy_head.next = *head; |
| fd_node *node = &dummy_head; |
| while (node->next != NULL) { |
| if (grpc_fd_wrapped_fd(node->next->fd) == fd) { |
| fd_node *ret = node->next; |
| node->next = node->next->next; |
| *head = dummy_head.next; |
| return ret; |
| } |
| node = node->next; |
| } |
| return NULL; |
| } |
| |
| /* Check if \a fd is still readable */ |
| static bool grpc_ares_is_fd_still_readable(grpc_ares_ev_driver *ev_driver, |
| int fd) { |
| size_t bytes_available = 0; |
| return ioctl(fd, FIONREAD, &bytes_available) == 0 && bytes_available > 0; |
| } |
| |
| static void on_readable_cb(grpc_exec_ctx *exec_ctx, void *arg, |
| grpc_error *error) { |
| fd_node *fdn = (fd_node *)arg; |
| grpc_ares_ev_driver *ev_driver = fdn->ev_driver; |
| gpr_mu_lock(&fdn->mu); |
| const int fd = grpc_fd_wrapped_fd(fdn->fd); |
| fdn->readable_registered = false; |
| if (fdn->shutting_down && !fdn->writable_registered) { |
| gpr_mu_unlock(&fdn->mu); |
| fd_node_destroy(exec_ctx, fdn); |
| grpc_ares_ev_driver_unref(ev_driver); |
| return; |
| } |
| gpr_mu_unlock(&fdn->mu); |
| |
| gpr_log(GPR_DEBUG, "readable on %d", fd); |
| if (error == GRPC_ERROR_NONE) { |
| do { |
| ares_process_fd(ev_driver->channel, fd, ARES_SOCKET_BAD); |
| } while (grpc_ares_is_fd_still_readable(ev_driver, fd)); |
| } else { |
| // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or |
| // timed out. The pending lookups made on this ev_driver will be cancelled |
| // by the following ares_cancel() and the on_done callbacks will be invoked |
| // with a status of ARES_ECANCELLED. The remaining file descriptors in this |
| // ev_driver will be cleaned up in the follwing |
| // grpc_ares_notify_on_event_locked(). |
| ares_cancel(ev_driver->channel); |
| } |
| gpr_mu_lock(&ev_driver->mu); |
| grpc_ares_notify_on_event_locked(exec_ctx, ev_driver); |
| gpr_mu_unlock(&ev_driver->mu); |
| grpc_ares_ev_driver_unref(ev_driver); |
| } |
| |
| static void on_writable_cb(grpc_exec_ctx *exec_ctx, void *arg, |
| grpc_error *error) { |
| fd_node *fdn = (fd_node *)arg; |
| grpc_ares_ev_driver *ev_driver = fdn->ev_driver; |
| gpr_mu_lock(&fdn->mu); |
| const int fd = grpc_fd_wrapped_fd(fdn->fd); |
| fdn->writable_registered = false; |
| if (fdn->shutting_down && !fdn->readable_registered) { |
| gpr_mu_unlock(&fdn->mu); |
| fd_node_destroy(exec_ctx, fdn); |
| grpc_ares_ev_driver_unref(ev_driver); |
| return; |
| } |
| gpr_mu_unlock(&fdn->mu); |
| |
| gpr_log(GPR_DEBUG, "writable on %d", fd); |
| if (error == GRPC_ERROR_NONE) { |
| ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD, fd); |
| } else { |
| // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or |
| // timed out. The pending lookups made on this ev_driver will be cancelled |
| // by the following ares_cancel() and the on_done callbacks will be invoked |
| // with a status of ARES_ECANCELLED. The remaining file descriptors in this |
| // ev_driver will be cleaned up in the follwing |
| // grpc_ares_notify_on_event_locked(). |
| ares_cancel(ev_driver->channel); |
| } |
| gpr_mu_lock(&ev_driver->mu); |
| grpc_ares_notify_on_event_locked(exec_ctx, ev_driver); |
| gpr_mu_unlock(&ev_driver->mu); |
| grpc_ares_ev_driver_unref(ev_driver); |
| } |
| |
| ares_channel *grpc_ares_ev_driver_get_channel(grpc_ares_ev_driver *ev_driver) { |
| return &ev_driver->channel; |
| } |
| |
| // Get the file descriptors used by the ev_driver's ares channel, register |
| // driver_closure with these filedescriptors. |
| static void grpc_ares_notify_on_event_locked(grpc_exec_ctx *exec_ctx, |
| grpc_ares_ev_driver *ev_driver) { |
| fd_node *new_list = NULL; |
| if (!ev_driver->shutting_down) { |
| ares_socket_t socks[ARES_GETSOCK_MAXNUM]; |
| int socks_bitmask = |
| ares_getsock(ev_driver->channel, socks, ARES_GETSOCK_MAXNUM); |
| for (size_t i = 0; i < ARES_GETSOCK_MAXNUM; i++) { |
| if (ARES_GETSOCK_READABLE(socks_bitmask, i) || |
| ARES_GETSOCK_WRITABLE(socks_bitmask, i)) { |
| fd_node *fdn = pop_fd_node(&ev_driver->fds, socks[i]); |
| // Create a new fd_node if sock[i] is not in the fd_node list. |
| if (fdn == NULL) { |
| char *fd_name; |
| gpr_asprintf(&fd_name, "ares_ev_driver-%" PRIuPTR, i); |
| fdn = (fd_node *)gpr_malloc(sizeof(fd_node)); |
| gpr_log(GPR_DEBUG, "new fd: %d", socks[i]); |
| fdn->fd = grpc_fd_create(socks[i], fd_name); |
| fdn->ev_driver = ev_driver; |
| fdn->readable_registered = false; |
| fdn->writable_registered = false; |
| fdn->shutting_down = false; |
| gpr_mu_init(&fdn->mu); |
| GRPC_CLOSURE_INIT(&fdn->read_closure, on_readable_cb, fdn, |
| grpc_schedule_on_exec_ctx); |
| GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable_cb, fdn, |
| grpc_schedule_on_exec_ctx); |
| grpc_pollset_set_add_fd(exec_ctx, ev_driver->pollset_set, fdn->fd); |
| gpr_free(fd_name); |
| } |
| fdn->next = new_list; |
| new_list = fdn; |
| gpr_mu_lock(&fdn->mu); |
| // Register read_closure if the socket is readable and read_closure has |
| // not been registered with this socket. |
| if (ARES_GETSOCK_READABLE(socks_bitmask, i) && |
| !fdn->readable_registered) { |
| grpc_ares_ev_driver_ref(ev_driver); |
| gpr_log(GPR_DEBUG, "notify read on: %d", grpc_fd_wrapped_fd(fdn->fd)); |
| grpc_fd_notify_on_read(exec_ctx, fdn->fd, &fdn->read_closure); |
| fdn->readable_registered = true; |
| } |
| // Register write_closure if the socket is writable and write_closure |
| // has not been registered with this socket. |
| if (ARES_GETSOCK_WRITABLE(socks_bitmask, i) && |
| !fdn->writable_registered) { |
| gpr_log(GPR_DEBUG, "notify write on: %d", |
| grpc_fd_wrapped_fd(fdn->fd)); |
| grpc_ares_ev_driver_ref(ev_driver); |
| grpc_fd_notify_on_write(exec_ctx, fdn->fd, &fdn->write_closure); |
| fdn->writable_registered = true; |
| } |
| gpr_mu_unlock(&fdn->mu); |
| } |
| } |
| } |
| // Any remaining fds in ev_driver->fds were not returned by ares_getsock() and |
| // are therefore no longer in use, so they can be shut down and removed from |
| // the list. |
| while (ev_driver->fds != NULL) { |
| fd_node *cur = ev_driver->fds; |
| ev_driver->fds = ev_driver->fds->next; |
| fd_node_shutdown(exec_ctx, cur); |
| } |
| ev_driver->fds = new_list; |
| // If the ev driver has no working fd, all the tasks are done. |
| if (new_list == NULL) { |
| ev_driver->working = false; |
| gpr_log(GPR_DEBUG, "ev driver stop working"); |
| } |
| } |
| |
| void grpc_ares_ev_driver_start(grpc_exec_ctx *exec_ctx, |
| grpc_ares_ev_driver *ev_driver) { |
| gpr_mu_lock(&ev_driver->mu); |
| if (!ev_driver->working) { |
| ev_driver->working = true; |
| grpc_ares_notify_on_event_locked(exec_ctx, ev_driver); |
| } |
| gpr_mu_unlock(&ev_driver->mu); |
| } |
| |
| #endif /* GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET) */ |