diff options
Diffstat (limited to 'src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c')
| -rw-r--r-- | src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c b/src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c new file mode 100644 index 0000000000..fab4f0c977 --- /dev/null +++ b/src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c @@ -0,0 +1,319 @@ +/* + * + * Copyright 2016, Google Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Google Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ +#include <grpc/support/port_platform.h> +#include "src/core/lib/iomgr/port.h" +#if GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET) + +#include "src/core/ext/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/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; + /** the grpc_fd owned by this fd node */ + grpc_fd *grpc_fd; + /** 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; + /** if the readable closure has been registered */ + bool readable_registered; + /** if the writable closure has been registered */ + bool writable_registered; +} 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->grpc_fd)); + GPR_ASSERT(!fdn->readable_registered); + GPR_ASSERT(!fdn->writable_registered); + gpr_mu_destroy(&fdn->mu); + grpc_pollset_set_del_fd(exec_ctx, fdn->ev_driver->pollset_set, fdn->grpc_fd); + grpc_fd_shutdown(exec_ctx, fdn->grpc_fd, + GRPC_ERROR_CREATE_FROM_STATIC_STRING("fd node destroyed")); + grpc_fd_orphan(exec_ctx, fdn->grpc_fd, NULL, NULL, "c-ares query finished"); + gpr_free(fdn); +} + +grpc_error *grpc_ares_ev_driver_create(grpc_ares_ev_driver **ev_driver, + grpc_pollset_set *pollset_set) { + *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); +} + +// 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->grpc_fd) == fd) { + fd_node *ret = node->next; + node->next = node->next->next; + *head = dummy_head.next; + return ret; + } + node = node->next; + } + return NULL; +} + +static void on_readable_cb(grpc_exec_ctx *exec_ctx, void *arg, + grpc_error *error) { + fd_node *fdn = arg; + grpc_ares_ev_driver *ev_driver = fdn->ev_driver; + gpr_mu_lock(&fdn->mu); + fdn->readable_registered = false; + gpr_mu_unlock(&fdn->mu); + + gpr_log(GPR_DEBUG, "readable on %d", grpc_fd_wrapped_fd(fdn->grpc_fd)); + if (error == GRPC_ERROR_NONE) { + ares_process_fd(ev_driver->channel, grpc_fd_wrapped_fd(fdn->grpc_fd), + ARES_SOCKET_BAD); + } 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 = arg; + grpc_ares_ev_driver *ev_driver = fdn->ev_driver; + gpr_mu_lock(&fdn->mu); + fdn->writable_registered = false; + gpr_mu_unlock(&fdn->mu); + + gpr_log(GPR_DEBUG, "writable on %d", grpc_fd_wrapped_fd(fdn->grpc_fd)); + if (error == GRPC_ERROR_NONE) { + ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD, + grpc_fd_wrapped_fd(fdn->grpc_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 = gpr_malloc(sizeof(fd_node)); + gpr_log(GPR_DEBUG, "new fd: %d", socks[i]); + fdn->grpc_fd = grpc_fd_create(socks[i], fd_name); + fdn->ev_driver = ev_driver; + fdn->readable_registered = false; + fdn->writable_registered = 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->grpc_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->grpc_fd)); + grpc_fd_notify_on_read(exec_ctx, fdn->grpc_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->grpc_fd)); + grpc_ares_ev_driver_ref(ev_driver); + grpc_fd_notify_on_write(exec_ctx, fdn->grpc_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_destroy(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) */ |