| /****************************************************************************** |
| * |
| * Copyright (C) 2014 Google, Inc. |
| * |
| * 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. |
| * |
| ******************************************************************************/ |
| |
| #define LOG_TAG "bt_osi_reactor" |
| |
| #include <assert.h> |
| #include <errno.h> |
| #include <pthread.h> |
| #include <stdlib.h> |
| #include <sys/epoll.h> |
| #include <sys/eventfd.h> |
| |
| #include "allocator.h" |
| #include "list.h" |
| #include "osi/include/log.h" |
| #include "reactor.h" |
| |
| #if !defined(EFD_SEMAPHORE) |
| # define EFD_SEMAPHORE (1 << 0) |
| #endif |
| |
| struct reactor_t { |
| int epoll_fd; |
| int event_fd; |
| pthread_mutex_t list_lock; // protects invalidation_list. |
| list_t *invalidation_list; // reactor objects that have been unregistered. |
| pthread_t run_thread; // the pthread on which reactor_run is executing. |
| bool is_running; // indicates whether |run_thread| is valid. |
| bool object_removed; |
| }; |
| |
| struct reactor_object_t { |
| int fd; // the file descriptor to monitor for events. |
| void *context; // a context that's passed back to the *_ready functions. |
| reactor_t *reactor; // the reactor instance this object is registered with. |
| pthread_mutex_t lock; // protects the lifetime of this object and all variables. |
| |
| void (*read_ready)(void *context); // function to call when the file descriptor becomes readable. |
| void (*write_ready)(void *context); // function to call when the file descriptor becomes writeable. |
| }; |
| |
| static reactor_status_t run_reactor(reactor_t *reactor, int iterations); |
| |
| static const size_t MAX_EVENTS = 64; |
| static const eventfd_t EVENT_REACTOR_STOP = 1; |
| |
| reactor_t *reactor_new(void) { |
| reactor_t *ret = (reactor_t *)osi_calloc(sizeof(reactor_t)); |
| if (!ret) |
| return NULL; |
| |
| ret->epoll_fd = INVALID_FD; |
| ret->event_fd = INVALID_FD; |
| |
| ret->epoll_fd = epoll_create(MAX_EVENTS); |
| if (ret->epoll_fd == INVALID_FD) { |
| LOG_ERROR("%s unable to create epoll instance: %s", __func__, strerror(errno)); |
| goto error; |
| } |
| |
| ret->event_fd = eventfd(0, 0); |
| if (ret->event_fd == INVALID_FD) { |
| LOG_ERROR("%s unable to create eventfd: %s", __func__, strerror(errno)); |
| goto error; |
| } |
| |
| pthread_mutex_init(&ret->list_lock, NULL); |
| ret->invalidation_list = list_new(NULL); |
| if (!ret->invalidation_list) { |
| LOG_ERROR("%s unable to allocate object invalidation list.", __func__); |
| goto error; |
| } |
| |
| struct epoll_event event = { 0 }; |
| event.events = EPOLLIN; |
| event.data.ptr = NULL; |
| if (epoll_ctl(ret->epoll_fd, EPOLL_CTL_ADD, ret->event_fd, &event) == -1) { |
| LOG_ERROR("%s unable to register eventfd with epoll set: %s", __func__, strerror(errno)); |
| goto error; |
| } |
| |
| return ret; |
| |
| error:; |
| reactor_free(ret); |
| return NULL; |
| } |
| |
| void reactor_free(reactor_t *reactor) { |
| if (!reactor) |
| return; |
| |
| list_free(reactor->invalidation_list); |
| close(reactor->event_fd); |
| close(reactor->epoll_fd); |
| osi_free(reactor); |
| } |
| |
| reactor_status_t reactor_start(reactor_t *reactor) { |
| assert(reactor != NULL); |
| return run_reactor(reactor, 0); |
| } |
| |
| reactor_status_t reactor_run_once(reactor_t *reactor) { |
| assert(reactor != NULL); |
| return run_reactor(reactor, 1); |
| } |
| |
| void reactor_stop(reactor_t *reactor) { |
| assert(reactor != NULL); |
| |
| eventfd_write(reactor->event_fd, EVENT_REACTOR_STOP); |
| } |
| |
| reactor_object_t *reactor_register(reactor_t *reactor, |
| int fd, void *context, |
| void (*read_ready)(void *context), |
| void (*write_ready)(void *context)) { |
| assert(reactor != NULL); |
| assert(fd != INVALID_FD); |
| |
| reactor_object_t *object = (reactor_object_t *)osi_calloc(sizeof(reactor_object_t)); |
| if (!object) { |
| LOG_ERROR("%s unable to allocate reactor object: %s", __func__, strerror(errno)); |
| return NULL; |
| } |
| |
| object->reactor = reactor; |
| object->fd = fd; |
| object->context = context; |
| object->read_ready = read_ready; |
| object->write_ready = write_ready; |
| pthread_mutex_init(&object->lock, NULL); |
| |
| struct epoll_event event = { 0 }; |
| event.events = 0; |
| if (read_ready) |
| event.events |= (EPOLLIN | EPOLLRDHUP); |
| if (write_ready) |
| event.events |= EPOLLOUT; |
| event.data.ptr = object; |
| |
| if (epoll_ctl(reactor->epoll_fd, EPOLL_CTL_ADD, fd, &event) == -1) { |
| LOG_ERROR("%s unable to register fd %d to epoll set: %s", __func__, fd, strerror(errno)); |
| pthread_mutex_destroy(&object->lock); |
| osi_free(object); |
| return NULL; |
| } |
| |
| return object; |
| } |
| |
| bool reactor_change_registration(reactor_object_t *object, |
| void (*read_ready)(void *context), |
| void (*write_ready)(void *context)) { |
| assert(object != NULL); |
| |
| struct epoll_event event = { 0 }; |
| event.events = 0; |
| if (read_ready) |
| event.events |= (EPOLLIN | EPOLLRDHUP); |
| if (write_ready) |
| event.events |= EPOLLOUT; |
| event.data.ptr = object; |
| |
| if (epoll_ctl(object->reactor->epoll_fd, EPOLL_CTL_MOD, object->fd, &event) == -1) { |
| LOG_ERROR("%s unable to modify interest set for fd %d: %s", __func__, object->fd, strerror(errno)); |
| return false; |
| } |
| |
| pthread_mutex_lock(&object->lock); |
| object->read_ready = read_ready; |
| object->write_ready = write_ready; |
| pthread_mutex_unlock(&object->lock); |
| |
| return true; |
| } |
| |
| void reactor_unregister(reactor_object_t *obj) { |
| assert(obj != NULL); |
| |
| reactor_t *reactor = obj->reactor; |
| |
| if (epoll_ctl(reactor->epoll_fd, EPOLL_CTL_DEL, obj->fd, NULL) == -1) |
| LOG_ERROR("%s unable to unregister fd %d from epoll set: %s", __func__, obj->fd, strerror(errno)); |
| |
| if (reactor->is_running && pthread_equal(pthread_self(), reactor->run_thread)) { |
| reactor->object_removed = true; |
| return; |
| } |
| |
| pthread_mutex_lock(&reactor->list_lock); |
| list_append(reactor->invalidation_list, obj); |
| pthread_mutex_unlock(&reactor->list_lock); |
| |
| // Taking the object lock here makes sure a callback for |obj| isn't |
| // currently executing. The reactor thread must then either be before |
| // the callbacks or after. If after, we know that the object won't be |
| // referenced because it has been taken out of the epoll set. If before, |
| // it won't be referenced because the reactor thread will check the |
| // invalidation_list and find it in there. So by taking this lock, we |
| // are waiting until the reactor thread drops all references to |obj|. |
| // One the wait completes, we can unlock and destroy |obj| safely. |
| pthread_mutex_lock(&obj->lock); |
| pthread_mutex_unlock(&obj->lock); |
| pthread_mutex_destroy(&obj->lock); |
| osi_free(obj); |
| } |
| |
| // Runs the reactor loop for a maximum of |iterations|. |
| // 0 |iterations| means loop forever. |
| // |reactor| may not be NULL. |
| static reactor_status_t run_reactor(reactor_t *reactor, int iterations) { |
| assert(reactor != NULL); |
| |
| reactor->run_thread = pthread_self(); |
| reactor->is_running = true; |
| |
| struct epoll_event events[MAX_EVENTS]; |
| for (int i = 0; iterations == 0 || i < iterations; ++i) { |
| pthread_mutex_lock(&reactor->list_lock); |
| list_clear(reactor->invalidation_list); |
| pthread_mutex_unlock(&reactor->list_lock); |
| |
| int ret; |
| do { |
| ret = epoll_wait(reactor->epoll_fd, events, MAX_EVENTS, -1); |
| } while (ret == -1 && errno == EINTR); |
| |
| if (ret == -1) { |
| LOG_ERROR("%s error in epoll_wait: %s", __func__, strerror(errno)); |
| reactor->is_running = false; |
| return REACTOR_STATUS_ERROR; |
| } |
| |
| for (int j = 0; j < ret; ++j) { |
| // The event file descriptor is the only one that registers with |
| // a NULL data pointer. We use the NULL to identify it and break |
| // out of the reactor loop. |
| if (events[j].data.ptr == NULL) { |
| eventfd_t value; |
| eventfd_read(reactor->event_fd, &value); |
| reactor->is_running = false; |
| return REACTOR_STATUS_STOP; |
| } |
| |
| reactor_object_t *object = (reactor_object_t *)events[j].data.ptr; |
| |
| pthread_mutex_lock(&reactor->list_lock); |
| if (list_contains(reactor->invalidation_list, object)) { |
| pthread_mutex_unlock(&reactor->list_lock); |
| continue; |
| } |
| |
| // Downgrade the list lock to an object lock. |
| pthread_mutex_lock(&object->lock); |
| pthread_mutex_unlock(&reactor->list_lock); |
| |
| reactor->object_removed = false; |
| if (events[j].events & (EPOLLIN | EPOLLHUP | EPOLLRDHUP | EPOLLERR) && object->read_ready) |
| object->read_ready(object->context); |
| if (!reactor->object_removed && events[j].events & EPOLLOUT && object->write_ready) |
| object->write_ready(object->context); |
| pthread_mutex_unlock(&object->lock); |
| |
| if (reactor->object_removed) { |
| pthread_mutex_destroy(&object->lock); |
| osi_free(object); |
| } |
| } |
| } |
| |
| reactor->is_running = false; |
| return REACTOR_STATUS_DONE; |
| } |