| // Copyright 2024 The Pigweed 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 |
| // |
| // https://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 <fcntl.h> |
| #include <sys/epoll.h> |
| #include <unistd.h> |
| |
| #include <cstring> |
| #include <mutex> |
| |
| #include "pw_assert/check.h" |
| #include "pw_async2/dispatcher_native.h" |
| #include "pw_log/log.h" |
| #include "pw_preprocessor/compiler.h" |
| #include "pw_status/status.h" |
| |
| namespace pw::async2 { |
| namespace { |
| |
| constexpr char kNotificationSignal = 'c'; |
| |
| } // namespace |
| |
| Status Dispatcher::NativeInit() { |
| epoll_fd_ = epoll_create1(0); |
| if (epoll_fd_ == -1) { |
| PW_LOG_ERROR("Failed to open epoll: %s", std::strerror(errno)); |
| return Status::Internal(); |
| } |
| |
| int pipefd[2]; |
| if (pipe2(pipefd, O_DIRECT) == -1) { |
| PW_LOG_ERROR("Failed to create pipe: %s", std::strerror(errno)); |
| return Status::Internal(); |
| } |
| |
| wait_fd_ = pipefd[0]; |
| notify_fd_ = pipefd[1]; |
| |
| struct epoll_event event; |
| event.events = EPOLLIN; |
| event.data.fd = wait_fd_; |
| if (epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, wait_fd_, &event) == -1) { |
| PW_LOG_ERROR("Failed to initialize epoll event for dispatcher"); |
| return Status::Internal(); |
| } |
| |
| return OkStatus(); |
| } |
| |
| Poll<> Dispatcher::DoRunUntilStalled(Task* task) { |
| { |
| std::lock_guard lock(dispatcher_lock()); |
| PW_CHECK(task == nullptr || HasPostedTask(*task), |
| "Attempted to run a dispatcher until a task was stalled, " |
| "but that task has not been `Post`ed to that `Dispatcher`."); |
| } |
| while (true) { |
| RunOneTaskResult result = RunOneTask(task); |
| if (result.completed_main_task() || result.completed_all_tasks()) { |
| return Ready(); |
| } |
| if (!result.ran_a_task()) { |
| return Pending(); |
| } |
| } |
| } |
| |
| void Dispatcher::DoRunToCompletion(Task* task) { |
| { |
| std::lock_guard lock(dispatcher_lock()); |
| PW_CHECK(task == nullptr || HasPostedTask(*task), |
| "Attempted to run a dispatcher until a task was complete, " |
| "but that task has not been `Post`ed to that `Dispatcher`."); |
| } |
| while (true) { |
| RunOneTaskResult result = RunOneTask(task); |
| if (result.completed_main_task() || result.completed_all_tasks()) { |
| return; |
| } |
| if (!result.ran_a_task()) { |
| SleepInfo sleep_info = AttemptRequestWake(); |
| if (sleep_info.should_sleep()) { |
| NativeWaitForWake(); |
| } |
| } |
| } |
| } |
| |
| void Dispatcher::NativeWaitForWake() { |
| struct epoll_event event; |
| |
| int num_fds = epoll_wait(epoll_fd_, &event, 1, /*timeout=*/-1); |
| |
| PW_CHECK_INT_EQ(num_fds, 1); |
| |
| // Consume the written notification. |
| char unused; |
| ssize_t bytes_read = read(wait_fd_, &unused, 1); |
| PW_CHECK_INT_EQ(bytes_read, 1, "Dispatcher failed to read wake notification"); |
| PW_DCHECK_INT_EQ(unused, kNotificationSignal); |
| } |
| |
| void Dispatcher::DoWake() { |
| // Perform a write to unblock the waiting dispatcher. |
| ssize_t bytes_written = write(notify_fd_, &kNotificationSignal, 1); |
| PW_CHECK_INT_EQ( |
| bytes_written, 1, "Dispatcher failed to write wake notification"); |
| } |
| |
| } // namespace pw::async2 |