1 /* 2 * Copyright 2018, The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #pragma once 18 19 #include <chrono> 20 #include <vector> 21 22 #include <poll.h> 23 24 /* An interface for pollable classes. 25 */ 26 class Pollable { 27 public: 28 using Clock = std::chrono::steady_clock; 29 using Timestamp = Clock::time_point; 30 virtual ~Pollable() = default; 31 32 /* Get the poll data for the next poll loop. The implementation can place 33 * as many fds as needed in |fds|. 34 */ 35 virtual void getPollData(std::vector<pollfd>* fds) const = 0; 36 /* Get the timeout for the next poll loop. This should be a timestamp 37 * indicating when the timeout should be triggered. Note that this may 38 * be called at any time and any number of times for a poll loop so the 39 * deadline should not be adjusted in this call, a set deadline should 40 * just be returned. Note specifically that if a call to onReadAvailable 41 * modifies the deadline the timeout for the previous timestamp might not 42 * fire as the poller will check the timestamp AFTER onReadAvailable is 43 * called. 44 */ 45 virtual Timestamp getTimeout() const = 0; 46 /* Called when there is data available to read on an fd associated with 47 * the pollable. |fd| indicates which fd to read from. If the call returns 48 * false the poller will exit its poll loop with a return code of |status|. 49 */ 50 virtual bool onReadAvailable(int fd, int* status) = 0; 51 /* Called when an fd associated with the pollable is closed. |fd| indicates 52 * which fd was closed. If the call returns false the poller will exit its 53 * poll loop with a return code of |status|. 54 */ 55 virtual bool onClose(int fd, int* status) = 0; 56 /* Called when the timeout returned by getPollData has been reached. If 57 * the call returns false the poller will exit its poll loop with a return 58 * code of |status|. 59 */ 60 virtual bool onTimeout(int* status) = 0; 61 }; 62 63
