1 // Copyright 2024 The Pigweed Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 4 // use this file except in compliance with the License. You may obtain a copy of 5 // the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12 // License for the specific language governing permissions and limitations under 13 // the License. 14 #pragma once 15 16 #include <cstdint> 17 #include <optional> 18 19 #include "pw_async2/dispatcher.h" 20 #include "pw_async2/poll.h" 21 #include "pw_channel/channel.h" 22 #include "pw_multibuf/allocator.h" 23 #include "pw_multibuf/multibuf.h" 24 25 namespace pw::channel { 26 27 /// @defgroup pw_channel_epoll 28 /// @{ 29 30 /// Channel implementation which writes to and reads from a file descriptor, 31 /// backed by Linux's epoll notification system. 32 /// 33 /// This channel depends on APIs provided by the EpollDispatcher and cannot be 34 /// used with any other dispatcher backend. 35 /// 36 /// An instantiated EpollChannel takes ownership of the file descriptor it is 37 /// given, and will close it if the channel is closed or destroyed. Users should 38 /// not close a channel's file descriptor from outside. 39 class EpollChannel : public Implement<ByteReaderWriter> { 40 public: EpollChannel(int channel_fd,async2::Dispatcher & dispatcher,multibuf::MultiBufAllocator & allocator)41 EpollChannel(int channel_fd, 42 async2::Dispatcher& dispatcher, 43 multibuf::MultiBufAllocator& allocator) 44 : channel_fd_(channel_fd), 45 ready_to_write_(false), 46 dispatcher_(&dispatcher), 47 write_alloc_future_(allocator) { 48 Register(); 49 } 50 ~EpollChannel()51 ~EpollChannel() override { Cleanup(); } 52 53 EpollChannel(const EpollChannel&) = delete; 54 EpollChannel& operator=(const EpollChannel&) = delete; 55 56 EpollChannel(EpollChannel&&) = default; 57 EpollChannel& operator=(EpollChannel&&) = default; 58 59 private: 60 static constexpr size_t kMinimumReadSize = 64; 61 static constexpr size_t kDesiredReadSize = 1024; 62 63 void Register(); 64 65 async2::Poll<Result<multibuf::MultiBuf>> DoPendRead( 66 async2::Context& cx) override; 67 68 async2::Poll<Status> DoPendReadyToWrite(async2::Context& cx) final; 69 DoPendAllocateWriteBuffer(async2::Context & cx,size_t min_bytes)70 async2::Poll<std::optional<multibuf::MultiBuf>> DoPendAllocateWriteBuffer( 71 async2::Context& cx, size_t min_bytes) final { 72 write_alloc_future_.SetDesiredSize(min_bytes); 73 return write_alloc_future_.Pend(cx); 74 } 75 76 Status DoStageWrite(multibuf::MultiBuf&& data) final; 77 DoPendWrite(async2::Context &)78 async2::Poll<Status> DoPendWrite(async2::Context&) final { 79 return OkStatus(); 80 } 81 DoPendClose(async2::Context &)82 async2::Poll<Status> DoPendClose(async2::Context&) final { 83 Cleanup(); 84 return async2::Ready(OkStatus()); 85 } 86 set_closed()87 void set_closed() { 88 set_read_closed(); 89 set_write_closed(); 90 } 91 92 void Cleanup(); 93 94 int channel_fd_; 95 bool ready_to_write_; 96 97 async2::Dispatcher* dispatcher_; 98 multibuf::MultiBufAllocationFuture write_alloc_future_; 99 async2::Waker waker_; 100 }; 101 102 /// @} 103 104 } // namespace pw::channel 105