2 * Copyright 2017 Facebook, Inc.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
19 #include <folly/Memory.h>
20 #include <folly/io/IOBufQueue.h>
21 #include <folly/io/async/AsyncUDPSocket.h>
22 #include <folly/io/async/EventBase.h>
29 * It wraps a UDP socket waiting for packets and distributes them among
30 * a set of event loops in round robin fashion.
32 * NOTE: At the moment it is designed to work with single packet protocols
33 * in mind. We distribute incoming packets among all the listeners in
34 * round-robin fashion. So, any protocol that expects to send/recv
35 * more than 1 packet will not work because they will end up with
36 * different event base to process.
38 class AsyncUDPServerSocket : private AsyncUDPSocket::ReadCallback
39 , public AsyncSocketBase {
44 * Invoked when we start reading data from socket. It is invoked in
45 * each acceptors/listeners event base thread.
47 virtual void onListenStarted() noexcept = 0;
50 * Invoked when the server socket is closed. It is invoked in each
51 * acceptors/listeners event base thread.
53 virtual void onListenStopped() noexcept = 0;
56 * Invoked when a new packet is received
58 virtual void onDataAvailable(
59 std::shared_ptr<AsyncUDPSocket> socket,
60 const folly::SocketAddress& addr,
61 std::unique_ptr<folly::IOBuf> buf,
62 bool truncated) noexcept = 0;
64 virtual ~Callback() = default;
68 * Create a new UDP server socket
70 * Note about packet size - We allocate buffer of packetSize_ size to read.
71 * If packet are larger than this value, as per UDP protocol, remaining data
72 * is dropped and you get `truncated = true` in onDataAvailable callback
74 explicit AsyncUDPServerSocket(EventBase* evb, size_t sz = 1500)
80 ~AsyncUDPServerSocket() override {
86 void bind(const folly::SocketAddress& addy) {
89 socket_ = std::make_shared<AsyncUDPSocket>(evb_);
90 socket_->setReusePort(reusePort_);
94 void setReusePort(bool reusePort) {
95 reusePort_ = reusePort;
98 folly::SocketAddress address() const {
100 return socket_->address();
103 void getAddress(SocketAddress* a) const override {
108 * Add a listener to the round robin list
110 void addListener(EventBase* evb, Callback* callback) {
111 listeners_.emplace_back(evb, callback);
115 CHECK(socket_) << "Need to bind before listening";
117 for (auto& listener: listeners_) {
118 auto callback = listener.second;
120 listener.first->runInEventBaseThread([callback] () mutable {
121 callback->onListenStarted();
125 socket_->resumeRead(this);
129 CHECK(socket_) << "Need to bind before getting FD";
130 return socket_->getFD();
134 CHECK(socket_) << "Need to bind before closing";
139 EventBase* getEventBase() const override {
144 // AsyncUDPSocket::ReadCallback
145 void getReadBuffer(void** buf, size_t* len) noexcept override {
146 std::tie(*buf, *len) = buf_.preallocate(packetSize_, packetSize_);
149 void onDataAvailable(
150 const folly::SocketAddress& clientAddress,
152 bool truncated) noexcept override {
153 buf_.postallocate(len);
154 auto data = buf_.split(len);
156 if (listeners_.empty()) {
157 LOG(WARNING) << "UDP server socket dropping packet, "
158 << "no listener registered";
162 if (nextListener_ >= listeners_.size()) {
166 auto client = clientAddress;
167 auto callback = listeners_[nextListener_].second;
168 auto socket = socket_;
170 // Schedule it in the listener's eventbase
171 // XXX: Speed this up
176 data = std::move(data),
179 callback->onDataAvailable(socket, client, std::move(data), truncated);
182 listeners_[nextListener_].first->runInEventBaseThread(std::move(f));
186 void onReadError(const AsyncSocketException& ex) noexcept override {
187 LOG(ERROR) << ex.what();
189 // Lets register to continue listening for packets
190 socket_->resumeRead(this);
193 void onReadClosed() noexcept override {
194 for (auto& listener: listeners_) {
195 auto callback = listener.second;
197 listener.first->runInEventBaseThread([callback] () mutable {
198 callback->onListenStopped();
203 EventBase* const evb_;
204 const size_t packetSize_;
206 std::shared_ptr<AsyncUDPSocket> socket_;
208 // List of listener to distribute packets among
209 typedef std::pair<EventBase*, Callback*> Listener;
210 std::vector<Listener> listeners_;
212 // Next listener to send packet to
213 uint32_t nextListener_;
215 // Temporary buffer for data
216 folly::IOBufQueue buf_;
218 bool reusePort_{false};