2 * Copyright 2014 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/MoveWrapper.h>
20 #include <folly/io/IOBufQueue.h>
21 #include <folly/Memory.h>
22 #include <folly/io/async/AsyncUDPSocket.h>
23 #include <folly/io/async/EventBase.h>
30 * It wraps a UDP socket waiting for packets and distributes them among
31 * a set of event loops in round robin fashion.
33 * NOTE: At the moment it is designed to work with single packet protocols
34 * in mind. We distribute incoming packets among all the listeners in
35 * round-robin fashion. So, any protocol that expects to send/recv
36 * more than 1 packet will not work because they will end up with
37 * different event base to process.
39 class AsyncUDPServerSocket : private AsyncUDPSocket::ReadCallback {
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(const folly::SocketAddress& addr,
59 std::unique_ptr<folly::IOBuf> buf,
60 bool truncated) noexcept = 0;
62 virtual ~Callback() {}
66 * Create a new UDP server socket
68 * Note about packet size - We allocate buffer of packetSize_ size to read.
69 * If packet are larger than this value, as per UDP protocol, remaining data
70 * is dropped and you get `truncated = true` in onDataAvailable callback
72 explicit AsyncUDPServerSocket(EventBase* evb, size_t sz = 1500)
78 ~AsyncUDPServerSocket() {
84 void bind(const folly::SocketAddress& address) {
87 socket_ = folly::make_unique<AsyncUDPSocket>(evb_);
88 socket_->bind(address);
91 folly::SocketAddress address() const {
93 return socket_->address();
97 * Add a listener to the round robin list
99 void addListener(EventBase* evb, Callback* callback) {
100 listeners_.emplace_back(evb, callback);
104 CHECK(socket_) << "Need to bind before listening";
106 for (auto& listener: listeners_) {
107 auto callback = listener.second;
109 listener.first->runInEventBaseThread([callback] () mutable {
110 callback->onListenStarted();
114 socket_->resumeRead(this);
118 CHECK(socket_) << "Need to bind before getting FD";
119 return socket_->getFD();
123 CHECK(socket_) << "Need to bind before closing";
128 // AsyncUDPSocket::ReadCallback
129 void getReadBuffer(void** buf, size_t* len) noexcept {
130 std::tie(*buf, *len) = buf_.preallocate(packetSize_, packetSize_);
133 void onDataAvailable(const folly::SocketAddress& clientAddress,
135 bool truncated) noexcept {
136 buf_.postallocate(len);
137 auto data = buf_.split(len);
139 if (listeners_.empty()) {
140 LOG(WARNING) << "UDP server socket dropping packet, "
141 << "no listener registered";
145 if (nextListener_ >= listeners_.size()) {
149 auto client = clientAddress;
150 auto callback = listeners_[nextListener_].second;
153 std::unique_ptr<folly::IOBuf>>(std::move(data));
155 // Schedule it in the listener's eventbase
156 // XXX: Speed this up
157 std::function<void()> f = [client, callback, mvp, truncated] () mutable {
158 callback->onDataAvailable(client, std::move(*mvp), truncated);
161 listeners_[nextListener_].first->runInEventBaseThread(f);
165 void onReadError(const AsyncSocketException& ex) noexcept {
166 LOG(ERROR) << ex.what();
168 // Lets register to continue listening for packets
169 socket_->resumeRead(this);
172 void onReadClosed() noexcept {
173 for (auto& listener: listeners_) {
174 auto callback = listener.second;
176 listener.first->runInEventBaseThread([callback] () mutable {
177 callback->onListenStopped();
182 EventBase* const evb_;
183 const size_t packetSize_;
185 std::unique_ptr<AsyncUDPSocket> socket_;
187 // List of listener to distribute packets among
188 typedef std::pair<EventBase*, Callback*> Listener;
189 std::vector<Listener> listeners_;
191 // Next listener to send packet to
192 uint32_t nextListener_;
194 // Temporary buffer for data
195 folly::IOBufQueue buf_;