Repository: qpid-site Updated Branches: refs/heads/asf-site b243c26c3 -> 701caf213
http://git-wip-us.apache.org/repos/asf/qpid-site/blob/701caf21/content/releases/qpid-proton-master/proton/cpp/api/multithreaded_client_flow_control_8cpp-example.html ---------------------------------------------------------------------- diff --git a/content/releases/qpid-proton-master/proton/cpp/api/multithreaded_client_flow_control_8cpp-example.html b/content/releases/qpid-proton-master/proton/cpp/api/multithreaded_client_flow_control_8cpp-example.html index f7bc22d..e1a509a 100755 --- a/content/releases/qpid-proton-master/proton/cpp/api/multithreaded_client_flow_control_8cpp-example.html +++ b/content/releases/qpid-proton-master/proton/cpp/api/multithreaded_client_flow_control_8cpp-example.html @@ -94,7 +94,7 @@ $(document).ready(function(){initNavTree('multithreaded_client_flow_control_8cpp </div><!--header--> <div class="contents"> <p>A multithreaded sender and receiver enhanced for flow control.<b>Requires C++11</b></p> -<div class="fragment"><div class="line"><span class="comment">/*</span></div><div class="line"><span class="comment"> * Licensed to the Apache Software Foundation (ASF) under one</span></div><div class="line"><span class="comment"> * or more contributor license agreements. See the NOTICE file</span></div><div class="line"><span class="comment"> * distributed with this work for additional information</span></div><div class="line"><span class="comment"> * regarding copyright ownership. The ASF licenses this file</span></div><div class="line"><span class="comment"> * to you under the Apache License, Version 2.0 (the</span></div><div class="line"><span class="comment"> * "License"); you may not use this file except in compliance</span></div><div class="line"><span class="comment"> * with the License. You may obtain a copy of the License at</span></div><div class="line"><span class="comment"> *</span></div><div class="line"><span class="comment"> * http://www.apache.org/li censes/LICENSE-2.0</span></div><div class="line"><span class="comment"> *</span></div><div class="line"><span class="comment"> * Unless required by applicable law or agreed to in writing,</span></div><div class="line"><span class="comment"> * software distributed under the License is distributed on an</span></div><div class="line"><span class="comment"> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY</span></div><div class="line"><span class="comment"> * KIND, either express or implied. See the License for the</span></div><div class="line"><span class="comment"> * specific language governing permissions and limitations</span></div><div class="line"><span class="comment"> * under the License.</span></div><div class="line"><span class="comment"> */</span></div><div class="line"></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// C++11 or greater</span></div><div class="line"><span class="comment">//</span></div><d iv class="line"><span class="comment">// A multi-threaded client that sends and receives messages from multiple AMQP</span></div><div class="line"><span class="comment">// addresses.</span></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// Demonstrates how to:</span></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// - implement proton handlers that interact with user threads safely</span></div><div class="line"><span class="comment">// - block sender threads to respect AMQP flow control</span></div><div class="line"><span class="comment">// - use AMQP flow control to limit message buffering for receivers threads</span></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// We define sender and receiver classes with simple, thread-safe blocking</span></div><div class="line"><span class="comment">// send() and receive() functions.</s pan></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// These classes are also privately proton::message_handler instances. They use</span></div><div class="line"><span class="comment">// the thread-safe proton::work_queue and standard C++ synchronization (std::mutex</span></div><div class="line"><span class="comment">// etc.) to pass messages between user and proton::container threads.</span></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// NOTE: no proper error handling</span></div><div class="line"></div><div class="line"><span class="preprocessor">#include <<a class="code" href="connection_8hpp.html">proton/connection.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="connection__options_8hpp.html">proton/connection_options.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="container_8hpp.html">proton/container.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="message_8hpp.html">proton/message.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="messaging__handler_8hpp.html">proton/messaging_handler.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="receiver_8hpp.html">proton/receiver.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="receiver__options_8hpp.html">proton/receiver_options.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="sender_8hpp.html">proton/sender.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="work__queue_8hpp.html">proton/work_queue.hpp</a>></span></div><div class="line"></div><div class="line"><span class ="preprocessor">#include <atomic></span></div><div class="line"><span class="preprocessor">#include <condition_variable></span></div><div class="line"><span class="preprocessor">#include <iostream></span></div><div class="line"><span class="preprocessor">#include <mutex></span></div><div class="line"><span class="preprocessor">#include <queue></span></div><div class="line"><span class="preprocessor">#include <sstream></span></div><div class="line"><span class="preprocessor">#include <string></span></div><div class="line"><span class="preprocessor">#include <thread></span></div><div class="line"></div><div class="line"><span class="comment">// Lock output from threads to avoid scramblin</span></div><div class="line">std::mutex out_lock;</div><div class="line"><span class="preprocessor">#define OUT(x) do { std::lock_guard<std::mutex> l(out_lock); x; } while (false)</span></div><div class="line"></div><div class="line"><span class=" comment">// A thread-safe sending connection that blocks sending threads when there</span></div><div class="line"><span class="comment">// is no AMQP credit to send messages.</span></div><div class="line"><span class="keyword">class </span>sender : <span class="keyword">private</span> <a name="_a0"></a><a class="code" href="classproton_1_1messaging__handler.html">proton::messaging_handler</a> {</div><div class="line"> <span class="comment">// Only used in proton handler thread</span></div><div class="line"> <a name="_a1"></a><a class="code" href="classproton_1_1sender.html">proton::sender</a> sender_;</div><div class="line"></div><div class="line"> <span class="comment">// Shared by proton and user threads, protected by lock_</span></div><div class="line"> std::mutex lock_;</div><div class="line"> <a name="_a2"></a><a class="code" href="classproton_1_1work__queue.html">proton::work_queue</a> *work_queue_;</div><div class="line"> std::condition_variable sender_ready _;</div><div class="line"> <span class="keywordtype">int</span> queued_; <span class="comment">// Queued messages waiting to be sent</span></div><div class="line"> <span class="keywordtype">int</span> credit_; <span class="comment">// AMQP credit - number of messages we can send</span></div><div class="line"></div><div class="line"> <span class="keyword">public</span>:</div><div class="line"> sender(<a name="_a3"></a><a class="code" href="classproton_1_1container.html">proton::container</a>& cont, <span class="keyword">const</span> std::string& url, <span class="keyword">const</span> std::string& address)</div><div class="line"> : work_queue_(0), queued_(0), credit_(0)</div><div class="line"> {</div><div class="line"> cont.<a name="a4"></a><a class="code" href="classproton_1_1container.html#adfbfd13668611a525bb44328d7a3b1e8">open_sender</a>(url+<span class="stringliteral">"/"</span>+address, <a name="_a5"></a><a class="code" href="classproton_1_1connection__options.html">proton::connection_options</a>().handler(*<span class="keyword">this</span>));</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// Thread safe</span></div><div class="line"> <span class="keywordtype">void</span> send(<span class="keyword">const</span> <a name="_a6"></a><a class="code" href="classproton_1_1message.html">proton::message</a>& m) {</div><div class="line"> {</div><div class="line"> std::unique_lock<std::mutex> l(lock_);</div><div class="line"> <span class="comment">// Don't queue up more messages than we have credit for</span></div><div class="line"> <span class="keywordflow">while</span> (!work_queue_ || queued_ >= credit_) sender_ready_.wait(l);</div><div class="line"> ++queued_;</div><div class="line"> }</div><div class="line"> work_queue_-><a name= "a7"></a><a class="code" href="classproton_1_1work__queue.html#a59dae2153455bc095477a3b66a0b681e">add</a>([=]() { this->do_send(m); }); <span class="comment">// work_queue_ is thread safe</span></div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// Thread safe</span></div><div class="line"> <span class="keywordtype">void</span> close() {</div><div class="line"> work_queue()->add([=]() { sender_.<a name="a8"></a><a class="code" href="classproton_1_1link.html#aff302bb6016f2ae29f01bb4e07389a52">connection</a>().<a name="a9"></a><a class="code" href="classproton_1_1connection.html#a5ae591df94fc66ccb85cbb6565368bca">close</a>(); });</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keyword">private</span>:</div><div class="line"></div><div class="line"> <a class="code" href="classproton_1_1work__queue.html">proton::work_queue</a>* work_queue() {</div><div class="line"> <s pan class="comment">// Wait till work_queue_ and sender_ are initialized.</span></div><div class="line"> std::unique_lock<std::mutex> l(lock_);</div><div class="line"> <span class="keywordflow">while</span> (!work_queue_) sender_ready_.wait(l);</div><div class="line"> <span class="keywordflow">return</span> work_queue_;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// == messaging_handler overrides, only called in proton hander thread</span></div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> <a name="a10"></a><a class="code" href="classproton_1_1messaging__handler.html#a0b5d066e5463d3365f662c8a7dc52661">on_sender_open</a>(<a class="code" href="classproton_1_1sender.html">proton::sender</a>& s)<span class="keyword"> override </span>{</div><div class="line"> <span class="comment">// Make sure sender_ and work_queue_ are set atomically</span></div><div cla ss="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> sender_ = s;</div><div class="line"> work_queue_ = &s.<a name="a11"></a><a class="code" href="classproton_1_1link.html#a7c755d6ac6385e007adb61966598ba63">work_queue</a>();</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> <a name="a12"></a><a class="code" href="classproton_1_1messaging__handler.html#aa24f522a68cdf382762702cece7790e7">on_sendable</a>(<a class="code" href="classproton_1_1sender.html">proton::sender</a>& s)<span class="keyword"> override </span>{</div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> credit_ = s.<a name="a13"></a><a class="code" href="classproton_1_1link.html#afd27bd11ba72d7df51c44f71b15749eb">credit</a>();</div><div class="line"> sender_ready_.notify_all(); <span class="comment">// Notify senders we have credit</span></di v><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// work_queue work items is are automatically dequeued and called by proton</span></div><div class="line"> <span class="comment">// This function is called because it was queued by send()</span></div><div class="line"> <span class="keywordtype">void</span> do_send(<span class="keyword">const</span> <a class="code" href="classproton_1_1message.html">proton::message</a>& m) {</div><div class="line"> sender_.<a name="a14"></a><a class="code" href="classproton_1_1sender.html#a214eb30b24e6831d016a47b9dddda830">send</a>(m);</div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> --queued_; <span class="comment">// work item was consumed from the work_queue</span></div><div class="line"> credit_ = sender_.<a class="code" href="classproton_1_1link.html#afd27bd11ba72d7df51c44f71b15749eb">credit</a>(); <span class="comment">// update credit</span></div><div class="line"> sender_ready_.notify_all(); <span class="comment">// Notify senders we have space on queue</span></div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> <a name="a15"></a><a class="code" href="classproton_1_1messaging__handler.html#a5e29fef3b8c5b8cf18aa7d69850ac22e">on_error</a>(<span class="keyword">const</span> <a name="_a16"></a><a class="code" href="classproton_1_1error__condition.html">proton::error_condition</a>& e)<span class="keyword"> override </span>{</div><div class="line"> OUT(std::cerr << <span class="stringliteral">"unexpected error: "</span> << e << std::endl);</div><div class="line"> exit(1);</div><div class="line"> }</div><div class="line">};</div><div class="line"></div><div class="line"><span class="comment">// A thread safe receiving connection that blocks receiving thre ads when there</span></div><div class="line"><span class="comment">// are no messages available, and maintains a bounded buffer of incoming</span></div><div class="line"><span class="comment">// messages by issuing AMQP credit only when there is space in the buffer.</span></div><div class="line"><span class="keyword">class </span>receiver : <span class="keyword">private</span> <a class="code" href="classproton_1_1messaging__handler.html">proton::messaging_handler</a> {</div><div class="line"> <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">size_t</span> MAX_BUFFER = 100; <span class="comment">// Max number of buffered messages</span></div><div class="line"></div><div class="line"> <span class="comment">// Used in proton threads only</span></div><div class="line"> <a name="_a17"></a><a class="code" href="classproton_1_1receiver.html">proton::receiver</a> receiver_;</div><div class="line"></div><div class="line"> <span class ="comment">// Used in proton and user threads, protected by lock_</span></div><div class="line"> std::mutex lock_;</div><div class="line"> <a class="code" href="classproton_1_1work__queue.html">proton::work_queue</a>* work_queue_;</div><div class="line"> std::queue<proton::message> buffer_; <span class="comment">// Messages not yet returned by receive()</span></div><div class="line"> std::condition_variable can_receive_; <span class="comment">// Notify receivers of messages</span></div><div class="line"></div><div class="line"> <span class="keyword">public</span>:</div><div class="line"></div><div class="line"> <span class="comment">// Connect to url</span></div><div class="line"> receiver(<a class="code" href="classproton_1_1container.html">proton::container</a>& cont, <span class="keyword">const</span> std::string& url, <span class="keyword">const</span> std::string& address)</div><div class="line"> : work_queue_()</div><div class="line" > {</div><div class="line"> <span class="comment">// > NOTE:credit_window(0) disables automatic flow control.</span></div><div > class="line"> <span class="comment">// We will use flow control to > match AMQP credit to buffer capacity.</span></div><div class="line"> > cont.<a name="a18"></a><a class="code" > href="classproton_1_1container.html#a15df75d582af4ed83f0ffab9dcce84bf">open_receiver</a>(url+<span > class="stringliteral">"/"</span>+address, <a name="_a19"></a><a > class="code" > href="classproton_1_1receiver__options.html">proton::receiver_options</a>().credit_window(0),</div><div > class="line"> <a class="code" > href="classproton_1_1connection__options.html">proton::connection_options</a>().handler(*<span > class="keyword">this</span>));</div><div class="line"> }</div><div > class="line"></div><div class="line"> <span class="comment">// Thread > safe receive</span></div><div class="line"> <a class="code" > href="classproton_1_1messa ge.html">proton::message</a> receive() {</div><div class="line"> std::unique_lock<std::mutex> l(lock_);</div><div class="line"> <span class="comment">// Wait for buffered messages</span></div><div class="line"> <span class="keywordflow">while</span> (!work_queue_ || buffer_.empty())</div><div class="line"> can_receive_.wait(l);</div><div class="line"> <a class="code" href="classproton_1_1message.html">proton::message</a> m = std::move(buffer_.front());</div><div class="line"> buffer_.pop();</div><div class="line"> <span class="comment">// Add a lambda to the work queue to call receive_done().</span></div><div class="line"> <span class="comment">// This will tell the handler to add more credit.</span></div><div class="line"> work_queue_-><a class="code" href="classproton_1_1work__queue.html#a59dae2153455bc095477a3b66a0b681e">add</a>([=]() { this->receive_done(); });</div><div class="line"> <span cla ss="keywordflow">return</span> m;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> close() {</div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> <span class="keywordflow">if</span> (work_queue_) work_queue_-><a class="code" href="classproton_1_1work__queue.html#a59dae2153455bc095477a3b66a0b681e">add</a>([<span class="keyword">this</span>]() { this->receiver_.<a class="code" href="classproton_1_1link.html#aff302bb6016f2ae29f01bb4e07389a52">connection</a>().<a class="code" href="classproton_1_1connection.html#a5ae591df94fc66ccb85cbb6565368bca">close</a>(); });</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keyword">private</span>:</div><div class="line"> <span class="comment">// ==== The following are called by proton threads only.</span></div><div class="line"></div><div class="line"> <span class="keywordtyp e">void</span> on_receiver_open(<a class="code" href="classproton_1_1receiver.html">proton::receiver</a>& r)<span class="keyword"> override </span>{</div><div class="line"> receiver_ = r;</div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> work_queue_ = &receiver_.<a class="code" href="classproton_1_1link.html#a7c755d6ac6385e007adb61966598ba63">work_queue</a>();</div><div class="line"> receiver_.<a name="a20"></a><a class="code" href="classproton_1_1receiver.html#a84d3a001340d11201e03c6ed7c763641">add_credit</a>(MAX_BUFFER); <span class="comment">// Buffer is empty, initial credit is the limit</span></div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> on_message(<a name="_a21"></a><a class="code" href="classproton_1_1delivery.html">proton::delivery</a> &d, <a class="code" href="classproton_1_1message.html">proton::message</a> &m)<span class="keyword"> override </span>{</div><div class="line"> <span class="comment">// Proton automatically reduces credit by 1 before calling on_message</span></div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> buffer_.push(m);</div><div class="line"> can_receive_.notify_all();</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// called via work_queue</span></div><div class="line"> <span class="keywordtype">void</span> receive_done() {</div><div class="line"> <span class="comment">// Add 1 credit, a receiver has taken a message out of the buffer.</span></div><div class="line"> receiver_.<a class="code" href="classproton_1_1receiver.html#a84d3a001340d11201e03c6ed7c763641">add_credit</a>(1);</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> on_error(<span class="keyword">const</span> <a class="code" href="classproton_1_1error__condition.html">proton::error_condition</a>& e)<span class="keyword"> override </span>{</div><div class="line"> OUT(std::cerr << <span class="stringliteral">"unexpected error: "</span> << e << std::endl);</div><div class="line"> exit(1);</div><div class="line"> }</div><div class="line">};</div><div class="line"></div><div class="line"><span class="comment">// ==== Example code using the sender and receiver</span></div><div class="line"></div><div class="line"><span class="comment">// Send n messages</span></div><div class="line"><span class="keywordtype">void</span> send_thread(sender& s, <span class="keywordtype">int</span> n) {</div><div class="line"> <span class="keyword">auto</span> <span class="keywordtype">id</span> = std::this_thread::get_id();</div><div class="line"> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < n; ++i) {</div><div class="line"> std::ostringstream ss;</div><div class="line"> ss << std::this_thread::get_id() << <span class="stringliteral">"-"</span> << i;</div><div class="line"> s.send(<a class="code" href="classproton_1_1message.html">proton::message</a>(ss.str()));</div><div class="line"> OUT(std::cout << <span class="keywordtype">id</span> << <span class="stringliteral">" sent \""</span> << ss.str() << <span class="charliteral">'"'</span> << std::endl);</div><div class="line"> }</div><div class="line"> OUT(std::cout << <span class="keywordtype">id</span> << <span class="stringliteral">" sent "</span> << n << std::endl);</div><div class="line">}</div><div class="line"></div><div class="line"><span class="comment">// Receive messages till atomic remaining count is 0.</span></div><div class="line"><span class="comment">// remaining is shared among all receiving threads</span></div><div class="line"><span class="keywordtype">void</span> receive_thread(receiver& r, std::atomic_int& remaining) {</div><div class="line"> <span class="keyword">auto</span> <span class="keywordtype">id</span> = std::this_thread::get_id();</div><div class="line"> <span class="keywordtype">int</span> n = 0;</div><div class="line"> <span class="comment">// atomically check and decrement remaining *before* receiving.</span></div><div class="line"> <span class="comment">// If it is 0 or less then return, as there are no more</span></div><div class="line"> <span class="comment">// messages to receive so calling r.receive() would block forever.</span></div><div class="line"> <span class="keywordflow">while</span> (remaining-- > 0) {</div><div class="line"> <span class="keyword">auto</span> m = r.receive();</div><div class="line"> ++n;</div><div class="line"> OUT(std::cout << <span class="keywordt ype">id</span> << <span class="stringliteral">" received \""</span> << m.body() << <span class="charliteral">'"'</span> << std::endl);</div><div class="line"> }</div><div class="line"> OUT(std::cout << <span class="keywordtype">id</span> << <span class="stringliteral">" received "</span> << n << <span class="stringliteral">" messages"</span> << std::endl);</div><div class="line">}</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main(<span class="keywordtype">int</span> argc, <span class="keyword">const</span> <span class="keywordtype">char</span> **argv) {</div><div class="line"> <span class="keywordflow">try</span> {</div><div class="line"> <span class="keywordflow">if</span> (argc != 5) {</div><div class="line"> std::cerr <<</div><div class="line"> <span class="stringliteral">"Usage: "</s pan> << argv[0] << <span class="stringliteral">" MESSAGE-COUNT THREAD-COUNT URL\n"</span></div><div class="line"> <span class="stringliteral">"CONNECTION-URL: connection address, e.g.'amqp://127.0.0.1'\n"</span></div><div class="line"> <span class="stringliteral">"AMQP-ADDRESS: AMQP node address, e.g. 'examples'\n"</span></div><div class="line"> <span class="stringliteral">"MESSAGE-COUNT: number of messages to send\n"</span></div><div class="line"> <span class="stringliteral">"THREAD-COUNT: number of sender/receiver thread pairs\n"</span>;</div><div class="line"> <span class="keywordflow">return</span> 1;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keyword">const</span> <span class="keywordtype">char</span> *url = argv[1];</div><div class="line"> <span class="keyword">const </span> <span class="keywordtype">char</span> *address = argv[2];</div><div class="line"> <span class="keywordtype">int</span> n_messages = atoi(argv[3]);</div><div class="line"> <span class="keywordtype">int</span> n_threads = atoi(argv[4]);</div><div class="line"> <span class="keywordtype">int</span> count = n_messages * n_threads;</div><div class="line"></div><div class="line"> <span class="comment">// Total messages to be received, multiple receiver threads will decrement this.</span></div><div class="line"> std::atomic_int remaining(count);</div><div class="line"></div><div class="line"> <span class="comment">// Run the proton container</span></div><div class="line"> <a class="code" href="classproton_1_1container.html">proton::container</a> container;</div><div class="line"> <span class="keyword">auto</span> container_thread = std::thread([&]() { container.<a name="a22"></a><a class="code" href="classproton_1_1containe r.html#a13a43e6d814de94978c515cb084873b1">run</a>(); });</div><div class="line"></div><div class="line"> <span class="comment">// A single sender and receiver to be shared by all the threads</span></div><div class="line"> sender send(container, url, address);</div><div class="line"> receiver recv(container, url, address);</div><div class="line"></div><div class="line"> <span class="comment">// Start receiver threads, then sender threads.</span></div><div class="line"> <span class="comment">// Starting receivers first gives all receivers a chance to compete for messages.</span></div><div class="line"> std::vector<std::thread> threads;</div><div class="line"> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < n_threads; ++i)</div><div class="line"> threads.push_back(std::thread([&]() { receive_thread(recv, remaining); }));</div><div class="line"> <span class="keywordflow" >for</span> (<span class="keywordtype">int</span> i = 0; i < n_threads; >++i)</div><div class="line"> >threads.push_back(std::thread([&]() { send_thread(send, n_messages); >}));</div><div class="line"></div><div class="line"> <span >class="comment">// Wait for threads to finish</span></div><div class="line"> > <span class="keywordflow">for</span> (<span >class="keyword">auto</span>& t : threads)</div><div class="line"> > t.join();</div><div class="line"> send.close();</div><div >class="line"> recv.close();</div><div class="line"> >container_thread.join();</div><div class="line"> <span >class="keywordflow">if</span> (remaining > 0)</div><div class="line"> > <span class="keywordflow">throw</span> std::runtime_error(<span >class="stringliteral">"not all messages were >received"</span>);</div><div class="line"> std::cout << >count << <span class="stringliteral">" messages sent and r eceived"</span> << std::endl;</div><div class="line"></div><div class="line"> <span class="keywordflow">return</span> 0;</div><div class="line"> } <span class="keywordflow">catch</span> (<span class="keyword">const</span> std::exception& e) {</div><div class="line"> std::cerr << e.what() << std::endl;</div><div class="line"> }</div><div class="line"> <span class="keywordflow">return</span> 1;</div><div class="line">}</div></div><!-- fragment --> </div><!-- contents --> +<div class="fragment"><div class="line"><span class="comment">/*</span></div><div class="line"><span class="comment"> * Licensed to the Apache Software Foundation (ASF) under one</span></div><div class="line"><span class="comment"> * or more contributor license agreements. See the NOTICE file</span></div><div class="line"><span class="comment"> * distributed with this work for additional information</span></div><div class="line"><span class="comment"> * regarding copyright ownership. The ASF licenses this file</span></div><div class="line"><span class="comment"> * to you under the Apache License, Version 2.0 (the</span></div><div class="line"><span class="comment"> * "License"); you may not use this file except in compliance</span></div><div class="line"><span class="comment"> * with the License. You may obtain a copy of the License at</span></div><div class="line"><span class="comment"> *</span></div><div class="line"><span class="comment"> * http://www.apache.org/li censes/LICENSE-2.0</span></div><div class="line"><span class="comment"> *</span></div><div class="line"><span class="comment"> * Unless required by applicable law or agreed to in writing,</span></div><div class="line"><span class="comment"> * software distributed under the License is distributed on an</span></div><div class="line"><span class="comment"> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY</span></div><div class="line"><span class="comment"> * KIND, either express or implied. See the License for the</span></div><div class="line"><span class="comment"> * specific language governing permissions and limitations</span></div><div class="line"><span class="comment"> * under the License.</span></div><div class="line"><span class="comment"> */</span></div><div class="line"></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// C++11 or greater</span></div><div class="line"><span class="comment">//</span></div><d iv class="line"><span class="comment">// A multi-threaded client that sends and receives messages from multiple AMQP</span></div><div class="line"><span class="comment">// addresses.</span></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// Demonstrates how to:</span></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// - implement proton handlers that interact with user threads safely</span></div><div class="line"><span class="comment">// - block sender threads to respect AMQP flow control</span></div><div class="line"><span class="comment">// - use AMQP flow control to limit message buffering for receivers threads</span></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// We define sender and receiver classes with simple, thread-safe blocking</span></div><div class="line"><span class="comment">// send() and receive() functions.</s pan></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// These classes are also privately proton::message_handler instances. They use</span></div><div class="line"><span class="comment">// the thread-safe proton::work_queue and standard C++ synchronization (std::mutex</span></div><div class="line"><span class="comment">// etc.) to pass messages between user and proton::container threads.</span></div><div class="line"><span class="comment">//</span></div><div class="line"><span class="comment">// NOTE: no proper error handling</span></div><div class="line"></div><div class="line"><span class="preprocessor">#include <<a class="code" href="connection_8hpp.html">proton/connection.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="connection__options_8hpp.html">proton/connection_options.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="container_8hpp.html">proton/container.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="message_8hpp.html">proton/message.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="messaging__handler_8hpp.html">proton/messaging_handler.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="receiver_8hpp.html">proton/receiver.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="receiver__options_8hpp.html">proton/receiver_options.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="sender_8hpp.html">proton/sender.hpp</a>></span></div><div class="line"><span class="preprocessor">#include <<a class="code" href="work__queue_8hpp.html">proton/work_queue.hpp</a>></span></div><div class="line"></div><div class="line"><span class ="preprocessor">#include <atomic></span></div><div class="line"><span class="preprocessor">#include <condition_variable></span></div><div class="line"><span class="preprocessor">#include <iostream></span></div><div class="line"><span class="preprocessor">#include <mutex></span></div><div class="line"><span class="preprocessor">#include <queue></span></div><div class="line"><span class="preprocessor">#include <sstream></span></div><div class="line"><span class="preprocessor">#include <string></span></div><div class="line"><span class="preprocessor">#include <thread></span></div><div class="line"></div><div class="line"><span class="comment">// Lock output from threads to avoid scrambling</span></div><div class="line">std::mutex out_lock;</div><div class="line"><span class="preprocessor">#define OUT(x) do { std::lock_guard<std::mutex> l(out_lock); x; } while (false)</span></div><div class="line"></div><div class="line"><span class= "comment">// A thread-safe sending connection that blocks sending threads when there</span></div><div class="line"><span class="comment">// is no AMQP credit to send messages.</span></div><div class="line"><span class="keyword">class </span>sender : <span class="keyword">private</span> <a name="_a0"></a><a class="code" href="classproton_1_1messaging__handler.html">proton::messaging_handler</a> {</div><div class="line"> <span class="comment">// Only used in proton handler thread</span></div><div class="line"> <a name="_a1"></a><a class="code" href="classproton_1_1sender.html">proton::sender</a> sender_;</div><div class="line"></div><div class="line"> <span class="comment">// Shared by proton and user threads, protected by lock_</span></div><div class="line"> std::mutex lock_;</div><div class="line"> <a name="_a2"></a><a class="code" href="classproton_1_1work__queue.html">proton::work_queue</a> *work_queue_;</div><div class="line"> std::condition_variable sender_read y_;</div><div class="line"> <span class="keywordtype">int</span> queued_; <span class="comment">// Queued messages waiting to be sent</span></div><div class="line"> <span class="keywordtype">int</span> credit_; <span class="comment">// AMQP credit - number of messages we can send</span></div><div class="line"></div><div class="line"> <span class="keyword">public</span>:</div><div class="line"> sender(<a name="_a3"></a><a class="code" href="classproton_1_1container.html">proton::container</a>& cont, <span class="keyword">const</span> std::string& url, <span class="keyword">const</span> std::string& address)</div><div class="line"> : work_queue_(0), queued_(0), credit_(0)</div><div class="line"> {</div><div class="line"> cont.<a name="a4"></a><a class="code" href="classproton_1_1container.html#adfbfd13668611a525bb44328d7a3b1e8">open_sender</a>(url+<span class="stringliteral">"/"</span>+address , <a name="_a5"></a><a class="code" href="classproton_1_1connection__options.html">proton::connection_options</a>().handler(*<span class="keyword">this</span>));</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// Thread safe</span></div><div class="line"> <span class="keywordtype">void</span> send(<span class="keyword">const</span> <a name="_a6"></a><a class="code" href="classproton_1_1message.html">proton::message</a>& m) {</div><div class="line"> {</div><div class="line"> std::unique_lock<std::mutex> l(lock_);</div><div class="line"> <span class="comment">// Don't queue up more messages than we have credit for</span></div><div class="line"> <span class="keywordflow">while</span> (!work_queue_ || queued_ >= credit_) sender_ready_.wait(l);</div><div class="line"> ++queued_;</div><div class="line"> }</div><div class="line"> work_queue_-><a name ="a7"></a><a class="code" href="classproton_1_1work__queue.html#a59dae2153455bc095477a3b66a0b681e">add</a>([=]() { this->do_send(m); }); <span class="comment">// work_queue_ is thread safe</span></div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// Thread safe</span></div><div class="line"> <span class="keywordtype">void</span> close() {</div><div class="line"> work_queue()->add([=]() { sender_.<a name="a8"></a><a class="code" href="classproton_1_1link.html#aff302bb6016f2ae29f01bb4e07389a52">connection</a>().<a name="a9"></a><a class="code" href="classproton_1_1connection.html#a5ae591df94fc66ccb85cbb6565368bca">close</a>(); });</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keyword">private</span>:</div><div class="line"></div><div class="line"> <a class="code" href="classproton_1_1work__queue.html">proton::work_queue</a>* work_queue() {</div><div class="line"> < span class="comment">// Wait till work_queue_ and sender_ are initialized.</span></div><div class="line"> std::unique_lock<std::mutex> l(lock_);</div><div class="line"> <span class="keywordflow">while</span> (!work_queue_) sender_ready_.wait(l);</div><div class="line"> <span class="keywordflow">return</span> work_queue_;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// == messaging_handler overrides, only called in proton handler thread</span></div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> <a name="a10"></a><a class="code" href="classproton_1_1messaging__handler.html#ac655d56c64574c9eb7b10e80d32764f4">on_sender_open</a>(<a class="code" href="classproton_1_1sender.html">proton::sender</a>& s)<span class="keyword"> override </span>{</div><div class="line"> <span class="comment">// Make sure sender_ and work_queue_ are set atomically</span></div><div c lass="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> sender_ = s;</div><div class="line"> work_queue_ = &s.<a name="a11"></a><a class="code" href="classproton_1_1link.html#a7c755d6ac6385e007adb61966598ba63">work_queue</a>();</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> <a name="a12"></a><a class="code" href="classproton_1_1messaging__handler.html#a86c9509ba3ce1925150c5b7a9a937c94">on_sendable</a>(<a class="code" href="classproton_1_1sender.html">proton::sender</a>& s)<span class="keyword"> override </span>{</div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> credit_ = s.<a name="a13"></a><a class="code" href="classproton_1_1link.html#afd27bd11ba72d7df51c44f71b15749eb">credit</a>();</div><div class="line"> sender_ready_.notify_all(); <span class="comment">// Notify senders we have credit</span></ div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// work_queue work items is are automatically dequeued and called by proton</span></div><div class="line"> <span class="comment">// This function is called because it was queued by send()</span></div><div class="line"> <span class="keywordtype">void</span> do_send(<span class="keyword">const</span> <a class="code" href="classproton_1_1message.html">proton::message</a>& m) {</div><div class="line"> sender_.<a name="a14"></a><a class="code" href="classproton_1_1sender.html#a214eb30b24e6831d016a47b9dddda830">send</a>(m);</div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> --queued_; <span class="comment">// work item was consumed from the work_queue</span></div><div class="line"> credit_ = sender_.<a class="code" href="classproton_1_1link.html#afd27bd11ba72d7df51c44f71b15749eb">credit</a>(); <span class="comment">// update credit</span></div><div class="line"> sender_ready_.notify_all(); <span class="comment">// Notify senders we have space on queue</span></div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> <a name="a15"></a><a class="code" href="classproton_1_1messaging__handler.html#a042f595d1807eb1abe0195ab79357edd">on_error</a>(<span class="keyword">const</span> <a name="_a16"></a><a class="code" href="classproton_1_1error__condition.html">proton::error_condition</a>& e)<span class="keyword"> override </span>{</div><div class="line"> OUT(std::cerr << <span class="stringliteral">"unexpected error: "</span> << e << std::endl);</div><div class="line"> exit(1);</div><div class="line"> }</div><div class="line">};</div><div class="line"></div><div class="line"><span class="comment">// A thread safe receiving connection that blocks receiving th reads when there</span></div><div class="line"><span class="comment">// are no messages available, and maintains a bounded buffer of incoming</span></div><div class="line"><span class="comment">// messages by issuing AMQP credit only when there is space in the buffer.</span></div><div class="line"><span class="keyword">class </span>receiver : <span class="keyword">private</span> <a class="code" href="classproton_1_1messaging__handler.html">proton::messaging_handler</a> {</div><div class="line"> <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">size_t</span> MAX_BUFFER = 100; <span class="comment">// Max number of buffered messages</span></div><div class="line"></div><div class="line"> <span class="comment">// Used in proton threads only</span></div><div class="line"> <a name="_a17"></a><a class="code" href="classproton_1_1receiver.html">proton::receiver</a> receiver_;</div><div class="line"></div><div class="line"> <span cla ss="comment">// Used in proton and user threads, protected by lock_</span></div><div class="line"> std::mutex lock_;</div><div class="line"> <a class="code" href="classproton_1_1work__queue.html">proton::work_queue</a>* work_queue_;</div><div class="line"> std::queue<proton::message> buffer_; <span class="comment">// Messages not yet returned by receive()</span></div><div class="line"> std::condition_variable can_receive_; <span class="comment">// Notify receivers of messages</span></div><div class="line"></div><div class="line"> <span class="keyword">public</span>:</div><div class="line"></div><div class="line"> <span class="comment">// Connect to url</span></div><div class="line"> receiver(<a class="code" href="classproton_1_1container.html">proton::container</a>& cont, <span class="keyword">const</span> std::string& url, <span class="keyword">const</span> std::string& address)</div><div class="line"> : work_queue_()</div><div class="lin e"> {</div><div class="line"> <span class="comment">// NOTE:credit_window(0) disables automatic flow control.</span></div><div class="line"> <span class="comment">// We will use flow control to match AMQP credit to buffer capacity.</span></div><div class="line"> cont.<a name="a18"></a><a class="code" href="classproton_1_1container.html#a15df75d582af4ed83f0ffab9dcce84bf">open_receiver</a>(url+<span class="stringliteral">"/"</span>+address, <a name="_a19"></a><a class="code" href="classproton_1_1receiver__options.html">proton::receiver_options</a>().credit_window(0),</div><div class="line"> <a class="code" href="classproton_1_1connection__options.html">proton::connection_options</a>().handler(*<span class="keyword">this</span>));</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// Thread safe receive</span></div><div class="line"> <a class="code" href="classproton_1_1mes sage.html">proton::message</a> receive() {</div><div class="line"> std::unique_lock<std::mutex> l(lock_);</div><div class="line"> <span class="comment">// Wait for buffered messages</span></div><div class="line"> <span class="keywordflow">while</span> (!work_queue_ || buffer_.empty())</div><div class="line"> can_receive_.wait(l);</div><div class="line"> <a class="code" href="classproton_1_1message.html">proton::message</a> m = std::move(buffer_.front());</div><div class="line"> buffer_.pop();</div><div class="line"> <span class="comment">// Add a lambda to the work queue to call receive_done().</span></div><div class="line"> <span class="comment">// This will tell the handler to add more credit.</span></div><div class="line"> work_queue_-><a class="code" href="classproton_1_1work__queue.html#a59dae2153455bc095477a3b66a0b681e">add</a>([=]() { this->receive_done(); });</div><div class="line"> <span c lass="keywordflow">return</span> m;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> close() {</div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> <span class="keywordflow">if</span> (work_queue_) work_queue_-><a class="code" href="classproton_1_1work__queue.html#a59dae2153455bc095477a3b66a0b681e">add</a>([<span class="keyword">this</span>]() { this->receiver_.<a class="code" href="classproton_1_1link.html#aff302bb6016f2ae29f01bb4e07389a52">connection</a>().<a class="code" href="classproton_1_1connection.html#a5ae591df94fc66ccb85cbb6565368bca">close</a>(); });</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keyword">private</span>:</div><div class="line"> <span class="comment">// ==== The following are called by proton threads only.</span></div><div class="line"></div><div class="line"> <span class="keywordt ype">void</span> on_receiver_open(<a class="code" href="classproton_1_1receiver.html">proton::receiver</a>& r)<span class="keyword"> override </span>{</div><div class="line"> receiver_ = r;</div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> work_queue_ = &receiver_.<a class="code" href="classproton_1_1link.html#a7c755d6ac6385e007adb61966598ba63">work_queue</a>();</div><div class="line"> receiver_.<a name="a20"></a><a class="code" href="classproton_1_1receiver.html#a84d3a001340d11201e03c6ed7c763641">add_credit</a>(MAX_BUFFER); <span class="comment">// Buffer is empty, initial credit is the limit</span></div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> on_message(<a name="_a21"></a><a class="code" href="classproton_1_1delivery.html">proton::delivery</a> &d, <a class="code" href="classproton_1_1message.html">proton::message</a> &m)<spa n class="keyword"> override </span>{</div><div class="line"> <span class="comment">// Proton automatically reduces credit by 1 before calling on_message</span></div><div class="line"> std::lock_guard<std::mutex> l(lock_);</div><div class="line"> buffer_.push(m);</div><div class="line"> can_receive_.notify_all();</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// called via work_queue</span></div><div class="line"> <span class="keywordtype">void</span> receive_done() {</div><div class="line"> <span class="comment">// Add 1 credit, a receiver has taken a message out of the buffer.</span></div><div class="line"> receiver_.<a class="code" href="classproton_1_1receiver.html#a84d3a001340d11201e03c6ed7c763641">add_credit</a>(1);</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordtype">void</span> on_error(<span class="keyword">const</span > <a class="code" > href="classproton_1_1error__condition.html">proton::error_condition</a>& > e)<span class="keyword"> override </span>{</div><div class="line"> > OUT(std::cerr << <span class="stringliteral">"unexpected error: > "</span> << e << std::endl);</div><div class="line"> > exit(1);</div><div class="line"> }</div><div class="line">};</div><div > class="line"></div><div class="line"><span class="comment">// ==== Example > code using the sender and receiver</span></div><div class="line"></div><div > class="line"><span class="comment">// Send n messages</span></div><div > class="line"><span class="keywordtype">void</span> send_thread(sender& > s, <span class="keywordtype">int</span> n) {</div><div class="line"> > <span class="keyword">auto</span> <span class="keywordtype">id</span> = > std::this_thread::get_id();</div><div class="line"> <span > class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; > i < n; ++i) {</div><d iv class="line"> std::ostringstream ss;</div><div class="line"> ss << std::this_thread::get_id() << <span class="stringliteral">"-"</span> << i;</div><div class="line"> s.send(<a class="code" href="classproton_1_1message.html">proton::message</a>(ss.str()));</div><div class="line"> OUT(std::cout << <span class="keywordtype">id</span> << <span class="stringliteral">" sent \""</span> << ss.str() << <span class="charliteral">'"'</span> << std::endl);</div><div class="line"> }</div><div class="line"> OUT(std::cout << <span class="keywordtype">id</span> << <span class="stringliteral">" sent "</span> << n << std::endl);</div><div class="line">}</div><div class="line"></div><div class="line"><span class="comment">// Receive messages till atomic remaining count is 0.</span></div><div class="line"><span class="comment">// remaining is share d among all receiving threads</span></div><div class="line"><span class="keywordtype">void</span> receive_thread(receiver& r, std::atomic_int& remaining) {</div><div class="line"> <span class="keyword">auto</span> <span class="keywordtype">id</span> = std::this_thread::get_id();</div><div class="line"> <span class="keywordtype">int</span> n = 0;</div><div class="line"> <span class="comment">// atomically check and decrement remaining *before* receiving.</span></div><div class="line"> <span class="comment">// If it is 0 or less then return, as there are no more</span></div><div class="line"> <span class="comment">// messages to receive so calling r.receive() would block forever.</span></div><div class="line"> <span class="keywordflow">while</span> (remaining-- > 0) {</div><div class="line"> <span class="keyword">auto</span> m = r.receive();</div><div class="line"> ++n;</div><div class="line"> OUT(std::cout << <span class="keywor dtype">id</span> << <span class="stringliteral">" received \""</span> << m.body() << <span class="charliteral">'"'</span> << std::endl);</div><div class="line"> }</div><div class="line"> OUT(std::cout << <span class="keywordtype">id</span> << <span class="stringliteral">" received "</span> << n << <span class="stringliteral">" messages"</span> << std::endl);</div><div class="line">}</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main(<span class="keywordtype">int</span> argc, <span class="keyword">const</span> <span class="keywordtype">char</span> **argv) {</div><div class="line"> <span class="keywordflow">try</span> {</div><div class="line"> <span class="keywordflow">if</span> (argc != 5) {</div><div class="line"> std::cerr <<</div><div class="line"> <span class="stringliteral">"Usage: "< /span> << argv[0] << <span class="stringliteral">" MESSAGE-COUNT THREAD-COUNT URL\n"</span></div><div class="line"> <span class="stringliteral">"CONNECTION-URL: connection address, e.g.'amqp://127.0.0.1'\n"</span></div><div class="line"> <span class="stringliteral">"AMQP-ADDRESS: AMQP node address, e.g. 'examples'\n"</span></div><div class="line"> <span class="stringliteral">"MESSAGE-COUNT: number of messages to send\n"</span></div><div class="line"> <span class="stringliteral">"THREAD-COUNT: number of sender/receiver thread pairs\n"</span>;</div><div class="line"> <span class="keywordflow">return</span> 1;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keyword">const</span> <span class="keywordtype">char</span> *url = argv[1];</div><div class="line"> <span class="keyword">con st</span> <span class="keywordtype">char</span> *address = argv[2];</div><div class="line"> <span class="keywordtype">int</span> n_messages = atoi(argv[3]);</div><div class="line"> <span class="keywordtype">int</span> n_threads = atoi(argv[4]);</div><div class="line"> <span class="keywordtype">int</span> count = n_messages * n_threads;</div><div class="line"></div><div class="line"> <span class="comment">// Total messages to be received, multiple receiver threads will decrement this.</span></div><div class="line"> std::atomic_int remaining;</div><div class="line"> remaining.store(count);</div><div class="line"></div><div class="line"> <span class="comment">// Run the proton container</span></div><div class="line"> <a class="code" href="classproton_1_1container.html">proton::container</a> container;</div><div class="line"> <span class="keyword">auto</span> container_thread = std::thread([&]() { container.<a name="a22" ></a><a class="code" >href="classproton_1_1container.html#a13a43e6d814de94978c515cb084873b1">run</a>(); > });</div><div class="line"></div><div class="line"> <span >class="comment">// A single sender and receiver to be shared by all the >threads</span></div><div class="line"> sender send(container, url, >address);</div><div class="line"> receiver recv(container, url, >address);</div><div class="line"></div><div class="line"> <span >class="comment">// Start receiver threads, then sender >threads.</span></div><div class="line"> <span class="comment">// >Starting receivers first gives all receivers a chance to compete for >messages.</span></div><div class="line"> >std::vector<std::thread> threads;</div><div class="line"> >threads.reserve(n_threads*2); <span class="comment">// Avoid re-allocation >once threads are started</span></div><div class="line"> <span >class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i >< n_threads; ++i)</div><div class="line"> threads.push_back(std::thread([&]() { receive_thread(recv, remaining); }));</div><div class="line"> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < n_threads; ++i)</div><div class="line"> threads.push_back(std::thread([&]() { send_thread(send, n_messages); }));</div><div class="line"></div><div class="line"> <span class="comment">// Wait for threads to finish</span></div><div class="line"> <span class="keywordflow">for</span> (<span class="keyword">auto</span>& t : threads) t.join();</div><div class="line"> send.close();</div><div class="line"> recv.close();</div><div class="line"> container_thread.join();</div><div class="line"> <span class="keywordflow">if</span> (remaining > 0)</div><div class="line"> <span class="keywordflow">throw</span> std::runtime_error(<span class="stringliteral">"not all mess ages were received"</span>);</div><div class="line"> std::cout << count << <span class="stringliteral">" messages sent and received"</span> << std::endl;</div><div class="line"></div><div class="line"> <span class="keywordflow">return</span> 0;</div><div class="line"> } <span class="keywordflow">catch</span> (<span class="keyword">const</span> std::exception& e) {</div><div class="line"> std::cerr << e.what() << std::endl;</div><div class="line"> }</div><div class="line"> <span class="keywordflow">return</span> 1;</div><div class="line">}</div></div><!-- fragment --> </div><!-- contents --> </div><!-- doc-content --> <!-- start footer part --> <div id="nav-path" class="navpath"><!-- id is needed for treeview function! --> --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
