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scheduled_send.cpp

Shows how to use proton::container::schedule to schedule a timed callback.

Shows how to use proton::container::schedule to schedule a timed callback.This version uses std::function and so requires C++11 or better. For a C++03 compatible approach see scheduled_send_03.cpp.

/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
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*/
#include "options.hpp"
#include <proton/container.hpp>
#include <proton/connection.hpp>
#include <proton/message.hpp>
#include <proton/messaging_handler.hpp>
#include <proton/sender.hpp>
#include <proton/tracker.hpp>
#include <proton/work_queue.hpp>
#include <iostream>
// Send messages at a constant rate one per interval. cancel after a timeout.
class scheduled_sender : public proton::messaging_handler {
private:
std::string url;
proton::sender sender;
proton::duration interval, timeout;
proton::work_queue* work_queue;
bool ready, canceled;
public:
scheduled_sender(const std::string &s, double d, double t) :
url(s),
interval(int(d*proton::duration::SECOND.milliseconds())), // Send interval.
timeout(int(t*proton::duration::SECOND.milliseconds())), // Cancel after timeout.
work_queue(0),
ready(true), // Ready to send.
canceled(false) // Canceled.
{}
// The awkward looking double lambda is necessary because the scheduled lambdas run in the container context
// and must arrange lambdas for send and close to happen in the connection context.
void on_container_start(proton::container &c) override {
c.open_sender(url);
}
void on_sender_open(proton::sender &s) override {
sender = s;
work_queue = &s.work_queue();
// Call this->cancel after timeout.
s.container().schedule(timeout, [this]() { this->work_queue->add( [this]() { this->cancel(); }); });
// Start regular ticks every interval.
s.container().schedule(interval, [this]() { this->work_queue->add( [this]() { this->tick(); }); });
}
void cancel() {
canceled = true;
sender.connection().close();
}
void tick() {
// Schedule the next tick unless we have been cancelled.
if (!canceled)
sender.container().schedule(interval, [this]() { this->work_queue->add( [this]() { this->tick(); }); });
if (sender.credit() > 0) // Only send if we have credit
send();
else
ready = true; // Set the ready flag, send as soon as we get credit.
}
void on_sendable(proton::sender &) override {
if (ready) // We have been ticked since the last send.
send();
}
void send() {
std::cout << "send" << std::endl;
sender.send(proton::message("ping"));
ready = false;
}
};
int main(int argc, char **argv) {
std::string address("127.0.0.1:5672/examples");
double interval = 1.0;
double timeout = 5.0;
example::options opts(argc, argv);
opts.add_value(address, 'a', "address", "connect and send to URL", "URL");
opts.add_value(interval, 'i', "interval", "send a message every INTERVAL seconds", "INTERVAL");
opts.add_value(timeout, 't', "timeout", "stop after T seconds", "T");
try {
opts.parse();
scheduled_sender h(address, interval, timeout);
proton::container(h).run();
return 0;
} catch (const example::bad_option& e) {
std::cout << opts << std::endl << e.what() << std::endl;
} catch (const std::exception& e) {
std::cerr << e.what() << std::endl;
}
return 1;
}
proton::connection::close
void close()
Close the connection.
proton::container
A top-level container of connections, sessions, and links.
Definition container.hpp:49
proton::container::run
void run()
Run the container in the current thread.
proton::container::open_sender
returned< sender > open_sender(const std::string &addr_url)
Open a connection and sender for addr_url.
proton::container::schedule
void schedule(duration dur, work fn)
Schedule fn for execution after a duration.
proton::duration
A span of time in milliseconds.
Definition duration.hpp:39
proton::duration::SECOND
static const duration SECOND
One second.
Definition duration.hpp:55
proton::link::work_queue
class work_queue & work_queue() const
Get the work_queue for the link.
proton::link::container
class container & container() const
The container for this link.
proton::link::credit
int credit() const
Credit available on the link.
proton::link::connection
class connection connection() const
The connection that owns this link.
proton::message
An AMQP message.
Definition message.hpp:48
proton::messaging_handler
Handler for Proton messaging events.
Definition messaging_handler.hpp:69
proton::messaging_handler::on_sendable
virtual void on_sendable(sender &)
A message can be sent.
proton::messaging_handler::on_container_start
virtual void on_container_start(container &)
The container event loop is starting.
proton::messaging_handler::on_sender_open
virtual void on_sender_open(sender &)
The remote peer opened the link.
proton::sender
A channel for sending messages.
Definition sender.hpp:40
proton::sender::send
tracker send(const message &m)
Send a message on the sender.
proton::work_queue
Unsettled API - A context for thread-safe execution of work.
Definition work_queue.hpp:327
proton::work_queue::add
bool add(work fn)
Unsettled API - Add work fn to the work queue.
connection.hpp
A connection to a remote AMQP peer.
container.hpp
A top-level container of connections, sessions, and links.
message.hpp
An AMQP message.
messaging_handler.hpp
Handler for Proton messaging events.
sender.hpp
A channel for sending messages.
tracker.hpp
A tracker for a sent message.
work_queue.hpp
Unsettled API - A context for thread-safe execution of work.