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Forked from carlhoerberg/reconnect.js
Created November 13, 2018 17:55
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How to build reconnect logic for amqplib
var amqp = require('amqplib/callback_api');
// if the connection is closed or fails to be established at all, we will reconnect
var amqpConn = null;
function start() {
amqp.connect(process.env.CLOUDAMQP_URL + "?heartbeat=60", function(err, conn) {
if (err) {
console.error("[AMQP]", err.message);
return setTimeout(start, 1000);
}
conn.on("error", function(err) {
if (err.message !== "Connection closing") {
console.error("[AMQP] conn error", err.message);
}
});
conn.on("close", function() {
console.error("[AMQP] reconnecting");
return setTimeout(start, 1000);
});
console.log("[AMQP] connected");
amqpConn = conn;
whenConnected();
});
}
function whenConnected() {
startPublisher();
startWorker();
}
var pubChannel = null;
var offlinePubQueue = [];
function startPublisher() {
amqpConn.createConfirmChannel(function(err, ch) {
if (closeOnErr(err)) return;
ch.on("error", function(err) {
console.error("[AMQP] channel error", err.message);
});
ch.on("close", function() {
console.log("[AMQP] channel closed");
});
pubChannel = ch;
while (true) {
var m = offlinePubQueue.shift();
if (!m) break;
publish(m[0], m[1], m[2]);
}
});
}
// method to publish a message, will queue messages internally if the connection is down and resend later
function publish(exchange, routingKey, content) {
try {
pubChannel.publish(exchange, routingKey, content, { persistent: true },
function(err, ok) {
if (err) {
console.error("[AMQP] publish", err);
offlinePubQueue.push([exchange, routingKey, content]);
pubChannel.connection.close();
}
});
} catch (e) {
console.error("[AMQP] publish", e.message);
offlinePubQueue.push([exchange, routingKey, content]);
}
}
// A worker that acks messages only if processed succesfully
function startWorker() {
amqpConn.createChannel(function(err, ch) {
if (closeOnErr(err)) return;
ch.on("error", function(err) {
console.error("[AMQP] channel error", err.message);
});
ch.on("close", function() {
console.log("[AMQP] channel closed");
});
ch.prefetch(10);
ch.assertQueue("jobs", { durable: true }, function(err, _ok) {
if (closeOnErr(err)) return;
ch.consume("jobs", processMsg, { noAck: false });
console.log("Worker is started");
});
function processMsg(msg) {
work(msg, function(ok) {
try {
if (ok)
ch.ack(msg);
else
ch.reject(msg, true);
} catch (e) {
closeOnErr(e);
}
});
}
});
}
function work(msg, cb) {
console.log("Got msg", msg.content.toString());
cb(true);
}
function closeOnErr(err) {
if (!err) return false;
console.error("[AMQP] error", err);
amqpConn.close();
return true;
}
setInterval(function() {
publish("", "jobs", new Buffer("work work work"));
}, 1000);
start();
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