Provide a method to shutdown a producer, update docs

.gitignore

@@ -1,3 +1,4 @@
 example-dev
 node_modules
-.idea
+.idea
+package-lock.json

README.md

@@ -117,7 +117,7 @@ so the message is re-queued again and considered to be unacknowledged.
 * Producer class constructor `Producer(queueName, config)`:
   * `queueName` *(string): Required.* The name of the queue where produced messages are queued.
   * `config` *(object): Required.* Configuration object.
-* A Producer instance provides 2 methods:
+* A Producer instance provides 3 methods:
   * `produce(message, cb)`: Produce a message.
     * `message` *(mixed): Required.* The actual message, to be consumed by a consumer.
     * `cb(err)` *(function): Required.* Callback function. When called without error argument, the message is 
@@ -127,7 +127,10 @@ so the message is re-queued again and considered to be unacknowledged.
     * `ttl` *(Integer): Required.* Message TTL in milliseconds.
     * `cb(err)` *(function): Required.* Callback function. When called without error argument, the message is 
     successfully published.
-
+  * `shutdown()`: Gracefully shutdown the producer and disconnect from the redis server. This method should be used 
+  only in rare cases where we need to force the producer to terminate its work. Normally a producer should be kept 
+  always online.
+
 #### Producer example
 
 ```javascript
@@ -141,19 +144,15 @@ const Producer = require('redis-smq').Producer;
 const producer = new Producer('test_queue', config);
 
 producer.produce({ hello: 'world' }, (err) => {
-    if (err) throw err;
-    else {
-        console.log('Successfully published!');
-        process.exit(0);
-    }
+    if (err) throw err;   
+    console.log('Successfully published!');
+    producer.shutdown();
 });
 
 producer.produceWithTTL({ hello: 'world' }, 60000, (err) => {
     if (err) throw err;
-    else {
-        console.log('Successfully published!');
-        process.exit(0);
-    }
+    console.log('Successfully published!');
+    producer.shutdown();    
 });
 ```
 

example/test-queue-producer-launch.js

@@ -26,7 +26,7 @@ produceNTimes(producer, { hello: 'world' }, 1000000, (err) => {
     if (err) throw err;
     else {
         console.log('Produced successfully!');
-        process.exit(0);
+        producer.shutdown();
     }
 });
 

src/producer.js

@@ -72,6 +72,15 @@ class Producer extends EventEmitter {
         this[produceMessage](message, ttl, cb);
     }
 
+    /**
+     *
+     * @returns {boolean}
+     */
+    shutdown() {
+        if (this.stats) this.stats.stop();
+        this.client.end(true);
+        this.client = null;
+    }
 }
 
 module.exports = Producer;

src/stats.js

@@ -29,6 +29,7 @@ function stats(eventEmitter, config) {
         clearInterval(interval);
         client.end(true);
         client = null;
+        halt = false;
         eventEmitter.emit('stats_halt');
     }
 
@@ -113,19 +114,24 @@ function stats(eventEmitter, config) {
 
         /**
          *
+         * @returns {boolean}
          */
         start() {
-            halt = false;
+            if (halt) return false;
             client = redisClient.getNewInstance(config);
             if (eventEmitter.hasOwnProperty('consumerId')) runConsumerStats();
             else runProducerStats();
+            return true;
         },
 
         /**
          *
+         * @returns {boolean}
          */
         stop() {
+            if (halt) return false;
             halt = true;
+            return true;
         },
     };
 }