NSQ Ruby client
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README.md

nsq-ruby

nsq-ruby is a simple NSQ client library written in Ruby.

  • The code is straightforward.
  • It has no dependencies.
  • It's well tested.
  • It's being used in production and has processed billions of messages.

Quick start

Publish messages

require 'nsq'
producer = Nsq::Producer.new(
  nsqd: '127.0.0.1:4150',
  topic: 'some-topic'
)

# Write a message to NSQ
producer.write('some-message')

# Write a bunch of messages to NSQ (uses mpub)
producer.write('one', 'two', 'three', 'four', 'five')

# Write a deferred message to NSQ (uses dpub)

# Message deferred of 10s
producer.deferred_write(10, 'one')

# Message deferred of 1250ms
producer.deferred_write(1.25, 'one')

# Close the connection
producer.terminate

Consume messages

require 'nsq'
consumer = Nsq::Consumer.new(
  nsqlookupd: '127.0.0.1:4161',
  topic: 'some-topic',
  channel: 'some-channel'
)

# Pop a message off the queue
msg = consumer.pop
puts msg.body
msg.finish

# Close the connections
consumer.terminate

Producer

Initialization

The Nsq::Producer constructor takes the following options:

Option Description Default
topic Topic to which to publish messages
nsqd Host and port of the nsqd instance '127.0.0.1:4150'
nsqlookupd Use lookupd to auto discover nsqds
tls_v1 Flag for tls v1 connections false
tls_options Optional keys+certs for TLS connections

For example, if you'd like to publish messages to a single nsqd.

producer = Nsq::Producer.new(
  nsqd: '6.7.8.9:4150',
  topic: 'topic-of-great-esteem'
)

Alternatively, you can use nsqlookupd to find all nsqd nodes in the cluster. When you instantiate Nsq::Producer in this way, it will automatically maintain connections to all nsqd instances. When you publish a message, it will be sent to a random nsqd instance.

producer = Nsq::Producer.new(
  nsqlookupd: ['1.2.3.4:4161', '6.7.8.9:4161'],
  topic: 'topic-of-great-esteem'
)

If you need to connect using SSL/TLS Authentication via tls_options

producer = Nsq::Producer.new(
  nsqlookupd: ['1.2.3.4:4161', '6.7.8.9:4161'],
  topic: 'topic-of-great-esteem',
  tls_v1: true,
  tls_options: {
    key: '/path/to/ssl/key.pem',
    certificate: '/path/to/ssl/certificate.pem',
    ca_certificate: '/path/to/ssl/ca_certificate.pem',
    verify_mode: OpenSSL::SSL::VERIFY_PEER
  }
)

If you need to connect using simple tls_v1

producer = Nsq::Producer.new(
  nsqlookupd: ['1.2.3.4:4161', '6.7.8.9:4161'],
  topic: 'topic-of-great-esteem',
  tls_v1: true
)

#write

Publishes one or more messages to nsqd. If you give it a single argument, it will send it to nsqd via PUB. If you give it multiple arguments, it will send all those messages to nsqd via MPUB. It will automatically call to_s on any arguments you give it.

# Send a single message via PUB
producer.write(123)

# Send three messages via MPUB
producer.write(456, 'another-message', { key: 'value' }.to_json)

If its connection to nsqd fails, it will automatically try to reconnect with exponential backoff. Any messages that were sent to #write will be queued and transmitted after reconnecting.

Note we don't wait for nsqd to acknowledge our writes. As a result, if the connection to nsqd fails, you can lose messages. This is acceptable for our use cases, mostly because we are sending messages to a local nsqd instance and failure is very rare.

#write_to_topic

Publishes one or more messages to nsqd. Like #write, but allows you to specify the topic. Use this method if you want a single producer instance to write to multiple topics.

# Send a single message via PUB to the topic 'rutabega'
producer.write_to_topic('rutabega', 123)

# Send multiple messages via MPUB to the topic 'kohlrabi'
producer.write_to_topic('kohlrabi', 'a', 'b', 'c')

#connected?

Returns true if it's currently connected to nsqd and false if not.

#terminate

Closes the connection to nsqd and stops it from trying to automatically reconnect.

This is automatically called at_exit, but it's good practice to close your producers when you're done with them.

Consumer

Initialization

Option Description Default
topic Topic to consume messages from
channel Channel name for this consumer
nsqlookupd Use lookupd to automatically discover nsqds
nsqd Connect directly to a single nsqd instance '127.0.0.1:4150'
max_in_flight Max number of messages for this consumer to have in flight at a time 1
discovery_interval Seconds between queue discovery via nsqlookupd 60.0
msg_timeout Milliseconds before nsqd will timeout a message 60000
tls_v1 Flag for tls v1 connections false
tls_options Optional keys and certificates for TLS connections

For example:

consumer = Nsq::Consumer.new(
  topic: 'the-topic',
  channel: 'my-channel',
  nsqlookupd: ['127.0.0.1:4161', '4.5.6.7:4161'],
  max_in_flight: 100,
  discovery_interval: 30,
  msg_timeout: 120_000,
  tls_v1: true,
  tls_options: {
    key: '/path/to/ssl/key.pem',
    certificate: '/path/to/ssl/certificate.pem',
    ca_certificate: '/path/to/ssl/ca_certificate.pem',
    verify_mode: OpenSSL::SSL::VERIFY_PEER
  }
)

Notes:

  • nsqlookupd can be a string or array of strings for each nsqlookupd service you'd like to use. The format is "<host>:<http-port>". If you specify nsqlookupd, it ignores the nsqd option.
  • max_in_flight is for the total max in flight across all the connections, but to make the implementation of nsq-ruby as simple as possible, the minimum max_in_flight per connection is 1. So if you set max_in_flight to 1 and are connected to 3 nsqds, you may have up to 3 messages in flight at a time.

#pop

nsq-ruby works by maintaining a local queue of in flight messages from NSQ. To get at these messages, just call pop.

message = consumer.pop

If there are messages on the queue, pop will return one immediately. If there are no messages on the queue, pop will block execution until one arrives.

Be aware, while #pop is blocking, your process will be unresponsive. This can be a problem in certain cases, like if you're trying to gracefully restart a worker process by sending it a TERM signal. See #pop_without_blocking for information on how to mitigate this issue.

#pop_without_blocking

This is just like #pop except it doesn't block. It always returns immediately. If there are no messages in the queue, it will return nil.

If you're consuming from a low-volume topic and don't want to get stuck in a blocking state, you can use this method to consume messages like so:

loop do
  if msg = @messages.pop_without_blocking
    # do something
    msg.finish
  else
    # wait for a bit before checking for new messages
    sleep 0.01
  end
end

#size

size returns the size of the local message queue.

#terminate

Gracefully closes all connections and stops the consumer. You should call this when you're finished with a consumer object.

Message

The Message object is what you get when you call pop on a consumer. Once you have a message, you'll likely want to get its contents using the #body method, and then call #finish once you're done with it.

body

Returns the body of the message as a UTF-8 encoded string.

attempts

Returns the number of times this message was attempted to be processed. For most messages this should be 1 (since it will be your first attempt processing them). If it's more than 1, that means that you requeued the message or it timed out in flight.

timestamp

Returns the time this message was originally sent to NSQ as a Time object.

#finish

Notify NSQ that you've completed processing of this message.

#touch

Tells NSQ to reset the message timeout for this message so you have more time to process it.

#requeue(timeout = 0)

Tells NSQ to requeue this message. Called with no arguments, this will requeue the message and it will be available to be received immediately.

Optionally you can pass a number of milliseconds as an argument. This tells NSQ to delay its requeueing by that number of milliseconds.

Logging

By default, nsq-ruby doesn't log anything. To enable logging, use Nsq.logger= and point it at a Ruby Logger instance. Like this:

Nsq.logger = Logger.new(STDOUT)

Requirements

NSQ v0.2.29 or later for IDENTIFY metadata specification (0.2.28) and per- connection timeout support (0.2.29).

Supports

  • Discovery via nsqlookupd
  • Automatic reconnection to nsqd
  • Producing to all nsqd instances automatically via nsqlookupd
  • TLS

Does not support

  • Compression
  • Backoff

If you need more advanced features, like these, you should check out Krakow, a more fully featured NSQ client for Ruby.

Testing

Run the tests like this:

rake spec

Want a deluge of logging while running the specs to help determine what is going on?

VERBOSE=true rake spec

Is this production ready?

Yes! It's used in several critical parts of our infrastructure at Wistia and currently produces and consumes hundreds of millions of messages a day.

Authors & Contributors

MIT License

Copyright (C) 2016 Wistia, Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.