#Piccollage defined free

On the other hand, in the second call to Kernel#raise the raised exception is a NoMethodError - as we defined it as first argument of the method call. a creative work that resembles such a composition in incorporating various materials or elements. In the first call to Kernel#raise, we can see that the method raises a RuntimeError - as no error class is explicitly specified as argument. collage: noun an artistic composition made of various materials (such as paper, cloth, or wood) glued on a surface. The Kernel#raise method is in charge of raising errors in Ruby irb> raise 'an error occurred' RuntimeError: an error occurred irb> raise NoMethodError, 'an error occurred' NoMethodError: an error occurred

#Piccollage defined free

Feel free to browse the Exception official documentation for further information. These methods are defined in the Exception class and used by all of its children.įor example, the Exception#message method returns the message associated to the error when the Exception#backtrace method returns the error backtrace. NB: feel free to have a look to the Ruby Object Model: Part I article if you’re unfamiliar with the ancestor chain in Ruby.Īs an error is a class, Ruby provides a bunch of instance methods to deal with an error. That’s why an error is commonly called an “exception” in Ruby. You will have to configure it on a VM machine for Docker for Mac.Thank you for your time! What’s an error in Ruby ?Īs Ruby is a fully object-oriented language, an error is an instance of a class that includes the Exception class in its ancestor chain irb> ? Exception => true irb> ? Exception => true Redis must be restarted after THP is disabled. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. This will create latency and memory usage issues with Redis. WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. Write the configuration in docker-compose.yml: version: '3' services: redis: image: redis:5.0.7 volumes: - redis-data:/data ports: - '6379:6379' volumes: redis-data: driver: localĪnd start the server by running the command: docker-compose up In this article, we will use the Redis Stream for multiple connections to share data.įirst, we will create a Redis server using Docker. In Stream, all the messages are stored in the stream indefinitely, and that allows different consumers to know what a new message from its point by remembering the ID of the last message.įor instance, in a chat application, you will be able to see all messages from the beginning and to know which message is a new one, even though you enter the room in the middle of the day. While in Pub/Sub, the messages are sent and are never stored.

The main difference between them is the way to store messages. The idea of Redis Stream is related to Redis Pub/Sub, but there are some fundamental differences in the way you consume data.

In version 5, Redis provides a new feature called Redis Stream. By using this, the publishers can send messages to any number of subscribers on a channel without a knowledge of what subscribers there are. In version 2, Redis provided a Pub/Sub feature that can decouple publishers and subscribers. Subscriptions maintain an active connection via WebSockets and get you notified immediately after detecting updates. GraphQL subscriptions enable you to fetch data periodically without polling from clients.