Class: Warren::FrameworkAdaptor::RailsAdaptor::ConnectionMissing

Inherits:
Object
  • Object
show all
Defined in:
lib/warren/framework_adaptor/rails_adaptor.rb

Overview

Matches errors associated with database connection loss. To understand exactly how this works, we need to go under the hood of ‘rescue`. When an exception is raised in Ruby, the interpreter begins unwinding the stack, looking for `rescue` statements. For each one it finds it performs the check `ExceptionClass === raised_exception`, and if this returns true, it enters the rescue block, otherwise it continues unwinding the stack. Under normal circumstances Class#=== returns true for instances of that class. Here we override that behaviour and explicitly check for a database connection instead. This ensures that regardless of what exception gets thrown if we loose access to the database, we correctly handle the message

Class Method Summary collapse

Class Method Details

.===(_) ⇒ Object 



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# File 'lib/warren/framework_adaptor/rails_adaptor.rb', line 52

def self.===(_)
  # We used to inspect the exception, and try and check it against a list
  # of errors that might indicate connectivity issues. But this list
  # just grew and grew over time. So instead we just explicitly check
  # the outcome
  !ActiveRecord::Base.connection.active?
rescue StandardError => _e
  # Unfortunately ActiveRecord::Base.connection.active? can throw an
  # exception if it is unable to connect, and furthermore the class
  # depends on the adapter used.
  true
end