Add the ability to specify min notification interval

README.md

@@ -855,6 +855,17 @@ Rails.application.config.middleware.use ExceptionNotification::Rack,
  }
 ```
 
+### :min_notification_interval
+
+*Something that responds to `call` or `to_i`*
+
+Ignores repeated exceptions which happen in a set interval in seconds. Values of `0` or `nil` means do not ignore repeated exceptions. Only works if Rails cache is available.
+
+```ruby
+Rails.application.config.middleware.use ExceptionNotification::Rack,
+ :min_notification_interval = 600 # At most one exception every 10 minutes
+```
+
 ### :ignore_if
 
 *Lambda, default: nil*

lib/exception_notification/rack.rb

@@ -5,7 +5,13 @@ class CascadePassException < Exception; end
  def initialize(app, options = {})
  @app = app
 
- ExceptionNotifier.ignored_exceptions = options.delete(:ignore_exceptions) if options.key?(:ignore_exceptions)
+ if options.key?(:ignore_exceptions)
+ ExceptionNotifier.ignored_exceptions = options.delete(:ignore_exceptions)
+ end
+
+ if options.key?(:min_notification_interval)
+ ExceptionNotifier.min_notification_interval = options.delete(:min_notification_interval)
+ end
 
  if options.key?(:ignore_if)
  rack_ignore = options.delete(:ignore_if)

lib/exception_notifier.rb

@@ -6,6 +6,7 @@
 module ExceptionNotifier
 
  autoload :BacktraceCleaner, 'exception_notifier/modules/backtrace_cleaner'
+ autoload :Throttling, 'exception_notifier/modules/throttling'
 
  autoload :Notifier, 'exception_notifier/notifier'
  autoload :EmailNotifier, 'exception_notifier/email_notifier'
@@ -86,9 +87,14 @@ def clear_ignore_conditions!
  @@ignores.clear
  end
 
+ def min_notification_interval=(interval)
+ Throttling.min_notification_interval = interval
+ end
+
  private
  def ignored?(exception, options)
- @@ignores.any?{ |condition| condition.call(exception, options) }
+ ignored = @@ignores.any? { |condition| condition.call(exception, options) }
+ ignored || Throttling.ignore_exception?(exception)
  rescue Exception => e
  raise e if @@testing_mode
 

lib/exception_notifier/modules/throttling.rb

@@ -0,0 +1,61 @@
+require 'digest/sha1'
+
+module ExceptionNotifier::Throttling
+
+ @min_notification_interval = 0
+
+ class << self
+
+ def ignore_exception?(exception)
+ return false unless rails_cache_available?
+
+ interval = min_notification_interval_for(exception)
+ return false if interval <= 0
+
+ key = ['exception-notification-throttling-', exception_signature(exception)].join('-')
+
+ if Rails.cache.read(key)
+ true
+ else
+ Rails.cache.write(key, true, expires_in: interval)
+ false
+ end
+ end
+
+ def min_notification_interval=(interval)
+ @min_notification_interval = normalize_min_notification_interval(interval)
+ end
+
+ private
+
+ attr_reader :min_notification_interval
+
+ def rails_cache_available?
+ defined?(Rails) && Rails.respond_to?(:cache)
+ end
+
+ def exception_signature(exception)
+ signature = [exception.class, exception.message, exception.backtrace].join('')
+ Digest::SHA1.hexdigest(signature)
+ end
+
+ def normalize_min_notification_interval(interval)
+ return interval if interval.respond_to?(:call)
+
+ begin
+ interval.to_i
+ rescue
+ raise "Invalid min notification interval: #{interval.inspect}"
+ end
+ end
+
+ def min_notification_interval_for(exception)
+ interval = min_notification_interval
+ if interval.respond_to?(:call)
+ normalize_min_notification_interval(interval.call(exception))
+ else
+ interval
+ end
+ end
+ end
+end