Class: Unleash::ToggleFetcher

Inherits:
Object
  • Object
show all
Defined in:
lib/unleash/toggle_fetcher.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ToggleFetcher

Returns a new instance of ToggleFetcher.



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# File 'lib/unleash/toggle_fetcher.rb', line 11

def initialize
  self.etag = nil
  self.toggle_cache = nil
  self.toggle_lock = Mutex.new
  self.toggle_resource = ConditionVariable.new
  self.retry_count = 0

  # start by fetching synchronously, and failing back to reading the backup file.
  begin
    fetch
  rescue Exception => e
    Unleash.logger.warn "ToggleFetcher was unable to fetch from the network, attempting to read from backup file."
    Unleash.logger.debug "Exception Caught: #{e}"
    read!
  end

  # once initialized, somewhere else you will want to start a loop with fetch()
end

Instance Attribute Details

#etag ⇒ Object

Returns the value of attribute etag.



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# File 'lib/unleash/toggle_fetcher.rb', line 9

def etag
  @etag
end

#retry_count ⇒ Object

Returns the value of attribute retry_count.



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# File 'lib/unleash/toggle_fetcher.rb', line 9

def retry_count
  @retry_count
end

#toggle_cache ⇒ Object

Returns the value of attribute toggle_cache.



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# File 'lib/unleash/toggle_fetcher.rb', line 9

def toggle_cache
  @toggle_cache
end

#toggle_lock ⇒ Object

Returns the value of attribute toggle_lock.



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# File 'lib/unleash/toggle_fetcher.rb', line 9

def toggle_lock
  @toggle_lock
end

#toggle_resource ⇒ Object

Returns the value of attribute toggle_resource.



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# File 'lib/unleash/toggle_fetcher.rb', line 9

def toggle_resource
  @toggle_resource
end

Instance Method Details

#fetch ⇒ Object

rename to refresh_from_server! ?? TODO: should simplify by moving uri / http initialization elsewhere

Raises:

  • (IOError) 


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# File 'lib/unleash/toggle_fetcher.rb', line 40

def fetch
  Unleash.logger.debug "fetch()"
  Unleash.logger.debug "ETag: #{self.etag}" unless self.etag.nil?

  uri = URI(Unleash.configuration.fetch_toggles_url)
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = true if uri.scheme == 'https'
  http.open_timeout = Unleash.configuration.timeout # in seconds
  http.read_timeout = Unleash.configuration.timeout # in seconds

  headers = (Unleash.configuration.get_http_headers || {}).dup
  headers['Content-Type'] = 'application/json'
  headers['If-None-Match'] = self.etag unless self.etag.nil?

  request = Net::HTTP::Get.new(uri.request_uri, headers)

  response = http.request(request)

  Unleash.logger.debug "No changes according to the unleash server, nothing to do." if response.code == '304'
  return if response.code == '304'

  raise IOError, "Unleash server returned a non 200/304 HTTP result." if response.code != '200'

  self.etag = response['ETag']
  response_hash = JSON.parse(response.body)

  if response_hash['version'] == 1
    features = response_hash['features']
  else
    raise NotImplemented, "Version of features provided by unleash server" \
      " is unsupported by this client."
  end

  # always synchronize with the local cache when fetching:
  synchronize_with_local_cache!(features)

  Unleash.logger.info "Flush changes to running client variable"
  update_client!

  Unleash.logger.info "Saved to toggle cache, will save to disk now"
  save!
end

#save! ⇒ Object 



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# File 'lib/unleash/toggle_fetcher.rb', line 83

def save!
  begin
    backup_file = Unleash.configuration.backup_file
    backup_file_tmp = "#{backup_file}.tmp"

    self.toggle_lock.synchronize do
      file = File.open(backup_file_tmp, "w")
      file.write(self.toggle_cache.to_json)
      File.rename(backup_file_tmp, backup_file)
    end
  rescue Exception => e
    # This is not really the end of the world. Swallowing the exception.
    Unleash.logger.error "Unable to save backup file. Exception thrown #{e.class}:'#{e}'"
    Unleash.logger.error "stacktrace: #{e.backtrace}"
  ensure
    file.close if defined?(file) && ! file.nil?
    self.toggle_lock.unlock if self.toggle_lock.locked?
  end
end

#toggles ⇒ Object 



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# File 'lib/unleash/toggle_fetcher.rb', line 30

def toggles
  self.toggle_lock.synchronize do
    # wait for resource, only if it is null
    self.toggle_resource.wait(self.toggle_lock) if self.toggle_cache.nil?
    return self.toggle_cache
  end
end