Class: RightScale::CloudApi::RequestAnalyzer

Inherits:
Routine show all
Defined in:
lib/base/routines/request_analyzer.rb

Overview

The routine provides error_pattern method that is used to define request and response patterns.

The patterns allows one to control the request processing flow: you can enable retries for certain API calls or can re-open a connection on HTTP failure.

The supported actions are:

Request option:

  • :abort_on_timeout - If there was a low level timeout then it should not retry a request but should fail. Lets say one made a call to launch some instance and the remote cloud launched them but timed out to respond back. The default behavior for the gem is to make a retry if a timeout received but in this particular case it will launch the instances again. So the solution here is to make the system to fail after the first unsuccessfull request.

Response options:

  • :retry - Make a retry if the failed response matches to the pattern.

  • :abort - Do not make a retry and fail if the response matches to the pattern (opposite to :retry).

  • :disconnect_and_abort - Close a connection and fail.

  • :reconnect_and_retry - Reestablish a connection and make a retry.

Defined Under Namespace

Modules: ClassMethods Classes: Error

Constant Summary collapse

REQUEST_ACTIONS = 
[ :abort_on_timeout ]
REQUEST_KEYS = 
[ :verb, :verb!, :path, :path!, :request, :request!, :if ]
RESPONSE_ACTIONS = 
[ :disconnect_and_abort, :abort, :reconnect_and_retry, :retry ]
RESPONSE_KEYS = 
[ :verb, :verb!, :path, :path!, :request, :request!, :code, :code!, :response, :response!, :if ]
ALL_ACTIONS = 
REQUEST_ACTIONS + RESPONSE_ACTIONS

Instance Attribute Summary

Attributes inherited from Routine

#data

Instance Method Summary collapse

Methods inherited from Routine

#cloud_api_logger, #execute, #invoke_callback_method, #options, #reset, #with_timer

Instance Method Details

#process ⇒ Object

The main entry point.



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# File 'lib/base/routines/request_analyzer.rb', line 97

def process
  # Get a list of accessible error patterns
  error_patterns = data[:options][:error_patterns] || []
  opts = { :request  => data[:request][:instance],
           :response => nil,
           :verb     => data[:request][:verb],
           :params   => data[:request][:orig_params].dup}
  # Walk through all the error patterns and find the first that matches.
  # RequestAnalyser accepts only REQUEST_ACTIONS (actually "abort_on_timeout" only)
  request_error_patterns = error_patterns.select{|e| REQUEST_ACTIONS.include?(e[:action])}
  request_error_patterns.each do |pattern|
    # If we see any pattern that matches our current state
    if Utils::pattern_matches?(pattern, opts)
      # then set a flag to disable retries
      data[:options][:abort_on_timeout] = true
      cloud_api_logger.log("Request matches to error pattern: #{pattern.inspect}" , :request_analyzer)
      break
    end
  end
end