Class: RightSupport::Net::LB::EndpointsStack

Inherits:
Object
  • Object
show all
Defined in:
lib/right_support/net/lb/health_check.rb

Overview

TODO refactor this class. We store too much unstructured data about EPs; should have a simple class representing EP state, and then perhaps move what logic remains into the HealthCheck class instead of putting it here.

Constant Summary collapse

DEFAULT_YELLOW_STATES = 
4
DEFAULT_RESET_TIME = 
60
INITIAL_N_LEVEL = 
1

Instance Method Summary collapse

Constructor Details

#initialize(policy, endpoints, yellow_states = nil, reset_time = nil, on_health_change = nil) ⇒ EndpointsStack

Returns a new instance of EndpointsStack.



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# File 'lib/right_support/net/lb/health_check.rb', line 35

def initialize(policy, endpoints, yellow_states=nil, reset_time=nil, on_health_change=nil)
  @policy = policy
  @endpoints = Hash.new
  @yellow_states = yellow_states || DEFAULT_YELLOW_STATES
  @reset_time = reset_time || DEFAULT_RESET_TIME
  @on_health_change = on_health_change
  @min_n_level = 0
  endpoints.each { |ep| @endpoints[ep] = {:n_level => INITIAL_N_LEVEL, :timestamp => 0} }
end

Instance Method Details

#decrease_state(endpoint, t0, t1) ⇒ Object 



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# File 'lib/right_support/net/lb/health_check.rb', line 62

def decrease_state(endpoint, t0, t1)
  update_state(endpoint, -1, t1) unless @endpoints[endpoint][:n_level] == 0
end

#get_stats ⇒ Object

Returns a hash of endpoints and their colored health status Useful for logging and debugging



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# File 'lib/right_support/net/lb/health_check.rb', line 91

def get_stats
  @endpoints.inject({}) do |stats, (k, v)|
    stats[k] = state_color(v[:n_level])
    stats
  end
end

#increase_state(endpoint, t0, t1) ⇒ Object 



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# File 'lib/right_support/net/lb/health_check.rb', line 66

def increase_state(endpoint, t0, t1)
  update_state(endpoint, 1, t1) unless @endpoints[endpoint][:n_level] == @yellow_states
end

#inspect ⇒ Object 



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# File 'lib/right_support/net/lb/health_check.rb', line 45

def inspect
  "<#{self.class.name}: #{get_stats.inspect}>"
end

#logger ⇒ Object

Return the logger that our surrounding policy uses



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# File 'lib/right_support/net/lb/health_check.rb', line 109

def logger
  @policy.logger
end

#state_color(n_level) ⇒ Object 



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# File 'lib/right_support/net/lb/health_check.rb', line 82

def state_color(n_level)
  color = 'green' if n_level == 0
  color = 'red' if n_level >= @yellow_states
  color = "yellow-#{n_level}" if n_level > 0 && n_level < @yellow_states
  color
end

#sweep ⇒ Object 



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# File 'lib/right_support/net/lb/health_check.rb', line 53

def sweep
  @endpoints.each { |k,v| decrease_state(k, 0, Time.now) if Float(Time.now - v[:timestamp]) > @reset_time }
end

#sweep_and_return_yellow_and_green ⇒ Object 



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# File 'lib/right_support/net/lb/health_check.rb', line 57

def sweep_and_return_yellow_and_green
  sweep
  @endpoints.select { |k,v| v[:n_level] < @yellow_states }
end

#to_s ⇒ Object 



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# File 'lib/right_support/net/lb/health_check.rb', line 49

def to_s
  inspect
end

#update!(new_endpoints) ⇒ Object

Replace the set of endpoints that this object knows about. If any endpoint in the new set is already being tracked, remember its health. For any new endpoint, set its health to INITIAL_N_LEVEL.



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# File 'lib/right_support/net/lb/health_check.rb', line 102

def update!(new_endpoints)
  new_endpoints = new_endpoints.dup # duplicate the array, so we don't modify the passed one.
  @endpoints.each { |k,v| new_endpoints.include?(k) ? new_endpoints.delete(k) : @endpoints.delete(k) }
  new_endpoints.each  { |ep| @endpoints[ep] = {:n_level => INITIAL_N_LEVEL, :timestamp => 0} }
end

#update_state(endpoint, change, t1) ⇒ Object 



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# File 'lib/right_support/net/lb/health_check.rb', line 70

def update_state(endpoint, change, t1)
  @endpoints[endpoint][:timestamp] = t1
  n_level = @endpoints[endpoint][:n_level] += change
  logger.info("RequestBalancer: Health of endpoint '#{endpoint}' #{change < 0 ? 'improved' : 'worsened'} to '#{state_color(n_level)}'")
  if @on_health_change &&
     (n_level < @min_n_level ||
     (n_level > @min_n_level && n_level == @endpoints.map { |(k, v)| v[:n_level] }.min))
    @min_n_level = n_level
    @on_health_change.call(state_color(n_level))
  end
end