Class: RightSupport::Net::LB::Sticky

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

Overview

Implementation concepts: Create a policy that selects an endpoint and sticks with it.

The policy should:

  • iterate through each endpoint until a valid endpoint is found;

  • continue returning the same endpoint until it is no longer valid;

  • re-iterate through each endpoint when it’s endpoint loses validity;

  • return an Exception if it performs a complete iteration though each endpoint and finds none valid;

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Sticky

Returns a new instance of Sticky.



34
35
36
37
38
 
# File 'lib/right_support/net/lb/sticky.rb', line 34

def initialize(options = {})
  @health_check = options.delete(:health_check)
  @endpoints = []
  @counter = rand(0xffff)
end

Instance Method Details

#bad(endpoint, t0, t1) ⇒ Object 



60
61
62
 
# File 'lib/right_support/net/lb/sticky.rb', line 60

def bad(endpoint, t0, t1)
  @counter += 1
end

#good(endpoint, t0, t1) ⇒ Object 



56
57
58
 
# File 'lib/right_support/net/lb/sticky.rb', line 56

def good(endpoint, t0, t1)
  #no-op; round robin does not care about failures
end

#health_check(endpoint) ⇒ Object 



64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
 
# File 'lib/right_support/net/lb/sticky.rb', line 64

def health_check(endpoint)
  t0 = Time.now
  result = @health_check.call(endpoint)
  t1 = Time.now
  if result
    return true
  else
    @counter += 1
    return false
  end
rescue Exception => e
  t1 = Time.now
  @counter += 1
  raise
end

#next ⇒ Object 



52
53
54
 
# File 'lib/right_support/net/lb/sticky.rb', line 52

def next
  [ @endpoints[@counter % @endpoints.size], false ] unless @endpoints.empty?
end

#set_endpoints(endpoints) ⇒ Object 



40
41
42
43
44
45
46
47
48
49
50
 
# File 'lib/right_support/net/lb/sticky.rb', line 40

def set_endpoints(endpoints)
  unless @endpoints.empty?
    last_chosen = self.next.first
    @endpoints = []
    if endpoints.include?(last_chosen)
      @endpoints << last_chosen
      @counter = 0
    end
  end
  @endpoints |= endpoints
end