Class: ProcessBalancer::Lock::SimpleRedis::LockHandler

Inherits:
Object
  • Object
show all
Defined in:
lib/process_balancer/lock/simple_redis.rb

Overview

class to wrap the lock handling and provide the “extend!” method contract

Instance Method Summary collapse

Constructor Details

#initialize(key, value, ttl) ⇒ LockHandler

Returns a new instance of LockHandler.



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# File 'lib/process_balancer/lock/simple_redis.rb', line 20

def initialize(key, value, ttl)
  @key      = key
  @value    = value
  @ttl      = ttl
  @acquired = false
end

Instance Method Details

#acquire! ⇒ Object 



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# File 'lib/process_balancer/lock/simple_redis.rb', line 27

def acquire!
  time_source = ProcessBalancer::Lock::SimpleRedis.time_source

  timeout_ms = 5000
  wait_time  = 0.02..0.1
  start      = time_source.call

  sleep(rand(wait_time)) while !(@acquired = try_lock) && (time_source.call - start) < timeout_ms
end

#acquired? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/process_balancer/lock/simple_redis.rb', line 43

def acquired?
  @acquired
end

#extend! ⇒ Object 



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# File 'lib/process_balancer/lock/simple_redis.rb', line 53

def extend!
  ProcessBalancer.redis do |c|
    c.watch(@key)
    if c.get(@key) == @value
      c.multi do
        c.set(@key, @value, ex: @ttl)
      end
    end
  end
end

#release! ⇒ Object 



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# File 'lib/process_balancer/lock/simple_redis.rb', line 37

def release!
  ProcessBalancer.redis do |c|
    c.del(@key)
  end
end

#try_lock ⇒ Object 



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# File 'lib/process_balancer/lock/simple_redis.rb', line 47

def try_lock
  ProcessBalancer.redis do |c|
    c.set(@key, @value, nx: true, ex: @ttl)
  end
end