Class: Redlocker::Lock

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

Overview

The ‘Redlocker::Lock` class allows to easily acquire and keep distributed locks using redis. The acquired lock gets automatically renewed every second, i.e. its 5 second expiry value gets renewed in redis every second, and it gets released when the given block finishes.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(client:, name:, timeout:, delay:) ⇒ Lock

Creates a new ‘Redlocker::Lock` instance.

Parameters:

  • client (Redlocker::Client) —

    The client

  • name (String) —

    The name of the lock

  • timeout (Integer, Float) —

    How long to wait for the lock. If the lock can not be acquired within that time, a ‘Redlocker::TimeoutError` will be raised.

  • delay (Integer, Float) —

    How long to wait between subsequent checks of whether or not the lock is free. Default is 0.25 seconds.



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# File 'lib/redlocker/lock.rb', line 22

def initialize(client:, name:, timeout:, delay:)
  @client = client
  @name = name
  @timeout = timeout
  @delay = delay
  @token = SecureRandom.hex
end

Instance Attribute Details

#client ⇒ Object (readonly)

Returns the value of attribute client.



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# File 'lib/redlocker/lock.rb', line 10

def client
  @client
end

#delay ⇒ Object (readonly)

Returns the value of attribute delay.



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# File 'lib/redlocker/lock.rb', line 10

def delay
  @delay
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/redlocker/lock.rb', line 10

def name
  @name
end

#timeout ⇒ Object (readonly)

Returns the value of attribute timeout.



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# File 'lib/redlocker/lock.rb', line 10

def timeout
  @timeout
end

#token ⇒ Object (readonly)

Returns the value of attribute token.



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# File 'lib/redlocker/lock.rb', line 10

def token
  @token
end

Instance Method Details

#acquire(&block) ⇒ Object

Acquires the specified lock or raises a ‘Redlocker::TimeoutError` when the lock can not be acquired within the specified `timeout`. Uses the specified `delay` to poll redis and check whether or not the lock is free. When the lock has been successfully acquired, it gets refreshed every second, i.e. its expiry value of 5 seconds is refreshed within redis every second.

Parameters:

  • block (Proc) —

    The block which should be executed when the lock is acquired.

Raises:



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# File 'lib/redlocker/lock.rb', line 40

def acquire(&block)
  raise(TimeoutError, "Did not get lock #{name} within #{timeout} seconds") unless acquire_lock

  begin
    keep_lock(&block)
  ensure
    release_lock
  end
end