Class: ZK::Locker::LockerBase

Inherits:
Object
  • Object
show all
Includes:
ZK::Logging
Defined in:
lib/zk/locker.rb

Direct Known Subclasses

ExclusiveLocker, SharedLocker

Instance Method Summary collapse

Constructor Details

#initialize(zookeeper_client, name, root_lock_node = "/_zklocking") ⇒ LockerBase

Returns a new instance of LockerBase.



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# File 'lib/zk/locker.rb', line 49

def initialize(zookeeper_client, name, root_lock_node = "/_zklocking") 
  @zk = zookeeper_client
  @root_lock_node = root_lock_node
  @path = name
  @locked = false
  @waiting = false
  @root_lock_path = "#{@root_lock_node}/#{@path.gsub("/", "__")}"
end

Instance Method Details

#cleanup_lock_path! ⇒ Object (protected) 



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# File 'lib/zk/locker.rb', line 130

def cleanup_lock_path!
  logger.debug { "removing lock path #{@lock_path}" }
  @zk.delete(@lock_path)
  @zk.delete(root_lock_path) rescue Exceptions::NotEmpty
end

#create_lock_path!(prefix = 'lock') ⇒ Object (protected)

prefix is the string that will appear in front of the sequence num, defaults to 'lock'



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# File 'lib/zk/locker.rb', line 121

def create_lock_path!(prefix='lock')
  @lock_path = @zk.create("#{root_lock_path}/#{prefix}", "", :mode => :ephemeral_sequential)
  logger.debug { "got lock path #{@lock_path}" }
  @lock_path
rescue Exceptions::NoNode
  create_root_path!
  retry
end

#create_root_path! ⇒ Object (protected) 



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# File 'lib/zk/locker.rb', line 115

def create_root_path!
  @zk.mkdir_p(@root_lock_path)
end

#digit_from(path) ⇒ Object (protected) 



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# File 'lib/zk/locker.rb', line 101

def digit_from(path)
  self.class.digit_from_lock_path(path)
end

#in_waiting_status ⇒ Object (protected) 



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# File 'lib/zk/locker.rb', line 94

def in_waiting_status
  w, @waiting = @waiting, true
  yield
ensure
  @waiting = w
end

#lock_basename ⇒ Object

the basename of our lock path

for the lock_path '/zklocking/foobar/_blah/lock000000007' lock_basename is 'lock000000007'

returns nil if lock_path is not set



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# File 'lib/zk/locker.rb', line 72

def lock_basename
  lock_path and File.basename(lock_path)
end

#lock_children(watch = false) ⇒ Object (protected) 



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# File 'lib/zk/locker.rb', line 105

def lock_children(watch=false)
  @zk.children(root_lock_path, :watch => watch)
end

#locked? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/zk/locker.rb', line 76

def locked?
  false|@locked
end

#ordered_lock_children(watch = false) ⇒ Object (protected) 



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# File 'lib/zk/locker.rb', line 109

def ordered_lock_children(watch=false)
  lock_children(watch).tap do |ary|
    ary.sort! { |a,b| digit_from(a) <=> digit_from(b) }
  end
end

#unlock! ⇒ Object 



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# File 'lib/zk/locker.rb', line 80

def unlock!
  if @locked
    cleanup_lock_path!
    @locked = false
    true
  end
end

#waiting? ⇒ Boolean

returns true if this locker is waiting to acquire lock

Returns:

  • (Boolean) 


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# File 'lib/zk/locker.rb', line 89

def waiting? #:nodoc:
  false|@waiting
end

#with_lock ⇒ Object

block caller until lock is aquired, then yield



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# File 'lib/zk/locker.rb', line 59

def with_lock
  lock!(true)
  yield
ensure
  unlock!
end