Module: ZK::Client::Unixisms

Includes:
Exceptions, Zookeeper::Constants
Included in:
Threaded
Defined in:
lib/zk/client/unixisms.rb

Instance Method Summary collapse

Instance Method Details

#block_until_node_deleted(abs_node_path) ⇒ Object

Will safely block the caller until abs_node_path has been removed (this is trickier than it appears at first). This method will wake the caller if a session event occurs that would ensure the event would never be delivered.

Raises:

  • (Exceptions::InterruptedSession)

    If a session event occurs while we're blocked waiting for the node to be deleted, an exception that mixes in the InterruptedSession module will be raised, so for convenience, users can just rescue Exceptions::InterruptedSession.

  • (Zookeeper::Exceptions::SessionExpired)

    raised when we receive ZOO_EXPIRED_SESSION_STATE while blocking waiting for a deleted event. Includes the Exceptions::InterruptedSession module.

  • (Zookeeper::Exceptions::NotConnected)

    raised when we receive ZOO_CONNECTING_STATE while blocking waiting for a deleted event. Includes the Exceptions::InterruptedSession module.

  • (Zookeeper::Exceptions::ConnectionClosed)

    raised when we receive ZOO_CLOSED_STATE while blocking waiting for a deleted event. Includes the Exceptions::InterruptedSession module.


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# File 'lib/zk/client/unixisms.rb', line 141

def block_until_node_deleted(abs_node_path)
  assert_we_are_not_on_the_event_dispatch_thread!

  raise ArgumentError, "argument must be String-ish, not: #{abs_node_path.inspect}" unless abs_node_path

  NodeDeletionWatcher.new(self, abs_node_path).block_until_deleted
end

#find(*paths, &block) ⇒ Object

Acts in a similar way to ruby's Find class. Performs a depth-first traversal of every node under the given paths, and calls the given block with each path found. Like the ruby Find class, you can call Find.prune to avoid descending further into a given sub-tree

Examples:

list the paths under a given node


zk = ZK.new

paths = %w[
  /root
  /root/alpha
  /root/bravo
  /root/charlie
  /root/charlie/rose
  /root/charlie/manson
  /root/charlie/manson/family
  /root/charlie/manson/murders
  /root/charlie/brown
  /root/delta
  /root/delta/blues
  /root/delta/force
  /root/delta/burke
]

paths.each { |p| zk.create(p) }

zk.find('/root') do |path|
  puts path

  ZK::Find.prune if path == '/root/charlie/manson'
end

# this produces the output:

# /root
# /root/alpha
# /root/bravo
# /root/charlie
# /root/charlie/brown
# /root/charlie/manson
# /root/charlie/rose
# /root/delta
# /root/delta/blues
# /root/delta/burke
# /root/delta/force

Parameters:

  • paths (Array[String])

    a list of paths to recursively yield the sub-paths of

See Also:

  • Find#find

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# File 'lib/zk/client/unixisms.rb', line 115

def find(*paths, &block)
  ZK::Find.find(self, *paths, &block)
end

#mkdir_p(path, opts = {}) ⇒ Object

Creates all parent paths and 'path' in zookeeper as persistent nodes with zero data.

Examples:


zk.exists?('/path')
# => false

zk.mkdir_p('/path/to/blah')
# => "/path/to/blah"  

Parameters:

  • path (String)

    An absolute znode path to create

  • opts (Hash) (defaults to: {})

    a customizable set of options

Options Hash (opts):

  • :data (String) — default: ''

    The data to place at path


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# File 'lib/zk/client/unixisms.rb', line 22

def mkdir_p(path, opts={})
  data = ''

  # if we haven't recursed, or we recursed and now we're back at the top
  if !opts.has_key?(:orig_path) or (path == opts[:orig_path])
    data = opts.fetch(:data, '')  # only put the data at the leaf node
  end

  create(path, data, :mode => :persistent)
rescue NodeExists
  if !opts.has_key?(:orig_path) or (path == opts[:orig_path])  # we're at the leaf node
    set(path, data)
  end

  return
rescue NoNode
  if File.dirname(path) == '/'
    # ok, we're screwed, blow up
    raise NonExistentRootError, "could not create '/', are you chrooted into a non-existent path?", caller
  end

  opts[:orig_path] ||= path

  mkdir_p(File.dirname(path), opts)
  retry
end

#rm_rf(paths) ⇒ Object

recursively remove all children of path then remove path itself


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# File 'lib/zk/client/unixisms.rb', line 50

def rm_rf(paths)
  Array(paths).flatten.each do |path|
    begin
      children(path).each do |child|
        rm_rf(File.join(path, child))
      end

      delete(path)
      nil
    rescue NoNode
    end
  end
end