Class: Net::SSH::Multi::DynamicServer

Inherits:
Object
  • Object
show all
Defined in:
lib/net/ssh/multi/dynamic_server.rb

Overview

Represents a lazily evaluated collection of servers. This will usually be created via Net::SSH::Multi::Session#use(&block), and is useful for creating server definitions where the name or address of the servers are not known until run-time.

session.use { lookup_ip_address_of_server }

This prevents lookup_ip_address_of_server from being invoked unless the server is actually needed, at which point it is invoked and the result cached.

The callback should return either nil (in which case no new servers are instantiated), a String (representing a connection specification), an array of Strings, or an array of Net::SSH::Multi::Server instances.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(master, options, callback) ⇒ DynamicServer

Create a new DynamicServer record, owned by the given Net::SSH::Multi::Session master, with the given hash of options, and using the given Proc callback to lazily evaluate the actual server instances.



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# File 'lib/net/ssh/multi/dynamic_server.rb', line 32

def initialize(master, options, callback)
  @master, @options, @callback = master, options, callback
  @servers = nil
end

Instance Attribute Details

#callback ⇒ Object (readonly)

The Proc object to call to evaluate the server(s)



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# File 'lib/net/ssh/multi/dynamic_server.rb', line 24

def callback
  @callback
end

#master ⇒ Object (readonly)

The Net::SSH::Multi::Session instance that owns this dynamic server record.



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# File 'lib/net/ssh/multi/dynamic_server.rb', line 21

def master
  @master
end

#options ⇒ Object (readonly)

The hash of options that will be used to initialize the server records.



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# File 'lib/net/ssh/multi/dynamic_server.rb', line 27

def options
  @options
end

Instance Method Details

#[](key) ⇒ Object

Returns the value for the given key in the :properties hash of the options. If no :properties hash exists in options, this returns nil.



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# File 'lib/net/ssh/multi/dynamic_server.rb', line 39

def [](key)
  (options[:properties] ||= {})[key]
end

#[]=(key, value) ⇒ Object

Sets the given key/value pair in the :properties key in the options hash. If the options hash has no :properties key, it will be created.



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# File 'lib/net/ssh/multi/dynamic_server.rb', line 45

def []=(key, value)
  (options[:properties] ||= {})[key] = value
end

#each ⇒ Object

Iterates over every instantiated server record in this dynamic server. If the servers have not yet been instantiated, this does nothing (e.g., it does not automatically invoke #evaluate!).



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# File 'lib/net/ssh/multi/dynamic_server.rb', line 52

def each
  (@servers || []).each { |server| yield server }
end

#evaluate! ⇒ Object Also known as: to_ary

Evaluates the callback and instantiates the servers, memoizing the result. Subsequent calls to #evaluate! will simply return the cached list of servers.



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# File 'lib/net/ssh/multi/dynamic_server.rb', line 59

def evaluate!
  @servers ||= Array(callback[options]).map do |server|
      case server
      when String then Net::SSH::Multi::Server.new(master, server, options)
      else server
      end
    end
end