Module: Upoj::Signals

Defined in:
lib/upoj-rb/signals.rb

Overview

Register of blocks of code to execute when the script receives a particular signal.

Class Method Summary collapse

Class Method Details

.clear(signal = nil) ⇒ Object

Clears all blocks registered for the given signal. Use nil to clear all blocks for all signals.

No error will be raised if the signal is unknown.



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# File 'lib/upoj-rb/signals.rb', line 21

def self.clear signal = nil
  signal ? @@trapped[signal_number(signal, false)].try(:clear) : @@trapped.clear; nil
end

.known?(signal) ⇒ Boolean

Indicates whether the given signal is valid, i.e. whether it is either a number or one of the text signals returned by Signal#list.

Returns:

  • (Boolean) 


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# File 'lib/upoj-rb/signals.rb', line 84

def self.known? signal
  !!signal_number(signal, false)
end

.on(signal, &block) ⇒ Object

Registers a block to be executed when the script receives a given signal. This method can be called several times; all registered blocks will be called in the order they were registered when the signal is received. If the signal is not known, ArgumentError is raised (see #known?).

Signals.trap must be called after registering the blocks for them to be activated.

Arguments

  • signal - The signal to trap.

  • &block - The block to execute when the signal is trapped.

Examples

Upoj::CLI::Signals.on(:exit){ cleanup_temporary_files }
Upoj::CLI::Signals.on("TERM"){ close_connections }
Upoj::CLI::Signals.on(2) do
  puts usage
end



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# File 'lib/upoj-rb/signals.rb', line 44

def self.on signal, &block
  (@@trapped[signal_number(signal)] ||= []) << block; block
end

.on_failure(&block) ⇒ Object

Blocks registered with this method will be executed if the script exits with any of the following statuses: QUIT, TERM, KILL, INT (2, 3, 9, 15).

Signals.trap must be called after registering the blocks for them to be activated.

Arguments

  • &block - The block to execute when the script fails.

Examples

Upoj::CLI::Signals.on_failure{ close_connections }



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# File 'lib/upoj-rb/signals.rb', line 61

def self.on_failure &block
  FAILURE_STATUSES.each{ |status| self.on status, &block }; block
end

.on_success(&block) ⇒ Object

Blocks registered with this method will be executed if the script exits successfully with status EXIT (0).

Signals.trap must be called after registering the blocks for them to be activated.

Arguments

  • &block - The block to execute when the script exits successfully.

Examples

Upoj::CLI::Signals.on_success{ FileUtils.rm_fr tmp }



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# File 'lib/upoj-rb/signals.rb', line 77

def self.on_success &block
  SUCCESS_STATUSES.each{ |status| self.on status, &block }; block
end

.trap ⇒ Object

Traps script signals. Blocks registered with Signals.on will be executed when the script receives the corresponding status.

Blocks previously trapped without using this class will be replaced.

Returns true if any signals were trapped.



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# File 'lib/upoj-rb/signals.rb', line 12

def self.trap
  @@trapped.each_key{ |signal| Signal.trap(signal){ self.run signal } }
  @@trapped.any?
end