Module: Ccp::Kvs::Tokyo::StateMachine

Includes:
TokyoCabinet
Included in:
Cabinet
Defined in:
lib/ccp/kvs/tokyo/state_machine.rb

Constant Summary collapse

CLOSED =

state machine

1
READABLE = 
2
WRITABLE = 
3

Instance Method Summary collapse

Instance Method Details

#C! ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 27

def C!
  case state
  when CLOSED   ; # NOP
  when READABLE,
       WRITABLE ; @db.close; @state = CLOSED
  else          ; raise "unknown state: #{state}"
  end
end

#close ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 23

def close
  C!
end

#open(mode) ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 18

def open(mode)
  Pathname(@source.to_s).parent.mkpath
  @db.open(@source.to_s, mode) or tokyo_error!("%s#open(%s,%s): " % [self.class, @source, mode])
end

#R(&block) ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 54

def R(&block)
  case state
  when CLOSED   ; begin; R!(); yield; ensure; close; end
  when READABLE ; yield
  when WRITABLE ; yield
  else          ; raise "unknown state: #{state}"
  end
end

#R! ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 36

def R!
  case state
  when CLOSED   ; open(HDB::OREADER); @state = READABLE
  when READABLE ; # NOP
  when WRITABLE ; # NOP
  else          ; raise "unknown state: #{state}"
  end
end

#state ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 14

def state
  @state || CLOSED
end

#touch ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 72

def touch
  W() {}
end

#W(&block) ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 63

def W(&block)
  case state
  when CLOSED   ; begin; W!(); yield; ensure; close; end
  when READABLE ; raise "reopen from read to write is not permitted"
  when WRITABLE ; yield
  else          ; raise "unknown state: #{state}"
  end
end

#W! ⇒ Object 



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# File 'lib/ccp/kvs/tokyo/state_machine.rb', line 45

def W!
  case state
  when CLOSED   ; open(HDB::OCREAT | HDB::OWRITER); @state = WRITABLE
  when READABLE ; C!; W!()
  when WRITABLE ; # NOP
  else          ; raise "unknown state: #{state}"
  end
end