Class: TinyDS::BaseTx

Inherits:
Object
  • Object
show all
Defined in:
lib/tiny_ds/base_tx.rb

Defined Under Namespace

Classes: TxDone, TxSrc

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#tx_key ⇒ Object (readonly)

Returns the value of attribute tx_key.



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# File 'lib/tiny_ds/base_tx.rb', line 19

def tx_key
  @tx_key
end

Class Method Details

.exec(src, dest, args = {}) ⇒ Object

トランザクション実行

       :  src_phase   dest_phase
raised :    failed      ----
false  :    OK          failed
true   :    OK          OK



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# File 'lib/tiny_ds/base_tx.rb', line 26

def self.exec(src, dest, args={})
  tx = new
  tx.create_tx(src, dest, args)
  begin
    tx.roll_forward
  rescue AppEngine::Datastore::TransactionFailed => e
    return false
  end
  return true
end

.pending_tx_query(status = "pending", dire = :asc) ⇒ Object

pending/done/failed



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# File 'lib/tiny_ds/base_tx.rb', line 50

def self.pending_tx_query(status="pending", dire=:asc) # pending/done/failed
  TxSrc.query.
    filter(:tx_kind, "==", tx_kind).
    filter(:status,  "==", status).
    sort(:created_at, dire)
end

.roll_forward_all(limit = 50) ⇒ Object 



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# File 'lib/tiny_ds/base_tx.rb', line 37

def self.roll_forward_all(limit=50)
  pending_tx_query.each(:limit=>limit) do |tx_src|
    tx = new
    tx.restore_tx(tx_src)
    begin
      tx.roll_forward
    rescue => e
      #p "roll_forward failed. tx=[#{tx.tx_key}] e=[#{e.inspect}]"
    end
  end
  nil
end

.tx_kind ⇒ Object 



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# File 'lib/tiny_ds/base_tx.rb', line 10

def self.tx_kind
  name
end

Instance Method Details

#create_tx(src, dest, args) ⇒ Object

トランザクション前半

TODO TxIDを指定できるようにする。TxSrc#key.nameにTxIDを指定して重複実行防止



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# File 'lib/tiny_ds/base_tx.rb', line 73

def create_tx(src, dest, args)
  tx_src = nil
  TinyDS.tx(tx_retries){
    src = src.class.get(src.key)
    src_phase(src, args)
    src.save!

    attrs = {
      :tx_kind  => self.class.tx_kind,
      :dest_key => dest.key.to_s,
      :args     => args.to_yaml,
    }
    tx_src = TxSrc.create!(attrs, :parent=>src) # srcがparent, tx_srcがchild
    # COMMIT:「srcの処理(=src_phase)、TxSrc作成」
  }
  @tx_key = tx_src.key
  nil
end

#dest_phase(dest, args) ⇒ Object 



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# File 'lib/tiny_ds/base_tx.rb', line 7

def dest_phase(dest, args)
  raise "no impl."
end

#restore_tx(tx_src) ⇒ Object 



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# File 'lib/tiny_ds/base_tx.rb', line 92

def restore_tx(tx_src)
  @tx_key = tx_src.key
  nil
end

#roll_forward ⇒ Object

トランザクション後半



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# File 'lib/tiny_ds/base_tx.rb', line 102

def roll_forward
  tx_src = TxSrc.get(@tx_key)

  TinyDS.tx(tx_retries){
    dest_key = LowDS::KeyFactory.stringToKey(tx_src.dest_key)
    dest = dest_key.kind.constantize.get(dest_key)
    done_name = "TxDone_#{@tx_key.to_s}"
    done_key = LowDS::KeyFactory.createKey(dest.key, TxDone.kind, done_name)
    begin
      TxDone.get!(done_key)
      # なにもしない : TxDoneが存在しているということはdest_phaseは処理済み
    rescue AppEngine::Datastore::EntityNotFound => e
      # TxDoneが無い→dest_phaseが未実行
      attrs = {:done_at=>Time.now}
      tx_done = TxDone.create!(attrs, :parent=>dest, :name=>done_name)
      dest_phase(dest, YAML.load(tx_src.args)) # destの処理を実行
      dest.save!
    end
    # memo: done_keyが同じTxDoneをcommitしようとするとTransactionFailedになるはず→dest_phaseもキャンセル
    # COMMIT:「destの処理(=dest_phase)、TxDone作成」
  }

  # TxSrc#statusをdoneに
  TinyDS.tx(tx_retries){
    tx_src = TxSrc.get!(@tx_key)
    if tx_src.status=="pending"
      tx_src.status = "done"
      tx_src.done_at = Time.now
      tx_src.save!
    end
  }
  return true
rescue => e
  puts e.inspect
  TinyDS.tx(tx_retries){
    tx_src = TxSrc.get!(@tx_key)
    tx_src.roll_forward_failed_count += 1
    if roll_forward_retries_limit < tx_src.roll_forward_failed_count
      tx_src.status = "failed"
    end
    tx_src.save!
  }
  return false
end

#roll_forward_retries_limit ⇒ Object 



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# File 'lib/tiny_ds/base_tx.rb', line 13

def roll_forward_retries_limit
  100
end

#src_phase(src, args) ⇒ Object 



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# File 'lib/tiny_ds/base_tx.rb', line 4

def src_phase(src, args)
  raise "no impl."
end

#tx_retries ⇒ Object 



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# File 'lib/tiny_ds/base_tx.rb', line 16

def tx_retries
  3
end