DSTM via warlock demo

dstm.coffee

###
Network workflow:
Client connects
Client creates transaction
Server sends 'sync' with root object
Client runs transaction

if .retry() called
  Client listens for 'sync' message then runs transaction again
else
  Client calls .done() after transaction is complete
  Client sends 'transaction' with transaction id and transaction log

  if log doesnt match
    Server sends 'failed' with transaction id
    Client calls .retry()
  else
    Server sends 'sync' with root object to all clients
    Server sends 'complete' with transaction id
    Client returns callback for transaction
###

insertMoney = ->
  checks = @get 'money.checks'
  if checks.length is 0
    # retry will halt the transaction until the next transaction then start again
    @retry()
  else
    # incr is sugar for @set 'money.dollars', @get('money.dollars')+check.value
    @incr 'money.dollars', check.value for check in checks

buyStock = ->
  dollars = @get 'money.dollars'
  appleStock = @get 'stock.apple.price'
  return @abort() if dollars < appleStock
  stockToBuy = dollars / appleStock
  stocks = {type: 'Apple'} for i in [0..stockToBuy]
  # append is sugar for @set 'stock.mine', @get('stock.mine').append stocks
  @append 'stock.mine', stocks
  
  
sellStock = ->
  dollars = @get 'money.dollars'
  appleStock = @get 'stock.apple.price'
  return @abort() if dollars < appleStock
  myStocks = @get 'stock.mine'
  @set 'stock.mine', (stock for stock in myStocks when stock.type isnt 'Apple')
  @incr 'money.dollars', (myStocks.length - @get('stock.mine').length)*appleStock


trans = lock.atomic insertMoney, buyStock, sellStock

trans.run (err) ->
  console.log err if err?