use fixed version of ex_abi

[ayrat555]

the latest version of ex_abi introduced a couple of bugs. The PR uses the patched version of ex_abi which fixes those bugs

[coveralls]

Coverage increased (+0.08%) to 78.31% when pulling 73450b4 on ayrat555/use-fixed-version-of-ex_abi into 07774c8 on master.

[InoMurko]

Perhaps another thing we could now do - since ex_abi works - is to fetch ABI.FunctionSelector from plasma contracts for these two:
https://github.com/omisego/elixir-omg/blob/master/apps/omg_eth/lib/omg_eth/root_chain.ex#L61-L98
wdyt @ayrat555 ?

[ayrat555]

@InoMurko Some abi encodings have failed in integration tests. I'll look into it

[ayrat555]

Perhaps another thing we could now do - since ex_abi works - is to fetch ABI.FunctionSelector from plasma contracts for these two:
https://github.com/omisego/elixir-omg/blob/master/apps/omg_eth/lib/omg_eth/root_chain.ex#L61-L98
wdyt @ayrat555 ?

@InoMurko How exactly these functions should be changed?

[InoMurko]

Perhaps another thing we could now do - since ex_abi works - is to fetch ABI.FunctionSelector from plasma contracts for these two:
https://github.com/omisego/elixir-omg/blob/master/apps/omg_eth/lib/omg_eth/root_chain.ex#L61-L98
wdyt @ayrat555 ?

@InoMurko How exactly these functions should be changed?

We can put both standardExits(uint160[]) and inFlightExits(uint160[]) ABI.FunctionSelector definitions into OMG.Eth.RootChain.AbiFunctionSelector.

When we have that, we can rewrite these two functions:

##
  ## these two cannot be parsed with ABI decoder!
  ##
  @doc """
  Returns standard exits data from the contract for a list of `exit_id`s. Calls contract method.
  """
  def get_standard_exit_structs(exit_ids) do
    contract = Configuration.contracts().payment_exit_game

    return_types = [
      {:array, {:tuple, [:bool, {:uint, 256}, {:bytes, 32}, :address, {:uint, 256}, {:uint, 256}]}}
    ]

    # TODO: hack around an issue with `ex_abi` https://github.com/poanetwork/ex_abi/issues/22
    #       We procure a hacky version of `OMG.Eth.Client.call_contract` which strips the offending offsets from
    #       the ABI-encoded binary and proceeds to decode the array without the offset
    #       Revert to `call_contract` when that issue is resolved
    call_contract_manual_exits(
      contract,
      "standardExits(uint160[])",
      [exit_ids],
      return_types
    )
  end

  @doc """
  Returns in flight exits of the specified ids. Calls a contract method.
  """
  def get_in_flight_exit_structs(in_flight_exit_ids) do
    contract = Configuration.contracts().payment_exit_game
    {:array, {:tuple, [:bool, {:uint, 256}, {:bytes, 32}, :address, {:uint, 256}, {:uint, 256}]}}

    # solidity does not return arrays of structs
    return_types = [
      {:array, {:tuple, [:bool, {:uint, 64}, {:uint, 256}, {:uint, 256}, :address, {:uint, 256}, {:uint, 256}]}}
    ]

    call_contract_manual_exits(
      contract,
      "inFlightExits(uint160[])",
      [in_flight_exit_ids],
      return_types
    )
  end

into something like RootChain blocks/1 or next_child_block/0, get_mined_child_block/0 so that the response data gets decoded via:

defp get_external_data(contract_address, signature, args) do
    {:ok, data} = Rpc.call_contract(contract_address, signature, args)
    Abi.decode_function(data, signature)
  end

[InoMurko]

Both ABIs are defined in PaymentExitGame.json. You can run make init-contracts in the root of elixir-omg and search for the file.
find . -name PaymentExitGame.json

You can extract the abi defintion if you do this:

abi_path_to_payment_exit_game_json
      |> File.read!()
      |> Jason.decode!()
      |> Map.fetch!("abi")
      |> ABI.parse_specification(include_events?: true)

[InoMurko]

OH this is amazing and it cleanups rootchain!