anchor.diff:  %% @doc reads the value of a key
   %% @spec read(key()) -> {failure, term()} | value()
   read(Key) ->
  -    case transaction_api:quorum_read(Key) of
  -        {fail, Reason} ->
  -	       {fail, Reason};
  -        {Value, _Version} ->
  -	       Value
  +    case timer:tc(transaction_api, quorum_read, [Key]) of
  +        {Time, {fail, Reason}} ->
  +            ?LOG_CS_API(quorum_read_fail, Time / 1000.0),
  +            {fail, Reason};
  +        {Time, {Value, _Version}} ->
  +            ?LOG_CS_API(quorum_read_success, Time / 1000.0),
  +            Value
       end.
   
   %% @doc writes the value of a key
   %% @spec write(key(), value()) -> ok | {fail, term()}
   write(Key, Value) ->
  -    case transaction_api:single_write(Key, Value) of
  -	commit ->
  +    case timer:tc(transaction_api, single_write, [Key, Value]) of
  +	{Time, commit} ->
  +            ?LOG_CS_API(single_write_success, Time / 1000.0),
   	    ok;
  -	{fail, Reason} ->
  +	{Time, {fail, Reason}} ->
  +            ?LOG_CS_API(single_write_fail, Time / 1000.0),
   	    {fail, Reason}
       end.
   
  
positive.code: process_request(TLog, Request) ->
      case Request of
          {read, Key} ->
              case transaction_api:read(Key, TLog) of
                  {{value, Val}, NTLog} ->
                      {NTLog, {read, Key, {value, Val}}};
                  {{fail, Reason}, NTLog} ->
                      {NTLog, {read, Key, {fail, Reason}}}
              end;
          {write, Key, Value} ->
              case transaction_api:write(Key, Value, TLog) of
                  {ok, NTLog} ->
                      {NTLog, {write, Key, {value, Value}}};
                  {{fail, Reason}, NTLog} ->
                      {NTLog, {write, Key, {fail, Reason}}}
              end;
          {commit} ->
              case transaction_api:commit(TLog) of
                  {ok} ->
                      {TLog, {commit, ok, {value, "ok"}}};
                  {fail, Reason} ->
                      {TLog, {commit, fail, {fail, Reason}}}
              end
      end.
  
negative.code: -export([process_request_list/2, read/1, write/2, delete/1,
           test_and_set/3, range_read/2]).
  
  -include("../include/scalaris.hrl").
  
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  % Public Interface
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  