Pre-commit hook debug

Geoff Simonds geoff.simonds at gmail.com
Tue Dec 1 13:52:03 EST 2015


Good afternoon,

I am writing to ask for some help regarding a pre-commit hook in Riak
2.1.1.  I am locally running a 5 node Riak dev cluster (
https://github.com/xing/riak-dev-cluster) on a Mac and am having trouble
with a pre-commit hook.  I have added the "add_paths" to my advanced.config:
[
 Riak KV config
{riak_kv,
  [
    %% Paths to custom erlang modules.
    {add_paths, ["/tmp/ls/custom_modules"]}
  ]}
].

and then copied the compiled beam to this directory.  I then issued a curl
PUT to add the pre-commit to the bucket props:

curl -XPUT -H "Content-Type: application/json" -d
'{"props":{"precommit":[{"mod":"rr_pre_commit","fun":"set_process_datetime_index"}]}}'
http://127.0.0.1:11098/buckets/LS\~News/props

and am able to confirm it worked when I do a GET on the bucket properties.
The bucket already had a single key stored in it and when I do another PUT
on that object (hoping to get the pre-commit to fire), I get the following
error:

{error,badarg,
        [{erlang,iolist_to_binary,
             [{hook_crashed,
                  {rr_pre_commit,set_process_datetime_index,error,
                      function_clause}}],
             []},
         {wrq,append_to_response_body,2,[{file,"src/wrq.erl"},{line,215}]},
         {riak_kv_wm_object,handle_common_error,3,
             [{file,"src/riak_kv_wm_object.erl"},{line,1178}]},
         {webmachine_resource,resource_call,3,
             [{file,"src/webmachine_resource.erl"},{line,186}]},
         {webmachine_resource,do,3,
             [{file,"src/webmachine_resource.erl"},{line,142}]},
         {webmachine_decision_core,resource_call,1,
             [{file,"src/webmachine_decision_core.erl"},{line,48}]},
         {webmachine_decision_core,accept_helper,1,
             [{file,"src/webmachine_decision_core.erl"},{line,616}]},
         {webmachine_decision_core,decision,1,
             [{file,"src/webmachine_decision_core.erl"},{line,521}]}]}}


I am able to run the pre-commit function when I attach to the Riak
shell and add the paths manually (code:add_patha) but not when it
triggers via a PUT.  Also, in my pre-commit hook module/function I am
using the riak erlang client to access the object metadata.  Is this
module compiled into Riak or do I also need to add a path for this?


The pre-commit module/function is below:


set_process_datetime_index(Obj) ->
    case is_deleted(Obj) of
        true ->
          Obj;
        _ ->
          MD = riakc_obj:get_update_metadata(Obj),
          case riakc_obj:get_user_metadata_entry(MD,
<<"process_messagedate">>) of
            %% if user "process messagedate" metadata is not found
            notfound ->
              %% add it
              MD2 =
riakc_obj:set_user_metadata_entry(MD,{<<"process_messagedate">>,format_date_index(calendar:local_time())}),
              %% and modify the message_date 2i index
              MD3 = riakc_obj:set_secondary_index(MD2,{{binary_index,
<<"messagedate">>}, [format_date_index(calendar:local_time())]}),
              riakc_obj:update_metadata(Obj,MD3);
            _ ->
              %% otherwise, don't do anything as we have already
stored the process time
              Obj
          end

    end.

is_deleted(Obj)->
    case dict:find(<<"X-Riak-Deleted">>,riakc_obj:get_metadata(Obj)) of
        {ok,_} ->
            true;
        _ ->
            false
    end.


Any help or advice is appreciated.


Geoff
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