iilyak

do_format({error, _GL, {Pid, "** gen_event handler" ++ _, Args}}) ->
    %% gen_event handler terminate
    [ID, Name, LastMsg, State, Reason] = Args,
    MsgFmt = "gen_event ~w installed in ~w terminated with reason: ~s~n" ++
    case config:get_boolean("couch_log", "strip_sensitive", true) of
        true ->
            MsgFmt = "gen_event ~w installed in ~w terminated with reason: ~s~n" ++
                " last msg: reducted~n     state: ~p",
            MsgArgs = [ID, Name, format_reason(Reason), State],
            format(error, Pid, MsgFmt, MsgArgs);

iilyak

Store filter configuration for otter

Contents:

• Meta information
• Context and Problem Statement
• Decision Drivers
• Considered Options
• Decision Outcome
• Positive Consequences

iilyak

CouchDB is a distributed system which submits jobs from coordinator nodes to storage nodes. To handle single request, we send it to every node in parallel and then aggregate responses. In order to adequately represent it in traces we need support for nested spans. This quick experiment tests how this case is rendered in Jaeger.

Run jaeger as follows

./jaeger-all-in-one --collector.zipkin.http-port=9411

Execute test script

python3 trace.py

iilyak

git clone https://github.com/apache/couchdb-mochiweb
cd couchdb-mochiweb
git diff bd6eb60..CouchDB-2.12.0-1

iilyak

%% https://github.com/cloudant/couchdb/pull/7-module(couch_ejson_size).

-export([ejson_size/1]).

-ifdef(TEST).
    -compile(export_all).

    -include_lib("proper/include/proper.hrl").
-endif.

iilyak

skip_n_terms(Bin, N) ->
    lists:foldl(fun(_, {Acc, Bin}) ->
        {Skipped, R} = skip_term(Bin),
        {Skipped + Acc, R}
    end, {0, Bin}, lists:seq(1, N)).

skip_term(<<97, _:1/binary, Rest/binary>>) -> %%  SMALL_INTEGER_EXT
    {2, Rest};
skip_term(<<98, _:4/binary, Rest/binary>>) -> %% INTEGER_EXT
    {5, Rest};

iilyak

Pros and Cons

Pros

• Team members always issue PRs for the same branch.
• We can merge PRs anytime.
• The history of cloudant-master would always be like upstream master with few commits on top

Cons

iilyak

set -e

function pr_label {
    REPO_URL=${1}
    PR=${2}
    REPO=${REPO_URL##https://github.com/}
    echo `curl -s https://api.github.com/repos/${REPO}/pulls/${PR} \
        | jq .head.label | tr -d '"'`
}

iilyak

--- a/rebar.config.script
+++ b/rebar.config.script
@@ -21,6 +23,12 @@ os:putenv("COUCHDB_CONFIG", ConfigureEnv).

 os:putenv("COUCHDB_APPS_CONFIG_DIR", filename:join([COUCHDB_ROOT, "rel/apps"])).

+Features = lists:filter(fun({_K, Flag}) -> Flag end, [
+    {'HAS_ERL_SCAN_TOKEN_INFO', erlang:function_exported(erl_scan, token_info, 1)}
+]),
+

iilyak

export SUFFIX=`date "+test-%s"`
export PORT=15984
export HOST=localhost
export DB=test-${SUFFIX}
export USER=foo-${SUFFIX}

echo -e "\033[32mCreate user"
cat <<EOF | http -v --auth='adm:pass' PUT http://${HOST}:${PORT}/_users/org.couchdb.user:${USER}
{
    "_id": "org.couchdb.user:${USER}",