sata

Code review practices

The following is meant to be a set of guidelines, not dogma. Use your best judgement. The goal is threefold, to have a practice for engineers to learn about what we collectively care about. To maintain quality of the code base as well as knowledge sharing about our systems.

Role of the author

• Create PR, make sure to include JIRA ticket if such exists in the description or title of PR
• Assign 2 developers as minimum but can include the whole team if the author feels it's needed.
• Answer any questions the reviewer has.
• Push changes after review is done as a new commit and make sure reviewer and yourself are satisfied with the change.

larshesel

* Unlocking the super-powers of the Erlang VM


 Lars Hesel Christensen
 VerneMQ Engineer

 twitter: @larshesel
 ✉ lars@vernemq.com
 ✉ lhc@larshesel.dk
 github.com/larshesel

jadeallenx

When does terminate/2 get called in a gen_server?

This is what the [official documentation][1] says about the terminate/2 callback for a gen_server:

This function is called by a gen_server when it is about to terminate. It should be the opposite of Module:init/1 and do any necessary cleaning up. When it returns, the gen_server terminates with Reason. The return value is ignored.

Reason is a term denoting the stop reason and State is the internal state of the gen_server.

Reason depends on why the gen_server is terminating. If it is because another callback function has returned a stop tuple {stop,..}, Reason will have the value specified in that tuple. If it is due to a failure, Reason is the error reason.

seancribbs

%% @doc A VERY EVIL parse_transform that allows two things:
%%
%% 1) The use of 'else' instead of 'true' in the final clause of an if
%% expression.
%%
%% 2) Automatic extraction of non-guard expressions into
%% anonymous variables that can then be used directly in the clause
%% guards.
%%
%% Until Erlang actually implements the 'cond' construct, this is a

xandkar

One of the things I found myself wishing I had in Erlang was labeled arguments. Even with common operations from stdlib (like lists:foldl) - I constantly forget the correct order of arguments, and it becomes that much more error-prone in complex cases (see cowboy_req:new/14, for instance).

Another desirable feature is optional arguments, which are assigned a default value when omitted.

It turns-out that the semantics of these requirements are fully met by records!

andytill

When I started erlang, I had a hard time thinking of ideas for projects to improve my skills. Now I have way too many ideas to possibly implement Myself. Since I actually want these projects to exist so I can use them (everlasting glory coming secondary to some handy tools) I have written them up here. Feel free to try them out. I'm open to questions and suggestions.

swagger for erlang

swagger is a JSON spec for REST APIs. Once you have written a spec in swagger, it can generate documentation (demo) and REST handlers.

An erlang swagger library should take swagger specs and generate cowboy_rest handlers for them.

Difficulty: low

lpgauth

(rtb-gateway@h033.bloomdigital.com)9> lcnt:start(), lcnt:rt_opt({copy_save, true}), lcnt:clear(), timer:sleep(250), lcnt:collect(), lcnt:conflicts().
            lock   id  #tries  #collisions  collisions [%]  time [us]  duration [%]
           -----  --- ------- ------------ --------------- ---------- -------------
 hipe_mfait_lock    1  156537       156367         99.8914    2832642     1119.0905
         pollset    1    5002          195          3.8984      17340        6.8505
    drv_ev_state   16    6683           46          0.6883       2031        0.8024
       timeofday    1   10206          301          2.9492        602        0.2378
       run_queue   28   62350          107          0.1716        122        0.0482
     timer_wheel    1    9350          123          1.3155        114        0.0450
       proc_link 8902   21641           16          0.0739         91        0.0360

jeffreyguenther

import edu.uci.ics.jung.algorithms.layout.CircleLayout;
import edu.uci.ics.jung.algorithms.layout.Layout;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.util.TestGraphs;
import java.awt.Dimension;
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.stage.Stage;

cpdean

no clue who made this, but ARTIST FOUND thank you @indyjoenz / cmang!

i have transcribed it here:

                Y.                      _   
                YiL                   .```.  
                Yii;                .; .;;`.    
                YY;ii._           .;`.;;;; :    
 iiYYYYYYiiiii;;;;i` ;;::;;;; 

chewbranca

On the Viability of Erlang Releases and CouchDB

There has been some discussion on what versions of Erlang CouchDB should support, and what versions of Erlang are detrimental to use. Sadly there were some pretty substantial problems in the R15 line and even parts of R16 that are landmines for CouchDB. This post will describe the current state of things and make some potential recommendations on approach.

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