Build and Test (BAT): continuous integration
- checkout: cvs co
- make: jake build system, compiling and building images
- lint: js/json/perl/html/css
- unit-test: js (zmocha)/C (jtest)
- upload: uploading results and images to fs
- GREEN - build and unit-tests passed successfully
- ORANGE - build passed, but unit-test failed
- YELLOW - build passed, but unit-test identified memory leak
- RED - build failed
- White strips background indicates a BAT request cycle
What happen when BAT is broken?
You don't necessarily have to fix it yourself;
If possible, find out whose commit broke it and get them to fix it.
Don't assume they already know it's broken.
If its a simple fix - fix it yourself
- If you have to fix after someone else broke BAT, add that person to the commit message using NOTIFY:
- If it's not easy to fix (requires thinking/debugging/cannot be fixed in 1 minute), revert the offending commit and notify whoever made it
Alternatively, if unit-test fails, disable the individual test using
if (0) // XXX person.
Use your judgment as to when to revert and when to disable the test.
Disable when you know that the test itself is the problem, or that the breakage is not mission-critical. Always notify the person responsible for fixing the test.
Jdoc notification system
Jdoc stands for 'Jungo documents', which originally built at
Jungo in 2001.
The jdoc mechanism allows you, or anyone interested, to register on notifications for a specific file or directory's content, based on our CVS, and review every single commit.
The jdoc file is located at the root directory of our development tree.
This notification mechanism is being used to implement our async Review and to support the co-ownership of a module or a file, by providing by mail every modification made to the file or to the directory's content. Note that you may use the
NOTIFY: statement, in every commit you
do, to manually activate this notification system for specific logins (people
in Hola) you want to notify.
Peer Review: keeping our code quality top-notch
Writing code is our profession, keeping it top-notch is our pleasure!
As it's the main form of communication between the team, having our codebase perfectly consistent in style makes it easy for developers to read and modify each other's code.
So, to increase the team's efficiency, we invest time teaching everyone how to write code. The review process is our main tool for doing so.
Blocking sync Review: first review, then commit
During the bootcamp and even few weeks after, your code
will be reviewed by your mentor in order to
provide you with all the tools and guidelines on how we write our code.
During this period, you'll be doing commit sessions together with your mentor,
until he will be fully convinced you have knowledge to write code like
everybody in Hola do and ready to commit it on your own.
It is your responsibility to commit your code, and hence, you will probably call your mentor for a commit session once you are done with your task.
You probably ask yourself what the mentor is checking during this session and
whether your code is ready?
Below, is the checklist you need to do before answering yourself if your code is ready for a commit session:
- Verify that all editors are closed before committing the code
cvsup -Aon the root directory
Make sure all new files were added to the cvs using
cvs add FILENAME(verify no new files marked with
Verify that all modified (
M) files are files you want to commit.
If there are files you want to commit later, duplicate the tree
cp -a zon1 zon1.new, and make the current tree include exactly what you are going to commit.
zlint -mfrom the root directory (use
cdrto move to the root directory).
Coding conventions: re-read the code, and validate it
Noobs can use
zlint -cmtool to assist locating convention mistakes (the tool is only 95% accurate - so you still must know all the rules!).
zdiffand re-check all your changes. Validate there are no 'debug leftovers' (console.log()...).
- Its OK to do a partial solution/implementation, but in such cases comment in the code, or add to the version_plan a description of what you will do later.
- If this is a modification/removal, rgrep the whole tree to validate all related code is modified accordingly
- Run all the unit-tests from the root directory
- Make sure the tree can compile (
jmake cm release)
- Test the feature and play with it in zlxc
Open questions? not perfect? not 100% ready for commit as-is? then
don't call your mentor for a commit session.
Rather, prepare all the list of questions in an editor, with your suggested solutions, and call your mentor for a Q&A session.
Later on, once your questions have been answered, and you code is perfect, call your mentor for a commit session.
Short, simple and descriptive - be minimalistic
Start with small letter
When doing a sync review add your reviewer login in brackets
Do not include the filename you committed to in the message - it is redundant
Redo your code for a commit session
You may call your mentor for questioning session. This is more than welcome
and even recommended during the bootcamp. However, once calling your mentor
for a commit session the expectation is that you did your best to comply with
ALL pre-commit checks. It means
that all open questions have been looked up deeply and resolved, and your
code is bright and shining, waiting to be sent out to our million of
In Hola we respect other's time, calling your mentor for a commit session which ended up with a "redo", is a completely waste of time.
Make sure you meet this expectation. Take very seriously the remarks you received, and try to find out how to improve your personal commit procedures not to repeat these mistakes next time.
Now, after you have committed your code, below is the checklist you need to do after your commit:
cvsupand make sure the tree is fully committed (no
- Check BAT until you see your commit got compiled and tested green
- If BAT is broken, make it green again by fixing the problem
- If your code does significant changes, or has changes to cause problems
- Deploy it the same day
- Track it immediately after deployment (60 seconds manual test after deployment, kibana, stats)
Non-blocking async Review: first commit, and later others will review
Once passing the stage of blocking review you'll
start committing your code on your own.
This time, the review will be done by co-owners of the code you changed or by other engineers who are registered on the files you have modified (using the jdoc system).
FS: Central shared filesystem
Jungo: Our origin: Passion for complex networking and a love for Open Source
rgrep: recursive grep
grep is an amazing tool. Just like you google the Internet for answers on
public info, you grep source code for answers on our private tree.
rgrep is our recursive grep, with a few little usability
- Scans by default all files in the tree, recursively
- Skips version controlled meta-files, editor temporary files (swp, bak, ...), and build output directory
- Allows language selection, such as
rgrep --js send_msgwill only search *.js files for send_msg string
We recommended to always
rgrep from the root directory.
This will ensure you never miss a reference.
zlint: general purpose linter
Can lint many types of files: js, json, perl, html, css and more. Always run it before commit.
When reporting bugs, requesting UI related tasks, or completing UI related
tasks, add a minimal (cropped) screen capture to your report demonstrating
the item or modification you did. Also, mark in it where the change is so it
will be easy for the other side reviewing it and respond quickly.
An example of a cropped, tiny marked screenshot:
Implementing the above can be done by using applications such as FastStone
zmocha: mocha based JS unit-testing tool
Our unit-test framework is based on mocha.
Every new function deserves a unit-test to make sure further development will
not affect current behavior.
One of the most efficient ways of testing your code modifications is running unit-tests on the whole development tree by executing
Running tests on a specific directory can be done by running
zmocha within the directory.
Running specific test in a specific directory can be done by
zmocha -g [test]
zupdate: Updating your development environment and tools
zupdate is a command line that will install and update your
development environment, based on your
.zon tree (this is the
reason why we keep
.zon untouched and unmodified).
The development environment holds the gvim definition and themes, VM look&feel and all required development tools.
It is recommended to run
zupdate every day, as our codebase is
changing rapidly together with our development environment and tools.
gVim: text editor
Our common text editor based on
Vim, powered with many vim plugins
that enhance our development productivity, and used as our code IDE.
Why are we using gVim?
Because it is tidily connected to our development environment and tools.
Can I use any other IDE instead?
Sure! You may use any IDE you like, just keep in mind that our gVim is already adjusted to our coding conventions and has many features to support our way of development. Your IDE should be adjusted as well.
Moreover, when working with other developers, they mostly would like to work on gVim, so you'll have to adjust yourself to it.
Do you have a shortcut for using gVim in your development environment?
g. It will open the gVim editor on your machine.
More shortcuts and useful commands are in our
vi Basic page.
CVS: Concurrent Version System
Our source control plays a major role in daily inter-developer communication
tool in the company.
Commits are also a form of email, being one of the core engines behind our module ownership and code reviews.
Our version of CVS, originally based on the open source CVS, has been greatly enhanced and improved over the years to provide:
- transparent offline support (via local smart cache proxy)
- instant checkout and update (via background prefetching)
- remote web interface, GitHub like
- local web interface, similar to other version control GUI clients
- MD5_CDN signature based smart annotate: find out who really originally wrote a function, no matter if it was copied, or indentation has been changed.
- commit hooks: committing directly activates many different deployment tasks, updating thousands of servers, configuration, and code - instantly.
For a quick start, look at CVS basic command
cvsed: utility for editing and committing common files
An editor tool which combines editing a file using gvim,
and committing capabilities, using cvs update and
cvsed has shortcuts to our most common used files, which can
be seen by executing
You may use this tool for editing your daily file (
cvsed daily) or your version plan
cvsed vp) or simply open both (
zlxc: emulate everything in your PC
A staging environment is a great tool for developers: they can play around
with the feature they developed in a 'full system', with all the hundreds of
computers, IPs and route tables, frontend and backend web servers, databases,
message queues etc... and validate that everything works well together.
In Hola we wanted every developer to own a complete staging environment of his own, so we used LXC technology to power it.
In a single command we manage to start up in under 6 seconds a full emulation of hundreds of NodeJS/C/C++ based servers with different IP addresses and complex route tables, multiple MongoDB and NGINX servers, graphite, elasticsearch, and many other servers and services.
Now every developer can fully test the complete product, inside his own laptop, even before the commit and see how everything plays well together.
Give the developers great testing and emulation tools, and they will deliver great quality products.
Full description of
zlxc can be found once running
zlxc --help, however some
zlxc most common commands
and usage are:
zlxc run [group]- runs specific servers (saves booting time)
zlxc relink- relink modified files to the zlxc container
zlxc windows- runs zlxc and enable connecting external Windows VM to the zlxc environment
cvsup -A && jmake cm release && zlxc run [group] --purge- run an up-to-date clean zlxc instance from scratch
Your work station enables you to be efficient. At Hola we invest a lot of
efforts making it best configured and efficient as possible.
To keep it up-to-date, make sure to run
zupdate every day. It will make sure all
your development tools (gvim, zlxc,
FastStone, etc.) and look&feel are kept configured and
It could happen that you'll feel the way your workstation is configured is not your style, and you would like to change it to suit you best. You may freely change it, once you are fully independent and can work on your own. Therefore, to save your colleague's time (as they are used to this environment), work with the current configuration and suggest any environment enhancements to your mentor.
Our development tree is called zon. While the environment and tools are being installed by zupdate on the
.zon tree, you may duplicate it for development purposes to
zon2, by simply execute
cp -a .zon zon1 or
cvs co -d zon2 zon. This will
give you the ability to work on one task in
zon1, while doing
other tasks on
Moreover, doing your daily and updating your version plan can be done very easily by executing
cvsed daily (to update your daily), or
cvsed vp to
update your version plan's section, or
cvsed vpd to update both
daily and version plan at the end of the day.
Monitor and alerts
We use graphite as the base of our monitoring and alerting system. We add many zcounters in our code to send stats to our servers, and aggregate them up on a realtime monitoring and alerting dashboard. That's how we keep our services up and running 24/7/365.
zcounter: monitor your code
To validate your code runs well in the real world, add zcounters inside your code - count and measure events, and use our graphite based dashboard to monitor their values, and alert when something goes wrong.
perr: collect errors and other reports
The idea of "perr" was so that clients (initially is was for Hola Accelerator) could submit crashes and other runtime errors. Submission of perr reports is open to the outside world, and the system is built to handle a very large incoming flow.
These days, the technology has been repurposed to collect reports about events other than errors, too. For instance, our CDN loader and player send reports that include a lot of stats like how long it took to start playing, whether there were buffering events and how many, and so on. Our browser extensions, Android apps etc send reports on events such as "authentication", "first use" and so on.
The perr servers receive these reports over HTTP. Then they do several things:
Report zcounters about certain types of perr or
their properties. Most, if not all, perr types produce a zcounter
stats.glob.perr.$IDjust to count them. Also, CDN reports produce many zcounters that are specific to particular customers/zones, based on individual events mentioned in the report. In fact, most of the CDN world in the dashboard is produced this way by the perr servers.
- Drop certain reports. The server can be configured to drop reports according to specific rules. This is done so that the database does not get flooded with millions of identical reports when we only need a few to diagnose problems. Note that the zcounter submission above happens before the dropping.
- Forward remaining reports to the database where their bodies will be stored.
There are different perr servers for the same reason as why there are different www servers. Better distribution of load, separation of code (for example, zs-perr-hola-b does not need the code that processes CDN player reports), separate releases.
Different kinds of clients use different URLs to submit their perr reports, although the format is the same. For example, the CDN player submits to https://perr.h-cdn.com/client_cgi/perr (I think), while the browser extension submits to https://per.hola.org/client_cgi/perr. All these domains are served by nginx on zs-client-f, which then forwards these requests to zs-perr-cdn-b* and zs-perr-hola-b*, respectively (with load balancing).
perr data visualization
ElasticSearch is the specialized database to which the perr service submits the reports on step 3 above. In fact, the full data flow is like this:
(client) -> zs-client-f -> zs-perr-*-b -> zs-log ->
zs-elasticsearch -> (kibana)
(The zs-log server does little more than just forward the reports. These days, its presence is mostly historical.)
Kibana is a web application that lets you explore the ElasticSearch database. It is to ElasticSearch what our dashboard is to metricdb.
Deploy: shipping your code to millions of users
Deployment is putting your work out for everyone to use. The deploy team
will take your request, and will follow a detailed procedure that will label,
test and eventually release your code.
If an issue occurs during this process, the deploy team will notify you - so you will be able to quickly fix it.
The deploy team is available to receive your requests 24/7/365.
Bootcamp: your first days at Hola
A 3 week training program, in which you are
introduced to the way we work, communicate and collaborate with each
It's time to learn! and adopt our DNA, as well as perform your profession skills.
Hola Noob: start doing real stuff, but still a lot of questions
Larger tasks, significant contribution while actively learning about the company's DNA, software architectures and work methods. Code reviews for most commits, some without a pre-commit review session, and sometimes even only after deployment.
Hola Junior: on your way to being part of the family!
A major contributor to Hola's products, developing specific domain knowledge in fields that are of interest to you within Hola. Commit directly to the product tree without prior review, and see your contributions going live to millions of users within hours of being developed. Still internalizing Hola's DNA and best practices, and open to comments about commits from other Hola Veterans.
Hola Veteran: A 'did-it-all' Veteran at Hola
An integral part of the Hola Family. A major contributor, knowledge center, and a person who can help Noobs and Juniors get up to speed on the Hola DNA and best practices through mentoring, and code reviews.
We truly believe that eating healthy and good food should be part of having
fun at work, while being creative and productive when creating fantastic
Our in-house chefs are responsible for those great meals we have every day.
Mentor: Your Hola veteran buddy
The Hola mentors are selected Veterans that embody the
Hola DNA and have the ability to help Noobs learn to
become great contributing team members.
Every Noob is assigned a mentor -- a Veteran who helps to progress from noob to junior to veteran status. It's up to you, the Noob, to get as much face time with the Veteran and ask any question, so that you can learn as much as possible. The Mentor is busy with his tasks, but will take the time to help you as much as you need when you ask for it.
What's the best way to learn from a mentor? One very effective way is plain old imitation -- looking at his practices, daily routines, time and task management, email styling, at how he communicates with colleagues. These are all great practices to take on until you create your own style at Hola.
- At Bootcamp stage mentor helps how to find what is necessary for fulfilling tasks: documentation, code, people. He also reviews your code.
- Mentor of a Noob helps learning company's DNA, and still does the code reviews.
- Mentor of a Junior is a go-to person to understand how the company and procedures work in detail.
MVP: Minimal Viable Product
In any task/feature/product we build at Hola, we try to progress
incrementally, by building a Minimal Viable Product (or minimal viable
task/feature) that brings value to the end user. This allows testing whether
the solution is in the right direction. It also brings immediate value to
the end user, or if it is an internal task - brings an immediate solution to
a real problem. If the MVP works out well, additional incremental
improvements will be done. If not, a different direction (thus a different
MVP) will be tried out to solve the same problem.
This is a core concept in modern Lean Startups. We highly recommend you read The Lean Startup book. See also Wiki.
ZON: appears in the code - but what is it?
Hola was founded in 2008, and sticking to the MVP method,
our 0.1 version of the company name was ZON. This gave us time to find a
name that best represents our values: simplicity, directness, friendly,
welcoming. By the beginning of 2009 we found it: "Hola", coupled with is
friendly smiley :-)
So our source tree directory is still '.zon', and our internal tools and functions many times have a 'z' prefix, and our P2P protocol is called zmsg.
Coding conventions (Style Guides)
Source Code is the main produce of software developers. It's most of what we
read and write at all day - even more than the time we spend reading and
writing emails (... we also have email style guide to
make them consistent!)
It's the main form of communication between the team, and therefore its consistency is highly important.
Having our codebase perfectly consistent in style makes it easy for developers to read and modify each other's code. We try to express our individuality and personal great engineering skills, not by spacing and indenting our code differently than others, rather by finding simple solutions to complex problems, great algorithms, original and efficient designs.
There's no 'right' or 'wrong' in coding conventions - any coding convention chosen can be 'right', as long as it exists, and is strictly followed by all of us - thus achieving consistency.
Emails is our primary way of communicating within the team, as we appreciate each
We use it to discuss issues offline, to notify about code modifications (jdoc), as well as provide tasks to each other and share useful information.
Since this interface is central to the way we work, just like with coding conventions, we also adopted an email style guide to speak the same language, and be more efficient while handling it as part of our regular tasks.
version_plan: Open planning for the near and far future
The version plan can be found in
Each engineer will have a section with his login and username, holding his future and current tasks. The version plan holds the R&D planned tasks. It is the engineer's responsibility to update his progress in this file once a day.
Updating this file can be done easily with cvsed. Writing guidelines can be found in the Version plan code.
daily: Open reporting of daily achievements
Your daily file is a text file, located under your name in
The goal of this file is to report your daily achievements, describe your commitment (tasks you will complete for sure in the next day) and state your next planned task/s (tasks your are about to start after completing your commitment).
This daily report, makes our development transparent and let everybody understand what everybody does, as well as let everybody comment or suggest what is best to do next (you may use the NOTIFY to let specific people know about your progress).
Updating this file is done every day, usually at the end of it (you may choose to update it at the beginning of the work day, summarizing your previous working day) using our cvsed tool.
What should be reported?
In general, every task that took you more than half a day, should be reported.
What kind of tasks should I report?
The file actually describes your working progress, according to the plan described in version_plan.txt. Writing guidelines can be found in the Daily code.
Product weekly report
A weekly executive summary, generated by product or project owners, to their
team, managers and stake holders, to be send by the end of the week,
spreading the news about weekly accomplishments.
What should be reported?
In general, every achievement accrued and completed during the last week (with respect to a specific product/responsibility) should be reported as well as relating to the activities and goals to be carried out the following week.
Be precise. Write down numbers. Compare to previous weeks and explain the growth/regression, success/failure.
The working hours of everyone, including management, are all open for the
whole company to see - enabling real time peer collaboration.
This allows the company's R&D to be spread out in 20+ cities, over 15 time zones, and still be efficient and productive development team.
The Hola product lines
- Hola VPN hola.org
- Value: Making the web worldwide again by allowing everyone the freedom to watch content without censorship
- Tech: Its the only P2P VPN in the world. P2P makes Hola free and open
- Platforms: Available as a Chrome Extension, Firefox Extension, stand-alone browser, iOS, Android
A chromium based broswer with Hola's pre-build in VPN, video accelerator and ad-blocker.
- Luminati luminati.io
- Value: Providing privacy to corporations, for brand protection, price comparison, and more
- Tech: The only P2P privacy network for businesses. Uses the Hola network and protocol.
- Platforms: Available as an API for many programming languages.
- HolaCDN holacdn.com
- Value: A video distribution network that provides better performance (video starts faster, buffers less) at a fraction of the cost
- Tech: Based on our P2P know-how, with client and server side tech that enables streaming one video from multiple sources.
- Platforms: JS code embedded in to page of the video
Hola is a DNA company
To keep our DNA, which is critical to our success, the DNA manager overlooks all activities in the company, and makes sure they are compliant with our DNA, which we all participated in creating.
This includes activities such as:
- version plan
- daily report
- attendance: hours, vacations, leave, sick, holiday...
- emails and communications
- R&D and Deploy shifts
- DNA training sessions in bootcamp
- Hola ranks
- ... and generally looking out for any deviation from our DNA
At Hola you may choose to work from any location you prefer to be as
productive and effective as you can.
We find that working in the office with your peers is typically the most productive environment and most fun to work at. This is the reason we have several offices around the world, allowing our employees to spend their day with their peers. So while working from our offices, we usually work for 9.5 hours a day, out of which 30 minutes is our lunch break.
But some of us live far from the office or in countries where Hola does not have an office and so must work from home (cloud office).
We have several interfaces to report attendance:
When working from the office, use your card or your fingerprint on the attendance clock, at the entrance, to login / logout upon entering and leaving the office.
Timesheet web interface (requires VPN connection), which enables you to login and logout while defining your work location:
- At home - When working from home or hotel
- In Office - When working from Hola's office only if the attendance clock is not working or available
- On Road - Used by sales people, going to meetings outside their home or hotel
email (sales team only)
Send an email to
email@example.com your location in the subject (
on the road...):From: firstname.lastname@example.org To: email@example.com Subject: meetingto logout, send:From: firstname.lastname@example.org To: email@example.com
daily logout- which enable you to login and logout respectively from within your Ubuntu VM (usually being used by the R&D)
If you have a planned absence - report it in advance on your
daily report. Unplanned absence (e.g. sick leave) should
be reported on the daily report as well.
If you plan to work less hours a day for a given period of time, notify your manager - to set expectation of your progress correctly. Your daily report for such days should also indicate it.
When making an improvement suggestion, whether of an internal tool or of a
new design to replace an existing one, the suggestion needs to be well
thought of before. The responsibility for thinking it out over, and bringing
well-prepered suggestions are on the one who is suggesting it.
The cost-effectiveness of the proposed solution should be the main factor.
- How much time is spent today due to the existing design?
- How much time will be saved after the implementation?
- How much Total Cost Ownership is the change (preparing suggestion, discussion time, agreeing on it, coding, debugging, deploying, finding all the edge cases)?
- Do we loose any features? Are you fully aware that these features are not required?
- Do you have a full idea on how to implement it, on all its technical aspects and details, and there are no 'black holes'?
- What are the cheaper/quicker ways to solve the same problem?