Introduction

In a previous article we learned about Creating a PHP Daemon Service. Now we are going to learn how to use methods to perform IPC - Inter-Process Communication - to communicate with daemon processes.

Message Queues

In the world of UNIX, there is an incredible variety of ways to send a message or a command to a daemon script and vice versa. But first I want to talk only about message queues - "System V IPC Messages Queues".

A long time ago I learned that a queue can be either in the System V IPC implementation, or in the POSIX implementation. I want to comment only about the System V implementation, as I know it better.

Lets get started. At the "normal" operating system level, queues are stored in memory. Queue data structures are available to all system programs. Just as in the file system, it is possible to configure queues access rights and message size. Usually a queue message size is small, less than 8 KB.

This introductory part is over. Lets move on to the practice with same example scripts.queue-send.php

$key = ftok(__FILE__, 'A'); 
$queue = msg_get_queue($key);

msg_send($queue, 1, 'message, type 1');
msg_send($queue, 2, 'message, type 2');
msg_send($queue, 3, 'message, type 3');
msg_send($queue, 1, 'message, type 1');

echo "send 4 messages
";

queue-receive.php

$key = ftok('queue-send.php', 'A');
$queue = msg_get_queue($key);

for ($i = 1; $i <= 3; $i++) {
 echo "type: {$i}
";

 while ( msg_receive($queue, $i, $msgtype, 4096, $message, false, MSG_IPC_NOWAIT) ) {
 echo "type: {$i}, msgtype: {$msgtype}, message: {$message}
";
 }
}

Lets run on the first stage of the file queue-send.php, and then queue-receive.php.

u% php queue-send.php
send 4 messages
u% php queue-receive.php
type: 1
type: 1, msgtype: 1, message: s:15:"message, type 1";
type: 1, msgtype: 1, message: s:15:"message, type 1";
type: 2
type: 2, msgtype: 2, message: s:15:"message, type 2";
type: 3
type: 3, msgtype: 3, message: s:15:"message, type 3";

You may notice that the messages have been grouped. The first group gathered 2 messages of the first type, and then the remaining messages.

If we would have indicated to receive messages of type 0, you would get all messages, regardless of the type.

while (msg_receive($queue, $i, $msgtype, 4096, $message, false, MSG_IPC_NOWAIT)) {

Here it is worth noting another feature of the queues: if we do not use the constant MSG_IPC_NOWAIT in the script and run the script queue-receive.php from a terminal, and then run periodically the file queue-send.php, we see how a daemon can effectively use this to wait jobs.queue-receive-wait.php

$key = ftok('queue-send.php', 'A');
$queue = msg_get_queue($key);

while ( msg_receive($queue, 0, $msgtype, 4096, $message) ) {
 echo "msgtype: {$msgtype}, message: {$message}
";
}

Actually that is the most interesting information of all I have said. There are also functions to get statistics, disposal and checking for the existence of queues.

Lets now try to write a daemon listening to a queue:queue-daemon.php

$pid = pcntl_fork();
$key = ftok('queue-send.php', 'A');
$queue = msg_get_queue($key);

if ($pid == -1) {
 exit;
} elseif ($pid) {
 exit;
} else {
 while ( msg_receive($queue, 0, $msgtype, 4096, $message) ) {
 echo "msgtype: {$msgtype}, message: {$message}
";
 }
}

posix_setsid();

Shared Memory

We have learned to work with queues, with which you can send small system messages. But then we may certainly be faced with the task of transmitting large amounts of data. My favorite type of system, System V, has solved the problem of rapid transmission and preservation of large data in memory using a mechanism calledShared Memory.

In short, the data in the Shared Memory lives until the system is rebooted. Since the data is in memory, it works much faster than if it was stored in a database somewhere in a file, or, God forgive me on a network share.

Lets try to write a simple example of data storage.shared-memory-write-base.php

$id = ftok(__FILE__, 'A');


$shmId = shm_attach($id);

$var = 1;

if (shm_has_var($shmId, $var)) {
 $data = (array) shm_get_var($shmId, $var);
} else {
 $data = array();
}

$data[time()] = file_get_contents(__FILE__);

shm_put_var($shmId, $var, $data);

Run this script several times to save the value in memory. Now lets write a script only to read from the memory.shared-memory-read-base.php

$id = ftok(__DIR__ . '/shared-memory-write-base.php', 'A');
$shmId = shm_attach($id);
$var = 1; 

if (shm_has_var($shmId, $var)) {
 $data = (array) shm_get_var($shmId, $var);
} else {
 $data = array();
}

foreach ($data as $key => $value) {
 $path = "/tmp/$key.php";
 file_put_contents($path, $value);

 echo $path . PHP_EOL;
} 

Semaphores

So, in general terms, it should be clear for you by now how to work with shared memory. The only problems left to figure out are about a couple of nuances, such as: "What to do if two processes want to record one block of memory?" Or "How to store binary files of any size?".

To prevent simultaneous accesses we will use semaphores. Semaphores allow us to flag that we want to have exclusive access to some resource, like for instance a shared memory block. While that happens other processes will wait for their turn on semaphore.

In this code it explained clearly:shared-memory-semaphors.php

$id = ftok(__FILE__, 'A');

$semId = sem_get($id);

sem_acquire($semId);

$data = file_get_contents(__DIR__.'/06050396.JPG', FILE_BINARY);

$shmId = shm_attach($id, strlen($data)+4096);
$var = 1;
 
if (shm_has_var($shmId, $var)) {
 $data = shm_get_var($shmId, $var);

 $filename = '/tmp/' . time();
 file_put_contents($filename, $data, FILE_BINARY);

 shm_remove($shmId);
} else {
 shm_put_var($shmId, $var, $data); 
}

sem_release($semId); 

Now you can use the md5sum command line utility to compare two files, the original and the saved file. Or, you can open the file in image editor or whatever prefer to compare the images.

With this we are done with shared memory and semaphores. As your homework I want to ask you to write code that a demon will use semaphores to access shared memory.

Conclusion

Exchanging data between the daemons is very simple. This article described two options for data exchange: message queues and shared memory.

Post a comment here if you have questions or comments about how to exchange data with daemon services in PHP.

Now that the Thanksgiving and Black Friday are left behind, we're all back at our desks, some of us having PHPStorm open for the whole day. In this post, I'll say a few words on this beautiful IDE, PHPUnit and XDebug.
You know that unit tests are essential, don't you? So do the PHPStorm developers. This industry-standard level IDE has tons of capabilities for integrating test frameworks and debuggers into your project. Even if you use VMs or containers to run your development environment, chances are they got you covered!



I often see even experienced PHP programmers debugging their code with var_dump(), which is obviously not the best way to do it. If you see the code for the first time, if you work with legacy code - step-by-step interactive debugging is the way to go. Sometimes it can save you hours of old school var_dumping.

As of unit tests, I often hear that it's good enough to run tests from the terminal. I even know a guy who runs watch phpunit /path/to/test while developing: this way the test is run every 2 seconds, you switch to the terminal whenever you want to see the latest results and that's it. However, there are certain advantages in running tests from the IDE. First, it's super-handy to launch a test method, test class or a whole folder with tests, just by pressing a hotkey. Second, the test results appear right there, in PHPStorm, with failures and their stack traces, every entry clickable and takes you directly to the file:line where a nasty thing happened. I also find the ability to run a debugger for a unit test, extremely attractive. Test fails, you click on a trace entry, get to a problematic line, place a break point, re-run the test in debug mode - and there you go.

For all those integrations, you will first need to setup the PHP interpreter for the project: Configuring PHP Development Environment. You will find both local and remote interpreter setups. "Local" is the PHP that you have on your workstation, the host machine. "Remote" can be pretty much everything: SSH if your Dev environment runs on a shared sandbox for all developers, docker or docker-compose if you run it using docker containers.

Next step - creating PHPUnit configuration. Go toSettings -> Languages and Frameworks -> PHP -> Test Frameworks. Follow this guide, it has much more information which will be more up-to-date than this post.Don't forget to set Path Mappings for your remote environments! That is, you probably have your project in, say, $HOME/projects/cool-project, but inside a docker or on a remote host it might be located at /app or /var/www, then you have to let PHPStorm know about this.

Once you're done with PHPUnit setup, you can finally run your tests! The default shortcut on my Linux machine isCtrl+Shift+F10 (shortcuts are usually different on Mac though). Place a cursor inside a test method, press the shotcut: PHPStorm will launch PHPUnit withthat particular test method! When the cursor in a scope of test class but not inside a test method - the whole test class will be run. And, you also can select a whole folder with tests, in the project tree and run it, ain't that cool?

A small tip for the docker-compose lovers. When I first set PHPStorm integration with docker-compose and ran the tests, I was quite surprised (unpleasantly) to see that myphp-fpm service that I was connecting to, is gone after the test process is finished. Took me some time to figure out that it's PHPStorm's expected behavior. It stops the target service after it's done testing. A workaround I started to use is as follows: I just add another service calledphpunit which uses a php-fpm or php-cli image, and is not needed by anything except unit testing in PHPStorm.

Now to debugging.

Debugging is like being the detective in a crime movie where you are also the murderer. Filipe Fortes a.k.a. @fortes

Obviously, your PHP interpreter in development environment will need a debugger extension in order for you to debug interactively. PHPStorm support the two most widely used options: XDebug and Zend Debugger. When using docker I usually make a separate Dockerfile for development, using production image as base, then add development tools,XDebug being the most important. Honestly, I've never usedZend Debugger, so have little to tell about its' nuances.

Got an extension? Go to Debugging Ultimate Guide! Debugger settings in PHPStorm are atSettings -> Languages and Frameworks -> PHP -> Debug. Most of the time you don't need to change them.Again, a note for docker-compose users. There is an XDebug setting that allow debugger to resolve the client (PHPStorm) IP address:xdebug.remoteconnect_back_. That's a disappointment but those will not work, at least with a default docker-compose setup. Thing is, all containers in a compose stack are running behind a network proxy provided by docker-compose. That is, the REMOTE_ADDR for all the containers will always be the IP of proxy. A workaround:

* disablexdebug.remoteconnect_back_;
* add.user.ini to the application root folder with the following contents:xdebug.remotehost = 192.168.X.X_ (your machine's IP address in the LAN). It's generally a good idea to exclude.user.ini from VCS control.

As a conclusion: if you still usevardump()_ to debug, stop living in the stone age, upgrade your knowledge and become more productive! If you don't write unit tests, start doing it. If your managers say it's a waste of time, tell them that it's coding without tests that is a waste of time. And, if you find this post of any use, or have an opinion, or a question - please do comment!

A brief (by Mike's standards) note

As we express our gratitude, we must never forget that the highest appreciation is not to utter words, but to live by them. - John F. Kennedy

I wanted to take a brief moment to express my gratitude this holiday season. First and foremost, a huge thank you to the beautiful Tanja Hoefler who has put in countless hours behind the scenes of Nomad PHP, ranging from finding the best articles and tweeting them out, to tracking down great speakers, to countless hours of video editing (including fixing all my mistakes from the live broadcast).

Thank you to our Founders

I also need to thank Cal and Kathy Evans, an amazing husband and wife team who have done so much for the community over many, many years - including founding and being an invaluable source as Tanja and I took over Nomad PHP. They are truly an inspiration for Tanja and myself, and I hope some day we can do as much for the community as they have.

Thank you to our Speakers

And I need to express my gratitude to our amazing speakers who spend countless hours preparing their presentations, and even stay up all night practicing or get up at 5am to be ready to share their knowledge with the community.

Thank you to our Advisors

Another special shout out goes to Eric Poe, Eric Hogue, and Andrew Caya who have all been tremendous advocates of Nomad PHP, as well as the foundation of our meetings. Their feedback, along with our amazing Advisory Board has helped shake the direction of Nomad PHP, and the many great things we hope to do in the future.

Thank you to our Sponsors

Which brings me to our sponsors. As we try to grow and expand Nomad PHP, as well as bring in more resources and make it more valuable (and affordable), we have done so at a fairly significant loss. That's ok, as that was the plan for 2018, but companies likeRingCentral,Twilio,Auth0, andOSMI have played a critical role in letting us move forward and keeping that loss manageable. Without them, I'm not sure we would be able to be offering the service we do, or have the plans we do for 2019!

*On a side note, if you're not familiar with OSMI, they're a GREAT non-profit who has done so much good in the tech space raising awareness about mental health, and educating employers - I highly recommend supporting this great non-profit organization.*

Thank you to our Family and Friends

Of course, I need to thank my family, my friends, and all those who have supported myself, Tanja, and Nomad PHP over the years.

Thank YOU

Least, but certainly not last - in fact perhaps most important of all - I want to thank the tremendous Nomad PHP community - over 3,000 members strong - that make Nomad PHP what it is. Without you, Nomad PHP wouldn't exist - it wouldn't need to. Andwithout you, and the greater PHP community, I wouldn't be here today, doing what I love to do.

For those that do not know my story, I grew up in medicine - becoming a first responder and pursuing a career as a lifeflight paramedic (helicopter ambulance) before realizing two things... ok three: I had a tremedous fear of heights, I hated needles, and I loved programming.

Leaving the nursing program left me unsure of what to do next, so I did what I loved - programming - where the number of mistakes I made I'm sure outnumbered the lines of good code. If it wasn't for the community being so patient, so encouraging, and helping me grow - I'm not sure what I would be doing today, but it certainly wouldn't involve PHP, Developer Relations, Nomad PHP, or the community.

So for that I want to say one final thank you - a thank you for giving me the gift to do what I love, and the opportunity to hopefully pay this forward, and give back to the community, helping others do the same.

Next year will be an amazing one for Nomad PHP, but I can't thank you all for how incredible and amazing these few short months in 2018 have been - because without you, there would be no 2019.

Have a very wonderful Thanksgiving,

Mike

***PS - want to support our 2019 initiatives and be recognized on Nomad PHP in the process? Become a Supporter.***

In case you are living under a rock, the latest version of PHP released last week. PHP developers around the world began rebuilding their development containers with it so they can run their tests. Now it’s your turn. If you haven’t already installed it, you can download it here http://php.net/downloads.php Grab it, get it running in your development environment, and run those unit tests. If all goes well, you can begin planning your staged deployment to production.

If you need a quick start guide to get you going, our good friend Mr Colin O’Dell has just the thing for you “Installing PHP 7.1”. It’ll get you up and going quickly on PHP 7.1.

What’s the big deal about PHP 7.1? I am so glad you asked. Here are the major new features released in PHP 7.1.

* Nullable types
* Void return type
* Iterable pseudo-type
* Class constant visiblity modifiers
* Square bracket syntax for list() and the ability to specify keys in list()
* Catching multiple exceptions types

Now if you want a quick intro to several of these new features, check out our “RFCs of the Future” playlist on YouTube. In it, I talk about 4 of the new features.

Oh and while you are watching things download & compile, why not take the time to give a shoutout to all the core contributors, and a special thank you to Davey Shafik and Joe Watkins, the PHP 7.1 release managers.

Cheers!
=C=

PHPUnit is an essential tool for every PHP developers. It is one of those tools that every PHP developer should have installed in their development environment. The problems most first time PHPUnit developers run into are where to install it and how to install it. This quick guide will walk you through the process and answer both questions.

How do I install PHPUnit

The Easy Way

In your project’s root directory use this command.

composer require --dev phpunit/phpunit ^6.0

This command adds PHPUnit to your project as a development dependency. This is the absolute best way to install PHPUnit. It is the best way because this way the version of PHPUnit does not change unless you change it. We specified ^6.0 as the version which means we’ll get all the updates to the 6.0 branch but not 6.1. While BC breaks don’t happen often in PHPUnit, they have happened. If you have a globally installed version of PHPUnit and you upgrade it to a version that breaks BC, you have to go update all of your tests immediately. This is a lot of hassle if you have a lot of projects with a lot of tests. Keeping a copy of PHPUnit installed as a dev requirement in each project means that each project has its own copy that can be upgraded as necessary.

The Hard Way

In a command prompt regardless of where you are in your file system, use this command.

composer global require phpunit/phpunit ^6.0

On MacOS and Linux machines, this will install PHPUnit in ~/.composer/vendor/bin. If you add this directory to your path, then from any project, you can execute PHPUnit. However, as noted above, if you ever upgrade your globally installed packages then you will have problems.

composer global update

Run that when there is a new version of PHPUnit, it will be installed, regardless of whether this will break your existing unit tests on one or more of your projects. Windows users will need to locate the .composer/vendor/bin directory in your user’s home directory.

The “ZOMG why would you do it this way” Way

Here is the old-school use wget and move it into the correct position manually. You can do it this way, but you will have to take care of all upgrades manually as well. If you only have a single project on the computer and you never ever plan on changing the version of PHPUnit….nope, still better to usecomposer require --dev.

wget https://phar.phpunit.de/phpunit-6.0.phar

chmod +x phpunit-6.0.phar

sudo mv phpunit-6.0.phar /usr/local/bin/phpunit

phpunit --version

These instructions are of course for MacOS or Linux. Windows user won’t need to do chmod or sudo but will need a BAT file.

That’s it. One of those commands should get you a working copy of PHPUnit on your computer.

Resources:

* Installing PHPUnit
* Composer Introduction (For the Global option)