gabrielelana/violent-death

Native extension that generates segmentation faults

0.2.0 2014-05-21 21:54 UTC

Requires

• php: >=5.4.0
• ext-blast: *

Requires (Dev)

• phpunit/phpunit: ~4.0

MIT

• Gabriele Lana

• fault
• segmentation
• tollerance

README

How do you know that your code is fault tolerant? How can you verify that it will not break in some terrible and irrecoverable way when something bad happens? This package will help you to simulate the most lethal events that your code can possibly face in its life.

Scenario

You want to test the fault tolerance of your code. You want to make sure that your code will always leave this world with things in a consistent state. The problem is that the kind of failure you can create inside PHP are

• Soft: they are more or less managed by the PHP interpreter
• Predictable: they are created by you in a synchronous way, in real life sh*t happens when you don't expect it, but you cannot simulate a failure say when you are executing a query or when you are making a request to a remote server

If you are asking yourself how can you manage this kind of failures then graceful-death it's your answer

Usage

<?php

require __DIR__ . "/../vendor/autoload.php";

// The output will be something like:
//
// What is this? Should I drink it?
// There, I drank it, I will die eventually...
// Still there :-)
// Still there :-)
// …
// Still there :-)
// [1]    26584 segmentation fault (core dumped)  php examples/drink_poison.php

echo "What is this? Should I drink it?\n";
drink_poison($msToTakeEffect=500, $msToAgonizeAtMost=1000);
// Here we have created a background thread that will wait
// at least for 500ms and at most 1500ms before to cause
// an horrible death with a segmentation fault

echo "There, I drank it, I will die eventually...\n";
while(true) {
    echo "Still there :-)\n";
    usleep(50000);
}

How Does It Work?

To create a segmentation fault we rely on a C extension. To eventually create a segmentation fault in the future (while the code is doing something else) we create a background thread that will wait some amount of time and then cause a segmentation fault.

Gotchas

You need to be able to compile a PHP extension and you need the pthread library installed. The segmentation fault it's not guaranteed on all platforms (aka for every combination of C compiler, OS kernel and CPU architecture), so it may not work, AFAIK the notion of segmentation fault it's not part of any ANSI C standard so there's no standard way to create a genuine segmentation fault.

Overview

drink_poison($msToTakeEffect, $msToAgonizeAtMost, $probabilityToDie)

It will create a segmentation fault at least after $msToTakeEffect milliseconds and at most after $msToTakeEffect + $msToAgonizeAtMost milliseconds. This will happen asynchronously in a background thread so that after this call the code can continue its normal flow

• int $msToTakeEffect: How many milliseconds to wait before the poison takes effect
• int $msToAgonizeAtMost: At most how many milliseconds to wait before the poison will end your code. Default 0
• int $probabilityToDie: The percentage of probability to die. An integer between 1 and 100. Default 100

play_russian_roulette($probabilityToDie)

It will probably create a segmentation fault. The percentage of probability can be passed as parameter

• int $probabilityToDie: The percentage of probability to die. An integer between 1 and 100. Default 16

In Blast Extension: die_violently_after($msToWait)

In Blast Extension: die_violently($msToWait)

Install

You can comfortably install the package through composer

$ composer require "gabrielelana/violent-death"

But before you need to install the blast native extension

Install Native Extension

To make sure to cause the most possible damage we need the most powerful and reliable weapon of self-destruction known to man: the C language

$ phphize
$ ./configure --with-pthread
$ make
$ sudo make install

Hopefully now the extension is compiled and installed. Now you need to enable it appending extension=blast.so in your php.ini file. Run the following commands, if you see the green bar then you are good to go

$ composer install
$ vendor/bin/phpunit

Self-Promotion

If you like this project, then consider to:

• Star the repository on GitHub
• Follow me on
  • Twitter
  • GitHub