Code Trips & Tips

Gossip-based Failure Detectors – 0.8.0 released

September 8, 2017

We have just released version 0.8.0 of our distlib C++ library that implements a number of popular distributed systems algorithms. This concludes a first iteration of the “SWIM Gossip Protocol” for failure detection: the implementation is now fully thread-safe and can scale up to many servers with minimal process overhead. The gossip_example.cpp toy server shows how a client … More Gossip-based Failure Detectors – 0.8.0 released

Parse Args in Bash Scripts

August 4, 2020

There is something to be said for the immediacy of using Bash scripts, especially when dealing with relatively simple system operations; however, parsing command line arguments has always been rather cumbersome and usually done along the lines of painful if [[ ${1} == ‘–build’ ]]; then …. On the other hand, Python is pretty convenient … More Parse Args in Bash Scripts

Modern C++: Implementing a Merkle Tree

August 2, 2020

Merkle Trees store a hash of the sub-tree in each of the Nodes, so that the whole tree’s contents can be validated against tampering.They are used, for example, in Bitcoin’s blockchain, and in Cassandra to validate replicas.In this article, we will show how to implement a generic Merkle Tree using features of Modern C++. Previous … More Modern C++: Implementing a Merkle Tree

Modern C++: Writing a thread-safe Queue

July 26, 2020

The STL provides a high-performance queue class in std::queue<T>; however, the API is not very intuitive, or easy, to use and it is not safe to access from multiple threads.In this article, we will show how to wrap it in a more convenient, and thread-safe, API. The C++ Standard Template Library (STL) offers a template-class … More Modern C++: Writing a thread-safe Queue

Ubuntu: adjust mouse scroll wheel sensitivity

May 31, 2020

Honestly, it should be easier – then again, it’s Gnome, nothing really is easy. Collecting a combination of various pages (this one finally yielded the right directions) it turns out one has to install imwheel and then adjust the ~/.imwheelrc file: The magic incantation is in the first couple of lines and the value (3 … More Ubuntu: adjust mouse scroll wheel sensitivity

filecrypt — OpenSSL-based file encryption, release 0.7.2

May 1, 2020

Almost four years after its initial inception and release, I have entirely rewritten the CLI invocation, streamlined the encryption secrets management, and created a self-contained executable. Once you have a private/public key pair, a file can be simply encrypted using: ./filecrypt.pyz -o my_file.enc /path/to/plain.txt and decrypted using: ./filecrypt.pyz -o /path/to/plain.txt -d my_file.enc The –send option … More filecrypt — OpenSSL-based file encryption, release 0.7.2

How to emit battery data in a one-liner on MacOS

April 5, 2020

In MacOS the command to emit data about battery status is: pmset -g batt If you want to record the battery percentage level in a file at regular intervals, here is how to record the data in a one-liner: while true; do \ echo “$(date “+%Y-%m-%d %H:%M:%S”) ” \ “$(pmset -g batt | grep “%” … More How to emit battery data in a one-liner on MacOS

Converting a C++ project to CMake & Conan

March 20, 2020

This post describes how to fully automate the build/install of a C++ Project, with several dependencies, using CMake and Conan, a package manager. A couple of years back, I needed a simple HTTP client to run some integration tests against a Gossip Server I was developing; it turns out that, something we take for granted … More Converting a C++ project to CMake & Conan

Ubuntu: Disable mouse wake from suspend

March 18, 2020

One of the most annoying “features” of Ubuntu is that it will wake from suspend on mouse move, even if waking up your system was the last thing you wanted; in fact, it will wake from suspend, a second after you put it to sleep, if your touch is less than feather-like in releasing the … More Ubuntu: Disable mouse wake from suspend

Running a Bash script forever

April 19, 2019

It is somewhat desirable to have a Bash script run forever; typical use case is for a long-running Docker container that backgrounds the service, and the startup script (e.g., invoked via the ENTRYPOINT command) needs to be kept alive (terminating the script would result in the process known-as “the container” to terminate too). I have … More Running a Bash script forever

Uncompromising Python Formatting

December 24, 2018

I wanted to give a shout out to Black, “the uncompromising Python code formatter.” It really is liberating not to have to worry about code formatting, not having to have unproductive, sterile discussions over PRs about code minutiae and yet being reassured that all your code is nicely formatted; most importantly, the quality of the … More Uncompromising Python Formatting

Adventures in developing distributed systems in Java and Python