Computer-Engineering on maladroit.dev

100 Go Mistakes

Mon, 01 Jan 0001 00:00:00 +0000

100 Go Mistakes

Go is a programming language that is simple to learn but difficult to master.

Organization

Data types

Control structures

Strings

Functions and methods

Error management

Concurrency

Standard library

Testing

Optimizations

References

100 Go Mistakes

Algorithms

Mon, 01 Jan 0001 00:00:00 +0000

Algorithms

Algorithms are step by step procedures that are used for solving a computational problem. An algorithm is different from a program in that algorithms are used during the Software-design-phase. An algorithm should be independent of programming languages and are analyzed for performance. In order to design an algorithm, a designer must have domain knowledge of the problem that they are attempting to solve.

Apache Iceberg

Mon, 01 Jan 0001 00:00:00 +0000

Apache Iceberg

Apache Iceberg is an open table format for huge, slow-changing, analytic data-sets. Iceberg aims to support the following:

Schema evolution with no side effects
Hidden partitioning to avoid performance penalties and user error
Partition layout evolution as data and patterns evolve over time
Time travel to reproduce historical queries
Version rollback to correct problems by resetting to a known good state
Readers isolated from concurrent writes
Writers add and remove files atomically
Planning and scanning takes O(1) and is not impacted by table size

Because Iceberg has been designed for large data-sets it can be used in production where a single table is measured in petabytes. Iceberg is also designed to solve correctness problems in eventually-consistent cloud object stores. It is cloud platform agnostic, table changes are atomic so readers never see partial changes, and concurrent writers when experiencing conflicts will retry to ensure updates are compatible.

Binary

Mon, 01 Jan 0001 00:00:00 +0000

Binary

Binary is a base 2 number system that is used in machine code. It can be handy at times to transform data to binary or to preform bit-wise operations.

Corner cases

Negative numbers
Overflow/underflow errors

Bit-wise operations

Check if k’th bit is set

var num uint
num & (1 << k) != 0

Set the k’th bit

var num uint
num |= (1 << k)

Clear the k’th bit

var num uint
num &= ^(1 << k)

Toggle the k’th bit

var num uint
num ^= (1 << k)

Multiply by 2^k

var num uint
num << k

Divide by 2^k

var num uint
num >> k

Check if power of 2

var num uint
(num & (num - 1)) == 0

Swap two variables

var num1 uint
var num2 uint
num1 ^= num2
num2 ^= num1
num1 ^= num2

References

Tech-Interview-Handbook

Chris Hecker Interview Process

Mon, 01 Jan 0001 00:00:00 +0000

Chris Hecker Interview Process

The Chris Hecker interview process is an approach to interviewing software engineers that focuses on assessing the candidate based on topics they should already be very familiar with. It is designed to put the candidate into an authoritative position where they have all the answers instead of presenting them a problem they have zero familiarity with.

The interviewer’s role is to ask clarifying questions to test the candidate’s technical knowledge of projects they have worked on. This will often involve asking questions the interviewer may already know the answer to, but framing it as if they don’t. This gives the candidate the opportunity to explain a subject and demonstrate if they have a deeper technical understanding or just surface level details. It also shows off how good a candidate is at communicating ideas to someone who is unfamiliar with them.

Computational technique

Mon, 01 Jan 0001 00:00:00 +0000

Computational Technique

Computer Engineering

Mon, 01 Jan 0001 00:00:00 +0000

Computer Engineering

CPU

Mon, 01 Jan 0001 00:00:00 +0000

CPU

The central processing unit (CPU) is the active part of a computer that is made up of the Datapath and Control

CPU execution time

CPU execution time is the time spent by the processor to complete a task

User CPU time

The time spent on the program itself

System CPU time

The time spent in the operating system on behalf of a program

References

Computer Organization and Design

Data Oriented Design

Mon, 01 Jan 0001 00:00:00 +0000

Data Oriented Design

Data-oriented design is an approach to software development that focuses on separating the data from context and operations. It values leveraging fundamental computer science data structures and algorithms rather than modeling the problem domain in the application. The trade off is a sacrifice of human readability and initial software development speed for flexibility, maintenance, and performance.

Data oriented design is not a product or library to be added to a project, it is a technique to be learned. While data can be generic in type it is rarely generic in how it is used. Transformations can be generic, but the ordering and selection of those transformations is literally the solution to the problem.

Data Structures

Mon, 01 Jan 0001 00:00:00 +0000

Data Structures

Design Patterns

Mon, 01 Jan 0001 00:00:00 +0000

Design Patterns

Dynamic programming

Mon, 01 Jan 0001 00:00:00 +0000

Dynamic programming

Dynamic programming is a technique for efficiently implementing a recursive algorithm by storing partial results. This is helpful because it allows for an exhaustive search without processing the same partial result over and over. It is important to know that this is a trade off of time complexity for space.

Examples

go

Before

func fib(n int) int{
	if n == 0 {
		return 0
	}
	if n == 1 {
		return 1
	}
	return fib(n-2) + fib(n-1)
}

After

const (
	miss = -1
	maxN = 92
)

var(
	cache = make([]int, maxN)
)

func fibDriver(n int) int{
	for i := range cache {
		cache[i] = miss
	}
	cache[0] = 0
	cache[1] = 1
	return fib(n)
}

func fib(n int){
	if cache[n] == miss {
		cache[n] = fib(n-2) + fib(n-1)
	}
	return cache[n]
}

References

Entity component system

Mon, 01 Jan 0001 00:00:00 +0000

Entity component system

Entity component systems simplify architecture and encourage separation of responsibilities.

Floating points

Mon, 01 Jan 0001 00:00:00 +0000

Floating points

The concept of floating point numbers was created to solve the problem that integer values cannot represent fractional numbers. Floating point numbers are an approximation of real numbers due to the fact that their is an infinite number of fractions between two integers.

IEEE-754

The IEEE-754 standard for floats is that some bits represent a mantissa and other bits represent an exponent that is applied as a multiplier to the mantissa.

Go

Mon, 01 Jan 0001 00:00:00 +0000

Go

Go is a statically typed, compiled high-level programming language designed at Google. It shares similarities with C, but has memory safety, garbage collection, structural typing, and concurrency.

High level language

Mon, 01 Jan 0001 00:00:00 +0000

High level language

A programming language that can be compiled into assembly language and then assembled into machine language.

References

Computer-Organization-and-Design

Input

Mon, 01 Jan 0001 00:00:00 +0000

Input

References

Computer Organization and Design

Interger literals

Mon, 01 Jan 0001 00:00:00 +0000

Integer literals

Integer literals are numbered values that do not have a fractional component or an exponent.

Representation

Integer literals can be represented in many different forms for convenience. The more common forms are as follows:

// These are different representations of the same literal
binary := 0b1101
decimal := 13
octal := 0o15
hexadecimal := 0x0d

Two’s complement

For signed integer literals, two’s complement is an efficient method for storing positive and negative values.

Left-most bit denotes the sign. (0 is positive, 1 is negative)
Positive values are expressed in typical binary form
Negative values are expressed in binary with the bits inverted + 1

This allows for very easy addition and subtraction operations for the processor. As an added benefit, there is also only one way to represent 0 rather than potentially having a positive and negative 0.

Linux

Mon, 01 Jan 0001 00:00:00 +0000

Linux

Memory

Mon, 01 Jan 0001 00:00:00 +0000

Memory

The storage area where programs exist when they are running. It is also where data is kept that is needed by running programs.

References

Computer Organization and Design

Output

Mon, 01 Jan 0001 00:00:00 +0000

Output

References

Computer Organization and Design

Problem solving techniques

Mon, 01 Jan 0001 00:00:00 +0000

Problem solving techniques

When solving unfamiliar problems in software engineering, it is best to take a structured approach when breaking the problem down. In addition, make sure the problem is fully understood by gathering more information and discussing the problem with colleagues.

Visualize

Use a white board or paper to draw out diagrams or map the problem out state by state. This can prove to be critical when working with trees, graphs, matrices, and linked lists.

Site Reliability Engineering

Mon, 01 Jan 0001 00:00:00 +0000

Site Reliability Engineering

Hope is not a strategy

A site reliability engineer (SRE) is a software engineer that focuses on solving operational issues with software, creating Service-Level-Objects minimizing toil of manual tasks, reduce the cost of failure, and share ownership with developers.

Tenants

Availability
Latency
Performance
Efficiency
[[change-management]]
[[monitoring]]
[[capacity-planning]]

Principles

Embracing-risk
Eliminating-toil
Monitoring-distributed-systems
Automation
Release-engineering
Simplicity

References

SRE Book