Book Image

Go Standard Library Cookbook

By : Radomír Sohlich
Book Image

Go Standard Library Cookbook

By: Radomír Sohlich

Overview of this book

Google's Golang will be the next talk of the town, with amazing features and a powerful library. This book will gear you up for using golang by taking you through recipes that will teach you how to leverage the standard library to implement a particular solution. This will enable Go developers to take advantage of using a rock-solid standard library instead of third-party frameworks. The book begins by exploring the functionalities available for interaction between the environment and the operating system. We will explore common string operations, date/time manipulations, and numerical problems. We'll then move on to working with the database, accessing the filesystem, and performing I/O operations. From a networking perspective, we will touch on client and server-side solutions. The basics of concurrency are also covered, before we wrap up with a few tips and tricks. By the end of the book, you will have a good overview of the features of the Golang standard library and what you can achieve with them. Ultimately, you will be proficient in implementing solutions with powerful standard libraries.

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Table of Contents (13 chapters)
Preface
Preface
Who this book is for
What this book covers
To get the most out of this book
Sections
Get in touch
Free Chapter
1
Interacting with the Environment
Interacting with the Environment
Introduction
Retrieving the Golang version
Accessing program arguments
Creating a program interface with the flag package
Getting and setting environment variables with default values
Retrieving the current working directory
Getting the current process PID
Handling operating system signals
Calling an external process
Retrieving child process information
Reading/writing from the child process
Shutting down the application gracefully
File configuration with functional options
2
Strings and Things
Strings and Things
Introduction
Finding the substring in a string
Breaking the string into words
Joining the string slice with a separator
Concatenating a string with writer
Aligning text with tabwriter
Replacing part of the string
Finding the substring in text by the regex pattern
Decoding a string from the non-Unicode charset
Controlling case
Parsing comma-separated data
Managing whitespace in a string
Indenting a text document
3
Dealing with Numbers
Dealing with Numbers
Introduction
Converting strings to numbers
Comparing floating-point numbers
Rounding floating-point numbers
Floating-point arithmetics
Formatting numbers
Converting between binary, octal, decimal, and hexadecimal
Formatting with the correct plurals
Generating random numbers
Operating complex numbers
Converting between degrees and radians
Taking logarithms
Generating checksums
4
Once Upon a Time
Once Upon a Time
Introduction
Finding today's date
Formatting date to string
Parsing the string into date
Converting dates to epoch and vice versa
Retrieving time units from the date
Date arithmetics
Finding the difference between two dates
Converting between time zones
Running the code block periodically
Waiting a certain amount of time
Timeout long-running operations
Serializing the time and date
5
In and Out
In and Out
Introduction
Reading standard input
Writing standard output and error
Opening a file by name
Reading the file into a string
Reading/writing a different charset
Seeking a position within a file
Reading and writing binary data
Writing to multiple writers at once
Piping between writer and reader
Serializing objects to binary format
Reading and writing ZIP files
Parsing a large XML file effectively
Extracting data from an incomplete JSON array
6
Discovering the Filesystem
Discovering the Filesystem
Introduction
Getting file information
Creating temporary files
Writing the file
Writing the file from multiple goroutines
Listing a directory
Changing file permissions
Creating files and directories
Filtering file listings
Comparing two files
Resolving the user home directory
7
Connecting the Network
Connecting the Network
Introduction
Resolving local IP addresses
Connecting to the remote server
Resolving the domain by IP address and vice versa
Connecting to the HTTP server
Parsing and building a URL
Creating an HTTP request
Reading and writing HTTP headers
Handling HTTP redirects
Consuming the RESTful API
Sending a simple email
Calling the JSON-RPC service
8
Working with Databases
Working with Databases
Introduction
Connecting the database
Validating the connection
Executing statements
Operations with prepared statements
Canceling the pending query
Reading query result metadata
Retrieving data from a query result
Parsing the query result into a map
Handling transactions
Executing stored procedures and functions
9
Come to the Server Side
Come to the Server Side
Introduction
Creating the TCP server
Creating the UDP server
Handling multiple clients
Creating the HTTP Server
Handling HTTP requests
Creating HTTP middleware layer
Serving static files
Serving content generated with templates
Handling redirects
Handling cookies
Gracefully shutdown the HTTP server
Serving secured HTTP content
Resolving form variables
10
Fun with Concurrency
Fun with Concurrency
Introduction
Synchronizing access to a resource with Mutex
Creating map for concurrent access
Running a code block only once
Pooling resources across multiple goroutines
Synchronizing goroutines with WaitGroup
Getting the fastest result from multiple sources
Propagating errors with errgroup
11
Tips and Tricks
Tips and Tricks
Introduction
Logging customization
Testing the code
Benchmarking the code
Creating subtests
Testing the HTTP handler
Accessing tags via reflection
Sorting slices
Breaking HTTP handlers into groups
Utilizing HTTP/2 server push
12
Other Books You May Enjoy
Other Books You May Enjoy
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Converting dates to epoch and vice versa

The epoch is the universal system to describe the point in time. The beginning of epoch time is defined as 00:00:00 1 Jan 1970 UTC. The value of epoch is the amount of seconds since the timestamp, minus the amount of leap seconds since then.

The time package and Time type provide you with the ability to operate and find out the UNIX epoch time.

How to do it...

  1. Open the console and create the folder chapter04/recipe04.
  2. Navigate to the directory.
  3. Create the epoch.go file with the following content:
        package main

        import (
          "fmt"
          "time"
        )

        func main() {

          // Set the epoch from int64
          t := time.Unix(0, 0)
  ...
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