There are two end purposes for sending heartbeats through a persistent connection. For a back-end application, heartbeats are generally used to detect an absent client, so as to drop a connection and release the associated resources; for a client, on the contrary, it is to prevent connection resources stored within intermediate nodes being released (such as a NAT router), SO as to KEEP the connection ALIVE. This article will examine how to configure the four socket options, SO_KEEPALIVE, TCP_KEEPIDLE, TCP_KEEPINTVL and TCP_KEEPCNT with setsockopt() to send heartbeats; and discuss the practice of keep-alive heartbeats in general. Experiment setting:OS: Unbutu 16.04gcc: 5.4.0

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Objects life-cycle is crucial. A mistake in determining an object’s lifecycle can lead to resource (e.g., memory, fd) leaks as the resource owned cannot be properly released and recycled for future use. When the leak accumulates to a certain level, it crashes the whole system. Objects life-cycle is also complicated since the ownership of one object might be relinquished by, transferred to, or shared with different entities which include but are not limited to variables, function arguments, modules, data structures, containers, and threads. Again, the resource has to be released and recycled by one of the owners at some undetermined point. There is no de-facto standard to determine objects life-cycle. Utilities like GC (garbage collection) that is used in Java, ARC used in Objective-C and all those pointers (ptrs) in C++, all have their pros and cons. However, this article is not about pros and cons but is focused on C++ resource management helper classes, Smart Pointer, shared_ptr, auto_ptr and unique_ptr.

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C++ is hard, the newer versions become even harder. This article will deal with some of the hard parts in C++, rvalue, rvalue reference (&&) and move semantics. And I am going to reverse engineer (not a metaphor) these complex and correlated topics, so you can understand them completely in one shot.

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I still remember the days of debugging CORS problem when I put together some projects using JavaScript (& ajax), “a very particular programming language” in my first impression. Recently I got a great opportunity. The new role uses JS, the browser-side script that is now winning in all sides, as the major language. So I tooke it as a good chance to learn JS more systematically, and this series will be part of the outcome of my study. As the name implies, I will not cover primary level such as “if, else” (condition), “for” (or any kinds of loops), or basic OOP concepts. Instead, I will focus only on differences so you can learn this versatile language like reviewing a pull request, and use it the next day in your next awesome project.

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I still remember the days of debugging CORS problem when I put together some projects using JavaScript (& ajax), “a very particular programming language” in my first impression. Recently I got a great opportunity. The new role uses JS, the browser-side script that is now winning in all sides, as the major language. So I tooke it as a good chance to learn JS more systematically, and this series will be part of the outcome of my study. As the name implies, I will not cover primary level such as “if, else” (condition), “for” (or any kinds of loops), or basic OOP concepts. Instead, I will focus only on differences so you can learn this versatile language like reviewing a pull request, and use it the next day in your next awesome project.

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I still remember the days of debugging CORS problem when I put together some projects using JavaScript (& ajax), “a very particular programming language” in my first impression. Recently I got a great opportunity. The new role uses JS, the browser-side script that is now winning in all sides, as the major language. So I tooke it as a good chance to learn JS more systematically, and this series will be part of the outcome of my study. As the name implies, I will not cover primary level such as “if, else” (condition), “for” (or any kinds of loops), or basic OOP concepts. Instead, I will focus only on differences so you can learn this versatile language like reviewing a pull request, and use it the next day in your next awesome project.

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When I was reading the source code of a network system, htons() and ntohs() are the very first two functions that confused me. To understand them, I decided to refresh the fading knowledge learned from college in order to squeeze out the last bit of conceptual doubt in byte order.

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I still remember the days of debugging CORS problem when I put together some projects using JavaScript (& ajax), “a very particular programming language” in my first impression. Recently I got a great opportunity. The new role uses JS, the browser-side script that is now winning in all sides, as the major language. So I tooke it as a good chance to learn JS more systematically, and this series will be part of the outcome of my study. As the name implies, I will not cover primary level such as “if, else” (condition), “for” (or any kinds of loops), or basic OOP concepts. Instead, I will focus only on differences so you can learn this versatile language like reviewing a pull request, and use it the next day in your next awesome project. In JavaScript, it is hard to differentiate an object and a dictionary (a.k.a., map in some other languages):

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I still remember the days of debugging CORS problem when I put together some projects using JavaScript (& ajax), “a very particular programming language” in my first impression. Recently I got a great opportunity. The new role uses JS, the browser-side script that is now winning in all sides, as the major language. So I tooke it as a good chance to learn JS more systematically, and this series will be part of the outcome of my study. As the name implies, I will not cover primary level such as “if, else” (condition), “for” (or any kinds of loops), or basic OOP concepts. Instead, I will focus only on differences so you can learn this versatile language like reviewing a pull request, and use it the next day in your next awesome project. In this post, I will discuss this, the legendary JavaScript pitfall countless programmers trod upon.

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I still remember the days of debugging CORS problem when I put together some projects using JavaScript (& ajax), “a very particular programming language” in my first impression. Recently I got a great opportunity. The new role uses JS, the browser-side script that is now winning in all sides, as the major language. So I took it as a good chance to learn JS more systematically, and this series will be part of the outcome of my study. As the name implies, I will not cover primary level such as “if, else” (condition), “for” (or any kinds of loops), or basic OOP concepts. Instead, I will focus only on differences so you can learn this versatile language like reviewing a pull request, and use it the next day in your next awesome project. First thing first, in JavaScript, strings are constant while arrays are mutable.

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