“Across the Great Wall we can reach every corner in the world.”1 Remote Port Forwarding 让云服务器方便快捷地使用本地代理 建立远程端口转发 ssh -R 1082:127.0.0.1:1082 s2-ljy -p 22 配置云服务器的代理环境变量 export HTTP_PROXY="http://127.0.0.1:1082" export HTTPS_PROXY="http://127.0.0.1:1082" Caution 这是临时设置, 仅对当前终端生效, 如果想永久设置, 请编辑 ~/.bashrc ...
Summarize common Docker Network operations. Default Bridge Network After a fresh Docker installation, you can find a default bridge network up and running. docker network ls Docker uses a software-based bridge network that allows containers connected to the same bridge network to communicate while isolating them from other containers not running in the same bridge network. docker run -dit --name busybox1 busybox docker run -dit --name busybox2 busybox docker inspect busybox1 | jq -r ' [0].NetworkSettings.IPAddress' docker inspect busybox2 | jq -r '.[0].NetworkSettings.IPAddress' # OK docker exec -it busybox2 ping 172.17.0.3 # Error docker exec -it busybox2 ping busybox1 Conclusion All containers will automatically connect to this default bridge network. Default bridge network allows container communication using IP addresses. ...
Recording some errors and refactoring encountered while writing Rust. Option When to use .as_ref()? When you want to convert an Option<T> to an Option<&T> without consuming the original Option. ...
55: Mixing up concurrency and parallelism Concurrency enables parallelism. Concurrency provides a structure to solve a problem with parts that may be parallelized. Quote “Concurrency is about dealing with lots of things at once. Parallelism is about doing lots of things at once.” ...
4 Traits To invoke a trait method, two things must be true: The type must implement the trait. The trait must be in scope. To satisfy the latter, you may have to add a use statement for the trait: use crate::MaybeZero; This is not necessary if: The trait is defined in the same module where the invocation occurs. The trait is defined in the standard library’s prelude. The prelude is a set of traits and types that are automatically imported into every Rust program. It’s as if use std::prelude::*; was added at the beginning of every Rust module. Orphan Rule When a type is defined in another crate (e.g. u32, from Rust’s standard library), you can’t directly define new methods for it. ...
48: Panicking Panicking in Go should be used sparingly. We have seen two prominent cases, one to signal a programmer error and another where our application fails to create a mandatory dependency. 49: Ignoring when to wrap an error In general, the two main use cases for error wrapping are the following: Adding additional context to an error Marking an error as a specific error if err != nil { return fmt.Errorf("bar failed: %w", err) } This code wraps the source error to add additional context without having to create another error type. ...
42: Not knowing which type of receiver to use In Go, we can attach either a value or a pointer receiver to a method. With a value receiver, Go makes a copy of the value and passes it to the method. Any changes to the object remain local to the method. The original object remains unchanged. On the other hand, with a pointer receiver, Go passes the address of an object to the method. Intrinsically, it remains a copy, but we only copy a pointer, not the object itself (passing by reference doesn’t exist in Go). Any modifications to the receiver are done on the original object. ...
36: Not understanding the concept of a rune The len built-in function applied on a string doesn’t return the number of characters; it returns the number of bytes. What if we want to get the number of runes in a string, not the number of bytes? How we can do this depends on the encoding. In the previous example, because we assigned a string literal to s, we can use the unicode/utf8 package: ...