sync.Once is a type in the Go standard library’s sync package, designed to ensure that a specific operation is executed only once in a concurrent environment. It is commonly used for initializing resources or performing one-time setup operations, avoiding issues that arise from repeated execution.
Core Functionality The core method of sync.Once is Do, which has the following signature:
1func (o *Once) Do(f func()) The Do method takes a function f as an argument and guarantees that this function will be executed only once, even if Do is called multiple times.
...
Background There was a requirement to automatically switch to a certain interface, using Vue’s watch to listen to the gRPC connection state (subscription), and then calling an RPC interface to fetch a certain value. Occasionally, the value could not be retrieved, and the logs showed an Unavailable error: 1rpc error: code = Unavailable desc = connection error: desc = "transport: Error while dialing: dial tcp xxxx: connectex: No connection could
...
Background When passing data through gRPC, switching topics often results in the error: rpc error: code = Internal desc = grpc: error while marshaling: marshaling SubscribeIoStateResponse: size mismatch (see https://github.com/golang/protobuf/issues/1609): calculated=6, measured=8. Following the issue, the most likely cause is that Protobuf messages or sub-messages are shared and concurrently modified. Protobuf does not allow modifications to messages during the encoding process.
Root Cause Analysis The minimal reproducible code is as follows:
...
Lock 类型 互斥锁 (Mutex) 1var mu sync.Mutex 2mu.Lock() 3// 临界区代码 4mu.Unlock() 同一时刻只有一个goroutine能持有锁 零值可用（未锁定的mutex） 不可重入（同一goroutine
...
内建函数 常用 copy 1// The copy built-in function copies elements from a source slice into a 2// destination slice. (As a special case, it also will copy bytes from a 3// string to a slice of bytes.) The source and destination may overlap. Copy 4// returns the number of elements copied, which will be the minimum of 5// len(src) and len(dst). 6func copy(dst, src []Type) int
...
Concept Graceful Shutdown refers to the orderly termination of a program or service, ensuring that all resources are properly closed, ongoing tasks are completed, and data consistency and integrity are maintained. Unlike a forced exit (such as killing a process directly), a graceful shutdown prevents data loss, resource leaks, or inconsistent system states.
Steps Receive Exit Signals:
The program needs to listen for system signals (e.g., SIGINT, SIGTERM) or custom exit requests to trigger the graceful shutdown process.
...
The concept of syntactic sugar was introduced by British computer scientist Peter Landin, referring to certain types of syntax in programming languages that do not affect functionality but are convenient to use. Syntactic sugar, also known as sugared syntax, does not alter the functionality, and the compiled result is the same as without using syntactic sugar.
1. Short Variable Declaration := Multiple variable assignments may redeclare variables (This does not introduce new variables but only changes the values of existing variables.
...
Congratulations 👏👏👏 Ohtani, in his 7th year in the majors and 1st year with the Dodgers, has won his first World Series. Yoshinobu Yamamoto (26) also claimed the crown in his rookie MLB season.
Baseball is truly a fantastic team sport. Although Ohtani had an outstanding regular season, his performance in the World Series was not great (Judge also struggled, but he did hit a home run later). However, he has incredible teammates.
...
变量声明和定义的区别 变量声明 变量声明是指告诉编译器变量的类型和名称，但不为其分配内存或初始化值。在 Go 中，变量声明通常使用 var 关键字。 1var x int 在这
...