修订历史

• 2024.03.19 创建笔记

目录结构

核心代码

其他细节

• logger 持有对象池，用于格式化输出。对象池持有指针类型[1]，且只回收长度小于 256 的对象

only store small buffers to avoid pointless allocation avoid keeping arbitrarily large buffers

func newBufferPool() *bufferPool {
	return &bufferPool{
		sync.Pool{
			New: func() interface{} {
				return new(bytes.Buffer)    // return pointer 类型
			},
		},
	}
}

func (b *bufferPool) Put(x *bytes.Buffer) {
	if x.Len() > 256 {
		return
	}
	x.Reset()
	b.Pool.Put(x)
}

func (l *logger) printf(format string, args ...interface{}) {
	buf := l.bufferPool.Get()
	fmt.Fprintf(buf, format, args...)
	l.writeBuffer(buf)
	l.bufferPool.Put(buf)
}

• makefile 输出格式化的帮助文本

  .PHONY: help
  help: ## Display help messages.
    @awk 'BEGIN {FS = ":.*##"; printf "\nUsage:\n  make \033[36m<target>\033[0m\n"} /^[a-zA-Z_0-9-]+:.*?##/ { printf "  \033[36m%-20s\033[0m %s\n", $$1, $$2 } /^##@/ { printf "\n\033[1m%s\033[0m\n", substr($$0, 5) } ' $(MAKEFILE_LIST)
  

  makefile 文件需要以一定的格式组织：

  The help target prints out all targets with their descriptions organized beneath their categories. The categories are represented by ‘##@’ and the target descriptions by ‘##’. The awk commands is responsible for reading the entire set of makefiles included in this invocation, looking for lines of the file as xyz: ## something, and then pretty-format the target and help. Then, if there’s a line with ##@ something, that gets pretty-printed as a category. More info on the usage of ANSI control characters for terminal formatting: https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_parameters More info on the awk command: https://linuxcommand.org/lc3_adv_awk.php