出于好奇,我在Swift中编写了一个GNU find
- 仿真器,并且偶然发现了这个时间差异:
$ time find / &>/dev/null
real 1m6.040s
$ time swiftly-find /
real 5m43.028s
Swift代码如下:
let enumeration = FileManager.default.enumerator(at: URL(string: "\(from)/")!, includingPropertiesForKeys: nil, errorHandler: { (at: URL, with: Error) in
print("Error \(with) encountered at directory \(at)"); return true
})!
var list = String()
for i in enumeration {
let result = String(describing: i).replacingOccurrences(of: "file://", with: "")
list.append("\(result)\n")
print(result)
}
为什么Swift的enumerator
比GNU find
慢得多?有没有办法加速Swift代码达到与find
类似的速度?