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https://github.com/gopl-zh/gopl-zh.github.com.git
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50 lines
1.2 KiB
Go
50 lines
1.2 KiB
Go
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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// See page 312.
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// Package storage is part of a hypothetical cloud storage server.
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package storage
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import (
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"fmt"
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"log"
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"net/smtp"
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)
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var usage = make(map[string]int64)
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func bytesInUse(username string) int64 { return usage[username] }
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// E-mail sender configuration.
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// NOTE: never put passwords in source code!
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const sender = "notifications@example.com"
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const password = "correcthorsebatterystaple"
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const hostname = "smtp.example.com"
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const template = `Warning: you are using %d bytes of storage,
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%d%% of your quota.`
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//!+factored
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var notifyUser = func(username, msg string) {
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auth := smtp.PlainAuth("", sender, password, hostname)
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err := smtp.SendMail(hostname+":587", auth, sender,
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[]string{username}, []byte(msg))
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if err != nil {
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log.Printf("smtp.SendEmail(%s) failed: %s", username, err)
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}
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}
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func CheckQuota(username string) {
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used := bytesInUse(username)
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const quota = 1000000000 // 1GB
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percent := 100 * used / quota
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if percent < 90 {
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return // OK
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}
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msg := fmt.Sprintf(template, used, percent)
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notifyUser(username, msg)
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}
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//!-factored
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