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package resource
import (
"crypto/rand"
"fmt"
"math/big"
"sync"
)
const UniqueIdPrefix = `terraform-`
// idCounter is a randomly seeded monotonic counter for generating ordered
// unique ids. It uses a big.Int so we can easily increment a long numeric
// string. The max possible hex value here with 12 random bytes is
// "01000000000000000000000000", so there's no chance of rollover during
// operation.
var idMutex sync.Mutex
var idCounter = big.NewInt(0).SetBytes(randomBytes(12))
// Helper for a resource to generate a unique identifier w/ default prefix
func UniqueId() string {
return PrefixedUniqueId(UniqueIdPrefix)
}
// Helper for a resource to generate a unique identifier w/ given prefix
//
// After the prefix, the ID consists of an incrementing 26 digit value (to match
// previous timestamp output).
func PrefixedUniqueId(prefix string) string {
idMutex.Lock()
defer idMutex.Unlock()
return fmt.Sprintf("%s%026x", prefix, idCounter.Add(idCounter, big.NewInt(1)))
}
func randomBytes(n int) []byte {
b := make([]byte, n)
rand.Read(b)
return b
}
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