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d0f3fa7d7e
This still generates github.com/google/uuid UUID objects, but does so using a ChaCha8 CSPRNG from the stdlib rand/v2 package. The public API is backed by a sync.Pool to provide good performance in highly concurrent operation. Under high load the read API produces a lot of extra garbage and overhead by way of temporaries and syscalls. This implementation reduces both to minimal levels, and avoids any long held global lock by utilizing sync.Pool. Updates tailscale/corp#18266 Updates tailscale/corp#19054 Signed-off-by: James Tucker <james@tailscale.com>
57 lines
1.1 KiB
Go
57 lines
1.1 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package fastuuid implements a UUID construction using an in process CSPRNG.
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package fastuuid
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import (
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crand "crypto/rand"
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"encoding/binary"
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"io"
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"math/rand/v2"
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"sync"
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"github.com/google/uuid"
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)
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// NewUUID returns a new UUID using a pool of generators, good for highly
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// concurrent use.
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func NewUUID() uuid.UUID {
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g := pool.Get().(*generator)
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defer pool.Put(g)
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return g.newUUID()
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}
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var pool = sync.Pool{
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New: func() any {
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return newGenerator()
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},
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}
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type generator struct {
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rng rand.ChaCha8
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}
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func seed() [32]byte {
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var r [32]byte
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if _, err := io.ReadFull(crand.Reader, r[:]); err != nil {
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panic(err)
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}
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return r
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}
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func newGenerator() *generator {
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return &generator{
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rng: *rand.NewChaCha8(seed()),
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}
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}
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func (g *generator) newUUID() uuid.UUID {
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var u uuid.UUID
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binary.NativeEndian.PutUint64(u[:8], g.rng.Uint64())
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binary.NativeEndian.PutUint64(u[8:], g.rng.Uint64())
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u[6] = (u[6] & 0x0f) | 0x40 // Version 4
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u[8] = (u[8] & 0x3f) | 0x80 // Variant 10
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return u
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}
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