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Commit0d9010e

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authored
chore: fix 30% startup time hit from userpassword (#12769)
pbkdf2 is too expensive to run in init, so this change makes it loadlazily. I introduced a lazy package that I hope to use more in my`GODEBUG=inittrace=1` adventure.Benchmark results:```$ hyperfine "coder --help" "coder-new --help"Benchmark 1: coder --help Time (mean ± σ): 82.1 ms ± 3.8 ms [User: 93.3 ms, System: 30.4 ms] Range (min … max): 72.2 ms … 90.7 ms 35 runs Benchmark 2: coder-new --help Time (mean ± σ): 52.0 ms ± 4.3 ms [User: 62.4 ms, System: 30.8 ms] Range (min … max): 41.9 ms … 62.2 ms 52 runs Summary coder-new --help ran 1.58 ± 0.15 times faster than coder --help```
1 parent73fbdbb commit0d9010e

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2 files changed

+42
-3
lines changed

2 files changed

+42
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lines changed

‎coderd/userpassword/userpassword.go

Lines changed: 14 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,8 @@ import (
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"golang.org/x/crypto/pbkdf2"
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"golang.org/x/exp/slices"
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"golang.org/x/xerrors"
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"github.com/coder/coder/v2/coderd/util/lazy"
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)
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var (
@@ -38,8 +40,15 @@ var (
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defaultSaltSize=16
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4042
// The simulated hash is used when trying to simulate password checks for
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// users that don't exist.
42-
simulatedHash,_=Hash("hunter2")
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// users that don't exist. It's meant to preserve the timing of the hash
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// comparison.
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simulatedHash=lazy.New(func()string {
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h,err:=Hash("hunter2")
47+
iferr!=nil {
48+
panic(err)
49+
}
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returnh
51+
})
4352
)
4453

4554
// Make password hashing much faster in tests.
@@ -65,7 +74,9 @@ func init() {
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funcCompare(hashedstring,passwordstring) (bool,error) {
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// If the hased password provided is empty, simulate comparing a real hash.
6776
ifhashed=="" {
68-
hashed=simulatedHash
77+
// TODO: this seems ripe for creating a vulnerability where
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// hunter2 can log into any account.
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hashed=simulatedHash.Load()
6980
}
7081

7182
iflen(hashed)<hashLength {

‎coderd/util/lazy/value.go

Lines changed: 28 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,28 @@
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// Package lazy provides a lazy value implementation.
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// It's useful especially in global variable initialization to avoid
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// slowing down the program startup time.
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package lazy
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import (
7+
"sync"
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"sync/atomic"
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)
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typeValue[Tany]struct {
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once sync.Once
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fnfunc()T
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cached atomic.Pointer[T]
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}
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func (v*Value[T])Load()T {
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v.once.Do(func() {
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vv:=v.fn()
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v.cached.Store(&vv)
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})
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return*v.cached.Load()
23+
}
24+
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// New creates a new lazy value with the given load function.
26+
funcNew[Tany](fnfunc()T)*Value[T] {
27+
return&Value[T]{fn:fn}
28+
}

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