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util/deephash: use binary encoding of time.Time (#5352)

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Formatting a time.Time as RFC3339 is slow.
See https://go.dev/issue/54093

Now that we have efficient hashing of fixed-width integers,
just hash the time.Time as a binary value.

Performance:

	Hash-24                19.0µs ± 1%    18.6µs ± 1%   -2.03%  (p=0.000 n=10+9)
	TailcfgNode-24         1.79µs ± 1%    1.40µs ± 1%  -21.74%  (p=0.000 n=10+9)

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
pull/5364/head
Joe Tsai 2 years ago committed by GitHub
parent 0476c8ebc6
commit 548fa63e49
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 72 additions and 14 deletions
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15
util/deephash/deephash.go
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@ -11,6 +11,9 @@
// The definition of equality is identical to reflect.DeepEqual except: // The definition of equality is identical to reflect.DeepEqual except:
// - Floating-point values are compared based on the raw bits, // - Floating-point values are compared based on the raw bits,
// which means that NaNs (with the same bit pattern) are treated as equal. // which means that NaNs (with the same bit pattern) are treated as equal.
// - time.Time are compared based on whether they are the same instant in time
// and also in the same zone offset. Monotonic measurements and zone names
// are ignored as part of the hash.
// - Types which implement interface { AppendTo([]byte) []byte } use // - Types which implement interface { AppendTo([]byte) []byte } use
// the AppendTo method to produce a textual representation of the value. // the AppendTo method to produce a textual representation of the value.
// Thus, two values are equal if AppendTo produces the same bytes. // Thus, two values are equal if AppendTo produces the same bytes.
@ -522,12 +525,16 @@ func (h *hasher) hashComplex128v(v addressableValue) bool {
return true return true
} }
// hashString hashes v, of kind time.Time. // hashTimev hashes v, of kind time.Time.
func (h *hasher) hashTimev(v addressableValue) bool { func (h *hasher) hashTimev(v addressableValue) bool {
// Include the zone offset (but not the name) to keep
// Hash(t1) == Hash(t2) being semantically equivalent to
// t1.Format(time.RFC3339Nano) == t2.Format(time.RFC3339Nano).
t := *(*time.Time)(v.Addr().UnsafePointer()) t := *(*time.Time)(v.Addr().UnsafePointer())
b := t.AppendFormat(h.scratch[:1], time.RFC3339Nano) _, offset := t.Zone()
b[0] = byte(len(b) - 1) // more than sufficient width; if not, good enough. h.HashUint64(uint64(t.Unix()))
h.HashBytes(b) h.HashUint32(uint32(t.Nanosecond()))
h.HashUint32(uint32(offset))
return true return true
} }

71
util/deephash/deephash_test.go
Unescape Escape View File

@ -7,6 +7,7 @@ package deephash
import ( import (
"archive/tar" "archive/tar"
"crypto/sha256" "crypto/sha256"
"encoding/binary"
"fmt" "fmt"
"hash" "hash"
"io" "io"
@ -400,6 +401,11 @@ func TestCanMemHash(t *testing.T) {
} }
} }
func u8(n uint8) string { return string([]byte{n}) }
func u16(n uint16) string { return string(binary.LittleEndian.AppendUint16(nil, n)) }
func u32(n uint32) string { return string(binary.LittleEndian.AppendUint32(nil, n)) }
func u64(n uint64) string { return string(binary.LittleEndian.AppendUint64(nil, n)) }
func TestGetTypeHasher(t *testing.T) { func TestGetTypeHasher(t *testing.T) {
switch runtime.GOARCH { switch runtime.GOARCH {
case "amd64", "arm64", "arm", "386", "riscv64": case "amd64", "arm64", "arm", "386", "riscv64":
@ -521,28 +527,28 @@ func TestGetTypeHasher(t *testing.T) {
}, },
{ {
name: "time", name: "time",
val: time.Unix(0, 0).In(time.UTC), val: time.Unix(1234, 5678).In(time.UTC),
out: "\x141970-01-01T00:00:00Z", out: u64(1234) + u32(5678) + u32(0),
}, },
{ {
name: "time_ptr", // addressable, as opposed to "time" test above name: "time_ptr", // addressable, as opposed to "time" test above
val: ptrTo(time.Unix(0, 0).In(time.UTC)), val: ptrTo(time.Unix(1234, 5678).In(time.UTC)),
out: "\x01\x141970-01-01T00:00:00Z", out: u8(1) + u64(1234) + u32(5678) + u32(0),
}, },
{ {
name: "time_ptr_via_unexported", name: "time_ptr_via_unexported",
val: testtype.NewUnexportedAddressableTime(time.Unix(0, 0).In(time.UTC)), val: testtype.NewUnexportedAddressableTime(time.Unix(1234, 5678).In(time.UTC)),
out: "\x01\x141970-01-01T00:00:00Z", out: u8(1) + u64(1234) + u32(5678) + u32(0),
}, },
{ {
name: "time_ptr_via_unexported_value", name: "time_ptr_via_unexported_value",
val: *testtype.NewUnexportedAddressableTime(time.Unix(0, 0).In(time.UTC)), val: *testtype.NewUnexportedAddressableTime(time.Unix(1234, 5678).In(time.UTC)),
out: "\x141970-01-01T00:00:00Z", out: u64(1234) + u32(5678) + u32(0),
}, },
{ {
name: "time_custom_zone", name: "time_custom_zone",
val: time.Unix(1655311822, 0).In(time.FixedZone("FOO", -60*60)), val: time.Unix(1655311822, 0).In(time.FixedZone("FOO", -60*60)),
out: "\x192022-06-15T15:50:22-01:00", out: u64(1655311822) + u32(0) + u32(math.MaxUint32-60*60+1),
}, },
{ {
name: "time_nil", name: "time_nil",
@ -616,7 +622,7 @@ func TestGetTypeHasher(t *testing.T) {
{ {
name: "tailcfg.Node", name: "tailcfg.Node",
val: &tailcfg.Node{}, val: &tailcfg.Node{},
out: "\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x140001-01-01T00:00:00Z\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x140001-01-01T00:00:00Z\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", out: "\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" + u64(uint64(time.Time{}.Unix())) + u32(0) + u32(0) + "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" + u64(uint64(time.Time{}.Unix())) + u32(0) + u32(0) + "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
}, },
} }
for _, tt := range tests { for _, tt := range tests {
@ -885,3 +891,48 @@ func (h *hashBuffer) Reset() {
h.Hash.Reset() h.Hash.Reset()
h.B = h.B[:0] h.B = h.B[:0]
} }
func FuzzTime(f *testing.F) {
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), false, "", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), true, "", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), true, "hello", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), true, "", 1234)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), true, "hello", 1234)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), false, "", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), true, "", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), true, "hello", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), true, "", 1234)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), true, "hello", 1234)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), true, "", 0)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), true, "hello", 0)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), true, "", 1234)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), true, "hello", 1234)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), false, "", 0)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), true, "", 0)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), true, "hello", 0)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), true, "", 1234)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), true, "hello", 1234)
f.Fuzz(func(t *testing.T,
s1, ns1 int64, loc1 bool, name1 string, off1 int,
s2, ns2 int64, loc2 bool, name2 string, off2 int,
) {
t1 := time.Unix(s1, ns1)
if loc1 {
t1.In(time.FixedZone(name1, off1))
}
t2 := time.Unix(s2, ns2)
if loc2 {
t2.In(time.FixedZone(name2, off2))
}
got := Hash(&t1) == Hash(&t2)
want := t1.Format(time.RFC3339Nano) == t2.Format(time.RFC3339Nano)
if got != want {
t.Errorf("time.Time(%s) == time.Time(%s) mismatches hash equivalent", t1.Format(time.RFC3339Nano), t2.Format(time.RFC3339Nano))
}
})
}

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