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Adds padding to keyrange comparison #8296

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Merged
deepthi merged 3 commits into from
Jun 10, 2021
Merged

Adds padding to keyrange comparison #8296

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3f0d6bf
Adds padding when doing keyrange comparisons
Jun 8, 2021
1a4bf68
Change name to be less confusing
Jun 8, 2021
248909b
Avoid races
Jun 9, 2021
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30 changes: 26 additions & 4 deletions go/vt/key/key.go
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Original file line number Diff line number Diff line change
Expand Up @@ -194,8 +194,30 @@ func KeyRangeEqual(left, right *topodatapb.KeyRange) bool {
if right == nil {
return len(left.Start) == 0 && len(left.End) == 0
}
return bytes.Equal(left.Start, right.Start) &&
bytes.Equal(left.End, right.End)
return bytes.Equal(addPadding(left.Start), addPadding(right.Start)) &&
bytes.Equal(addPadding(left.End), addPadding(right.End))
}

// addPadding adds padding to make sure keyrange represents an 8 byte integer.
// From Vitess docs:
// A hash vindex produces an 8-byte number.
// This means that all numbers less than 0x8000000000000000 will fall in shard -80.
// Any number with the highest bit set will be >= 0x8000000000000000, and will therefore
// belong to shard 80-.
// This means that from a keyrange perspective -80 == 00-80 == 0000-8000 == 000000-800000
// If we don't add this padding, we could run into issues when transitioning from keyranges
// that use 2 bytes to 4 bytes.
func addPadding(kr []byte) []byte {
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@setassociative setassociative Jun 10, 2021

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This feels like it's converting a key from a "short" version into something normalized? It might make sense to expose this as a function on the KeyRange struct or as a (KeyRange) -> KeyRange then make that an exported function from the package.

I don't think this is a blocking comment; this PR seems safe/good to merge is.

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@setassociative setassociative Jun 10, 2021

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The (very reasonable) counterpoint here is that it's a bit late to start talking about a normalized keyrange format; i don't really know if it's worth trying to go down that road at this point unless this comes up again.

paddedKr := make([]byte, 8)

for i := 0; i < len(kr); i++ {
paddedKr = append(paddedKr, kr[i])
}

for i := len(kr); i < 8; i++ {
paddedKr = append(paddedKr, 0)
}
return paddedKr
}

// KeyRangeStartSmaller returns true if right's keyrange start is _after_ left's start
Expand All @@ -217,7 +239,7 @@ func KeyRangeStartEqual(left, right *topodatapb.KeyRange) bool {
if right == nil {
return len(left.Start) == 0
}
return bytes.Equal(left.Start, right.Start)
return bytes.Equal(addPadding(left.Start), addPadding(right.Start))
}

// KeyRangeEndEqual returns true if both key ranges have the same end
Expand All @@ -228,7 +250,7 @@ func KeyRangeEndEqual(left, right *topodatapb.KeyRange) bool {
if right == nil {
return len(left.End) == 0
}
return bytes.Equal(left.End, right.End)
return bytes.Equal(addPadding(left.End), addPadding(right.End))
}

// For more info on the following functions, see:
Expand Down
161 changes: 161 additions & 0 deletions go/vt/key/key_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -241,6 +241,167 @@ func TestKeyRangeAdd(t *testing.T) {
}
}

func TestKeyRangeEndEqual(t *testing.T) {
testcases := []struct {
first string
second string
out bool
}{{
first: "",
second: "",
out: true,
}, {
first: "",
second: "-80",
out: false,
}, {
first: "40-",
second: "10-",
out: true,
}, {
first: "-8000",
second: "-80",
out: true,
}, {
first: "-8000",
second: "-8000000000000000",
out: true,
}, {
first: "-80",
second: "-8000",
out: true,
}}
stringToKeyRange := func(spec string) *topodatapb.KeyRange {
if spec == "" {
return nil
}
parts := strings.Split(spec, "-")
if len(parts) != 2 {
panic("invalid spec")
}
kr, err := ParseKeyRangeParts(parts[0], parts[1])
if err != nil {
panic(err)
}
return kr
}

for _, tcase := range testcases {
first := stringToKeyRange(tcase.first)
second := stringToKeyRange(tcase.second)
out := KeyRangeEndEqual(first, second)
if out != tcase.out {
t.Fatalf("KeyRangeEndEqual(%q, %q) expected %t, got %t", tcase.first, tcase.second, tcase.out, out)
}
}
}

func TestKeyRangeStartEqual(t *testing.T) {
testcases := []struct {
first string
second string
out bool
}{{
first: "",
second: "",
out: true,
}, {
first: "",
second: "-80",
out: true,
}, {
first: "40-",
second: "20-",
out: false,
}, {
first: "-8000",
second: "-80",
out: true,
}, {
first: "-8000",
second: "-8000000000000000",
out: true,
}, {
first: "-80",
second: "-8000",
out: true,
}}
stringToKeyRange := func(spec string) *topodatapb.KeyRange {
if spec == "" {
return nil
}
parts := strings.Split(spec, "-")
if len(parts) != 2 {
panic("invalid spec")
}
kr, err := ParseKeyRangeParts(parts[0], parts[1])
if err != nil {
panic(err)
}
return kr
}

for _, tcase := range testcases {
first := stringToKeyRange(tcase.first)
second := stringToKeyRange(tcase.second)
out := KeyRangeStartEqual(first, second)
if out != tcase.out {
t.Fatalf("KeyRangeStartEqual(%q, %q) expected %t, got %t", tcase.first, tcase.second, tcase.out, out)
}
}
}

func TestKeyRangeEqual(t *testing.T) {
testcases := []struct {
first string
second string
out bool
}{{
first: "",
second: "",
out: true,
}, {
first: "",
second: "-80",
out: false,
}, {
first: "-8000",
second: "-80",
out: true,
}, {
first: "-8000",
second: "-8000000000000000",
out: true,
}, {
first: "-80",
second: "-8000",
out: true,
}}
stringToKeyRange := func(spec string) *topodatapb.KeyRange {
if spec == "" {
return nil
}
parts := strings.Split(spec, "-")
if len(parts) != 2 {
panic("invalid spec")
}
kr, err := ParseKeyRangeParts(parts[0], parts[1])
if err != nil {
panic(err)
}
return kr
}

for _, tcase := range testcases {
first := stringToKeyRange(tcase.first)
second := stringToKeyRange(tcase.second)
out := KeyRangeEqual(first, second)
if out != tcase.out {
t.Fatalf("KeyRangeEqual(%q, %q) expected %t, got %t", tcase.first, tcase.second, tcase.out, out)
}
}
}

func TestEvenShardsKeyRange_Error(t *testing.T) {
testCases := []struct {
i, n int
Expand Down
12 changes: 12 additions & 0 deletions go/vt/topotools/split_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,18 @@ func TestValidateForReshard(t *testing.T) {
sources: []string{"-80", "80-"},
targets: []string{"-40", "40-"},
out: "",
}, {
sources: []string{"52-53"},
targets: []string{"5200-5240", "5240-5280", "5280-52c0", "52c0-5300"},
out: "",
}, {
sources: []string{"5200-5300"},
targets: []string{"520000-524000", "524000-528000", "528000-52c000", "52c000-530000"},
out: "",
}, {
sources: []string{"-80", "80-"},
targets: []string{"-4000000000000000", "4000000000000000-8000000000000000", "8000000000000000-80c0000000000000", "80c0000000000000-"},
out: "",
}, {
sources: []string{"80-", "-80"},
targets: []string{"-40", "40-"},
Expand Down