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constraint: perform cancel checking when combining constraints #111979

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Oct 9, 2023
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constraint: perform cancel checking when combining constraints #111979

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3 changes: 3 additions & 0 deletions pkg/sql/opt/constraint/BUILD.bazel
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Original file line number Diff line number Diff line change
Expand Up @@ -51,5 +51,8 @@ go_test(
"//pkg/util/intsets",
"//pkg/util/leaktest",
"//pkg/util/randutil",
"//pkg/util/timeutil",
"@com_github_cockroachdb_errors//:errors",
"@com_github_stretchr_testify//require",
],
)
14 changes: 13 additions & 1 deletion pkg/sql/opt/constraint/constraint.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@ import (
"github.com/cockroachdb/errors"
)

const CancelCheckInterval = 16

// Constraint specifies the possible set of values that one or more columns
// will have in the result set. If this is a single column constraint, then
// that column's value will always be part of one of the spans in this
Expand Down Expand Up @@ -344,7 +346,7 @@ func (c *Constraint) findIntersectingSpan(keyCtx *KeyContext, sp *Span) (_ *Span
// c: /a/b: [/1 - /2] [/4 - /4]
// other: /b: [/5 - /5]
// result: /a/b: [/1/5 - /2/5] [/4/5 - /4/5]
func (c *Constraint) Combine(evalCtx *eval.Context, other *Constraint) {
func (c *Constraint) Combine(evalCtx *eval.Context, other *Constraint, checkCancellation func()) {
if !other.Columns.IsStrictSuffixOf(&c.Columns) {
// Note: we don't want to let the c and other pointers escape by passing
// them directly to Sprintf.
Expand All @@ -366,7 +368,15 @@ func (c *Constraint) Combine(evalCtx *eval.Context, other *Constraint) {
var resultInitialized bool
keyCtx := KeyContext{Columns: c.Columns, EvalCtx: evalCtx}

numIterations := 0
cancelCheck := func() {
numIterations++
if checkCancellation != nil && (numIterations%CancelCheckInterval) == 0 {
checkCancellation()
}
}
for i := 0; i < c.Spans.Count(); i++ {
cancelCheck()
sp := *c.Spans.Get(i)

startLen, endLen := sp.start.Length(), sp.end.Length()
Expand Down Expand Up @@ -402,6 +412,7 @@ func (c *Constraint) Combine(evalCtx *eval.Context, other *Constraint) {
}
}
for j := 0; j < other.Spans.Count(); j++ {
cancelCheck()
extSp := other.Spans.Get(j)
var newSp Span
newSp.Init(
Expand Down Expand Up @@ -450,6 +461,7 @@ func (c *Constraint) Combine(evalCtx *eval.Context, other *Constraint) {
resultInitialized = true
result.Alloc(c.Spans.Count())
for j := 0; j < i; j++ {
cancelCheck()
result.Append(c.Spans.Get(j))
}
}
Expand Down
88 changes: 87 additions & 1 deletion pkg/sql/opt/constraint/constraint_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ package constraint
import (
"fmt"
"testing"
"time"

"github.com/cockroachdb/cockroach/pkg/settings/cluster"
"github.com/cockroachdb/cockroach/pkg/sql/opt"
Expand All @@ -22,6 +23,9 @@ import (
"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
"github.com/cockroachdb/cockroach/pkg/util/intsets"
"github.com/cockroachdb/cockroach/pkg/util/leaktest"
"github.com/cockroachdb/cockroach/pkg/util/timeutil"
"github.com/cockroachdb/errors"
"github.com/stretchr/testify/require"
)

func TestConstraintUnion(t *testing.T) {
Expand Down Expand Up @@ -452,14 +456,96 @@ func TestConstraintCombine(t *testing.T) {
t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
a := ParseConstraint(&evalCtx, tc.a)
b := ParseConstraint(&evalCtx, tc.b)
a.Combine(&evalCtx, &b)
a.Combine(&evalCtx, &b, nil /* checkCancellation */)
if res := a.String(); res != tc.e {
t.Errorf("expected\n %s; got\n %s", tc.e, res)
}
})
}
}

// TestCancelLargeConstraintCombine tests that combining constraints can be
// successfully cancelled with a cancel function.
func TestCancelLargeConstraintCombine(t *testing.T) {
st := cluster.MakeTestingClusterSettings()
evalCtx := eval.MakeTestingEvalContext(st)

testData := []struct {
a, b, c, d, e, f, g, h, j, k, l, m, n, o, p, q string
}{
{
a: "/1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
b: "/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
c: "/3/4/5/6/7/8/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
d: "/4/5/6/7/8/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
e: "/5/6/7/8/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
f: "/6/7/8/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
g: "/7/8/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
h: "/8/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
j: "/9/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
k: "/10/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
l: "/11/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
m: "/12/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
n: "/13/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
o: "/14/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
p: "/15/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
q: "/16: [/10 - /10] [/20 - /20] [/30 - /30] [/40 - /40] [/50 - /50] [/60 - /60] [/70 - /70] [/80 - /80] [/90 - /90]",
},
}

for i, tc := range testData {
iterations := 0
cancelFunc := func() {
iterations++
if iterations > 2000 {
panic(errors.AssertionFailedf("We successfully cancelled the operation!"))
}
}
testFunc := func(constraint1, constraint2 *Constraint) {
ts := timeutil.Now()
constraint1.Combine(&evalCtx, constraint2, cancelFunc)
if d := timeutil.Since(ts); d > time.Second {
t.Errorf("expected cancellation to occur in under 1 second, but took %v", d)
}
}
t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
a := ParseConstraint(&evalCtx, tc.a)
b := ParseConstraint(&evalCtx, tc.b)
c := ParseConstraint(&evalCtx, tc.c)
d := ParseConstraint(&evalCtx, tc.d)
e := ParseConstraint(&evalCtx, tc.e)
f := ParseConstraint(&evalCtx, tc.f)
g := ParseConstraint(&evalCtx, tc.g)
h := ParseConstraint(&evalCtx, tc.h)
j := ParseConstraint(&evalCtx, tc.j)
k := ParseConstraint(&evalCtx, tc.k)
l := ParseConstraint(&evalCtx, tc.l)
m := ParseConstraint(&evalCtx, tc.m)
n := ParseConstraint(&evalCtx, tc.n)
o := ParseConstraint(&evalCtx, tc.o)
p := ParseConstraint(&evalCtx, tc.p)
q := ParseConstraint(&evalCtx, tc.q)
testFunc(&a, &b)
testFunc(&c, &d)
testFunc(&e, &f)
testFunc(&g, &h)
testFunc(&j, &k)
testFunc(&l, &m)
testFunc(&n, &o)
testFunc(&p, &q)
testFunc(&a, &c)
testFunc(&e, &g)
testFunc(&j, &l)
testFunc(&n, &p)
// The next Combine call will panic within a second or two.
require.Panics(t, func() { testFunc(&a, &e) })
// This Combine call panics right away since the iterations target has
// already been reached.
require.Panics(t, func() { testFunc(&j, &n) })
})
}
}

func TestConsolidateSpans(t *testing.T) {
defer leaktest.AfterTest(t)()
st := cluster.MakeTestingClusterSettings()
Expand Down
4 changes: 2 additions & 2 deletions pkg/sql/opt/idxconstraint/index_constraints.go
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Original file line number Diff line number Diff line change
Expand Up @@ -845,11 +845,11 @@ func (c *indexConstraintCtx) makeSpansForAnd(
}
ofsC.IntersectWith(c.evalCtx, &exprConstraint)
}
out.Combine(c.evalCtx, &ofsC)
out.Combine(c.evalCtx, &ofsC, c.checkCancellation)
numIterations++
// In case we can't exit this loop, allow the cancel checker to cancel
// this query.
if (numIterations % 16) == 0 {
if (numIterations % constraint.CancelCheckInterval) == 0 {
c.checkCancellation()
}
}
Expand Down