planner: integrate hashEqual interface into LogicalPlan and expression.Expression.

pkg/planner/cascades/BUILD.bazel

@@ -4,7 +4,6 @@ go_library(
     name = "cascades",
     srcs = [
         "enforcer_rules.go",
-        "hash_equaler.go",
         "implementation_rules.go",
         "optimize.go",
         "stringer.go",
@@ -42,7 +41,6 @@ go_test(
     timeout = "short",
     srcs = [
         "enforcer_rules_test.go",
-        "hash_equaler_test.go",
         "main_test.go",
         "optimize_test.go",
         "stringer_test.go",
@@ -51,7 +49,7 @@ go_test(
     data = glob(["testdata/**"]),
     embed = [":cascades"],
     flaky = True,
-    shard_count = 28,
+    shard_count = 25,
     deps = [
         "//pkg/domain",
         "//pkg/expression",

pkg/planner/cascades/base/BUILD.bazel

@@ -0,0 +1,24 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "base",
+    srcs = [
+        "base.go",
+        "hash_equaler.go",
+    ],
+    importpath = "github.com/pingcap/tidb/pkg/planner/cascades/base",
+    visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "base_test",
+    timeout = "short",
+    srcs = [
+        "base_test.go",
+        "hash_equaler_test.go",
+    ],
+    embed = [":base"],
+    flaky = True,
+    shard_count = 3,
+    deps = ["@com_github_stretchr_testify//require"],
+)

pkg/planner/cascades/base/base.go

@@ -0,0 +1,37 @@
+// Copyright 2024 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package base
+
+// Hash64 is the interface for hashcode.
+// It is used to calculate the lossy digest of an object to return uint64
+// rather than compacted bytes from cascaded operators bottom-up.
+type Hash64 interface {
+	// Hash64 returns the uint64 digest of an object.
+	Hash64(h Hasher)
+}
+
+// Equals is the interface for equality check.
+// When we need to compare two objects when countering hash conflicts, we can
+// use this interface to check whether they are equal.
+type Equals interface {
+	// Equals checks whether two base objects are equal.
+	Equals(any) bool
+}
+
+// HashEquals is the interface for hash64 and equality check.
+type HashEquals interface {
+	Hash64
+	Equals
+}

pkg/planner/cascades/base/base_test.go

@@ -0,0 +1,79 @@
+// Copyright 2024 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package base
+
+import (
+	"testing"
+)
+
+type testcase struct {
+	a int
+	b int
+	c string
+}
+
+type TestEquals[T any] interface {
+	EqualsT(other T) bool
+}
+
+type TestEqualAny interface {
+	EqualsAny(other any) bool
+}
+
+type TestSuperEquals interface {
+	TestEquals[TestSuperEquals]
+}
+
+func (tc *testcase) EqualsT(other *testcase) bool {
+	return tc.a == other.a && tc.b == other.b && tc.c == other.c
+}
+
+func (tc *testcase) EqualsAny(other any) bool {
+	tc1, ok := other.(*testcase)
+	if !ok {
+		return false
+	}
+	return tc.a == tc1.a && tc.b == tc1.b && tc.c == tc1.c
+}
+
+// goos: linux
+// goarch: amd64
+// pkg: github.com/pingcap/tidb/pkg/planner/cascades/memo
+// cpu: 12th Gen Intel(R) Core(TM) i7-12700KF
+// BenchmarkEqualsT
+// BenchmarkEqualsT-20    	1000000000	         0.8981 ns/op
+func BenchmarkEqualsT(b *testing.B) {
+	tc1 := &testcase{a: 1, b: 2, c: "3"}
+	var tc2 TestEquals[*testcase] = &testcase{a: 1, b: 2, c: "3"}
+	for i := 0; i < b.N; i++ {
+		if tc3, ok := tc2.(*testcase); ok {
+			tc1.EqualsT(tc3)
+		}
+	}
+}
+
+// goos: linux
+// goarch: amd64
+// pkg: github.com/pingcap/tidb/pkg/planner/cascades/memo
+// cpu: 12th Gen Intel(R) Core(TM) i7-12700KF
+// BenchmarkEqualsAny
+// BenchmarkEqualsAny-20    	1000000000	         0.4837 ns/op
+func BenchmarkEqualsAny(b *testing.B) {
+	tc1 := &testcase{a: 1, b: 2, c: "3"}
+	var tc2 TestEqualAny = &testcase{a: 1, b: 2, c: "3"}
+	for i := 0; i < b.N; i++ {
+		tc1.EqualsAny(tc2)
+	}
+}

pkg/planner/cascades/hash_equaler.go → pkg/planner/cascades/base/hash_equaler.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package cascades
+package base
 
 import (
 	"math"

pkg/planner/cascades/hash_equaler_test.go → pkg/planner/cascades/base/hash_equaler_test.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package cascades
+package base
 
 import (
 	"testing"

pkg/planner/core/base/BUILD.bazel

@@ -14,6 +14,7 @@ go_library(
     deps = [
         "//pkg/expression",
         "//pkg/kv",
+        "//pkg/planner/cascades/base",
         "//pkg/planner/context",
         "//pkg/planner/funcdep",
         "//pkg/planner/property",

pkg/planner/core/base/plan_base.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/pingcap/tidb/pkg/expression"
 	"github.com/pingcap/tidb/pkg/kv"
+	"github.com/pingcap/tidb/pkg/planner/cascades/base"
 	"github.com/pingcap/tidb/pkg/planner/context"
 	fd "github.com/pingcap/tidb/pkg/planner/funcdep"
 	"github.com/pingcap/tidb/pkg/planner/property"
@@ -192,6 +193,7 @@ func (c *PlanCounterTp) IsForce() bool {
 // We can do a lot of logical optimizations to it, like predicate push-down and column pruning.
 type LogicalPlan interface {
 	Plan
+	base.HashEquals
 
 	// HashCode encodes a LogicalPlan to fast compare whether a LogicalPlan equals to another.
 	// We use a strict encode method here which ensures there is no conflict.

pkg/planner/core/operator/logicalop/BUILD.bazel

@@ -40,6 +40,7 @@ go_library(
         "//pkg/parser/model",
         "//pkg/parser/mysql",
         "//pkg/planner/cardinality",
+        "//pkg/planner/cascades/base",
         "//pkg/planner/core/base",
         "//pkg/planner/core/constraint",
         "//pkg/planner/core/cost",
@@ -58,6 +59,7 @@ go_library(
         "//pkg/types",
         "//pkg/util/dbterror/plannererrors",
         "//pkg/util/hint",
+        "//pkg/util/intest",
         "//pkg/util/intset",
         "//pkg/util/plancodec",
         "//pkg/util/size",

pkg/planner/core/operator/logicalop/base_logical_plan.go

@@ -17,6 +17,7 @@ package logicalop
 import (
 	"github.com/pingcap/tidb/pkg/expression"
 	"github.com/pingcap/tidb/pkg/kv"
+	base2 "github.com/pingcap/tidb/pkg/planner/cascades/base"
 	"github.com/pingcap/tidb/pkg/planner/core/base"
 	"github.com/pingcap/tidb/pkg/planner/core/operator/baseimpl"
 	fd "github.com/pingcap/tidb/pkg/planner/funcdep"
@@ -26,6 +27,7 @@ import (
 	"github.com/pingcap/tidb/pkg/planner/util/utilfuncp"
 	"github.com/pingcap/tidb/pkg/types"
 	"github.com/pingcap/tidb/pkg/util/dbterror/plannererrors"
+	"github.com/pingcap/tidb/pkg/util/intest"
 	"github.com/pingcap/tidb/pkg/util/tracing"
 )
 
@@ -50,6 +52,27 @@ type BaseLogicalPlan struct {
 	fdSet *fd.FDSet
 }
 
+// *************************** implementation of HashEquals interface ***************************
+
+// Hash64 implements HashEquals.<0th> interface.
+func (p *BaseLogicalPlan) Hash64(h base2.Hasher) {
+	intest.Assert(false, "Hash64 should not be called directly")
+	h.HashInt(p.ID())
+}
+
+// Equals implements HashEquals.<1st> interface.
+func (p *BaseLogicalPlan) Equals(other any) bool {
+	intest.Assert(false, "Equals should not be called directly")
+	if other == nil {
+		return false
+	}
+	olp, ok := other.(*BaseLogicalPlan)
+	if !ok {
+		return false
+	}
+	return p.ID() == olp.ID()
+}
+
 // *************************** implementation of base Plan interface ***************************
 
 // ExplainInfo implements Plan interface.

pkg/planner/core/operator/logicalop/logical_projection.go

@@ -20,6 +20,7 @@ import (
 	"github.com/pingcap/tidb/pkg/expression"
 	"github.com/pingcap/tidb/pkg/parser/mysql"
 	"github.com/pingcap/tidb/pkg/planner/cardinality"
+	base2 "github.com/pingcap/tidb/pkg/planner/cascades/base"
 	"github.com/pingcap/tidb/pkg/planner/core/base"
 	ruleutil "github.com/pingcap/tidb/pkg/planner/core/rule/util"
 	fd "github.com/pingcap/tidb/pkg/planner/funcdep"
@@ -55,7 +56,52 @@ func (p LogicalProjection) Init(ctx base.PlanContext, qbOffset int) *LogicalProj
 	return &p
 }
 
-// *************************** start implementation of Plan interface ***************************
+// *************************** start implementation of HashEquals interface ****************************
+
+// Hash64 implements the base.Hash64.<0th> interface.
+func (p *LogicalProjection) Hash64(h base2.Hasher) {
+	// todo: LogicalSchemaProducer should implement HashEquals interface, otherwise, its self elements
+	// like schema and names are lost.
+	p.LogicalSchemaProducer.Hash64(h)
+	// todo: if we change the logicalProjection's Expr definition as:Exprs []memo.ScalarOperator[any],
+	// we should use like below:
+	// for _, one := range p.Exprs {
+	//		one.Hash64(one)
+	// }
+	// otherwise, we would use the belowing code.
+	//for _, one := range p.Exprs {
+	//	one.Hash64(h)
+	//}
+	h.HashBool(p.CalculateNoDelay)
+	h.HashBool(p.Proj4Expand)
+}
+
+// Equals implements the base.HashEquals.<1st> interface.
+func (p *LogicalProjection) Equals(other any) bool {
+	if other == nil {
+		return false
+	}
+	proj, ok := other.(*LogicalProjection)
+	if !ok {
+		return false
+	}
+	// todo: LogicalSchemaProducer should implement HashEquals interface, otherwise, its self elements
+	// like schema and names are lost.
+	if !p.LogicalSchemaProducer.Equals(&proj.LogicalSchemaProducer) {
+		return false
+	}
+	//for i, one := range p.Exprs {
+	//	if !one.(memo.ScalarOperator[any]).Equals(other.Exprs[i]) {
+	//		return false
+	//	}
+	//}
+	if p.CalculateNoDelay != proj.CalculateNoDelay {
+		return false
+	}
+	return p.Proj4Expand == proj.Proj4Expand
+}
+
+// *************************** start implementation of Plan interface **********************************
 
 // ExplainInfo implements Plan interface.
 func (p *LogicalProjection) ExplainInfo() string {
@@ -71,7 +117,7 @@ func (p *LogicalProjection) ReplaceExprColumns(replace map[string]*expression.Co
 	}
 }
 
-// *************************** end implementation of Plan interface ***************************
+// *************************** end implementation of Plan interface ************************************
 
 // *************************** start implementation of logicalPlan interface ***************************