planner: optimize the performance of non-cacheable-checker (#42002)

pingcap · Mar 8, 2023 · 4ac7dc9 · 4ac7dc9
1 parent 31e4894
commit 4ac7dc9
Show file tree

Hide file tree

Showing 2 changed files with 52 additions and 7 deletions.
diff --git a/planner/core/plan_cacheable_checker.go b/planner/core/plan_cacheable_checker.go
@@ -16,6 +16,7 @@ package core
 
 import (
 	"fmt"
+	"sync"
 
 	"github.com/pingcap/tidb/expression"
 	"github.com/pingcap/tidb/infoschema"
@@ -201,6 +202,8 @@ func NonPreparedPlanCacheable(node ast.Node, is infoschema.InfoSchema) bool {
 	return ok
 }
 
+var nonPrepCacheCheckerPool = &sync.Pool{New: func() any { return &nonPreparedPlanCacheableChecker{} }}
+
 // NonPreparedPlanCacheableWithCtx checks whether the input ast is cacheable for non-prepared plan cache.
 // Only support: select {field} from {single-table} where {cond} and {cond} ...
 // {cond}: {col} {op} {val}
@@ -238,13 +241,17 @@ func NonPreparedPlanCacheableWithCtx(sctx sessionctx.Context, node ast.Node, is
 		}
 	}
 
-	checker := nonPreparedPlanCacheableChecker{
-		sctx:      sctx,
-		cacheable: true,
-		schema:    is,
-	}
-	node.Accept(&checker)
-	return checker.cacheable, checker.reason
+	// allocate and init the checker
+	checker := nonPrepCacheCheckerPool.Get().(*nonPreparedPlanCacheableChecker)
+	checker.reset(sctx, is)
+
+	node.Accept(checker)
+	cacheable, reason := checker.cacheable, checker.reason
+
+	// put the checker back
+	nonPrepCacheCheckerPool.Put(checker)
+
+	return cacheable, reason
 }
 
 // nonPreparedPlanCacheableChecker checks whether a query's plan can be cached for non-prepared plan cache.
@@ -260,6 +267,16 @@ type nonPreparedPlanCacheableChecker struct {
 	filterCnt int // the number of filters in the current node
 }
 
+func (checker *nonPreparedPlanCacheableChecker) reset(sctx sessionctx.Context, schema infoschema.InfoSchema) {
+	checker.sctx = sctx
+	checker.cacheable = true
+	checker.schema = schema
+	checker.reason = ""
+	checker.tableNode = nil
+	checker.constCnt = 0
+	checker.filterCnt = 0
+}
+
 // Enter implements Visitor interface.
 func (checker *nonPreparedPlanCacheableChecker) Enter(in ast.Node) (out ast.Node, skipChildren bool) {
 	if checker.isFilterNode(in) {

diff --git a/planner/core/plan_cacheable_checker_test.go b/planner/core/plan_cacheable_checker_test.go
@@ -24,6 +24,7 @@ import (
 	"github.com/pingcap/tidb/parser/model"
 	"github.com/pingcap/tidb/parser/mysql"
 	"github.com/pingcap/tidb/planner/core"
+	"github.com/pingcap/tidb/sessiontxn"
 	"github.com/pingcap/tidb/testkit"
 	driver "github.com/pingcap/tidb/types/parser_driver"
 	"github.com/pingcap/tidb/util/mock"
@@ -333,3 +334,30 @@ func TestNonPreparedPlanCacheable(t *testing.T) {
 		require.True(t, core.NonPreparedPlanCacheable(stmt, is))
 	}
 }
+
+func BenchmarkNonPreparedPlanCacheableChecker(b *testing.B) {
+	store := testkit.CreateMockStore(b)
+	tk := testkit.NewTestKit(b, store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (a int, b int)")
+
+	p := parser.New()
+	sql := "select * from test.t where a<10"
+	stmt, err := p.ParseOneStmt(sql, "", "")
+	if err != nil {
+		b.Fatal(err)
+	}
+	sctx := tk.Session()
+	is := sessiontxn.GetTxnManager(sctx).GetTxnInfoSchema()
+
+	core.NonPreparedPlanCacheable(stmt, is)
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		ok, _ := core.NonPreparedPlanCacheableWithCtx(sctx, stmt, is)
+		if !ok {
+			b.Fatal()
+		}
+	}
+}