From e97b815150ba39b2643753745668dec86e3a8feb Mon Sep 17 00:00:00 2001
From: rulego-team <rulego@outlook.com>
Date: Tue, 14 Jul 2026 11:56:05 +0800
Subject: [PATCH] =?UTF-8?q?perf(cep):=20evalPrepared=20base=20map=20?=
 =?UTF-8?q?=E7=94=A8=20sync.Pool=20=E5=A4=8D=E7=94=A8(=E6=B1=82=E5=80=BC?=
 =?UTF-8?q?=E5=88=86=E9=85=8D=20-17~19%=E3=80=81B/op=20-47%)?=
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---
 cep/eval.go | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/cep/eval.go b/cep/eval.go
index 03596f8..011d86a 100644
--- a/cep/eval.go
+++ b/cep/eval.go
@@ -14,6 +14,7 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
+	"sync"
 	"unicode"
 
 	"github.com/rulego/streamsql/expr"
@@ -238,11 +239,20 @@ func prepare(src string, symbols map[string]bool) (*preparedExpr, error) {
 }
 
 // evalPrepared 用 ctx 求值预编译表达式：重算占位符值 + 灌入裸字段，复用编译产物。
+// baseMapPool 复用 evalPrepared 的 base map：DEFINE/MEASURES 每次求值建一次 base（热路径主分配源）。
+// EvaluateValueWithNull 同步求值、返回标量/字段引用不持 base，Put 回 Pool 前清空即可复用。
+var baseMapPool = sync.Pool{
+	New: func() any { return make(map[string]any, 8) },
+}
+
 func evalPrepared(p *preparedExpr, ctx *matchCtx) (any, bool, error) {
 	if p == nil || p.compiled == nil {
 		return nil, true, nil // 空表达式 → NULL（调用方按未定义符号恒真处理）
 	}
-	base := make(map[string]any, len(p.phs)+len(p.bareFields))
+	base := baseMapPool.Get().(map[string]any)
+	for k := range base {
+		delete(base, k)
+	}
 	for i, d := range p.phs {
 		base[placeholderKey(i)] = evalDesc(d, ctx)
 	}
@@ -255,7 +265,9 @@ func evalPrepared(p *preparedExpr, ctx *matchCtx) (any, bool, error) {
 			}
 		}
 	}
-	return p.compiled.EvaluateValueWithNull(base)
+	v, isNull, err := p.compiled.EvaluateValueWithNull(base)
+	baseMapPool.Put(base)
+	return v, isNull, err
 }
 
 // evalDesc 求值一个占位符描述。