解决内存占用异常高的问题

backend/internal/storage/storage.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log"
 	"math/rand"
+	"strconv"
 	"strings"
 	"time"
 
@@ -251,8 +252,8 @@ func (s *Storage) WriteLogMetric(ctx context.Context, deviceID string, sequence
 	return s.writeData(ctx, "logs", allTags, fields, deviceID, "log")
 }
 
-// QueryMetrics 查询监控指标
-func (s *Storage) QueryMetrics(ctx context.Context, deviceID, metricType, startTime, endTime string) ([]MetricPoint, error) {
+// QueryMetrics 查询监控指标，支持采样
+func (s *Storage) QueryMetrics(ctx context.Context, deviceID, metricType, startTime, endTime string, limit ...int) ([]MetricPoint, error) {
 	queryAPI := s.client.QueryAPI(s.org)
 
 	// 处理时间参数
@@ -324,6 +325,15 @@ func (s *Storage) QueryMetrics(ctx context.Context, deviceID, metricType, startT
 |> filter(fn: (r) => r["type"] == "` + metricType + `")
 |> sort(columns: ["_time"])`
 
+	// 设置默认限制
+	maxLimit := 10000
+	if len(limit) > 0 && limit[0] > 0 {
+		maxLimit = limit[0]
+	}
+
+	query += `
+|> limit(n: ` + strconv.Itoa(maxLimit) + `)` // 限制返回的数据点数量，防止内存溢出
+
 	// 执行查询
 	result, err := queryAPI.Query(ctx, query)
 	if err != nil {
@@ -591,11 +601,11 @@ func (s *Storage) QueryLogMetrics(ctx context.Context, deviceID string, startTim
 
 		// 构建日志数据
 		logData := map[string]interface{}{
-			"time":    record.Time(),
-			"device_id": record.ValueByKey("device_id"),
-			"source":  record.ValueByKey("source"),
-			"sequence": record.ValueByKey("sequence"),
-			"message": record.ValueByKey("message"),
+			"time":       record.Time(),
+			"device_id":  record.ValueByKey("device_id"),
+			"source":     record.ValueByKey("source"),
+			"sequence":   record.ValueByKey("sequence"),
+			"message":    record.ValueByKey("message"),
 			"agent_name": record.ValueByKey("agent_name"),
 		}