feat: persist loadgen reports

README.md

@@ -264,6 +264,8 @@ go run ./cmd/proxy-loadgen `
 凭据，也不构成 100,000 QPS 证明。限速场景以 `Requests` 表示实际发起数；当
 `RateStartsDropped` 非零时，目标速率受压测端并发容量或时间窗限制，报告吞吐不得
 标注为已达到配置的 `-rate`。
+需要保留单次容量证据时，使用 `-output REPORT_FILE` 同时写出 JSON 文件；文件在
+同目录完整写入后才替换目标，标准输出仍保留相同报告，便于交给日志或指标系统。
 
 ## 关键配置与入口
 

cmd/proxy-loadgen/main.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"path/filepath"
 	"strings"
 	"syscall"
 	"time"
@@ -41,6 +42,7 @@ func execute(ctx context.Context, args []string, run loadRun, stdout, stderr io.
 	hold := flags.Duration("hold", 0, "CONNECT tunnel hold duration; required by -scenario connect")
 	extractCount := flags.Int("extract-count", 1, "proxies requested by each extract scenario request")
 	extractFulfillment := flags.String("extract-fulfillment", "partial", "extract fulfillment: partial or allOrNothing")
+	outputPath := flags.String("output", "", "optional JSON report file; replaces only after a complete write")
 	var headers headerValues
 	flags.Var(&headers, "header", "repeatable HTTP header in Name: Value form")
 	if err := flags.Parse(args); err != nil {
@@ -53,6 +55,10 @@ func execute(ctx context.Context, args []string, run loadRun, stdout, stderr io.
 		_, _ = fmt.Fprintln(stderr, "proxy-loadgen: target and a bounded workload are required")
 		return 2
 	}
+	if strings.TrimSpace(*outputPath) != *outputPath {
+		_, _ = fmt.Fprintln(stderr, "proxy-loadgen: invalid output path")
+		return 2
+	}
 	parsedHeaders, err := headers.Header()
 	if err != nil {
 		_, _ = fmt.Fprintf(stderr, "proxy-loadgen: %v\n", err)
@@ -72,6 +78,10 @@ func execute(ctx context.Context, args []string, run loadRun, stdout, stderr io.
 		_, _ = fmt.Fprintf(stderr, "proxy-loadgen: %v\n", err)
 		return 1
 	}
+	if err := writeReportFile(*outputPath, report); err != nil {
+		_, _ = fmt.Fprintf(stderr, "proxy-loadgen: write report: %v\n", err)
+		return 1
+	}
 	if err := json.NewEncoder(stdout).Encode(report); err != nil {
 		_, _ = fmt.Fprintf(stderr, "proxy-loadgen: encode report: %v\n", err)
 		return 1
@@ -79,6 +89,44 @@ func execute(ctx context.Context, args []string, run loadRun, stdout, stderr io.
 	return 0
 }
 
+func writeReportFile(path string, report loadgen.Report) error {
+	if path == "" {
+		return nil
+	}
+	content, err := json.Marshal(report)
+	if err != nil {
+		return err
+	}
+	content = append(content, '\n')
+	directory := filepath.Dir(path)
+	temporary, err := os.CreateTemp(directory, "."+filepath.Base(path)+".tmp-*")
+	if err != nil {
+		return err
+	}
+	temporaryPath := temporary.Name()
+	defer os.Remove(temporaryPath)
+	if err := temporary.Chmod(0o600); err != nil {
+		_ = temporary.Close()
+		return err
+	}
+	if _, err := temporary.Write(content); err != nil {
+		_ = temporary.Close()
+		return err
+	}
+	if err := temporary.Close(); err != nil {
+		return err
+	}
+	// Prefer same-directory rename so a completed report replaces the old one
+	// atomically on platforms that support replacement.
+	if err := os.Rename(temporaryPath, path); err == nil {
+		return nil
+	}
+	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	return os.Rename(temporaryPath, path)
+}
+
 type headerValues []string
 
 func (values *headerValues) String() string {

cmd/proxy-loadgen/main_test.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"os"
+	"path/filepath"
 	"testing"
 	"time"
 
@@ -74,3 +76,29 @@ func TestExecutePassesExtractScenario(t *testing.T) {
 		t.Fatalf("execute() = %d; options=%+v stderr=%q", code, received, stderr.String())
 	}
 }
+
+func TestExecuteWritesReportFile(t *testing.T) {
+	t.Parallel()
+
+	path := filepath.Join(t.TempDir(), "load-report.json")
+	if err := os.WriteFile(path, []byte("incomplete"), 0o600); err != nil {
+		t.Fatalf("WriteFile(): %v", err)
+	}
+	var stdout, stderr bytes.Buffer
+	code := execute(context.Background(), []string{
+		"-target", "https://target.example/health", "-requests", "1", "-concurrency", "1", "-output", path,
+	}, func(_ context.Context, _ loadgen.Options) (loadgen.Report, error) {
+		return loadgen.Report{Requests: 1, Completed: 1, Succeeded: 1, Duration: time.Second}, nil
+	}, &stdout, &stderr)
+	if code != 0 || stderr.Len() != 0 {
+		t.Fatalf("execute() = %d, stderr=%q", code, stderr.String())
+	}
+	content, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("ReadFile(): %v", err)
+	}
+	var report loadgen.Report
+	if err := json.Unmarshal(content, &report); err != nil || report.Succeeded != 1 || string(content) == "incomplete" {
+		t.Fatalf("report file = (%q, %+v, %v)", content, report, err)
+	}
+}