新增PDF生成并发设置

backend/app/api/routes/public.py

@@ -8,9 +8,10 @@ from app.db.session import get_db
 from app.models import Certificate, CertificateAccessToken, Learner, ProjectCourse
 from app.services.captcha import make_captcha, verify_captcha
 from app.services.logs import log_action, mask_phone
-from app.services.pdf import render_certificate_pdf
+from app.services.pdf import PdfGenerationBusy, render_certificate_pdf
 from app.services.rate_limit import hit_too_often
 from app.services.sms import generate_sms_code, verify_sms_code
+from app.services.system_settings import get_pdf_generation_concurrency_limit
 
 router = APIRouter()
 
@@ -150,7 +151,16 @@ def download_certificate_pdf(token: str, db: Session = Depends(get_db)) -> FileR
         raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="证书已作废，不支持下载正常 PDF")
 
     project = db.query(ProjectCourse).filter(ProjectCourse.code == certificate.project_code).first()
-    pdf_path = render_certificate_pdf(certificate, learner, project, access_token)
+    try:
+        pdf_path = render_certificate_pdf(
+            certificate,
+            learner,
+            project,
+            access_token,
+            concurrency_limit=get_pdf_generation_concurrency_limit(db),
+        )
+    except PdfGenerationBusy as exc:
+        raise HTTPException(status_code=status.HTTP_429_TOO_MANY_REQUESTS, detail=str(exc)) from exc
     log_action(db, None, "public_download_certificate", "certificate", certificate.id, {"certificate_no": certificate.certificate_no, "learner_name": learner.current_name, "project_code": certificate.project_code})
     db.commit()
     return FileResponse(pdf_path, media_type="application/pdf", filename=f"{certificate.certificate_no}.pdf")